Source file src/go/types/api_test.go

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package types_test
     6  
     7  import (
     8  	"bytes"
     9  	"errors"
    10  	"fmt"
    11  	"go/ast"
    12  	"go/importer"
    13  	"go/internal/typeparams"
    14  	"go/parser"
    15  	"go/token"
    16  	"internal/testenv"
    17  	"reflect"
    18  	"regexp"
    19  	"sort"
    20  	"strings"
    21  	"testing"
    22  
    23  	. "go/types"
    24  )
    25  
    26  // pkgFor parses and type checks the package specified by path and source,
    27  // populating info if provided.
    28  //
    29  // If source begins with "package generic_" and type parameters are enabled,
    30  // generic code is permitted.
    31  func pkgFor(path, source string, info *Info) (*Package, error) {
    32  	mode := modeForSource(source)
    33  	return pkgForMode(path, source, info, mode)
    34  }
    35  
    36  func pkgForMode(path, source string, info *Info, mode parser.Mode) (*Package, error) {
    37  	fset := token.NewFileSet()
    38  	f, err := parser.ParseFile(fset, path, source, mode)
    39  	if err != nil {
    40  		return nil, err
    41  	}
    42  	conf := Config{Importer: importer.Default()}
    43  	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
    44  }
    45  
    46  func mustTypecheck(t *testing.T, path, source string, info *Info) string {
    47  	pkg, err := pkgFor(path, source, info)
    48  	if err != nil {
    49  		name := path
    50  		if pkg != nil {
    51  			name = "package " + pkg.Name()
    52  		}
    53  		t.Fatalf("%s: didn't type-check (%s)", name, err)
    54  	}
    55  	return pkg.Name()
    56  }
    57  
    58  // genericPkg is a prefix for packages that should be type checked with
    59  // generics.
    60  const genericPkg = "package generic_"
    61  
    62  func modeForSource(src string) parser.Mode {
    63  	if !strings.HasPrefix(src, genericPkg) {
    64  		return typeparams.DisallowParsing
    65  	}
    66  	return 0
    67  }
    68  
    69  func mayTypecheck(t *testing.T, path, source string, info *Info) (string, error) {
    70  	fset := token.NewFileSet()
    71  	mode := modeForSource(source)
    72  	f, err := parser.ParseFile(fset, path, source, mode)
    73  	if f == nil { // ignore errors unless f is nil
    74  		t.Fatalf("%s: unable to parse: %s", path, err)
    75  	}
    76  	conf := Config{
    77  		Error:    func(err error) {},
    78  		Importer: importer.Default(),
    79  	}
    80  	pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
    81  	return pkg.Name(), err
    82  }
    83  
    84  func TestValuesInfo(t *testing.T) {
    85  	var tests = []struct {
    86  		src  string
    87  		expr string // constant expression
    88  		typ  string // constant type
    89  		val  string // constant value
    90  	}{
    91  		{`package a0; const _ = false`, `false`, `untyped bool`, `false`},
    92  		{`package a1; const _ = 0`, `0`, `untyped int`, `0`},
    93  		{`package a2; const _ = 'A'`, `'A'`, `untyped rune`, `65`},
    94  		{`package a3; const _ = 0.`, `0.`, `untyped float`, `0`},
    95  		{`package a4; const _ = 0i`, `0i`, `untyped complex`, `(0 + 0i)`},
    96  		{`package a5; const _ = "foo"`, `"foo"`, `untyped string`, `"foo"`},
    97  
    98  		{`package b0; var _ = false`, `false`, `bool`, `false`},
    99  		{`package b1; var _ = 0`, `0`, `int`, `0`},
   100  		{`package b2; var _ = 'A'`, `'A'`, `rune`, `65`},
   101  		{`package b3; var _ = 0.`, `0.`, `float64`, `0`},
   102  		{`package b4; var _ = 0i`, `0i`, `complex128`, `(0 + 0i)`},
   103  		{`package b5; var _ = "foo"`, `"foo"`, `string`, `"foo"`},
   104  
   105  		{`package c0a; var _ = bool(false)`, `false`, `bool`, `false`},
   106  		{`package c0b; var _ = bool(false)`, `bool(false)`, `bool`, `false`},
   107  		{`package c0c; type T bool; var _ = T(false)`, `T(false)`, `c0c.T`, `false`},
   108  
   109  		{`package c1a; var _ = int(0)`, `0`, `int`, `0`},
   110  		{`package c1b; var _ = int(0)`, `int(0)`, `int`, `0`},
   111  		{`package c1c; type T int; var _ = T(0)`, `T(0)`, `c1c.T`, `0`},
   112  
   113  		{`package c2a; var _ = rune('A')`, `'A'`, `rune`, `65`},
   114  		{`package c2b; var _ = rune('A')`, `rune('A')`, `rune`, `65`},
   115  		{`package c2c; type T rune; var _ = T('A')`, `T('A')`, `c2c.T`, `65`},
   116  
   117  		{`package c3a; var _ = float32(0.)`, `0.`, `float32`, `0`},
   118  		{`package c3b; var _ = float32(0.)`, `float32(0.)`, `float32`, `0`},
   119  		{`package c3c; type T float32; var _ = T(0.)`, `T(0.)`, `c3c.T`, `0`},
   120  
   121  		{`package c4a; var _ = complex64(0i)`, `0i`, `complex64`, `(0 + 0i)`},
   122  		{`package c4b; var _ = complex64(0i)`, `complex64(0i)`, `complex64`, `(0 + 0i)`},
   123  		{`package c4c; type T complex64; var _ = T(0i)`, `T(0i)`, `c4c.T`, `(0 + 0i)`},
   124  
   125  		{`package c5a; var _ = string("foo")`, `"foo"`, `string`, `"foo"`},
   126  		{`package c5b; var _ = string("foo")`, `string("foo")`, `string`, `"foo"`},
   127  		{`package c5c; type T string; var _ = T("foo")`, `T("foo")`, `c5c.T`, `"foo"`},
   128  		{`package c5d; var _ = string(65)`, `65`, `untyped int`, `65`},
   129  		{`package c5e; var _ = string('A')`, `'A'`, `untyped rune`, `65`},
   130  		{`package c5f; type T string; var _ = T('A')`, `'A'`, `untyped rune`, `65`},
   131  
   132  		{`package d0; var _ = []byte("foo")`, `"foo"`, `string`, `"foo"`},
   133  		{`package d1; var _ = []byte(string("foo"))`, `"foo"`, `string`, `"foo"`},
   134  		{`package d2; var _ = []byte(string("foo"))`, `string("foo")`, `string`, `"foo"`},
   135  		{`package d3; type T []byte; var _ = T("foo")`, `"foo"`, `string`, `"foo"`},
   136  
   137  		{`package e0; const _ = float32( 1e-200)`, `float32(1e-200)`, `float32`, `0`},
   138  		{`package e1; const _ = float32(-1e-200)`, `float32(-1e-200)`, `float32`, `0`},
   139  		{`package e2; const _ = float64( 1e-2000)`, `float64(1e-2000)`, `float64`, `0`},
   140  		{`package e3; const _ = float64(-1e-2000)`, `float64(-1e-2000)`, `float64`, `0`},
   141  		{`package e4; const _ = complex64( 1e-200)`, `complex64(1e-200)`, `complex64`, `(0 + 0i)`},
   142  		{`package e5; const _ = complex64(-1e-200)`, `complex64(-1e-200)`, `complex64`, `(0 + 0i)`},
   143  		{`package e6; const _ = complex128( 1e-2000)`, `complex128(1e-2000)`, `complex128`, `(0 + 0i)`},
   144  		{`package e7; const _ = complex128(-1e-2000)`, `complex128(-1e-2000)`, `complex128`, `(0 + 0i)`},
   145  
   146  		{`package f0 ; var _ float32 =  1e-200`, `1e-200`, `float32`, `0`},
   147  		{`package f1 ; var _ float32 = -1e-200`, `-1e-200`, `float32`, `0`},
   148  		{`package f2a; var _ float64 =  1e-2000`, `1e-2000`, `float64`, `0`},
   149  		{`package f3a; var _ float64 = -1e-2000`, `-1e-2000`, `float64`, `0`},
   150  		{`package f2b; var _         =  1e-2000`, `1e-2000`, `float64`, `0`},
   151  		{`package f3b; var _         = -1e-2000`, `-1e-2000`, `float64`, `0`},
   152  		{`package f4 ; var _ complex64  =  1e-200 `, `1e-200`, `complex64`, `(0 + 0i)`},
   153  		{`package f5 ; var _ complex64  = -1e-200 `, `-1e-200`, `complex64`, `(0 + 0i)`},
   154  		{`package f6a; var _ complex128 =  1e-2000i`, `1e-2000i`, `complex128`, `(0 + 0i)`},
   155  		{`package f7a; var _ complex128 = -1e-2000i`, `-1e-2000i`, `complex128`, `(0 + 0i)`},
   156  		{`package f6b; var _            =  1e-2000i`, `1e-2000i`, `complex128`, `(0 + 0i)`},
   157  		{`package f7b; var _            = -1e-2000i`, `-1e-2000i`, `complex128`, `(0 + 0i)`},
   158  
   159  		{`package g0; const (a = len([iota]int{}); b; c); const _ = c`, `c`, `int`, `2`}, // issue #22341
   160  		{`package g1; var(j int32; s int; n = 1.0<<s == j)`, `1.0`, `int32`, `1`},        // issue #48422
   161  	}
   162  
   163  	for _, test := range tests {
   164  		info := Info{
   165  			Types: make(map[ast.Expr]TypeAndValue),
   166  		}
   167  		name := mustTypecheck(t, "ValuesInfo", test.src, &info)
   168  
   169  		// look for expression
   170  		var expr ast.Expr
   171  		for e := range info.Types {
   172  			if ExprString(e) == test.expr {
   173  				expr = e
   174  				break
   175  			}
   176  		}
   177  		if expr == nil {
   178  			t.Errorf("package %s: no expression found for %s", name, test.expr)
   179  			continue
   180  		}
   181  		tv := info.Types[expr]
   182  
   183  		// check that type is correct
   184  		if got := tv.Type.String(); got != test.typ {
   185  			t.Errorf("package %s: got type %s; want %s", name, got, test.typ)
   186  			continue
   187  		}
   188  
   189  		// if we have a constant, check that value is correct
   190  		if tv.Value != nil {
   191  			if got := tv.Value.ExactString(); got != test.val {
   192  				t.Errorf("package %s: got value %s; want %s", name, got, test.val)
   193  			}
   194  		} else {
   195  			if test.val != "" {
   196  				t.Errorf("package %s: no constant found; want %s", name, test.val)
   197  			}
   198  		}
   199  	}
   200  }
   201  
   202  func TestTypesInfo(t *testing.T) {
   203  	// Test sources that are not expected to typecheck must start with the broken prefix.
   204  	const broken = "package broken_"
   205  
   206  	var tests = []struct {
   207  		src  string
   208  		expr string // expression
   209  		typ  string // value type
   210  	}{
   211  		// single-valued expressions of untyped constants
   212  		{`package b0; var x interface{} = false`, `false`, `bool`},
   213  		{`package b1; var x interface{} = 0`, `0`, `int`},
   214  		{`package b2; var x interface{} = 0.`, `0.`, `float64`},
   215  		{`package b3; var x interface{} = 0i`, `0i`, `complex128`},
   216  		{`package b4; var x interface{} = "foo"`, `"foo"`, `string`},
   217  
   218  		// uses of nil
   219  		{`package n0; var _ *int = nil`, `nil`, `untyped nil`},
   220  		{`package n1; var _ func() = nil`, `nil`, `untyped nil`},
   221  		{`package n2; var _ []byte = nil`, `nil`, `untyped nil`},
   222  		{`package n3; var _ map[int]int = nil`, `nil`, `untyped nil`},
   223  		{`package n4; var _ chan int = nil`, `nil`, `untyped nil`},
   224  		{`package n5; var _ interface{} = nil`, `nil`, `untyped nil`},
   225  		{`package n6; import "unsafe"; var _ unsafe.Pointer = nil`, `nil`, `untyped nil`},
   226  
   227  		{`package n10; var (x *int; _ = x == nil)`, `nil`, `untyped nil`},
   228  		{`package n11; var (x func(); _ = x == nil)`, `nil`, `untyped nil`},
   229  		{`package n12; var (x []byte; _ = x == nil)`, `nil`, `untyped nil`},
   230  		{`package n13; var (x map[int]int; _ = x == nil)`, `nil`, `untyped nil`},
   231  		{`package n14; var (x chan int; _ = x == nil)`, `nil`, `untyped nil`},
   232  		{`package n15; var (x interface{}; _ = x == nil)`, `nil`, `untyped nil`},
   233  		{`package n15; import "unsafe"; var (x unsafe.Pointer; _ = x == nil)`, `nil`, `untyped nil`},
   234  
   235  		{`package n20; var _ = (*int)(nil)`, `nil`, `untyped nil`},
   236  		{`package n21; var _ = (func())(nil)`, `nil`, `untyped nil`},
   237  		{`package n22; var _ = ([]byte)(nil)`, `nil`, `untyped nil`},
   238  		{`package n23; var _ = (map[int]int)(nil)`, `nil`, `untyped nil`},
   239  		{`package n24; var _ = (chan int)(nil)`, `nil`, `untyped nil`},
   240  		{`package n25; var _ = (interface{})(nil)`, `nil`, `untyped nil`},
   241  		{`package n26; import "unsafe"; var _ = unsafe.Pointer(nil)`, `nil`, `untyped nil`},
   242  
   243  		{`package n30; func f(*int) { f(nil) }`, `nil`, `untyped nil`},
   244  		{`package n31; func f(func()) { f(nil) }`, `nil`, `untyped nil`},
   245  		{`package n32; func f([]byte) { f(nil) }`, `nil`, `untyped nil`},
   246  		{`package n33; func f(map[int]int) { f(nil) }`, `nil`, `untyped nil`},
   247  		{`package n34; func f(chan int) { f(nil) }`, `nil`, `untyped nil`},
   248  		{`package n35; func f(interface{}) { f(nil) }`, `nil`, `untyped nil`},
   249  		{`package n35; import "unsafe"; func f(unsafe.Pointer) { f(nil) }`, `nil`, `untyped nil`},
   250  
   251  		// comma-ok expressions
   252  		{`package p0; var x interface{}; var _, _ = x.(int)`,
   253  			`x.(int)`,
   254  			`(int, bool)`,
   255  		},
   256  		{`package p1; var x interface{}; func _() { _, _ = x.(int) }`,
   257  			`x.(int)`,
   258  			`(int, bool)`,
   259  		},
   260  		{`package p2a; type mybool bool; var m map[string]complex128; var b mybool; func _() { _, b = m["foo"] }`,
   261  			`m["foo"]`,
   262  			`(complex128, p2a.mybool)`,
   263  		},
   264  		{`package p2b; var m map[string]complex128; var b bool; func _() { _, b = m["foo"] }`,
   265  			`m["foo"]`,
   266  			`(complex128, bool)`,
   267  		},
   268  		{`package p3; var c chan string; var _, _ = <-c`,
   269  			`<-c`,
   270  			`(string, bool)`,
   271  		},
   272  
   273  		// issue 6796
   274  		{`package issue6796_a; var x interface{}; var _, _ = (x.(int))`,
   275  			`x.(int)`,
   276  			`(int, bool)`,
   277  		},
   278  		{`package issue6796_b; var c chan string; var _, _ = (<-c)`,
   279  			`(<-c)`,
   280  			`(string, bool)`,
   281  		},
   282  		{`package issue6796_c; var c chan string; var _, _ = (<-c)`,
   283  			`<-c`,
   284  			`(string, bool)`,
   285  		},
   286  		{`package issue6796_d; var c chan string; var _, _ = ((<-c))`,
   287  			`(<-c)`,
   288  			`(string, bool)`,
   289  		},
   290  		{`package issue6796_e; func f(c chan string) { _, _ = ((<-c)) }`,
   291  			`(<-c)`,
   292  			`(string, bool)`,
   293  		},
   294  
   295  		// issue 7060
   296  		{`package issue7060_a; var ( m map[int]string; x, ok = m[0] )`,
   297  			`m[0]`,
   298  			`(string, bool)`,
   299  		},
   300  		{`package issue7060_b; var ( m map[int]string; x, ok interface{} = m[0] )`,
   301  			`m[0]`,
   302  			`(string, bool)`,
   303  		},
   304  		{`package issue7060_c; func f(x interface{}, ok bool, m map[int]string) { x, ok = m[0] }`,
   305  			`m[0]`,
   306  			`(string, bool)`,
   307  		},
   308  		{`package issue7060_d; var ( ch chan string; x, ok = <-ch )`,
   309  			`<-ch`,
   310  			`(string, bool)`,
   311  		},
   312  		{`package issue7060_e; var ( ch chan string; x, ok interface{} = <-ch )`,
   313  			`<-ch`,
   314  			`(string, bool)`,
   315  		},
   316  		{`package issue7060_f; func f(x interface{}, ok bool, ch chan string) { x, ok = <-ch }`,
   317  			`<-ch`,
   318  			`(string, bool)`,
   319  		},
   320  
   321  		// issue 28277
   322  		{`package issue28277_a; func f(...int)`,
   323  			`...int`,
   324  			`[]int`,
   325  		},
   326  		{`package issue28277_b; func f(a, b int, c ...[]struct{})`,
   327  			`...[]struct{}`,
   328  			`[][]struct{}`,
   329  		},
   330  
   331  		// issue 47243
   332  		{`package issue47243_a; var x int32; var _ = x << 3`, `3`, `untyped int`},
   333  		{`package issue47243_b; var x int32; var _ = x << 3.`, `3.`, `untyped float`},
   334  		{`package issue47243_c; var x int32; var _ = 1 << x`, `1 << x`, `int`},
   335  		{`package issue47243_d; var x int32; var _ = 1 << x`, `1`, `int`},
   336  		{`package issue47243_e; var x int32; var _ = 1 << 2`, `1`, `untyped int`},
   337  		{`package issue47243_f; var x int32; var _ = 1 << 2`, `2`, `untyped int`},
   338  		{`package issue47243_g; var x int32; var _ = int(1) << 2`, `2`, `untyped int`},
   339  		{`package issue47243_h; var x int32; var _ = 1 << (2 << x)`, `1`, `int`},
   340  		{`package issue47243_i; var x int32; var _ = 1 << (2 << x)`, `(2 << x)`, `untyped int`},
   341  		{`package issue47243_j; var x int32; var _ = 1 << (2 << x)`, `2`, `untyped int`},
   342  
   343  		// tests for broken code that doesn't parse or type-check
   344  		{broken + `x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
   345  		{broken + `x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},
   346  		{broken + `x2; func _() { var a, b string; type x struct {f string}; z := &x{f: a; f: b;}}`, `b`, `string`},
   347  		{broken + `x3; var x = panic("");`, `panic`, `func(interface{})`},
   348  		{`package x4; func _() { panic("") }`, `panic`, `func(interface{})`},
   349  		{broken + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string]invalid type`},
   350  
   351  		// parameterized functions
   352  		{genericPkg + `p0; func f[T any](T) {}; var _ = f[int]`, `f`, `func[T any](T)`},
   353  		{genericPkg + `p1; func f[T any](T) {}; var _ = f[int]`, `f[int]`, `func(int)`},
   354  		{genericPkg + `p2; func f[T any](T) {}; func _() { f(42) }`, `f`, `func(int)`},
   355  		{genericPkg + `p3; func f[T any](T) {}; func _() { f[int](42) }`, `f[int]`, `func(int)`},
   356  		{genericPkg + `p4; func f[T any](T) {}; func _() { f[int](42) }`, `f`, `func[T any](T)`},
   357  		{genericPkg + `p5; func f[T any](T) {}; func _() { f(42) }`, `f(42)`, `()`},
   358  
   359  		// type parameters
   360  		{genericPkg + `t0; type t[] int; var _ t`, `t`, `generic_t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
   361  		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[P any]`},
   362  		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[P interface{}]`},
   363  		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[P, Q interface{}]`},
   364  
   365  		// TODO (rFindley): compare with types2, which resolves the type broken_t4.t[P₁, Q₂ interface{m()}] here
   366  		{broken + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t`},
   367  
   368  		// instantiated types must be sanitized
   369  		{genericPkg + `g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `generic_g0.t[int]`},
   370  
   371  		// issue 45096
   372  		{genericPkg + `issue45096; func _[T interface{ ~int8 | ~int16 | ~int32  }](x T) { _ = x < 0 }`, `0`, `T`},
   373  
   374  		// issue 47895
   375  		{`package p; import "unsafe"; type S struct { f int }; var s S; var _ = unsafe.Offsetof(s.f)`, `s.f`, `int`},
   376  
   377  		// issue 50093
   378  		{genericPkg + `u0a; func _[_ interface{int}]() {}`, `int`, `int`},
   379  		{genericPkg + `u1a; func _[_ interface{~int}]() {}`, `~int`, `~int`},
   380  		{genericPkg + `u2a; func _[_ interface{int|string}]() {}`, `int | string`, `int|string`},
   381  		{genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string | ~bool`, `int|string|~bool`},
   382  		{genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string`, `int|string`},
   383  		{genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `~bool`, `~bool`},
   384  		{genericPkg + `u3a; func _[_ interface{int|string|~float64|~bool}]() {}`, `int | string | ~float64`, `int|string|~float64`},
   385  
   386  		{genericPkg + `u0b; func _[_ int]() {}`, `int`, `int`},
   387  		{genericPkg + `u1b; func _[_ ~int]() {}`, `~int`, `~int`},
   388  		{genericPkg + `u2b; func _[_ int|string]() {}`, `int | string`, `int|string`},
   389  		{genericPkg + `u3b; func _[_ int|string|~bool]() {}`, `int | string | ~bool`, `int|string|~bool`},
   390  		{genericPkg + `u3b; func _[_ int|string|~bool]() {}`, `int | string`, `int|string`},
   391  		{genericPkg + `u3b; func _[_ int|string|~bool]() {}`, `~bool`, `~bool`},
   392  		{genericPkg + `u3b; func _[_ int|string|~float64|~bool]() {}`, `int | string | ~float64`, `int|string|~float64`},
   393  
   394  		{genericPkg + `u0c; type _ interface{int}`, `int`, `int`},
   395  		{genericPkg + `u1c; type _ interface{~int}`, `~int`, `~int`},
   396  		{genericPkg + `u2c; type _ interface{int|string}`, `int | string`, `int|string`},
   397  		{genericPkg + `u3c; type _ interface{int|string|~bool}`, `int | string | ~bool`, `int|string|~bool`},
   398  		{genericPkg + `u3c; type _ interface{int|string|~bool}`, `int | string`, `int|string`},
   399  		{genericPkg + `u3c; type _ interface{int|string|~bool}`, `~bool`, `~bool`},
   400  		{genericPkg + `u3c; type _ interface{int|string|~float64|~bool}`, `int | string | ~float64`, `int|string|~float64`},
   401  	}
   402  
   403  	for _, test := range tests {
   404  		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
   405  		var name string
   406  		if strings.HasPrefix(test.src, broken) {
   407  			var err error
   408  			name, err = mayTypecheck(t, "TypesInfo", test.src, &info)
   409  			if err == nil {
   410  				t.Errorf("package %s: expected to fail but passed", name)
   411  				continue
   412  			}
   413  		} else {
   414  			name = mustTypecheck(t, "TypesInfo", test.src, &info)
   415  		}
   416  
   417  		// look for expression type
   418  		var typ Type
   419  		for e, tv := range info.Types {
   420  			if ExprString(e) == test.expr {
   421  				typ = tv.Type
   422  				break
   423  			}
   424  		}
   425  		if typ == nil {
   426  			t.Errorf("package %s: no type found for %s", name, test.expr)
   427  			continue
   428  		}
   429  
   430  		// check that type is correct
   431  		if got := typ.String(); got != test.typ {
   432  			t.Errorf("package %s: got %s; want %s", name, got, test.typ)
   433  		}
   434  	}
   435  }
   436  
   437  func TestInstanceInfo(t *testing.T) {
   438  	const lib = `package lib
   439  
   440  func F[P any](P) {}
   441  
   442  type T[P any] []P
   443  `
   444  
   445  	type testInst struct {
   446  		name  string
   447  		targs []string
   448  		typ   string
   449  	}
   450  
   451  	var tests = []struct {
   452  		src       string
   453  		instances []testInst // recorded instances in source order
   454  	}{
   455  		{`package p0; func f[T any](T) {}; func _() { f(42) }`,
   456  			[]testInst{{`f`, []string{`int`}, `func(int)`}},
   457  		},
   458  		{`package p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
   459  			[]testInst{{`f`, []string{`rune`}, `func(rune) rune`}},
   460  		},
   461  		{`package p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
   462  			[]testInst{{`f`, []string{`complex128`}, `func(...complex128) complex128`}},
   463  		},
   464  		{`package p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
   465  			[]testInst{{`f`, []string{`float64`, `string`, `byte`}, `func(float64, *string, []byte)`}},
   466  		},
   467  		{`package p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
   468  			[]testInst{{`f`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
   469  		},
   470  
   471  		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
   472  			[]testInst{{`f`, []string{`string`, `*string`}, `func(x string)`}},
   473  		},
   474  		{`package s2; func f[T any, P interface{*T}](x []T) {}; func _(x []int) { f(x) }`,
   475  			[]testInst{{`f`, []string{`int`, `*int`}, `func(x []int)`}},
   476  		},
   477  		{`package s3; type C[T any] interface{chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
   478  			[]testInst{
   479  				{`C`, []string{`T`}, `interface{chan<- T}`},
   480  				{`f`, []string{`int`, `chan<- int`}, `func(x []int)`},
   481  			},
   482  		},
   483  		{`package s4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
   484  			[]testInst{
   485  				{`C`, []string{`T`}, `interface{chan<- T}`},
   486  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   487  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func(x []int)`},
   488  			},
   489  		},
   490  
   491  		{`package t1; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = f[string] }`,
   492  			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
   493  		},
   494  		{`package t2; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
   495  			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
   496  		},
   497  		{`package t3; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
   498  			[]testInst{
   499  				{`C`, []string{`T`}, `interface{chan<- T}`},
   500  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   501  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
   502  			},
   503  		},
   504  		{`package t4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = (f[int]) }`,
   505  			[]testInst{
   506  				{`C`, []string{`T`}, `interface{chan<- T}`},
   507  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   508  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
   509  			},
   510  		},
   511  		{`package i0; import "lib"; func _() { lib.F(42) }`,
   512  			[]testInst{{`F`, []string{`int`}, `func(int)`}},
   513  		},
   514  
   515  		{`package duplfunc0; func f[T any](T) {}; func _() { f(42); f("foo"); f[int](3) }`,
   516  			[]testInst{
   517  				{`f`, []string{`int`}, `func(int)`},
   518  				{`f`, []string{`string`}, `func(string)`},
   519  				{`f`, []string{`int`}, `func(int)`},
   520  			},
   521  		},
   522  		{`package duplfunc1; import "lib"; func _() { lib.F(42); lib.F("foo"); lib.F(3) }`,
   523  			[]testInst{
   524  				{`F`, []string{`int`}, `func(int)`},
   525  				{`F`, []string{`string`}, `func(string)`},
   526  				{`F`, []string{`int`}, `func(int)`},
   527  			},
   528  		},
   529  
   530  		{`package type0; type T[P interface{~int}] struct{ x P }; var _ T[int]`,
   531  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   532  		},
   533  		{`package type1; type T[P interface{~int}] struct{ x P }; var _ (T[int])`,
   534  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   535  		},
   536  		{`package type2; type T[P interface{~int}] struct{ x P }; var _ T[(int)]`,
   537  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   538  		},
   539  		{`package type3; type T[P1 interface{~[]P2}, P2 any] struct{ x P1; y P2 }; var _ T[[]int, int]`,
   540  			[]testInst{{`T`, []string{`[]int`, `int`}, `struct{x []int; y int}`}},
   541  		},
   542  		{`package type4; import "lib"; var _ lib.T[int]`,
   543  			[]testInst{{`T`, []string{`int`}, `[]int`}},
   544  		},
   545  
   546  		{`package dupltype0; type T[P interface{~int}] struct{ x P }; var x T[int]; var y T[int]`,
   547  			[]testInst{
   548  				{`T`, []string{`int`}, `struct{x int}`},
   549  				{`T`, []string{`int`}, `struct{x int}`},
   550  			},
   551  		},
   552  		{`package dupltype1; type T[P ~int] struct{ x P }; func (r *T[Q]) add(z T[Q]) { r.x += z.x }`,
   553  			[]testInst{
   554  				{`T`, []string{`Q`}, `struct{x Q}`},
   555  				{`T`, []string{`Q`}, `struct{x Q}`},
   556  			},
   557  		},
   558  		{`package dupltype1; import "lib"; var x lib.T[int]; var y lib.T[int]; var z lib.T[string]`,
   559  			[]testInst{
   560  				{`T`, []string{`int`}, `[]int`},
   561  				{`T`, []string{`int`}, `[]int`},
   562  				{`T`, []string{`string`}, `[]string`},
   563  			},
   564  		},
   565  	}
   566  
   567  	for _, test := range tests {
   568  		imports := make(testImporter)
   569  		conf := Config{Importer: imports}
   570  		instMap := make(map[*ast.Ident]Instance)
   571  		useMap := make(map[*ast.Ident]Object)
   572  		makePkg := func(src string) *Package {
   573  			f, err := parser.ParseFile(fset, "p.go", src, 0)
   574  			if err != nil {
   575  				t.Fatal(err)
   576  			}
   577  			pkg, err := conf.Check("", fset, []*ast.File{f}, &Info{Instances: instMap, Uses: useMap})
   578  			if err != nil {
   579  				t.Fatal(err)
   580  			}
   581  			imports[pkg.Name()] = pkg
   582  			return pkg
   583  		}
   584  		makePkg(lib)
   585  		pkg := makePkg(test.src)
   586  
   587  		t.Run(pkg.Name(), func(t *testing.T) {
   588  			// Sort instances in source order for stability.
   589  			instances := sortedInstances(instMap)
   590  			if got, want := len(instances), len(test.instances); got != want {
   591  				t.Fatalf("got %d instances, want %d", got, want)
   592  			}
   593  
   594  			// Pairwise compare with the expected instances.
   595  			for ii, inst := range instances {
   596  				var targs []Type
   597  				for i := 0; i < inst.Inst.TypeArgs.Len(); i++ {
   598  					targs = append(targs, inst.Inst.TypeArgs.At(i))
   599  				}
   600  				typ := inst.Inst.Type
   601  
   602  				testInst := test.instances[ii]
   603  				if got := inst.Ident.Name; got != testInst.name {
   604  					t.Fatalf("got name %s, want %s", got, testInst.name)
   605  				}
   606  				if len(targs) != len(testInst.targs) {
   607  					t.Fatalf("got %d type arguments; want %d", len(targs), len(testInst.targs))
   608  				}
   609  				for i, targ := range targs {
   610  					if got := targ.String(); got != testInst.targs[i] {
   611  						t.Errorf("type argument %d: got %s; want %s", i, got, testInst.targs[i])
   612  					}
   613  				}
   614  				if got := typ.Underlying().String(); got != testInst.typ {
   615  					t.Errorf("package %s: got %s; want %s", pkg.Name(), got, testInst.typ)
   616  				}
   617  
   618  				// Verify the invariant that re-instantiating the corresponding generic
   619  				// type with TypeArgs results in an identical instance.
   620  				ptype := useMap[inst.Ident].Type()
   621  				lister, _ := ptype.(interface{ TypeParams() *TypeParamList })
   622  				if lister == nil || lister.TypeParams().Len() == 0 {
   623  					t.Fatalf("info.Types[%v] = %v, want parameterized type", inst.Ident, ptype)
   624  				}
   625  				inst2, err := Instantiate(nil, ptype, targs, true)
   626  				if err != nil {
   627  					t.Errorf("Instantiate(%v, %v) failed: %v", ptype, targs, err)
   628  				}
   629  				if !Identical(inst.Inst.Type, inst2) {
   630  					t.Errorf("%v and %v are not identical", inst.Inst.Type, inst2)
   631  				}
   632  			}
   633  		})
   634  	}
   635  }
   636  
   637  type recordedInstance struct {
   638  	Ident *ast.Ident
   639  	Inst  Instance
   640  }
   641  
   642  func sortedInstances(m map[*ast.Ident]Instance) (instances []recordedInstance) {
   643  	for id, inst := range m {
   644  		instances = append(instances, recordedInstance{id, inst})
   645  	}
   646  	sort.Slice(instances, func(i, j int) bool {
   647  		return instances[i].Ident.Pos() < instances[j].Ident.Pos()
   648  	})
   649  	return instances
   650  }
   651  
   652  func TestDefsInfo(t *testing.T) {
   653  	var tests = []struct {
   654  		src  string
   655  		obj  string
   656  		want string
   657  	}{
   658  		{`package p0; const x = 42`, `x`, `const p0.x untyped int`},
   659  		{`package p1; const x int = 42`, `x`, `const p1.x int`},
   660  		{`package p2; var x int`, `x`, `var p2.x int`},
   661  		{`package p3; type x int`, `x`, `type p3.x int`},
   662  		{`package p4; func f()`, `f`, `func p4.f()`},
   663  		{`package p5; func f() int { x, _ := 1, 2; return x }`, `_`, `var _ int`},
   664  
   665  		// Tests using generics.
   666  		{`package generic_g0; type x[T any] int`, `x`, `type generic_g0.x[T any] int`},
   667  		{`package generic_g1; func f[T any]() {}`, `f`, `func generic_g1.f[T any]()`},
   668  		{`package generic_g2; type x[T any] int; func (*x[_]) m() {}`, `m`, `func (*generic_g2.x[_]).m()`},
   669  	}
   670  
   671  	for _, test := range tests {
   672  		info := Info{
   673  			Defs: make(map[*ast.Ident]Object),
   674  		}
   675  		name := mustTypecheck(t, "DefsInfo", test.src, &info)
   676  
   677  		// find object
   678  		var def Object
   679  		for id, obj := range info.Defs {
   680  			if id.Name == test.obj {
   681  				def = obj
   682  				break
   683  			}
   684  		}
   685  		if def == nil {
   686  			t.Errorf("package %s: %s not found", name, test.obj)
   687  			continue
   688  		}
   689  
   690  		if got := def.String(); got != test.want {
   691  			t.Errorf("package %s: got %s; want %s", name, got, test.want)
   692  		}
   693  	}
   694  }
   695  
   696  func TestUsesInfo(t *testing.T) {
   697  	var tests = []struct {
   698  		src  string
   699  		obj  string
   700  		want string
   701  	}{
   702  		{`package p0; func _() { _ = x }; const x = 42`, `x`, `const p0.x untyped int`},
   703  		{`package p1; func _() { _ = x }; const x int = 42`, `x`, `const p1.x int`},
   704  		{`package p2; func _() { _ = x }; var x int`, `x`, `var p2.x int`},
   705  		{`package p3; func _() { type _ x }; type x int`, `x`, `type p3.x int`},
   706  		{`package p4; func _() { _ = f }; func f()`, `f`, `func p4.f()`},
   707  
   708  		// Tests using generics.
   709  		{`package generic_g0; func _[T any]() { _ = x }; const x = 42`, `x`, `const generic_g0.x untyped int`},
   710  		{`package generic_g1; func _[T any](x T) { }`, `T`, `type parameter T any`},
   711  		{`package generic_g2; type N[A any] int; var _ N[int]`, `N`, `type generic_g2.N[A any] int`},
   712  		{`package generic_g3; type N[A any] int; func (N[_]) m() {}`, `N`, `type generic_g3.N[A any] int`},
   713  
   714  		// Uses of fields are instantiated.
   715  		{`package generic_s1; type N[A any] struct{ a A }; var f = N[int]{}.a`, `a`, `field a int`},
   716  		{`package generic_s1; type N[A any] struct{ a A }; func (r N[B]) m(b B) { r.a = b }`, `a`, `field a B`},
   717  
   718  		// Uses of methods are uses of the instantiated method.
   719  		{`package generic_m0; type N[A any] int; func (r N[B]) m() { r.n() }; func (N[C]) n() {}`, `n`, `func (generic_m0.N[B]).n()`},
   720  		{`package generic_m1; type N[A any] int; func (r N[B]) m() { }; var f = N[int].m`, `m`, `func (generic_m1.N[int]).m()`},
   721  		{`package generic_m2; func _[A any](v interface{ m() A }) { v.m() }`, `m`, `func (interface).m() A`},
   722  		{`package generic_m3; func f[A any]() interface{ m() A } { return nil }; var _ = f[int]().m()`, `m`, `func (interface).m() int`},
   723  		{`package generic_m4; type T[A any] func() interface{ m() A }; var x T[int]; var y = x().m`, `m`, `func (interface).m() int`},
   724  		{`package generic_m5; type T[A any] interface{ m() A }; func _[B any](t T[B]) { t.m() }`, `m`, `func (generic_m5.T[B]).m() B`},
   725  		{`package generic_m6; type T[A any] interface{ m() }; func _[B any](t T[B]) { t.m() }`, `m`, `func (generic_m6.T[B]).m()`},
   726  		{`package generic_m7; type T[A any] interface{ m() A }; func _(t T[int]) { t.m() }`, `m`, `func (generic_m7.T[int]).m() int`},
   727  		{`package generic_m8; type T[A any] interface{ m() }; func _(t T[int]) { t.m() }`, `m`, `func (generic_m8.T[int]).m()`},
   728  		{`package generic_m9; type T[A any] interface{ m() }; func _(t T[int]) { _ = t.m }`, `m`, `func (generic_m9.T[int]).m()`},
   729  		{
   730  			`package generic_m10; type E[A any] interface{ m() }; type T[B any] interface{ E[B]; n() }; func _(t T[int]) { t.m() }`,
   731  			`m`,
   732  			`func (generic_m10.E[int]).m()`,
   733  		},
   734  	}
   735  
   736  	for _, test := range tests {
   737  		info := Info{
   738  			Uses: make(map[*ast.Ident]Object),
   739  		}
   740  		name := mustTypecheck(t, "UsesInfo", test.src, &info)
   741  
   742  		// find object
   743  		var use Object
   744  		for id, obj := range info.Uses {
   745  			if id.Name == test.obj {
   746  				if use != nil {
   747  					panic(fmt.Sprintf("multiple uses of %q", id.Name))
   748  				}
   749  				use = obj
   750  			}
   751  		}
   752  		if use == nil {
   753  			t.Errorf("package %s: %s not found", name, test.obj)
   754  			continue
   755  		}
   756  
   757  		if got := use.String(); got != test.want {
   758  			t.Errorf("package %s: got %s; want %s", name, got, test.want)
   759  		}
   760  	}
   761  }
   762  
   763  func TestGenericMethodInfo(t *testing.T) {
   764  	src := `package p
   765  
   766  type N[A any] int
   767  
   768  func (r N[B]) m() { r.m(); r.n() }
   769  
   770  func (r *N[C]) n() {  }
   771  `
   772  	fset := token.NewFileSet()
   773  	f, err := parser.ParseFile(fset, "p.go", src, 0)
   774  	if err != nil {
   775  		t.Fatal(err)
   776  	}
   777  	info := Info{
   778  		Defs:       make(map[*ast.Ident]Object),
   779  		Uses:       make(map[*ast.Ident]Object),
   780  		Selections: make(map[*ast.SelectorExpr]*Selection),
   781  	}
   782  	var conf Config
   783  	pkg, err := conf.Check("p", fset, []*ast.File{f}, &info)
   784  	if err != nil {
   785  		t.Fatal(err)
   786  	}
   787  
   788  	N := pkg.Scope().Lookup("N").Type().(*Named)
   789  
   790  	// Find the generic methods stored on N.
   791  	gm, gn := N.Method(0), N.Method(1)
   792  	if gm.Name() == "n" {
   793  		gm, gn = gn, gm
   794  	}
   795  
   796  	// Collect objects from info.
   797  	var dm, dn *Func   // the declared methods
   798  	var dmm, dmn *Func // the methods used in the body of m
   799  	for _, decl := range f.Decls {
   800  		fdecl, ok := decl.(*ast.FuncDecl)
   801  		if !ok {
   802  			continue
   803  		}
   804  		def := info.Defs[fdecl.Name].(*Func)
   805  		switch fdecl.Name.Name {
   806  		case "m":
   807  			dm = def
   808  			ast.Inspect(fdecl.Body, func(n ast.Node) bool {
   809  				if call, ok := n.(*ast.CallExpr); ok {
   810  					sel := call.Fun.(*ast.SelectorExpr)
   811  					use := info.Uses[sel.Sel].(*Func)
   812  					selection := info.Selections[sel]
   813  					if selection.Kind() != MethodVal {
   814  						t.Errorf("Selection kind = %v, want %v", selection.Kind(), MethodVal)
   815  					}
   816  					if selection.Obj() != use {
   817  						t.Errorf("info.Selections contains %v, want %v", selection.Obj(), use)
   818  					}
   819  					switch sel.Sel.Name {
   820  					case "m":
   821  						dmm = use
   822  					case "n":
   823  						dmn = use
   824  					}
   825  				}
   826  				return true
   827  			})
   828  		case "n":
   829  			dn = def
   830  		}
   831  	}
   832  
   833  	if gm != dm {
   834  		t.Errorf(`N.Method(...) returns %v for "m", but Info.Defs has %v`, gm, dm)
   835  	}
   836  	if gn != dn {
   837  		t.Errorf(`N.Method(...) returns %v for "m", but Info.Defs has %v`, gm, dm)
   838  	}
   839  	if dmm != dm {
   840  		t.Errorf(`Inside "m", r.m uses %v, want the defined func %v`, dmm, dm)
   841  	}
   842  	if dmn == dn {
   843  		t.Errorf(`Inside "m", r.n uses %v, want a func distinct from %v`, dmm, dm)
   844  	}
   845  }
   846  
   847  func TestImplicitsInfo(t *testing.T) {
   848  	testenv.MustHaveGoBuild(t)
   849  
   850  	var tests = []struct {
   851  		src  string
   852  		want string
   853  	}{
   854  		{`package p2; import . "fmt"; var _ = Println`, ""},           // no Implicits entry
   855  		{`package p0; import local "fmt"; var _ = local.Println`, ""}, // no Implicits entry
   856  		{`package p1; import "fmt"; var _ = fmt.Println`, "importSpec: package fmt"},
   857  
   858  		{`package p3; func f(x interface{}) { switch x.(type) { case int: } }`, ""}, // no Implicits entry
   859  		{`package p4; func f(x interface{}) { switch t := x.(type) { case int: _ = t } }`, "caseClause: var t int"},
   860  		{`package p5; func f(x interface{}) { switch t := x.(type) { case int, uint: _ = t } }`, "caseClause: var t interface{}"},
   861  		{`package p6; func f(x interface{}) { switch t := x.(type) { default: _ = t } }`, "caseClause: var t interface{}"},
   862  
   863  		{`package p7; func f(x int) {}`, ""}, // no Implicits entry
   864  		{`package p8; func f(int) {}`, "field: var  int"},
   865  		{`package p9; func f() (complex64) { return 0 }`, "field: var  complex64"},
   866  		{`package p10; type T struct{}; func (*T) f() {}`, "field: var  *p10.T"},
   867  
   868  		// Tests using generics.
   869  		{`package generic_f0; func f[T any](x int) {}`, ""}, // no Implicits entry
   870  		{`package generic_f1; func f[T any](int) {}`, "field: var  int"},
   871  		{`package generic_f2; func f[T any](T) {}`, "field: var  T"},
   872  		{`package generic_f3; func f[T any]() (complex64) { return 0 }`, "field: var  complex64"},
   873  		{`package generic_f4; func f[T any](t T) (T) { return t }`, "field: var  T"},
   874  		{`package generic_t0; type T[A any] struct{}; func (*T[_]) f() {}`, "field: var  *generic_t0.T[_]"},
   875  		{`package generic_t1; type T[A any] struct{}; func _(x interface{}) { switch t := x.(type) { case T[int]: _ = t } }`, "caseClause: var t generic_t1.T[int]"},
   876  		{`package generic_t2; type T[A any] struct{}; func _[P any](x interface{}) { switch t := x.(type) { case T[P]: _ = t } }`, "caseClause: var t generic_t2.T[P]"},
   877  		{`package generic_t3; func _[P any](x interface{}) { switch t := x.(type) { case P: _ = t } }`, "caseClause: var t P"},
   878  	}
   879  
   880  	for _, test := range tests {
   881  		info := Info{
   882  			Implicits: make(map[ast.Node]Object),
   883  		}
   884  		name := mustTypecheck(t, "ImplicitsInfo", test.src, &info)
   885  
   886  		// the test cases expect at most one Implicits entry
   887  		if len(info.Implicits) > 1 {
   888  			t.Errorf("package %s: %d Implicits entries found", name, len(info.Implicits))
   889  			continue
   890  		}
   891  
   892  		// extract Implicits entry, if any
   893  		var got string
   894  		for n, obj := range info.Implicits {
   895  			switch x := n.(type) {
   896  			case *ast.ImportSpec:
   897  				got = "importSpec"
   898  			case *ast.CaseClause:
   899  				got = "caseClause"
   900  			case *ast.Field:
   901  				got = "field"
   902  			default:
   903  				t.Fatalf("package %s: unexpected %T", name, x)
   904  			}
   905  			got += ": " + obj.String()
   906  		}
   907  
   908  		// verify entry
   909  		if got != test.want {
   910  			t.Errorf("package %s: got %q; want %q", name, got, test.want)
   911  		}
   912  	}
   913  }
   914  
   915  func predString(tv TypeAndValue) string {
   916  	var buf bytes.Buffer
   917  	pred := func(b bool, s string) {
   918  		if b {
   919  			if buf.Len() > 0 {
   920  				buf.WriteString(", ")
   921  			}
   922  			buf.WriteString(s)
   923  		}
   924  	}
   925  
   926  	pred(tv.IsVoid(), "void")
   927  	pred(tv.IsType(), "type")
   928  	pred(tv.IsBuiltin(), "builtin")
   929  	pred(tv.IsValue() && tv.Value != nil, "const")
   930  	pred(tv.IsValue() && tv.Value == nil, "value")
   931  	pred(tv.IsNil(), "nil")
   932  	pred(tv.Addressable(), "addressable")
   933  	pred(tv.Assignable(), "assignable")
   934  	pred(tv.HasOk(), "hasOk")
   935  
   936  	if buf.Len() == 0 {
   937  		return "invalid"
   938  	}
   939  	return buf.String()
   940  }
   941  
   942  func TestPredicatesInfo(t *testing.T) {
   943  	testenv.MustHaveGoBuild(t)
   944  
   945  	var tests = []struct {
   946  		src  string
   947  		expr string
   948  		pred string
   949  	}{
   950  		// void
   951  		{`package n0; func f() { f() }`, `f()`, `void`},
   952  
   953  		// types
   954  		{`package t0; type _ int`, `int`, `type`},
   955  		{`package t1; type _ []int`, `[]int`, `type`},
   956  		{`package t2; type _ func()`, `func()`, `type`},
   957  		{`package t3; type _ func(int)`, `int`, `type`},
   958  		{`package t3; type _ func(...int)`, `...int`, `type`},
   959  
   960  		// built-ins
   961  		{`package b0; var _ = len("")`, `len`, `builtin`},
   962  		{`package b1; var _ = (len)("")`, `(len)`, `builtin`},
   963  
   964  		// constants
   965  		{`package c0; var _ = 42`, `42`, `const`},
   966  		{`package c1; var _ = "foo" + "bar"`, `"foo" + "bar"`, `const`},
   967  		{`package c2; const (i = 1i; _ = i)`, `i`, `const`},
   968  
   969  		// values
   970  		{`package v0; var (a, b int; _ = a + b)`, `a + b`, `value`},
   971  		{`package v1; var _ = &[]int{1}`, `([]int literal)`, `value`},
   972  		{`package v2; var _ = func(){}`, `(func() literal)`, `value`},
   973  		{`package v4; func f() { _ = f }`, `f`, `value`},
   974  		{`package v3; var _ *int = nil`, `nil`, `value, nil`},
   975  		{`package v3; var _ *int = (nil)`, `(nil)`, `value, nil`},
   976  
   977  		// addressable (and thus assignable) operands
   978  		{`package a0; var (x int; _ = x)`, `x`, `value, addressable, assignable`},
   979  		{`package a1; var (p *int; _ = *p)`, `*p`, `value, addressable, assignable`},
   980  		{`package a2; var (s []int; _ = s[0])`, `s[0]`, `value, addressable, assignable`},
   981  		{`package a3; var (s struct{f int}; _ = s.f)`, `s.f`, `value, addressable, assignable`},
   982  		{`package a4; var (a [10]int; _ = a[0])`, `a[0]`, `value, addressable, assignable`},
   983  		{`package a5; func _(x int) { _ = x }`, `x`, `value, addressable, assignable`},
   984  		{`package a6; func _()(x int) { _ = x; return }`, `x`, `value, addressable, assignable`},
   985  		{`package a7; type T int; func (x T) _() { _ = x }`, `x`, `value, addressable, assignable`},
   986  		// composite literals are not addressable
   987  
   988  		// assignable but not addressable values
   989  		{`package s0; var (m map[int]int; _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
   990  		{`package s1; var (m map[int]int; _, _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
   991  
   992  		// hasOk expressions
   993  		{`package k0; var (ch chan int; _ = <-ch)`, `<-ch`, `value, hasOk`},
   994  		{`package k1; var (ch chan int; _, _ = <-ch)`, `<-ch`, `value, hasOk`},
   995  
   996  		// missing entries
   997  		// - package names are collected in the Uses map
   998  		// - identifiers being declared are collected in the Defs map
   999  		{`package m0; import "os"; func _() { _ = os.Stdout }`, `os`, `<missing>`},
  1000  		{`package m1; import p "os"; func _() { _ = p.Stdout }`, `p`, `<missing>`},
  1001  		{`package m2; const c = 0`, `c`, `<missing>`},
  1002  		{`package m3; type T int`, `T`, `<missing>`},
  1003  		{`package m4; var v int`, `v`, `<missing>`},
  1004  		{`package m5; func f() {}`, `f`, `<missing>`},
  1005  		{`package m6; func _(x int) {}`, `x`, `<missing>`},
  1006  		{`package m6; func _()(x int) { return }`, `x`, `<missing>`},
  1007  		{`package m6; type T int; func (x T) _() {}`, `x`, `<missing>`},
  1008  	}
  1009  
  1010  	for _, test := range tests {
  1011  		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
  1012  		name := mustTypecheck(t, "PredicatesInfo", test.src, &info)
  1013  
  1014  		// look for expression predicates
  1015  		got := "<missing>"
  1016  		for e, tv := range info.Types {
  1017  			//println(name, ExprString(e))
  1018  			if ExprString(e) == test.expr {
  1019  				got = predString(tv)
  1020  				break
  1021  			}
  1022  		}
  1023  
  1024  		if got != test.pred {
  1025  			t.Errorf("package %s: got %s; want %s", name, got, test.pred)
  1026  		}
  1027  	}
  1028  }
  1029  
  1030  func TestScopesInfo(t *testing.T) {
  1031  	testenv.MustHaveGoBuild(t)
  1032  
  1033  	var tests = []struct {
  1034  		src    string
  1035  		scopes []string // list of scope descriptors of the form kind:varlist
  1036  	}{
  1037  		{`package p0`, []string{
  1038  			"file:",
  1039  		}},
  1040  		{`package p1; import ( "fmt"; m "math"; _ "os" ); var ( _ = fmt.Println; _ = m.Pi )`, []string{
  1041  			"file:fmt m",
  1042  		}},
  1043  		{`package p2; func _() {}`, []string{
  1044  			"file:", "func:",
  1045  		}},
  1046  		{`package p3; func _(x, y int) {}`, []string{
  1047  			"file:", "func:x y",
  1048  		}},
  1049  		{`package p4; func _(x, y int) { x, z := 1, 2; _ = z }`, []string{
  1050  			"file:", "func:x y z", // redeclaration of x
  1051  		}},
  1052  		{`package p5; func _(x, y int) (u, _ int) { return }`, []string{
  1053  			"file:", "func:u x y",
  1054  		}},
  1055  		{`package p6; func _() { { var x int; _ = x } }`, []string{
  1056  			"file:", "func:", "block:x",
  1057  		}},
  1058  		{`package p7; func _() { if true {} }`, []string{
  1059  			"file:", "func:", "if:", "block:",
  1060  		}},
  1061  		{`package p8; func _() { if x := 0; x < 0 { y := x; _ = y } }`, []string{
  1062  			"file:", "func:", "if:x", "block:y",
  1063  		}},
  1064  		{`package p9; func _() { switch x := 0; x {} }`, []string{
  1065  			"file:", "func:", "switch:x",
  1066  		}},
  1067  		{`package p10; func _() { switch x := 0; x { case 1: y := x; _ = y; default: }}`, []string{
  1068  			"file:", "func:", "switch:x", "case:y", "case:",
  1069  		}},
  1070  		{`package p11; func _(t interface{}) { switch t.(type) {} }`, []string{
  1071  			"file:", "func:t", "type switch:",
  1072  		}},
  1073  		{`package p12; func _(t interface{}) { switch t := t; t.(type) {} }`, []string{
  1074  			"file:", "func:t", "type switch:t",
  1075  		}},
  1076  		{`package p13; func _(t interface{}) { switch x := t.(type) { case int: _ = x } }`, []string{
  1077  			"file:", "func:t", "type switch:", "case:x", // x implicitly declared
  1078  		}},
  1079  		{`package p14; func _() { select{} }`, []string{
  1080  			"file:", "func:",
  1081  		}},
  1082  		{`package p15; func _(c chan int) { select{ case <-c: } }`, []string{
  1083  			"file:", "func:c", "comm:",
  1084  		}},
  1085  		{`package p16; func _(c chan int) { select{ case i := <-c: x := i; _ = x} }`, []string{
  1086  			"file:", "func:c", "comm:i x",
  1087  		}},
  1088  		{`package p17; func _() { for{} }`, []string{
  1089  			"file:", "func:", "for:", "block:",
  1090  		}},
  1091  		{`package p18; func _(n int) { for i := 0; i < n; i++ { _ = i } }`, []string{
  1092  			"file:", "func:n", "for:i", "block:",
  1093  		}},
  1094  		{`package p19; func _(a []int) { for i := range a { _ = i} }`, []string{
  1095  			"file:", "func:a", "range:i", "block:",
  1096  		}},
  1097  		{`package p20; var s int; func _(a []int) { for i, x := range a { s += x; _ = i } }`, []string{
  1098  			"file:", "func:a", "range:i x", "block:",
  1099  		}},
  1100  	}
  1101  
  1102  	for _, test := range tests {
  1103  		info := Info{Scopes: make(map[ast.Node]*Scope)}
  1104  		name := mustTypecheck(t, "ScopesInfo", test.src, &info)
  1105  
  1106  		// number of scopes must match
  1107  		if len(info.Scopes) != len(test.scopes) {
  1108  			t.Errorf("package %s: got %d scopes; want %d", name, len(info.Scopes), len(test.scopes))
  1109  		}
  1110  
  1111  		// scope descriptions must match
  1112  		for node, scope := range info.Scopes {
  1113  			kind := "<unknown node kind>"
  1114  			switch node.(type) {
  1115  			case *ast.File:
  1116  				kind = "file"
  1117  			case *ast.FuncType:
  1118  				kind = "func"
  1119  			case *ast.BlockStmt:
  1120  				kind = "block"
  1121  			case *ast.IfStmt:
  1122  				kind = "if"
  1123  			case *ast.SwitchStmt:
  1124  				kind = "switch"
  1125  			case *ast.TypeSwitchStmt:
  1126  				kind = "type switch"
  1127  			case *ast.CaseClause:
  1128  				kind = "case"
  1129  			case *ast.CommClause:
  1130  				kind = "comm"
  1131  			case *ast.ForStmt:
  1132  				kind = "for"
  1133  			case *ast.RangeStmt:
  1134  				kind = "range"
  1135  			}
  1136  
  1137  			// look for matching scope description
  1138  			desc := kind + ":" + strings.Join(scope.Names(), " ")
  1139  			found := false
  1140  			for _, d := range test.scopes {
  1141  				if desc == d {
  1142  					found = true
  1143  					break
  1144  				}
  1145  			}
  1146  			if !found {
  1147  				t.Errorf("package %s: no matching scope found for %s", name, desc)
  1148  			}
  1149  		}
  1150  	}
  1151  }
  1152  
  1153  func TestInitOrderInfo(t *testing.T) {
  1154  	var tests = []struct {
  1155  		src   string
  1156  		inits []string
  1157  	}{
  1158  		{`package p0; var (x = 1; y = x)`, []string{
  1159  			"x = 1", "y = x",
  1160  		}},
  1161  		{`package p1; var (a = 1; b = 2; c = 3)`, []string{
  1162  			"a = 1", "b = 2", "c = 3",
  1163  		}},
  1164  		{`package p2; var (a, b, c = 1, 2, 3)`, []string{
  1165  			"a = 1", "b = 2", "c = 3",
  1166  		}},
  1167  		{`package p3; var _ = f(); func f() int { return 1 }`, []string{
  1168  			"_ = f()", // blank var
  1169  		}},
  1170  		{`package p4; var (a = 0; x = y; y = z; z = 0)`, []string{
  1171  			"a = 0", "z = 0", "y = z", "x = y",
  1172  		}},
  1173  		{`package p5; var (a, _ = m[0]; m map[int]string)`, []string{
  1174  			"a, _ = m[0]", // blank var
  1175  		}},
  1176  		{`package p6; var a, b = f(); func f() (_, _ int) { return z, z }; var z = 0`, []string{
  1177  			"z = 0", "a, b = f()",
  1178  		}},
  1179  		{`package p7; var (a = func() int { return b }(); b = 1)`, []string{
  1180  			"b = 1", "a = (func() int literal)()",
  1181  		}},
  1182  		{`package p8; var (a, b = func() (_, _ int) { return c, c }(); c = 1)`, []string{
  1183  			"c = 1", "a, b = (func() (_, _ int) literal)()",
  1184  		}},
  1185  		{`package p9; type T struct{}; func (T) m() int { _ = y; return 0 }; var x, y = T.m, 1`, []string{
  1186  			"y = 1", "x = T.m",
  1187  		}},
  1188  		{`package p10; var (d = c + b; a = 0; b = 0; c = 0)`, []string{
  1189  			"a = 0", "b = 0", "c = 0", "d = c + b",
  1190  		}},
  1191  		{`package p11; var (a = e + c; b = d + c; c = 0; d = 0; e = 0)`, []string{
  1192  			"c = 0", "d = 0", "b = d + c", "e = 0", "a = e + c",
  1193  		}},
  1194  		// emit an initializer for n:1 initializations only once (not for each node
  1195  		// on the lhs which may appear in different order in the dependency graph)
  1196  		{`package p12; var (a = x; b = 0; x, y = m[0]; m map[int]int)`, []string{
  1197  			"b = 0", "x, y = m[0]", "a = x",
  1198  		}},
  1199  		// test case from spec section on package initialization
  1200  		{`package p12
  1201  
  1202  		var (
  1203  			a = c + b
  1204  			b = f()
  1205  			c = f()
  1206  			d = 3
  1207  		)
  1208  
  1209  		func f() int {
  1210  			d++
  1211  			return d
  1212  		}`, []string{
  1213  			"d = 3", "b = f()", "c = f()", "a = c + b",
  1214  		}},
  1215  		// test case for issue 7131
  1216  		{`package main
  1217  
  1218  		var counter int
  1219  		func next() int { counter++; return counter }
  1220  
  1221  		var _ = makeOrder()
  1222  		func makeOrder() []int { return []int{f, b, d, e, c, a} }
  1223  
  1224  		var a       = next()
  1225  		var b, c    = next(), next()
  1226  		var d, e, f = next(), next(), next()
  1227  		`, []string{
  1228  			"a = next()", "b = next()", "c = next()", "d = next()", "e = next()", "f = next()", "_ = makeOrder()",
  1229  		}},
  1230  		// test case for issue 10709
  1231  		{`package p13
  1232  
  1233  		var (
  1234  		    v = t.m()
  1235  		    t = makeT(0)
  1236  		)
  1237  
  1238  		type T struct{}
  1239  
  1240  		func (T) m() int { return 0 }
  1241  
  1242  		func makeT(n int) T {
  1243  		    if n > 0 {
  1244  		        return makeT(n-1)
  1245  		    }
  1246  		    return T{}
  1247  		}`, []string{
  1248  			"t = makeT(0)", "v = t.m()",
  1249  		}},
  1250  		// test case for issue 10709: same as test before, but variable decls swapped
  1251  		{`package p14
  1252  
  1253  		var (
  1254  		    t = makeT(0)
  1255  		    v = t.m()
  1256  		)
  1257  
  1258  		type T struct{}
  1259  
  1260  		func (T) m() int { return 0 }
  1261  
  1262  		func makeT(n int) T {
  1263  		    if n > 0 {
  1264  		        return makeT(n-1)
  1265  		    }
  1266  		    return T{}
  1267  		}`, []string{
  1268  			"t = makeT(0)", "v = t.m()",
  1269  		}},
  1270  		// another candidate possibly causing problems with issue 10709
  1271  		{`package p15
  1272  
  1273  		var y1 = f1()
  1274  
  1275  		func f1() int { return g1() }
  1276  		func g1() int { f1(); return x1 }
  1277  
  1278  		var x1 = 0
  1279  
  1280  		var y2 = f2()
  1281  
  1282  		func f2() int { return g2() }
  1283  		func g2() int { return x2 }
  1284  
  1285  		var x2 = 0`, []string{
  1286  			"x1 = 0", "y1 = f1()", "x2 = 0", "y2 = f2()",
  1287  		}},
  1288  	}
  1289  
  1290  	for _, test := range tests {
  1291  		info := Info{}
  1292  		name := mustTypecheck(t, "InitOrderInfo", test.src, &info)
  1293  
  1294  		// number of initializers must match
  1295  		if len(info.InitOrder) != len(test.inits) {
  1296  			t.Errorf("package %s: got %d initializers; want %d", name, len(info.InitOrder), len(test.inits))
  1297  			continue
  1298  		}
  1299  
  1300  		// initializers must match
  1301  		for i, want := range test.inits {
  1302  			got := info.InitOrder[i].String()
  1303  			if got != want {
  1304  				t.Errorf("package %s, init %d: got %s; want %s", name, i, got, want)
  1305  				continue
  1306  			}
  1307  		}
  1308  	}
  1309  }
  1310  
  1311  func TestMultiFileInitOrder(t *testing.T) {
  1312  	fset := token.NewFileSet()
  1313  	mustParse := func(src string) *ast.File {
  1314  		f, err := parser.ParseFile(fset, "main", src, 0)
  1315  		if err != nil {
  1316  			t.Fatal(err)
  1317  		}
  1318  		return f
  1319  	}
  1320  
  1321  	fileA := mustParse(`package main; var a = 1`)
  1322  	fileB := mustParse(`package main; var b = 2`)
  1323  
  1324  	// The initialization order must not depend on the parse
  1325  	// order of the files, only on the presentation order to
  1326  	// the type-checker.
  1327  	for _, test := range []struct {
  1328  		files []*ast.File
  1329  		want  string
  1330  	}{
  1331  		{[]*ast.File{fileA, fileB}, "[a = 1 b = 2]"},
  1332  		{[]*ast.File{fileB, fileA}, "[b = 2 a = 1]"},
  1333  	} {
  1334  		var info Info
  1335  		if _, err := new(Config).Check("main", fset, test.files, &info); err != nil {
  1336  			t.Fatal(err)
  1337  		}
  1338  		if got := fmt.Sprint(info.InitOrder); got != test.want {
  1339  			t.Fatalf("got %s; want %s", got, test.want)
  1340  		}
  1341  	}
  1342  }
  1343  
  1344  func TestFiles(t *testing.T) {
  1345  	var sources = []string{
  1346  		"package p; type T struct{}; func (T) m1() {}",
  1347  		"package p; func (T) m2() {}; var x interface{ m1(); m2() } = T{}",
  1348  		"package p; func (T) m3() {}; var y interface{ m1(); m2(); m3() } = T{}",
  1349  		"package p",
  1350  	}
  1351  
  1352  	var conf Config
  1353  	fset := token.NewFileSet()
  1354  	pkg := NewPackage("p", "p")
  1355  	var info Info
  1356  	check := NewChecker(&conf, fset, pkg, &info)
  1357  
  1358  	for i, src := range sources {
  1359  		filename := fmt.Sprintf("sources%d", i)
  1360  		f, err := parser.ParseFile(fset, filename, src, 0)
  1361  		if err != nil {
  1362  			t.Fatal(err)
  1363  		}
  1364  		if err := check.Files([]*ast.File{f}); err != nil {
  1365  			t.Error(err)
  1366  		}
  1367  	}
  1368  
  1369  	// check InitOrder is [x y]
  1370  	var vars []string
  1371  	for _, init := range info.InitOrder {
  1372  		for _, v := range init.Lhs {
  1373  			vars = append(vars, v.Name())
  1374  		}
  1375  	}
  1376  	if got, want := fmt.Sprint(vars), "[x y]"; got != want {
  1377  		t.Errorf("InitOrder == %s, want %s", got, want)
  1378  	}
  1379  }
  1380  
  1381  type testImporter map[string]*Package
  1382  
  1383  func (m testImporter) Import(path string) (*Package, error) {
  1384  	if pkg := m[path]; pkg != nil {
  1385  		return pkg, nil
  1386  	}
  1387  	return nil, fmt.Errorf("package %q not found", path)
  1388  }
  1389  
  1390  func TestSelection(t *testing.T) {
  1391  	selections := make(map[*ast.SelectorExpr]*Selection)
  1392  
  1393  	fset := token.NewFileSet()
  1394  	imports := make(testImporter)
  1395  	conf := Config{Importer: imports}
  1396  	makePkg := func(path, src string) {
  1397  		f, err := parser.ParseFile(fset, path+".go", src, 0)
  1398  		if err != nil {
  1399  			t.Fatal(err)
  1400  		}
  1401  		pkg, err := conf.Check(path, fset, []*ast.File{f}, &Info{Selections: selections})
  1402  		if err != nil {
  1403  			t.Fatal(err)
  1404  		}
  1405  		imports[path] = pkg
  1406  	}
  1407  
  1408  	const libSrc = `
  1409  package lib
  1410  type T float64
  1411  const C T = 3
  1412  var V T
  1413  func F() {}
  1414  func (T) M() {}
  1415  `
  1416  	const mainSrc = `
  1417  package main
  1418  import "lib"
  1419  
  1420  type A struct {
  1421  	*B
  1422  	C
  1423  }
  1424  
  1425  type B struct {
  1426  	b int
  1427  }
  1428  
  1429  func (B) f(int)
  1430  
  1431  type C struct {
  1432  	c int
  1433  }
  1434  
  1435  func (C) g()
  1436  func (*C) h()
  1437  
  1438  func main() {
  1439  	// qualified identifiers
  1440  	var _ lib.T
  1441          _ = lib.C
  1442          _ = lib.F
  1443          _ = lib.V
  1444  	_ = lib.T.M
  1445  
  1446  	// fields
  1447  	_ = A{}.B
  1448  	_ = new(A).B
  1449  
  1450  	_ = A{}.C
  1451  	_ = new(A).C
  1452  
  1453  	_ = A{}.b
  1454  	_ = new(A).b
  1455  
  1456  	_ = A{}.c
  1457  	_ = new(A).c
  1458  
  1459  	// methods
  1460          _ = A{}.f
  1461          _ = new(A).f
  1462          _ = A{}.g
  1463          _ = new(A).g
  1464          _ = new(A).h
  1465  
  1466          _ = B{}.f
  1467          _ = new(B).f
  1468  
  1469          _ = C{}.g
  1470          _ = new(C).g
  1471          _ = new(C).h
  1472  
  1473  	// method expressions
  1474          _ = A.f
  1475          _ = (*A).f
  1476          _ = B.f
  1477          _ = (*B).f
  1478  }`
  1479  
  1480  	wantOut := map[string][2]string{
  1481  		"lib.T.M": {"method expr (lib.T) M(lib.T)", ".[0]"},
  1482  
  1483  		"A{}.B":    {"field (main.A) B *main.B", ".[0]"},
  1484  		"new(A).B": {"field (*main.A) B *main.B", "->[0]"},
  1485  		"A{}.C":    {"field (main.A) C main.C", ".[1]"},
  1486  		"new(A).C": {"field (*main.A) C main.C", "->[1]"},
  1487  		"A{}.b":    {"field (main.A) b int", "->[0 0]"},
  1488  		"new(A).b": {"field (*main.A) b int", "->[0 0]"},
  1489  		"A{}.c":    {"field (main.A) c int", ".[1 0]"},
  1490  		"new(A).c": {"field (*main.A) c int", "->[1 0]"},
  1491  
  1492  		"A{}.f":    {"method (main.A) f(int)", "->[0 0]"},
  1493  		"new(A).f": {"method (*main.A) f(int)", "->[0 0]"},
  1494  		"A{}.g":    {"method (main.A) g()", ".[1 0]"},
  1495  		"new(A).g": {"method (*main.A) g()", "->[1 0]"},
  1496  		"new(A).h": {"method (*main.A) h()", "->[1 1]"}, // TODO(gri) should this report .[1 1] ?
  1497  		"B{}.f":    {"method (main.B) f(int)", ".[0]"},
  1498  		"new(B).f": {"method (*main.B) f(int)", "->[0]"},
  1499  		"C{}.g":    {"method (main.C) g()", ".[0]"},
  1500  		"new(C).g": {"method (*main.C) g()", "->[0]"},
  1501  		"new(C).h": {"method (*main.C) h()", "->[1]"}, // TODO(gri) should this report .[1] ?
  1502  
  1503  		"A.f":    {"method expr (main.A) f(main.A, int)", "->[0 0]"},
  1504  		"(*A).f": {"method expr (*main.A) f(*main.A, int)", "->[0 0]"},
  1505  		"B.f":    {"method expr (main.B) f(main.B, int)", ".[0]"},
  1506  		"(*B).f": {"method expr (*main.B) f(*main.B, int)", "->[0]"},
  1507  	}
  1508  
  1509  	makePkg("lib", libSrc)
  1510  	makePkg("main", mainSrc)
  1511  
  1512  	for e, sel := range selections {
  1513  		_ = sel.String() // assertion: must not panic
  1514  
  1515  		start := fset.Position(e.Pos()).Offset
  1516  		end := fset.Position(e.End()).Offset
  1517  		syntax := mainSrc[start:end] // (all SelectorExprs are in main, not lib)
  1518  
  1519  		direct := "."
  1520  		if sel.Indirect() {
  1521  			direct = "->"
  1522  		}
  1523  		got := [2]string{
  1524  			sel.String(),
  1525  			fmt.Sprintf("%s%v", direct, sel.Index()),
  1526  		}
  1527  		want := wantOut[syntax]
  1528  		if want != got {
  1529  			t.Errorf("%s: got %q; want %q", syntax, got, want)
  1530  		}
  1531  		delete(wantOut, syntax)
  1532  
  1533  		// We must explicitly assert properties of the
  1534  		// Signature's receiver since it doesn't participate
  1535  		// in Identical() or String().
  1536  		sig, _ := sel.Type().(*Signature)
  1537  		if sel.Kind() == MethodVal {
  1538  			got := sig.Recv().Type()
  1539  			want := sel.Recv()
  1540  			if !Identical(got, want) {
  1541  				t.Errorf("%s: Recv() = %s, want %s", syntax, got, want)
  1542  			}
  1543  		} else if sig != nil && sig.Recv() != nil {
  1544  			t.Errorf("%s: signature has receiver %s", sig, sig.Recv().Type())
  1545  		}
  1546  	}
  1547  	// Assert that all wantOut entries were used exactly once.
  1548  	for syntax := range wantOut {
  1549  		t.Errorf("no ast.Selection found with syntax %q", syntax)
  1550  	}
  1551  }
  1552  
  1553  func TestIssue8518(t *testing.T) {
  1554  	fset := token.NewFileSet()
  1555  	imports := make(testImporter)
  1556  	conf := Config{
  1557  		Error:    func(err error) { t.Log(err) }, // don't exit after first error
  1558  		Importer: imports,
  1559  	}
  1560  	makePkg := func(path, src string) {
  1561  		f, err := parser.ParseFile(fset, path, src, 0)
  1562  		if err != nil {
  1563  			t.Fatal(err)
  1564  		}
  1565  		pkg, _ := conf.Check(path, fset, []*ast.File{f}, nil) // errors logged via conf.Error
  1566  		imports[path] = pkg
  1567  	}
  1568  
  1569  	const libSrc = `
  1570  package a
  1571  import "missing"
  1572  const C1 = foo
  1573  const C2 = missing.C
  1574  `
  1575  
  1576  	const mainSrc = `
  1577  package main
  1578  import "a"
  1579  var _ = a.C1
  1580  var _ = a.C2
  1581  `
  1582  
  1583  	makePkg("a", libSrc)
  1584  	makePkg("main", mainSrc) // don't crash when type-checking this package
  1585  }
  1586  
  1587  func TestLookupFieldOrMethodOnNil(t *testing.T) {
  1588  	// LookupFieldOrMethod on a nil type is expected to produce a run-time panic.
  1589  	defer func() {
  1590  		const want = "LookupFieldOrMethod on nil type"
  1591  		p := recover()
  1592  		if s, ok := p.(string); !ok || s != want {
  1593  			t.Fatalf("got %v, want %s", p, want)
  1594  		}
  1595  	}()
  1596  	LookupFieldOrMethod(nil, false, nil, "")
  1597  }
  1598  
  1599  func TestLookupFieldOrMethod(t *testing.T) {
  1600  	// Test cases assume a lookup of the form a.f or x.f, where a stands for an
  1601  	// addressable value, and x for a non-addressable value (even though a variable
  1602  	// for ease of test case writing).
  1603  	//
  1604  	// Should be kept in sync with TestMethodSet.
  1605  	var tests = []struct {
  1606  		src      string
  1607  		found    bool
  1608  		index    []int
  1609  		indirect bool
  1610  	}{
  1611  		// field lookups
  1612  		{"var x T; type T struct{}", false, nil, false},
  1613  		{"var x T; type T struct{ f int }", true, []int{0}, false},
  1614  		{"var x T; type T struct{ a, b, f, c int }", true, []int{2}, false},
  1615  
  1616  		// field lookups on a generic type
  1617  		{"var x T[int]; type T[P any] struct{}", false, nil, false},
  1618  		{"var x T[int]; type T[P any] struct{ f P }", true, []int{0}, false},
  1619  		{"var x T[int]; type T[P any] struct{ a, b, f, c P }", true, []int{2}, false},
  1620  
  1621  		// method lookups
  1622  		{"var a T; type T struct{}; func (T) f() {}", true, []int{0}, false},
  1623  		{"var a *T; type T struct{}; func (T) f() {}", true, []int{0}, true},
  1624  		{"var a T; type T struct{}; func (*T) f() {}", true, []int{0}, false},
  1625  		{"var a *T; type T struct{}; func (*T) f() {}", true, []int{0}, true}, // TODO(gri) should this report indirect = false?
  1626  
  1627  		// method lookups on a generic type
  1628  		{"var a T[int]; type T[P any] struct{}; func (T[P]) f() {}", true, []int{0}, false},
  1629  		{"var a *T[int]; type T[P any] struct{}; func (T[P]) f() {}", true, []int{0}, true},
  1630  		{"var a T[int]; type T[P any] struct{}; func (*T[P]) f() {}", true, []int{0}, false},
  1631  		{"var a *T[int]; type T[P any] struct{}; func (*T[P]) f() {}", true, []int{0}, true}, // TODO(gri) should this report indirect = false?
  1632  
  1633  		// collisions
  1634  		{"type ( E1 struct{ f int }; E2 struct{ f int }; x struct{ E1; *E2 })", false, []int{1, 0}, false},
  1635  		{"type ( E1 struct{ f int }; E2 struct{}; x struct{ E1; *E2 }); func (E2) f() {}", false, []int{1, 0}, false},
  1636  
  1637  		// collisions on a generic type
  1638  		{"type ( E1[P any] struct{ f P }; E2[P any] struct{ f P }; x struct{ E1[int]; *E2[int] })", false, []int{1, 0}, false},
  1639  		{"type ( E1[P any] struct{ f P }; E2[P any] struct{}; x struct{ E1[int]; *E2[int] }); func (E2[P]) f() {}", false, []int{1, 0}, false},
  1640  
  1641  		// outside methodset
  1642  		// (*T).f method exists, but value of type T is not addressable
  1643  		{"var x T; type T struct{}; func (*T) f() {}", false, nil, true},
  1644  
  1645  		// outside method set of a generic type
  1646  		{"var x T[int]; type T[P any] struct{}; func (*T[P]) f() {}", false, nil, true},
  1647  
  1648  		// recursive generic types; see golang/go#52715
  1649  		{"var a T[int]; type ( T[P any] struct { *N[P] }; N[P any] struct { *T[P] } ); func (N[P]) f() {}", true, []int{0, 0}, true},
  1650  		{"var a T[int]; type ( T[P any] struct { *N[P] }; N[P any] struct { *T[P] } ); func (T[P]) f() {}", true, []int{0}, false},
  1651  	}
  1652  
  1653  	for _, test := range tests {
  1654  		pkg, err := pkgForMode("test", "package p;"+test.src, nil, 0)
  1655  		if err != nil {
  1656  			t.Errorf("%s: incorrect test case: %s", test.src, err)
  1657  			continue
  1658  		}
  1659  
  1660  		obj := pkg.Scope().Lookup("a")
  1661  		if obj == nil {
  1662  			if obj = pkg.Scope().Lookup("x"); obj == nil {
  1663  				t.Errorf("%s: incorrect test case - no object a or x", test.src)
  1664  				continue
  1665  			}
  1666  		}
  1667  
  1668  		f, index, indirect := LookupFieldOrMethod(obj.Type(), obj.Name() == "a", pkg, "f")
  1669  		if (f != nil) != test.found {
  1670  			if f == nil {
  1671  				t.Errorf("%s: got no object; want one", test.src)
  1672  			} else {
  1673  				t.Errorf("%s: got object = %v; want none", test.src, f)
  1674  			}
  1675  		}
  1676  		if !sameSlice(index, test.index) {
  1677  			t.Errorf("%s: got index = %v; want %v", test.src, index, test.index)
  1678  		}
  1679  		if indirect != test.indirect {
  1680  			t.Errorf("%s: got indirect = %v; want %v", test.src, indirect, test.indirect)
  1681  		}
  1682  	}
  1683  }
  1684  
  1685  // Test for golang/go#52715
  1686  func TestLookupFieldOrMethod_RecursiveGeneric(t *testing.T) {
  1687  	const src = `
  1688  package pkg
  1689  
  1690  type Tree[T any] struct {
  1691  	*Node[T]
  1692  }
  1693  
  1694  func (*Tree[R]) N(r R) R { return r }
  1695  
  1696  type Node[T any] struct {
  1697  	*Tree[T]
  1698  }
  1699  
  1700  type Instance = *Tree[int]
  1701  `
  1702  
  1703  	fset := token.NewFileSet()
  1704  	f, err := parser.ParseFile(fset, "foo.go", src, 0)
  1705  	if err != nil {
  1706  		panic(err)
  1707  	}
  1708  	pkg := NewPackage("pkg", f.Name.Name)
  1709  	if err := NewChecker(nil, fset, pkg, nil).Files([]*ast.File{f}); err != nil {
  1710  		panic(err)
  1711  	}
  1712  
  1713  	T := pkg.Scope().Lookup("Instance").Type()
  1714  	_, _, _ = LookupFieldOrMethod(T, false, pkg, "M") // verify that LookupFieldOrMethod terminates
  1715  }
  1716  
  1717  func sameSlice(a, b []int) bool {
  1718  	if len(a) != len(b) {
  1719  		return false
  1720  	}
  1721  	for i, x := range a {
  1722  		if x != b[i] {
  1723  			return false
  1724  		}
  1725  	}
  1726  	return true
  1727  }
  1728  
  1729  // TestScopeLookupParent ensures that (*Scope).LookupParent returns
  1730  // the correct result at various positions with the source.
  1731  func TestScopeLookupParent(t *testing.T) {
  1732  	fset := token.NewFileSet()
  1733  	imports := make(testImporter)
  1734  	conf := Config{Importer: imports}
  1735  	mustParse := func(src string) *ast.File {
  1736  		f, err := parser.ParseFile(fset, "dummy.go", src, parser.ParseComments)
  1737  		if err != nil {
  1738  			t.Fatal(err)
  1739  		}
  1740  		return f
  1741  	}
  1742  	var info Info
  1743  	makePkg := func(path string, files ...*ast.File) {
  1744  		var err error
  1745  		imports[path], err = conf.Check(path, fset, files, &info)
  1746  		if err != nil {
  1747  			t.Fatal(err)
  1748  		}
  1749  	}
  1750  
  1751  	makePkg("lib", mustParse("package lib; var X int"))
  1752  	// Each /*name=kind:line*/ comment makes the test look up the
  1753  	// name at that point and checks that it resolves to a decl of
  1754  	// the specified kind and line number.  "undef" means undefined.
  1755  	mainSrc := `
  1756  /*lib=pkgname:5*/ /*X=var:1*/ /*Pi=const:8*/ /*T=typename:9*/ /*Y=var:10*/ /*F=func:12*/
  1757  package main
  1758  
  1759  import "lib"
  1760  import . "lib"
  1761  
  1762  const Pi = 3.1415
  1763  type T struct{}
  1764  var Y, _ = lib.X, X
  1765  
  1766  func F(){
  1767  	const pi, e = 3.1415, /*pi=undef*/ 2.71828 /*pi=const:13*/ /*e=const:13*/
  1768  	type /*t=undef*/ t /*t=typename:14*/ *t
  1769  	print(Y) /*Y=var:10*/
  1770  	x, Y := Y, /*x=undef*/ /*Y=var:10*/ Pi /*x=var:16*/ /*Y=var:16*/ ; _ = x; _ = Y
  1771  	var F = /*F=func:12*/ F /*F=var:17*/ ; _ = F
  1772  
  1773  	var a []int
  1774  	for i, x := range a /*i=undef*/ /*x=var:16*/ { _ = i; _ = x }
  1775  
  1776  	var i interface{}
  1777  	switch y := i.(type) { /*y=undef*/
  1778  	case /*y=undef*/ int /*y=var:23*/ :
  1779  	case float32, /*y=undef*/ float64 /*y=var:23*/ :
  1780  	default /*y=var:23*/:
  1781  		println(y)
  1782  	}
  1783  	/*y=undef*/
  1784  
  1785          switch int := i.(type) {
  1786          case /*int=typename:0*/ int /*int=var:31*/ :
  1787          	println(int)
  1788          default /*int=var:31*/ :
  1789          }
  1790  }
  1791  /*main=undef*/
  1792  `
  1793  
  1794  	info.Uses = make(map[*ast.Ident]Object)
  1795  	f := mustParse(mainSrc)
  1796  	makePkg("main", f)
  1797  	mainScope := imports["main"].Scope()
  1798  	rx := regexp.MustCompile(`^/\*(\w*)=([\w:]*)\*/$`)
  1799  	for _, group := range f.Comments {
  1800  		for _, comment := range group.List {
  1801  			// Parse the assertion in the comment.
  1802  			m := rx.FindStringSubmatch(comment.Text)
  1803  			if m == nil {
  1804  				t.Errorf("%s: bad comment: %s",
  1805  					fset.Position(comment.Pos()), comment.Text)
  1806  				continue
  1807  			}
  1808  			name, want := m[1], m[2]
  1809  
  1810  			// Look up the name in the innermost enclosing scope.
  1811  			inner := mainScope.Innermost(comment.Pos())
  1812  			if inner == nil {
  1813  				t.Errorf("%s: at %s: can't find innermost scope",
  1814  					fset.Position(comment.Pos()), comment.Text)
  1815  				continue
  1816  			}
  1817  			got := "undef"
  1818  			if _, obj := inner.LookupParent(name, comment.Pos()); obj != nil {
  1819  				kind := strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
  1820  				got = fmt.Sprintf("%s:%d", kind, fset.Position(obj.Pos()).Line)
  1821  			}
  1822  			if got != want {
  1823  				t.Errorf("%s: at %s: %s resolved to %s, want %s",
  1824  					fset.Position(comment.Pos()), comment.Text, name, got, want)
  1825  			}
  1826  		}
  1827  	}
  1828  
  1829  	// Check that for each referring identifier,
  1830  	// a lookup of its name on the innermost
  1831  	// enclosing scope returns the correct object.
  1832  
  1833  	for id, wantObj := range info.Uses {
  1834  		inner := mainScope.Innermost(id.Pos())
  1835  		if inner == nil {
  1836  			t.Errorf("%s: can't find innermost scope enclosing %q",
  1837  				fset.Position(id.Pos()), id.Name)
  1838  			continue
  1839  		}
  1840  
  1841  		// Exclude selectors and qualified identifiers---lexical
  1842  		// refs only.  (Ideally, we'd see if the AST parent is a
  1843  		// SelectorExpr, but that requires PathEnclosingInterval
  1844  		// from golang.org/x/tools/go/ast/astutil.)
  1845  		if id.Name == "X" {
  1846  			continue
  1847  		}
  1848  
  1849  		_, gotObj := inner.LookupParent(id.Name, id.Pos())
  1850  		if gotObj != wantObj {
  1851  			t.Errorf("%s: got %v, want %v",
  1852  				fset.Position(id.Pos()), gotObj, wantObj)
  1853  			continue
  1854  		}
  1855  	}
  1856  }
  1857  
  1858  // newDefined creates a new defined type named T with the given underlying type.
  1859  // Helper function for use with TestIncompleteInterfaces only.
  1860  func newDefined(underlying Type) *Named {
  1861  	tname := NewTypeName(token.NoPos, nil, "T", nil)
  1862  	return NewNamed(tname, underlying, nil)
  1863  }
  1864  
  1865  func TestConvertibleTo(t *testing.T) {
  1866  	for _, test := range []struct {
  1867  		v, t Type
  1868  		want bool
  1869  	}{
  1870  		{Typ[Int], Typ[Int], true},
  1871  		{Typ[Int], Typ[Float32], true},
  1872  		{Typ[Int], Typ[String], true},
  1873  		{newDefined(Typ[Int]), Typ[Int], true},
  1874  		{newDefined(new(Struct)), new(Struct), true},
  1875  		{newDefined(Typ[Int]), new(Struct), false},
  1876  		{Typ[UntypedInt], Typ[Int], true},
  1877  		{NewSlice(Typ[Int]), NewPointer(NewArray(Typ[Int], 10)), true},
  1878  		{NewSlice(Typ[Int]), NewArray(Typ[Int], 10), false},
  1879  		{NewSlice(Typ[Int]), NewPointer(NewArray(Typ[Uint], 10)), false},
  1880  		// Untyped string values are not permitted by the spec, so the behavior below is undefined.
  1881  		{Typ[UntypedString], Typ[String], true},
  1882  	} {
  1883  		if got := ConvertibleTo(test.v, test.t); got != test.want {
  1884  			t.Errorf("ConvertibleTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
  1885  		}
  1886  	}
  1887  }
  1888  
  1889  func TestAssignableTo(t *testing.T) {
  1890  	for _, test := range []struct {
  1891  		v, t Type
  1892  		want bool
  1893  	}{
  1894  		{Typ[Int], Typ[Int], true},
  1895  		{Typ[Int], Typ[Float32], false},
  1896  		{newDefined(Typ[Int]), Typ[Int], false},
  1897  		{newDefined(new(Struct)), new(Struct), true},
  1898  		{Typ[UntypedBool], Typ[Bool], true},
  1899  		{Typ[UntypedString], Typ[Bool], false},
  1900  		// Neither untyped string nor untyped numeric assignments arise during
  1901  		// normal type checking, so the below behavior is technically undefined by
  1902  		// the spec.
  1903  		{Typ[UntypedString], Typ[String], true},
  1904  		{Typ[UntypedInt], Typ[Int], true},
  1905  	} {
  1906  		if got := AssignableTo(test.v, test.t); got != test.want {
  1907  			t.Errorf("AssignableTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
  1908  		}
  1909  	}
  1910  }
  1911  
  1912  func TestIdentical(t *testing.T) {
  1913  	// For each test, we compare the types of objects X and Y in the source.
  1914  	tests := []struct {
  1915  		src  string
  1916  		want bool
  1917  	}{
  1918  		// Basic types.
  1919  		{"var X int; var Y int", true},
  1920  		{"var X int; var Y string", false},
  1921  
  1922  		// TODO: add more tests for complex types.
  1923  
  1924  		// Named types.
  1925  		{"type X int; type Y int", false},
  1926  
  1927  		// Aliases.
  1928  		{"type X = int; type Y = int", true},
  1929  
  1930  		// Functions.
  1931  		{`func X(int) string { return "" }; func Y(int) string { return "" }`, true},
  1932  		{`func X() string { return "" }; func Y(int) string { return "" }`, false},
  1933  		{`func X(int) string { return "" }; func Y(int) {}`, false},
  1934  
  1935  		// Generic functions. Type parameters should be considered identical modulo
  1936  		// renaming. See also issue #49722.
  1937  		{`func X[P ~int](){}; func Y[Q ~int]() {}`, true},
  1938  		{`func X[P1 any, P2 ~*P1](){}; func Y[Q1 any, Q2 ~*Q1]() {}`, true},
  1939  		{`func X[P1 any, P2 ~[]P1](){}; func Y[Q1 any, Q2 ~*Q1]() {}`, false},
  1940  		{`func X[P ~int](P){}; func Y[Q ~int](Q) {}`, true},
  1941  		{`func X[P ~string](P){}; func Y[Q ~int](Q) {}`, false},
  1942  		{`func X[P ~int]([]P){}; func Y[Q ~int]([]Q) {}`, true},
  1943  	}
  1944  
  1945  	for _, test := range tests {
  1946  		pkg, err := pkgForMode("test", "package p;"+test.src, nil, 0)
  1947  		if err != nil {
  1948  			t.Errorf("%s: incorrect test case: %s", test.src, err)
  1949  			continue
  1950  		}
  1951  		X := pkg.Scope().Lookup("X")
  1952  		Y := pkg.Scope().Lookup("Y")
  1953  		if X == nil || Y == nil {
  1954  			t.Fatal("test must declare both X and Y")
  1955  		}
  1956  		if got := Identical(X.Type(), Y.Type()); got != test.want {
  1957  			t.Errorf("Identical(%s, %s) = %t, want %t", X.Type(), Y.Type(), got, test.want)
  1958  		}
  1959  	}
  1960  }
  1961  
  1962  func TestIdentical_issue15173(t *testing.T) {
  1963  	// Identical should allow nil arguments and be symmetric.
  1964  	for _, test := range []struct {
  1965  		x, y Type
  1966  		want bool
  1967  	}{
  1968  		{Typ[Int], Typ[Int], true},
  1969  		{Typ[Int], nil, false},
  1970  		{nil, Typ[Int], false},
  1971  		{nil, nil, true},
  1972  	} {
  1973  		if got := Identical(test.x, test.y); got != test.want {
  1974  			t.Errorf("Identical(%v, %v) = %t", test.x, test.y, got)
  1975  		}
  1976  	}
  1977  }
  1978  
  1979  func TestIdenticalUnions(t *testing.T) {
  1980  	tname := NewTypeName(token.NoPos, nil, "myInt", nil)
  1981  	myInt := NewNamed(tname, Typ[Int], nil)
  1982  	tmap := map[string]*Term{
  1983  		"int":     NewTerm(false, Typ[Int]),
  1984  		"~int":    NewTerm(true, Typ[Int]),
  1985  		"string":  NewTerm(false, Typ[String]),
  1986  		"~string": NewTerm(true, Typ[String]),
  1987  		"myInt":   NewTerm(false, myInt),
  1988  	}
  1989  	makeUnion := func(s string) *Union {
  1990  		parts := strings.Split(s, "|")
  1991  		var terms []*Term
  1992  		for _, p := range parts {
  1993  			term := tmap[p]
  1994  			if term == nil {
  1995  				t.Fatalf("missing term %q", p)
  1996  			}
  1997  			terms = append(terms, term)
  1998  		}
  1999  		return NewUnion(terms)
  2000  	}
  2001  	for _, test := range []struct {
  2002  		x, y string
  2003  		want bool
  2004  	}{
  2005  		// These tests are just sanity checks. The tests for type sets and
  2006  		// interfaces provide much more test coverage.
  2007  		{"int|~int", "~int", true},
  2008  		{"myInt|~int", "~int", true},
  2009  		{"int|string", "string|int", true},
  2010  		{"int|int|string", "string|int", true},
  2011  		{"myInt|string", "int|string", false},
  2012  	} {
  2013  		x := makeUnion(test.x)
  2014  		y := makeUnion(test.y)
  2015  		if got := Identical(x, y); got != test.want {
  2016  			t.Errorf("Identical(%v, %v) = %t", test.x, test.y, got)
  2017  		}
  2018  	}
  2019  }
  2020  
  2021  func TestIssue15305(t *testing.T) {
  2022  	const src = "package p; func f() int16; var _ = f(undef)"
  2023  	fset := token.NewFileSet()
  2024  	f, err := parser.ParseFile(fset, "issue15305.go", src, 0)
  2025  	if err != nil {
  2026  		t.Fatal(err)
  2027  	}
  2028  	conf := Config{
  2029  		Error: func(err error) {}, // allow errors
  2030  	}
  2031  	info := &Info{
  2032  		Types: make(map[ast.Expr]TypeAndValue),
  2033  	}
  2034  	conf.Check("p", fset, []*ast.File{f}, info) // ignore result
  2035  	for e, tv := range info.Types {
  2036  		if _, ok := e.(*ast.CallExpr); ok {
  2037  			if tv.Type != Typ[Int16] {
  2038  				t.Errorf("CallExpr has type %v, want int16", tv.Type)
  2039  			}
  2040  			return
  2041  		}
  2042  	}
  2043  	t.Errorf("CallExpr has no type")
  2044  }
  2045  
  2046  // TestCompositeLitTypes verifies that Info.Types registers the correct
  2047  // types for composite literal expressions and composite literal type
  2048  // expressions.
  2049  func TestCompositeLitTypes(t *testing.T) {
  2050  	for _, test := range []struct {
  2051  		lit, typ string
  2052  	}{
  2053  		{`[16]byte{}`, `[16]byte`},
  2054  		{`[...]byte{}`, `[0]byte`},                // test for issue #14092
  2055  		{`[...]int{1, 2, 3}`, `[3]int`},           // test for issue #14092
  2056  		{`[...]int{90: 0, 98: 1, 2}`, `[100]int`}, // test for issue #14092
  2057  		{`[]int{}`, `[]int`},
  2058  		{`map[string]bool{"foo": true}`, `map[string]bool`},
  2059  		{`struct{}{}`, `struct{}`},
  2060  		{`struct{x, y int; z complex128}{}`, `struct{x int; y int; z complex128}`},
  2061  	} {
  2062  		fset := token.NewFileSet()
  2063  		f, err := parser.ParseFile(fset, test.lit, "package p; var _ = "+test.lit, 0)
  2064  		if err != nil {
  2065  			t.Fatalf("%s: %v", test.lit, err)
  2066  		}
  2067  
  2068  		info := &Info{
  2069  			Types: make(map[ast.Expr]TypeAndValue),
  2070  		}
  2071  		if _, err = new(Config).Check("p", fset, []*ast.File{f}, info); err != nil {
  2072  			t.Fatalf("%s: %v", test.lit, err)
  2073  		}
  2074  
  2075  		cmptype := func(x ast.Expr, want string) {
  2076  			tv, ok := info.Types[x]
  2077  			if !ok {
  2078  				t.Errorf("%s: no Types entry found", test.lit)
  2079  				return
  2080  			}
  2081  			if tv.Type == nil {
  2082  				t.Errorf("%s: type is nil", test.lit)
  2083  				return
  2084  			}
  2085  			if got := tv.Type.String(); got != want {
  2086  				t.Errorf("%s: got %v, want %s", test.lit, got, want)
  2087  			}
  2088  		}
  2089  
  2090  		// test type of composite literal expression
  2091  		rhs := f.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Values[0]
  2092  		cmptype(rhs, test.typ)
  2093  
  2094  		// test type of composite literal type expression
  2095  		cmptype(rhs.(*ast.CompositeLit).Type, test.typ)
  2096  	}
  2097  }
  2098  
  2099  // TestObjectParents verifies that objects have parent scopes or not
  2100  // as specified by the Object interface.
  2101  func TestObjectParents(t *testing.T) {
  2102  	const src = `
  2103  package p
  2104  
  2105  const C = 0
  2106  
  2107  type T1 struct {
  2108  	a, b int
  2109  	T2
  2110  }
  2111  
  2112  type T2 interface {
  2113  	im1()
  2114  	im2()
  2115  }
  2116  
  2117  func (T1) m1() {}
  2118  func (*T1) m2() {}
  2119  
  2120  func f(x int) { y := x; print(y) }
  2121  `
  2122  
  2123  	fset := token.NewFileSet()
  2124  	f, err := parser.ParseFile(fset, "src", src, 0)
  2125  	if err != nil {
  2126  		t.Fatal(err)
  2127  	}
  2128  
  2129  	info := &Info{
  2130  		Defs: make(map[*ast.Ident]Object),
  2131  	}
  2132  	if _, err = new(Config).Check("p", fset, []*ast.File{f}, info); err != nil {
  2133  		t.Fatal(err)
  2134  	}
  2135  
  2136  	for ident, obj := range info.Defs {
  2137  		if obj == nil {
  2138  			// only package names and implicit vars have a nil object
  2139  			// (in this test we only need to handle the package name)
  2140  			if ident.Name != "p" {
  2141  				t.Errorf("%v has nil object", ident)
  2142  			}
  2143  			continue
  2144  		}
  2145  
  2146  		// struct fields, type-associated and interface methods
  2147  		// have no parent scope
  2148  		wantParent := true
  2149  		switch obj := obj.(type) {
  2150  		case *Var:
  2151  			if obj.IsField() {
  2152  				wantParent = false
  2153  			}
  2154  		case *Func:
  2155  			if obj.Type().(*Signature).Recv() != nil { // method
  2156  				wantParent = false
  2157  			}
  2158  		}
  2159  
  2160  		gotParent := obj.Parent() != nil
  2161  		switch {
  2162  		case gotParent && !wantParent:
  2163  			t.Errorf("%v: want no parent, got %s", ident, obj.Parent())
  2164  		case !gotParent && wantParent:
  2165  			t.Errorf("%v: no parent found", ident)
  2166  		}
  2167  	}
  2168  }
  2169  
  2170  // TestFailedImport tests that we don't get follow-on errors
  2171  // elsewhere in a package due to failing to import a package.
  2172  func TestFailedImport(t *testing.T) {
  2173  	testenv.MustHaveGoBuild(t)
  2174  
  2175  	const src = `
  2176  package p
  2177  
  2178  import foo "go/types/thisdirectorymustnotexistotherwisethistestmayfail/foo" // should only see an error here
  2179  
  2180  const c = foo.C
  2181  type T = foo.T
  2182  var v T = c
  2183  func f(x T) T { return foo.F(x) }
  2184  `
  2185  	fset := token.NewFileSet()
  2186  	f, err := parser.ParseFile(fset, "src", src, 0)
  2187  	if err != nil {
  2188  		t.Fatal(err)
  2189  	}
  2190  	files := []*ast.File{f}
  2191  
  2192  	// type-check using all possible importers
  2193  	for _, compiler := range []string{"gc", "gccgo", "source"} {
  2194  		errcount := 0
  2195  		conf := Config{
  2196  			Error: func(err error) {
  2197  				// we should only see the import error
  2198  				if errcount > 0 || !strings.Contains(err.Error(), "could not import") {
  2199  					t.Errorf("for %s importer, got unexpected error: %v", compiler, err)
  2200  				}
  2201  				errcount++
  2202  			},
  2203  			Importer: importer.For(compiler, nil),
  2204  		}
  2205  
  2206  		info := &Info{
  2207  			Uses: make(map[*ast.Ident]Object),
  2208  		}
  2209  		pkg, _ := conf.Check("p", fset, files, info)
  2210  		if pkg == nil {
  2211  			t.Errorf("for %s importer, type-checking failed to return a package", compiler)
  2212  			continue
  2213  		}
  2214  
  2215  		imports := pkg.Imports()
  2216  		if len(imports) != 1 {
  2217  			t.Errorf("for %s importer, got %d imports, want 1", compiler, len(imports))
  2218  			continue
  2219  		}
  2220  		imp := imports[0]
  2221  		if imp.Name() != "foo" {
  2222  			t.Errorf(`for %s importer, got %q, want "foo"`, compiler, imp.Name())
  2223  			continue
  2224  		}
  2225  
  2226  		// verify that all uses of foo refer to the imported package foo (imp)
  2227  		for ident, obj := range info.Uses {
  2228  			if ident.Name == "foo" {
  2229  				if obj, ok := obj.(*PkgName); ok {
  2230  					if obj.Imported() != imp {
  2231  						t.Errorf("%s resolved to %v; want %v", ident, obj.Imported(), imp)
  2232  					}
  2233  				} else {
  2234  					t.Errorf("%s resolved to %v; want package name", ident, obj)
  2235  				}
  2236  			}
  2237  		}
  2238  	}
  2239  }
  2240  
  2241  func TestInstantiate(t *testing.T) {
  2242  	// eventually we like more tests but this is a start
  2243  	const src = "package p; type T[P any] *T[P]"
  2244  	pkg, err := pkgForMode(".", src, nil, 0)
  2245  	if err != nil {
  2246  		t.Fatal(err)
  2247  	}
  2248  
  2249  	// type T should have one type parameter
  2250  	T := pkg.Scope().Lookup("T").Type().(*Named)
  2251  	if n := T.TypeParams().Len(); n != 1 {
  2252  		t.Fatalf("expected 1 type parameter; found %d", n)
  2253  	}
  2254  
  2255  	// instantiation should succeed (no endless recursion)
  2256  	// even with a nil *Checker
  2257  	res, err := Instantiate(nil, T, []Type{Typ[Int]}, false)
  2258  	if err != nil {
  2259  		t.Fatal(err)
  2260  	}
  2261  
  2262  	// instantiated type should point to itself
  2263  	if p := res.Underlying().(*Pointer).Elem(); p != res {
  2264  		t.Fatalf("unexpected result type: %s points to %s", res, p)
  2265  	}
  2266  }
  2267  
  2268  func TestInstantiateErrors(t *testing.T) {
  2269  	tests := []struct {
  2270  		src    string // by convention, T must be the type being instantiated
  2271  		targs  []Type
  2272  		wantAt int // -1 indicates no error
  2273  	}{
  2274  		{"type T[P interface{~string}] int", []Type{Typ[Int]}, 0},
  2275  		{"type T[P1 interface{int}, P2 interface{~string}] int", []Type{Typ[Int], Typ[Int]}, 1},
  2276  		{"type T[P1 any, P2 interface{~[]P1}] int", []Type{Typ[Int], NewSlice(Typ[String])}, 1},
  2277  		{"type T[P1 interface{~[]P2}, P2 any] int", []Type{NewSlice(Typ[String]), Typ[Int]}, 0},
  2278  	}
  2279  
  2280  	for _, test := range tests {
  2281  		src := "package p; " + test.src
  2282  		pkg, err := pkgForMode(".", src, nil, 0)
  2283  		if err != nil {
  2284  			t.Fatal(err)
  2285  		}
  2286  
  2287  		T := pkg.Scope().Lookup("T").Type().(*Named)
  2288  
  2289  		_, err = Instantiate(nil, T, test.targs, true)
  2290  		if err == nil {
  2291  			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
  2292  		}
  2293  
  2294  		var argErr *ArgumentError
  2295  		if !errors.As(err, &argErr) {
  2296  			t.Fatalf("Instantiate(%v, %v): error is not an *ArgumentError", T, test.targs)
  2297  		}
  2298  
  2299  		if argErr.Index != test.wantAt {
  2300  			t.Errorf("Instantate(%v, %v): error at index %d, want index %d", T, test.targs, argErr.Index, test.wantAt)
  2301  		}
  2302  	}
  2303  }
  2304  
  2305  func TestArgumentErrorUnwrapping(t *testing.T) {
  2306  	var err error = &ArgumentError{
  2307  		Index: 1,
  2308  		Err:   Error{Msg: "test"},
  2309  	}
  2310  	var e Error
  2311  	if !errors.As(err, &e) {
  2312  		t.Fatalf("error %v does not wrap types.Error", err)
  2313  	}
  2314  	if e.Msg != "test" {
  2315  		t.Errorf("e.Msg = %q, want %q", e.Msg, "test")
  2316  	}
  2317  }
  2318  
  2319  func TestInstanceIdentity(t *testing.T) {
  2320  	imports := make(testImporter)
  2321  	conf := Config{Importer: imports}
  2322  	makePkg := func(src string) {
  2323  		fset := token.NewFileSet()
  2324  		f, err := parser.ParseFile(fset, "", src, 0)
  2325  		if err != nil {
  2326  			t.Fatal(err)
  2327  		}
  2328  		name := f.Name.Name
  2329  		pkg, err := conf.Check(name, fset, []*ast.File{f}, nil)
  2330  		if err != nil {
  2331  			t.Fatal(err)
  2332  		}
  2333  		imports[name] = pkg
  2334  	}
  2335  	makePkg(genericPkg + `lib; type T[P any] struct{}`)
  2336  	makePkg(genericPkg + `a; import "generic_lib"; var A generic_lib.T[int]`)
  2337  	makePkg(genericPkg + `b; import "generic_lib"; var B generic_lib.T[int]`)
  2338  	a := imports["generic_a"].Scope().Lookup("A")
  2339  	b := imports["generic_b"].Scope().Lookup("B")
  2340  	if !Identical(a.Type(), b.Type()) {
  2341  		t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
  2342  	}
  2343  }
  2344  
  2345  // TestInstantiatedObjects verifies properties of instantiated objects.
  2346  func TestInstantiatedObjects(t *testing.T) {
  2347  	const src = `
  2348  package p
  2349  
  2350  type T[P any] struct {
  2351  	field P
  2352  }
  2353  
  2354  func (recv *T[Q]) concreteMethod() {}
  2355  
  2356  type FT[P any] func(ftp P) (ftrp P)
  2357  
  2358  func F[P any](fp P) (frp P){ return }
  2359  
  2360  type I[P any] interface {
  2361  	interfaceMethod(P)
  2362  }
  2363  
  2364  var (
  2365  	t T[int]
  2366  	ft FT[int]
  2367  	f = F[int]
  2368  	i I[int]
  2369  )
  2370  `
  2371  	info := &Info{
  2372  		Defs: make(map[*ast.Ident]Object),
  2373  	}
  2374  	fset := token.NewFileSet()
  2375  	f, err := parser.ParseFile(fset, "p.go", src, 0)
  2376  	if err != nil {
  2377  		t.Fatal(err)
  2378  	}
  2379  	conf := Config{}
  2380  	pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
  2381  	if err != nil {
  2382  		t.Fatal(err)
  2383  	}
  2384  
  2385  	lookup := func(name string) Type { return pkg.Scope().Lookup(name).Type() }
  2386  	tests := []struct {
  2387  		name string
  2388  		obj  Object
  2389  	}{
  2390  		{"field", lookup("t").Underlying().(*Struct).Field(0)},
  2391  		{"concreteMethod", lookup("t").(*Named).Method(0)},
  2392  		{"recv", lookup("t").(*Named).Method(0).Type().(*Signature).Recv()},
  2393  		{"ftp", lookup("ft").Underlying().(*Signature).Params().At(0)},
  2394  		{"ftrp", lookup("ft").Underlying().(*Signature).Results().At(0)},
  2395  		{"fp", lookup("f").(*Signature).Params().At(0)},
  2396  		{"frp", lookup("f").(*Signature).Results().At(0)},
  2397  		{"interfaceMethod", lookup("i").Underlying().(*Interface).Method(0)},
  2398  	}
  2399  
  2400  	// Collect all identifiers by name.
  2401  	idents := make(map[string][]*ast.Ident)
  2402  	ast.Inspect(f, func(n ast.Node) bool {
  2403  		if id, ok := n.(*ast.Ident); ok {
  2404  			idents[id.Name] = append(idents[id.Name], id)
  2405  		}
  2406  		return true
  2407  	})
  2408  
  2409  	for _, test := range tests {
  2410  		test := test
  2411  		t.Run(test.name, func(t *testing.T) {
  2412  			if got := len(idents[test.name]); got != 1 {
  2413  				t.Fatalf("found %d identifiers named %s, want 1", got, test.name)
  2414  			}
  2415  			ident := idents[test.name][0]
  2416  			def := info.Defs[ident]
  2417  			if def == test.obj {
  2418  				t.Fatalf("info.Defs[%s] contains the test object", test.name)
  2419  			}
  2420  			if def.Pkg() != test.obj.Pkg() {
  2421  				t.Errorf("Pkg() = %v, want %v", def.Pkg(), test.obj.Pkg())
  2422  			}
  2423  			if def.Name() != test.obj.Name() {
  2424  				t.Errorf("Name() = %v, want %v", def.Name(), test.obj.Name())
  2425  			}
  2426  			if def.Pos() != test.obj.Pos() {
  2427  				t.Errorf("Pos() = %v, want %v", def.Pos(), test.obj.Pos())
  2428  			}
  2429  			if def.Parent() != test.obj.Parent() {
  2430  				t.Fatalf("Parent() = %v, want %v", def.Parent(), test.obj.Parent())
  2431  			}
  2432  			if def.Exported() != test.obj.Exported() {
  2433  				t.Fatalf("Exported() = %v, want %v", def.Exported(), test.obj.Exported())
  2434  			}
  2435  			if def.Id() != test.obj.Id() {
  2436  				t.Fatalf("Id() = %v, want %v", def.Id(), test.obj.Id())
  2437  			}
  2438  			// String and Type are expected to differ.
  2439  		})
  2440  	}
  2441  }
  2442  
  2443  func TestImplements(t *testing.T) {
  2444  	const src = `
  2445  package p
  2446  
  2447  type EmptyIface interface{}
  2448  
  2449  type I interface {
  2450  	m()
  2451  }
  2452  
  2453  type C interface {
  2454  	m()
  2455  	~int
  2456  }
  2457  
  2458  type Integer interface{
  2459  	int8 | int16 | int32 | int64
  2460  }
  2461  
  2462  type EmptyTypeSet interface{
  2463  	Integer
  2464  	~string
  2465  }
  2466  
  2467  type N1 int
  2468  func (N1) m() {}
  2469  
  2470  type N2 int
  2471  func (*N2) m() {}
  2472  
  2473  type N3 int
  2474  func (N3) m(int) {}
  2475  
  2476  type N4 string
  2477  func (N4) m()
  2478  
  2479  type Bad Bad // invalid type
  2480  `
  2481  
  2482  	fset := token.NewFileSet()
  2483  	f, err := parser.ParseFile(fset, "p.go", src, 0)
  2484  	if err != nil {
  2485  		t.Fatal(err)
  2486  	}
  2487  	conf := Config{Error: func(error) {}}
  2488  	pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
  2489  
  2490  	lookup := func(tname string) Type { return pkg.Scope().Lookup(tname).Type() }
  2491  	var (
  2492  		EmptyIface   = lookup("EmptyIface").Underlying().(*Interface)
  2493  		I            = lookup("I").(*Named)
  2494  		II           = I.Underlying().(*Interface)
  2495  		C            = lookup("C").(*Named)
  2496  		CI           = C.Underlying().(*Interface)
  2497  		Integer      = lookup("Integer").Underlying().(*Interface)
  2498  		EmptyTypeSet = lookup("EmptyTypeSet").Underlying().(*Interface)
  2499  		N1           = lookup("N1")
  2500  		N1p          = NewPointer(N1)
  2501  		N2           = lookup("N2")
  2502  		N2p          = NewPointer(N2)
  2503  		N3           = lookup("N3")
  2504  		N4           = lookup("N4")
  2505  		Bad          = lookup("Bad")
  2506  	)
  2507  
  2508  	tests := []struct {
  2509  		V    Type
  2510  		T    *Interface
  2511  		want bool
  2512  	}{
  2513  		{I, II, true},
  2514  		{I, CI, false},
  2515  		{C, II, true},
  2516  		{C, CI, true},
  2517  		{Typ[Int8], Integer, true},
  2518  		{Typ[Int64], Integer, true},
  2519  		{Typ[String], Integer, false},
  2520  		{EmptyTypeSet, II, true},
  2521  		{EmptyTypeSet, EmptyTypeSet, true},
  2522  		{Typ[Int], EmptyTypeSet, false},
  2523  		{N1, II, true},
  2524  		{N1, CI, true},
  2525  		{N1p, II, true},
  2526  		{N1p, CI, false},
  2527  		{N2, II, false},
  2528  		{N2, CI, false},
  2529  		{N2p, II, true},
  2530  		{N2p, CI, false},
  2531  		{N3, II, false},
  2532  		{N3, CI, false},
  2533  		{N4, II, true},
  2534  		{N4, CI, false},
  2535  		{Bad, II, false},
  2536  		{Bad, CI, false},
  2537  		{Bad, EmptyIface, true},
  2538  	}
  2539  
  2540  	for _, test := range tests {
  2541  		if got := Implements(test.V, test.T); got != test.want {
  2542  			t.Errorf("Implements(%s, %s) = %t, want %t", test.V, test.T, got, test.want)
  2543  		}
  2544  
  2545  		// The type assertion x.(T) is valid if T is an interface or if T implements the type of x.
  2546  		// The assertion is never valid if T is a bad type.
  2547  		V := test.T
  2548  		T := test.V
  2549  		want := false
  2550  		if _, ok := T.Underlying().(*Interface); (ok || Implements(T, V)) && T != Bad {
  2551  			want = true
  2552  		}
  2553  		if got := AssertableTo(V, T); got != want {
  2554  			t.Errorf("AssertableTo(%s, %s) = %t, want %t", V, T, got, want)
  2555  		}
  2556  	}
  2557  }
  2558  
  2559  func TestMissingMethodAlternative(t *testing.T) {
  2560  	const src = `
  2561  package p
  2562  type T interface {
  2563  	m()
  2564  }
  2565  
  2566  type V0 struct{}
  2567  func (V0) m() {}
  2568  
  2569  type V1 struct{}
  2570  
  2571  type V2 struct{}
  2572  func (V2) m() int
  2573  
  2574  type V3 struct{}
  2575  func (*V3) m()
  2576  
  2577  type V4 struct{}
  2578  func (V4) M()
  2579  `
  2580  
  2581  	pkg, err := pkgFor("p.go", src, nil)
  2582  	if err != nil {
  2583  		t.Fatal(err)
  2584  	}
  2585  
  2586  	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
  2587  	lookup := func(name string) (*Func, bool) {
  2588  		return MissingMethod(pkg.Scope().Lookup(name).Type(), T, true)
  2589  	}
  2590  
  2591  	// V0 has method m with correct signature. Should not report wrongType.
  2592  	method, wrongType := lookup("V0")
  2593  	if method != nil || wrongType {
  2594  		t.Fatalf("V0: got method = %v, wrongType = %v", method, wrongType)
  2595  	}
  2596  
  2597  	checkMissingMethod := func(tname string, reportWrongType bool) {
  2598  		method, wrongType := lookup(tname)
  2599  		if method == nil || method.Name() != "m" || wrongType != reportWrongType {
  2600  			t.Fatalf("%s: got method = %v, wrongType = %v", tname, method, wrongType)
  2601  		}
  2602  	}
  2603  
  2604  	// V1 has no method m. Should not report wrongType.
  2605  	checkMissingMethod("V1", false)
  2606  
  2607  	// V2 has method m with wrong signature type (ignoring receiver). Should report wrongType.
  2608  	checkMissingMethod("V2", true)
  2609  
  2610  	// V3 has no method m but it exists on *V3. Should report wrongType.
  2611  	checkMissingMethod("V3", true)
  2612  
  2613  	// V4 has no method m but has M. Should not report wrongType.
  2614  	checkMissingMethod("V4", false)
  2615  }
  2616  

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