From: Robert Griesemer <gri@golang.org>
Date: Wed, 19 Apr 2023 22:34:49 +0000 (-0700)
Subject: go/types, types2: extract package name from test sources automatically
X-Git-Tag: go1.21rc1~749
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=c9b0d8b61ef222b151206546b5d56c1cbe0d3449;p=gostls13.git

go/types, types2: extract package name from test sources automatically

This simplifies explicit tests and ensures that the error messages
contain the package name instead of a generic file name like "p.go".

Fixes #59736.

Change-Id: I1b42e30f53ba88456e92f990d80ca68ffc987e20
Reviewed-on: https://go-review.googlesource.com/c/go/+/486617
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
---

diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index dcd4d72328..0e76a73699 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -21,21 +21,21 @@ import (
 // nopos indicates an unknown position
 var nopos syntax.Pos
 
-func parse(path, src string) (*syntax.File, error) {
+func parse(src string) (*syntax.File, error) {
 	errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
-	return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, 0)
+	return syntax.Parse(syntax.NewFileBase(pkgName(src)), strings.NewReader(src), errh, nil, 0)
 }
 
-func mustParse(path, src string) *syntax.File {
-	f, err := parse(path, src)
+func mustParse(src string) *syntax.File {
+	f, err := parse(src)
 	if err != nil {
 		panic(err) // so we don't need to pass *testing.T
 	}
 	return f
 }
 
-func typecheck(path, src string, conf *Config, info *Info) (*Package, error) {
-	f, err := parse(path, src)
+func typecheck(src string, conf *Config, info *Info) (*Package, error) {
+	f, err := parse(src)
 	if f == nil { // ignore errors unless f is nil
 		return nil, err
 	}
@@ -48,8 +48,8 @@ func typecheck(path, src string, conf *Config, info *Info) (*Package, error) {
 	return conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
 }
 
-func mustTypecheck(path, src string, conf *Config, info *Info) *Package {
-	f := mustParse(path, src)
+func mustTypecheck(src string, conf *Config, info *Info) *Package {
+	f := mustParse(src)
 	if conf == nil {
 		conf = &Config{
 			Importer: defaultImporter(),
@@ -62,6 +62,20 @@ func mustTypecheck(path, src string, conf *Config, info *Info) *Package {
 	return pkg
 }
 
+// pkgName extracts the package name from src, which must contain a package header.
+func pkgName(src string) string {
+	const kw = "package "
+	if i := strings.Index(src, kw); i >= 0 {
+		after := src[i+len(kw):]
+		n := len(after)
+		if i := strings.IndexAny(after, "\n\t ;/"); i >= 0 {
+			n = i
+		}
+		return after[:n]
+	}
+	panic("missing package header: " + src)
+}
+
 func TestValuesInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -145,7 +159,7 @@ func TestValuesInfo(t *testing.T) {
 		info := Info{
 			Types: make(map[syntax.Expr]TypeAndValue),
 		}
-		name := mustTypecheck("ValuesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// look for expression
 		var expr syntax.Expr
@@ -387,7 +401,7 @@ func TestTypesInfo(t *testing.T) {
 		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, brokenPkg) {
-			pkg, err := typecheck("TypesInfo", test.src, nil, &info)
+			pkg, err := typecheck(test.src, nil, &info)
 			if err == nil {
 				t.Errorf("package %s: expected to fail but passed", pkg.Name())
 				continue
@@ -396,7 +410,7 @@ func TestTypesInfo(t *testing.T) {
 				name = pkg.Name()
 			}
 		} else {
-			name = mustTypecheck("TypesInfo", test.src, nil, &info).Name()
+			name = mustTypecheck(test.src, nil, &info).Name()
 		}
 
 		// look for expression type
@@ -561,7 +575,7 @@ type T[P any] []P
 		instMap := make(map[*syntax.Name]Instance)
 		useMap := make(map[*syntax.Name]Object)
 		makePkg := func(src string) *Package {
-			pkg, _ := typecheck("p.go", src, &conf, &Info{Instances: instMap, Uses: useMap})
+			pkg, _ := typecheck(src, &conf, &Info{Instances: instMap, Uses: useMap})
 			imports[pkg.Name()] = pkg
 			return pkg
 		}
@@ -657,7 +671,7 @@ func TestDefsInfo(t *testing.T) {
 		info := Info{
 			Defs: make(map[*syntax.Name]Object),
 		}
-		name := mustTypecheck("DefsInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// find object
 		var def Object
@@ -722,7 +736,7 @@ func TestUsesInfo(t *testing.T) {
 		info := Info{
 			Uses: make(map[*syntax.Name]Object),
 		}
-		name := mustTypecheck("UsesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// find object
 		var use Object
@@ -754,7 +768,7 @@ func (r N[B]) m() { r.m(); r.n() }
 
 func (r *N[C]) n() {  }
 `
-	f := mustParse("p.go", src)
+	f := mustParse(src)
 	info := Info{
 		Defs:       make(map[*syntax.Name]Object),
 		Uses:       make(map[*syntax.Name]Object),
@@ -862,7 +876,7 @@ func TestImplicitsInfo(t *testing.T) {
 		info := Info{
 			Implicits: make(map[syntax.Node]Object),
 		}
-		name := mustTypecheck("ImplicitsInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// the test cases expect at most one Implicits entry
 		if len(info.Implicits) > 1 {
@@ -990,7 +1004,7 @@ func TestPredicatesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
-		name := mustTypecheck("PredicatesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// look for expression predicates
 		got := "<missing>"
@@ -1082,7 +1096,7 @@ func TestScopesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Scopes: make(map[syntax.Node]*Scope)}
-		name := mustTypecheck("ScopesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// number of scopes must match
 		if len(info.Scopes) != len(test.scopes) {
@@ -1270,7 +1284,7 @@ func TestInitOrderInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{}
-		name := mustTypecheck("InitOrderInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// number of initializers must match
 		if len(info.InitOrder) != len(test.inits) {
@@ -1290,8 +1304,8 @@ func TestInitOrderInfo(t *testing.T) {
 }
 
 func TestMultiFileInitOrder(t *testing.T) {
-	fileA := mustParse("", `package main; var a = 1`)
-	fileB := mustParse("", `package main; var b = 2`)
+	fileA := mustParse(`package main; var a = 1`)
+	fileB := mustParse(`package main; var b = 2`)
 
 	// The initialization order must not depend on the parse
 	// order of the files, only on the presentation order to
@@ -1326,10 +1340,8 @@ func TestFiles(t *testing.T) {
 	var info Info
 	check := NewChecker(&conf, pkg, &info)
 
-	for i, src := range sources {
-		filename := fmt.Sprintf("sources%d", i)
-		f := mustParse(filename, src)
-		if err := check.Files([]*syntax.File{f}); err != nil {
+	for _, src := range sources {
+		if err := check.Files([]*syntax.File{mustParse(src)}); err != nil {
 			t.Error(err)
 		}
 	}
@@ -1361,7 +1373,7 @@ func TestSelection(t *testing.T) {
 	imports := make(testImporter)
 	conf := Config{Importer: imports}
 	makePkg := func(path, src string) {
-		pkg := mustTypecheck(path, src, &conf, &Info{Selections: selections})
+		pkg := mustTypecheck(src, &conf, &Info{Selections: selections})
 		imports[path] = pkg
 	}
 
@@ -1547,9 +1559,7 @@ func TestIssue8518(t *testing.T) {
 		Importer: imports,
 	}
 	makePkg := func(path, src string) {
-		f := mustParse(path, src)
-		pkg, _ := conf.Check(path, []*syntax.File{f}, nil) // errors logged via conf.Error
-		imports[path] = pkg
+		imports[path], _ = conf.Check(path, []*syntax.File{mustParse(src)}, nil) // errors logged via conf.Error
 	}
 
 	const libSrc = `
@@ -1577,9 +1587,7 @@ func TestIssue59603(t *testing.T) {
 		Importer: imports,
 	}
 	makePkg := func(path, src string) {
-		f := mustParse(path, src)
-		pkg, _ := conf.Check(path, []*syntax.File{f}, nil) // errors logged via conf.Error
-		imports[path] = pkg
+		imports[path], _ = conf.Check(path, []*syntax.File{mustParse(src)}, nil) // errors logged via conf.Error
 	}
 
 	const libSrc = `
@@ -1662,7 +1670,7 @@ func TestLookupFieldOrMethod(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck("test", "package p;"+test.src, nil, nil)
+		pkg := mustTypecheck("package p;"+test.src, nil, nil)
 
 		obj := pkg.Scope().Lookup("a")
 		if obj == nil {
@@ -1707,7 +1715,7 @@ type Node[T any] struct {
 type Instance = *Tree[int]
 `
 
-	f := mustParse("foo.go", src)
+	f := mustParse(src)
 	pkg := NewPackage("pkg", f.PkgName.Value)
 	if err := NewChecker(nil, pkg, nil).Files([]*syntax.File{f}); err != nil {
 		panic(err)
@@ -1736,9 +1744,8 @@ func TestScopeLookupParent(t *testing.T) {
 	conf := Config{Importer: imports}
 	var info Info
 	makePkg := func(path, src string) {
-		f := mustParse(path, src)
 		var err error
-		imports[path], err = conf.Check(path, []*syntax.File{f}, &info)
+		imports[path], err = conf.Check(path, []*syntax.File{mustParse(src)}, &info)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1942,7 +1949,7 @@ func TestIdentical(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck("test", "package p;"+test.src, nil, nil)
+		pkg := mustTypecheck("package p;"+test.src, nil, nil)
 		X := pkg.Scope().Lookup("X")
 		Y := pkg.Scope().Lookup("Y")
 		if X == nil || Y == nil {
@@ -2015,7 +2022,7 @@ func TestIdenticalUnions(t *testing.T) {
 
 func TestIssue15305(t *testing.T) {
 	const src = "package p; func f() int16; var _ = f(undef)"
-	f := mustParse("issue15305.go", src)
+	f := mustParse(src)
 	conf := Config{
 		Error: func(err error) {}, // allow errors
 	}
@@ -2038,7 +2045,7 @@ func TestIssue15305(t *testing.T) {
 // types for composite literal expressions and composite literal type
 // expressions.
 func TestCompositeLitTypes(t *testing.T) {
-	for _, test := range []struct {
+	for i, test := range []struct {
 		lit, typ string
 	}{
 		{`[16]byte{}`, `[16]byte`},
@@ -2050,7 +2057,7 @@ func TestCompositeLitTypes(t *testing.T) {
 		{`struct{}{}`, `struct{}`},
 		{`struct{x, y int; z complex128}{}`, `struct{x int; y int; z complex128}`},
 	} {
-		f := mustParse(test.lit, "package p; var _ = "+test.lit)
+		f := mustParse(fmt.Sprintf("package p%d; var _ = %s", i, test.lit))
 		types := make(map[syntax.Expr]TypeAndValue)
 		if _, err := new(Config).Check("p", []*syntax.File{f}, &Info{Types: types}); err != nil {
 			t.Fatalf("%s: %v", test.lit, err)
@@ -2104,7 +2111,7 @@ func (*T1) m2() {}
 func f(x int) { y := x; print(y) }
 `
 
-	f := mustParse("src", src)
+	f := mustParse(src)
 
 	info := &Info{
 		Defs: make(map[*syntax.Name]Object),
@@ -2162,7 +2169,7 @@ type T = foo.T
 var v T = c
 func f(x T) T { return foo.F(x) }
 `
-	f := mustParse("src", src)
+	f := mustParse(src)
 	files := []*syntax.File{f}
 
 	// type-check using all possible importers
@@ -2217,7 +2224,7 @@ func f(x T) T { return foo.F(x) }
 func TestInstantiate(t *testing.T) {
 	// eventually we like more tests but this is a start
 	const src = "package p; type T[P any] *T[P]"
-	pkg := mustTypecheck(".", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	// type T should have one type parameter
 	T := pkg.Scope().Lookup("T").Type().(*Named)
@@ -2252,7 +2259,7 @@ func TestInstantiateErrors(t *testing.T) {
 
 	for _, test := range tests {
 		src := "package p; " + test.src
-		pkg := mustTypecheck(".", src, nil, nil)
+		pkg := mustTypecheck(src, nil, nil)
 
 		T := pkg.Scope().Lookup("T").Type().(*Named)
 
@@ -2290,7 +2297,7 @@ func TestInstanceIdentity(t *testing.T) {
 	imports := make(testImporter)
 	conf := Config{Importer: imports}
 	makePkg := func(src string) {
-		f := mustParse("", src)
+		f := mustParse(src)
 		name := f.PkgName.Value
 		pkg, err := conf.Check(name, []*syntax.File{f}, nil)
 		if err != nil {
@@ -2346,7 +2353,7 @@ func fn() {
 	info := &Info{
 		Defs: make(map[*syntax.Name]Object),
 	}
-	f := mustParse("p.go", src)
+	f := mustParse(src)
 	conf := Config{}
 	pkg, err := conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
 	if err != nil {
@@ -2477,7 +2484,7 @@ func (N4) m()
 type Bad Bad // invalid type
 `
 
-	f := mustParse("p.go", src)
+	f := mustParse(src)
 	conf := Config{Error: func(error) {}}
 	pkg, _ := conf.Check(f.PkgName.Value, []*syntax.File{f}, nil)
 
@@ -2572,7 +2579,7 @@ type V4 struct{}
 func (V4) M()
 `
 
-	pkg := mustTypecheck("p.go", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
 	lookup := func(name string) (*Func, bool) {
diff --git a/src/cmd/compile/internal/types2/builtins_test.go b/src/cmd/compile/internal/types2/builtins_test.go
index 863aa95680..1066a91c61 100644
--- a/src/cmd/compile/internal/types2/builtins_test.go
+++ b/src/cmd/compile/internal/types2/builtins_test.go
@@ -174,7 +174,7 @@ func testBuiltinSignature(t *testing.T, name, src0, want string) {
 
 	uses := make(map[*syntax.Name]Object)
 	types := make(map[syntax.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Uses: uses, Types: types})
+	mustTypecheck(src, nil, &Info{Uses: uses, Types: types})
 
 	// find called function
 	n := 0
diff --git a/src/cmd/compile/internal/types2/example_test.go b/src/cmd/compile/internal/types2/example_test.go
index 3fcad04b77..7031fdb1ad 100644
--- a/src/cmd/compile/internal/types2/example_test.go
+++ b/src/cmd/compile/internal/types2/example_test.go
@@ -30,25 +30,23 @@ import (
 func ExampleScope() {
 	// Parse the source files for a package.
 	var files []*syntax.File
-	for _, file := range []struct{ name, input string }{
-		{"main.go", `
-package main
+	for _, src := range []string{
+		`package main
 import "fmt"
 func main() {
 	freezing := FToC(-18)
 	fmt.Println(freezing, Boiling) }
-`},
-		{"celsius.go", `
-package main
+`,
+		`package main
 import "fmt"
 type Celsius float64
 func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
 func FToC(f float64) Celsius { return Celsius(f - 32 / 9 * 5) }
 const Boiling Celsius = 100
 func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get printed
-`},
+`,
 	} {
-		files = append(files, mustParse(file.name, file.input))
+		files = append(files, mustParse(src))
 	}
 
 	// Type-check a package consisting of these files.
@@ -74,13 +72,13 @@ func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get
 	// .  func temperature.FToC(f float64) temperature.Celsius
 	// .  func temperature.Unused()
 	// .  func temperature.main()
-	// .  main.go scope {
+	// .  main scope {
 	// .  .  package fmt
 	// .  .  function scope {
 	// .  .  .  var freezing temperature.Celsius
 	// .  .  }
 	// .  }
-	// .  celsius.go scope {
+	// .  main scope {
 	// .  .  package fmt
 	// .  .  function scope {
 	// .  .  .  var c temperature.Celsius
@@ -127,7 +125,7 @@ func fib(x int) int {
 		Defs:  make(map[*syntax.Name]types2.Object),
 		Uses:  make(map[*syntax.Name]types2.Object),
 	}
-	pkg := mustTypecheck("fib.go", input, nil, &info)
+	pkg := mustTypecheck(input, nil, &info)
 
 	// Print package-level variables in initialization order.
 	fmt.Printf("InitOrder: %v\n\n", info.InitOrder)
@@ -181,10 +179,10 @@ func fib(x int) int {
 	//   defined at <unknown position>
 	//   used at 6:15
 	// func fib(x int) int:
-	//   defined at fib.go:8:6
+	//   defined at fib:8:6
 	//   used at 12:20, 12:9
 	// type S string:
-	//   defined at fib.go:4:6
+	//   defined at fib:4:6
 	//   used at 6:23
 	// type int:
 	//   defined at <unknown position>
@@ -193,13 +191,13 @@ func fib(x int) int {
 	//   defined at <unknown position>
 	//   used at 4:8
 	// var b S:
-	//   defined at fib.go:6:8
+	//   defined at fib:6:8
 	//   used at 6:19
 	// var c string:
-	//   defined at fib.go:6:11
+	//   defined at fib:6:11
 	//   used at 6:25
 	// var x int:
-	//   defined at fib.go:8:10
+	//   defined at fib:8:10
 	//   used at 10:10, 12:13, 12:24, 9:5
 }
 
diff --git a/src/cmd/compile/internal/types2/hilbert_test.go b/src/cmd/compile/internal/types2/hilbert_test.go
index 8b7ceb3c97..5b2b087820 100644
--- a/src/cmd/compile/internal/types2/hilbert_test.go
+++ b/src/cmd/compile/internal/types2/hilbert_test.go
@@ -25,7 +25,7 @@ func TestHilbert(t *testing.T) {
 		return
 	}
 
-	mustTypecheck("hilbert.go", string(src), nil, nil)
+	mustTypecheck(string(src), nil, nil)
 }
 
 func program(n int, out string) []byte {
diff --git a/src/cmd/compile/internal/types2/instantiate_test.go b/src/cmd/compile/internal/types2/instantiate_test.go
index e809d17de1..af772b993c 100644
--- a/src/cmd/compile/internal/types2/instantiate_test.go
+++ b/src/cmd/compile/internal/types2/instantiate_test.go
@@ -107,7 +107,7 @@ func TestInstantiateEquality(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck(".", test.src, nil, nil)
+		pkg := mustTypecheck(test.src, nil, nil)
 
 		t.Run(pkg.Name(), func(t *testing.T) {
 			ctxt := NewContext()
@@ -133,8 +133,8 @@ func TestInstantiateEquality(t *testing.T) {
 
 func TestInstantiateNonEquality(t *testing.T) {
 	const src = "package p; type T[P any] int"
-	pkg1 := mustTypecheck(".", src, nil, nil)
-	pkg2 := mustTypecheck(".", src, nil, nil)
+	pkg1 := mustTypecheck(src, nil, nil)
+	pkg2 := mustTypecheck(src, nil, nil)
 	// We consider T1 and T2 to be distinct types, so their instances should not
 	// be deduplicated by the context.
 	T1 := pkg1.Scope().Lookup("T").Type().(*Named)
@@ -179,7 +179,7 @@ var X T[int]
 
 	for _, test := range tests {
 		src := prefix + test.decl
-		pkg := mustTypecheck(".", src, nil, nil)
+		pkg := mustTypecheck(src, nil, nil)
 		typ := NewPointer(pkg.Scope().Lookup("X").Type())
 		obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 		m, _ := obj.(*Func)
@@ -201,7 +201,7 @@ func (T[P]) m() {}
 
 var _ T[int]
 `
-	pkg := mustTypecheck(".", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 	typ := pkg.Scope().Lookup("T").Type().(*Named)
 	obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 	if obj == nil {
diff --git a/src/cmd/compile/internal/types2/issues_test.go b/src/cmd/compile/internal/types2/issues_test.go
index c7b63a1e68..e3e295e079 100644
--- a/src/cmd/compile/internal/types2/issues_test.go
+++ b/src/cmd/compile/internal/types2/issues_test.go
@@ -19,7 +19,7 @@ import (
 )
 
 func TestIssue5770(t *testing.T) {
-	_, err := typecheck("p", `package p; type S struct{T}`, nil, nil)
+	_, err := typecheck(`package p; type S struct{T}`, nil, nil)
 	const want = "undefined: T"
 	if err == nil || !strings.Contains(err.Error(), want) {
 		t.Errorf("got: %v; want: %s", err, want)
@@ -39,7 +39,7 @@ var (
 	_ = (interface{})(nil)
 )`
 	types := make(map[syntax.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Types: types})
+	mustTypecheck(src, nil, &Info{Types: types})
 
 	for x, tv := range types {
 		var want Type
@@ -78,7 +78,7 @@ func f() int {
 }
 `
 	types := make(map[syntax.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Types: types})
+	mustTypecheck(src, nil, &Info{Types: types})
 
 	want := Typ[Int]
 	n := 0
@@ -102,7 +102,7 @@ package p
 func (T) m() (res bool) { return }
 type T struct{} // receiver type after method declaration
 `
-	f := mustParse("", src)
+	f := mustParse(src)
 
 	var conf Config
 	defs := make(map[*syntax.Name]Object)
@@ -148,7 +148,7 @@ L7 uses var z int`
 	conf := Config{Error: func(err error) { t.Log(err) }}
 	defs := make(map[*syntax.Name]Object)
 	uses := make(map[*syntax.Name]Object)
-	_, err := typecheck("p", src, &conf, &Info{Defs: defs, Uses: uses})
+	_, err := typecheck(src, &conf, &Info{Defs: defs, Uses: uses})
 	if s := err.Error(); !strings.HasSuffix(s, "cannot assign to w") {
 		t.Errorf("Check: unexpected error: %s", s)
 	}
@@ -228,7 +228,7 @@ func main() {
 `
 	f := func(test, src string) {
 		info := &Info{Uses: make(map[*syntax.Name]Object)}
-		mustTypecheck("main", src, nil, info)
+		mustTypecheck(src, nil, info)
 
 		var pkg *Package
 		count := 0
@@ -256,13 +256,13 @@ func TestIssue22525(t *testing.T) {
 
 	got := "\n"
 	conf := Config{Error: func(err error) { got += err.Error() + "\n" }}
-	typecheck("", src, &conf, nil) // do not crash
+	typecheck(src, &conf, nil) // do not crash
 	want := `
-:1:27: a declared and not used
-:1:30: b declared and not used
-:1:33: c declared and not used
-:1:36: d declared and not used
-:1:39: e declared and not used
+p:1:27: a declared and not used
+p:1:30: b declared and not used
+p:1:33: c declared and not used
+p:1:36: d declared and not used
+p:1:39: e declared and not used
 `
 	if got != want {
 		t.Errorf("got: %swant: %s", got, want)
@@ -282,7 +282,7 @@ func TestIssue25627(t *testing.T) {
 		`struct { *I }`,
 		`struct { a int; b Missing; *Missing }`,
 	} {
-		f := mustParse("", prefix+src)
+		f := mustParse(prefix + src)
 
 		conf := Config{Importer: defaultImporter(), Error: func(err error) {}}
 		info := &Info{Types: make(map[syntax.Expr]TypeAndValue)}
@@ -319,7 +319,7 @@ func TestIssue28005(t *testing.T) {
 	// compute original file ASTs
 	var orig [len(sources)]*syntax.File
 	for i, src := range sources {
-		orig[i] = mustParse("", src)
+		orig[i] = mustParse(src)
 	}
 
 	// run the test for all order permutations of the incoming files
@@ -394,8 +394,8 @@ func TestIssue28282(t *testing.T) {
 }
 
 func TestIssue29029(t *testing.T) {
-	f1 := mustParse("", `package p; type A interface { M() }`)
-	f2 := mustParse("", `package p; var B interface { A }`)
+	f1 := mustParse(`package p; type A interface { M() }`)
+	f2 := mustParse(`package p; var B interface { A }`)
 
 	// printInfo prints the *Func definitions recorded in info, one *Func per line.
 	printInfo := func(info *Info) string {
@@ -441,10 +441,10 @@ func TestIssue34151(t *testing.T) {
 	const asrc = `package a; type I interface{ M() }; type T struct { F interface { I } }`
 	const bsrc = `package b; import "a"; type T struct { F interface { a.I } }; var _ = a.T(T{})`
 
-	a := mustTypecheck("a", asrc, nil, nil)
+	a := mustTypecheck(asrc, nil, nil)
 
 	conf := Config{Importer: importHelper{pkg: a}}
-	mustTypecheck("b", bsrc, &conf, nil)
+	mustTypecheck(bsrc, &conf, nil)
 }
 
 type importHelper struct {
@@ -482,13 +482,8 @@ func TestIssue34921(t *testing.T) {
 
 	var pkg *Package
 	for _, src := range sources {
-		f := mustParse("", src)
 		conf := Config{Importer: importHelper{pkg: pkg}}
-		res, err := conf.Check(f.PkgName.Value, []*syntax.File{f}, nil)
-		if err != nil {
-			t.Errorf("%q failed to typecheck: %v", src, err)
-		}
-		pkg = res // res is imported by the next package in this test
+		pkg = mustTypecheck(src, &conf, nil) // pkg imported by the next package in this test
 	}
 }
 
@@ -551,12 +546,12 @@ func TestIssue43124(t *testing.T) {
 		csrc = `package c; import ("a"; "html/template"); func _() { a.G(template.Template{}) }`
 	)
 
-	a := mustTypecheck("a", asrc, nil, nil)
+	a := mustTypecheck(asrc, nil, nil)
 	conf := Config{Importer: importHelper{pkg: a, fallback: defaultImporter()}}
 
 	// Packages should be fully qualified when there is ambiguity within the
 	// error string itself.
-	_, err := typecheck("b", bsrc, &conf, nil)
+	_, err := typecheck(bsrc, &conf, nil)
 	if err == nil {
 		t.Fatal("package b had no errors")
 	}
@@ -565,7 +560,7 @@ func TestIssue43124(t *testing.T) {
 	}
 
 	// ...and also when there is any ambiguity in reachable packages.
-	_, err = typecheck("c", csrc, &conf, nil)
+	_, err = typecheck(csrc, &conf, nil)
 	if err == nil {
 		t.Fatal("package c had no errors")
 	}
@@ -663,7 +658,7 @@ func TestIssue51093(t *testing.T) {
 	for _, test := range tests {
 		src := fmt.Sprintf("package p; func _[P %s]() { _ = P(%s) }", test.typ, test.val)
 		types := make(map[syntax.Expr]TypeAndValue)
-		mustTypecheck("p", src, nil, &Info{Types: types})
+		mustTypecheck(src, nil, &Info{Types: types})
 
 		var n int
 		for x, tv := range types {
@@ -793,8 +788,8 @@ func (S) M5(struct {S;t}) {}
 
 	test := func(main, b, want string) {
 		re := regexp.MustCompile(want)
-		bpkg := mustTypecheck("b", b, nil, nil)
-		mast := mustParse("main.go", main)
+		bpkg := mustTypecheck(b, nil, nil)
+		mast := mustParse(main)
 		conf := Config{Importer: importHelper{pkg: bpkg}}
 		_, err := conf.Check(mast.PkgName.Value, []*syntax.File{mast}, nil)
 		if err == nil {
diff --git a/src/cmd/compile/internal/types2/mono_test.go b/src/cmd/compile/internal/types2/mono_test.go
index 17450aa04b..c2955a2828 100644
--- a/src/cmd/compile/internal/types2/mono_test.go
+++ b/src/cmd/compile/internal/types2/mono_test.go
@@ -20,7 +20,7 @@ func checkMono(t *testing.T, body string) error {
 		Error:    func(err error) { fmt.Fprintln(&buf, err) },
 		Importer: defaultImporter(),
 	}
-	typecheck("x", src, &conf, nil)
+	typecheck(src, &conf, nil)
 	if buf.Len() == 0 {
 		return nil
 	}
diff --git a/src/cmd/compile/internal/types2/named_test.go b/src/cmd/compile/internal/types2/named_test.go
index 0b1819bbf9..705dcaee27 100644
--- a/src/cmd/compile/internal/types2/named_test.go
+++ b/src/cmd/compile/internal/types2/named_test.go
@@ -31,7 +31,7 @@ func (G[P]) N() (p P) { return }
 
 type Inst = G[int]
 	`
-	pkg := mustTypecheck("p", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	var (
 		T        = pkg.Scope().Lookup("T").Type()
@@ -92,7 +92,7 @@ func (Node[Q]) M(Q) {}
 type Inst = *Tree[int]
 `
 
-	f := mustParse("foo.go", src)
+	f := mustParse(src)
 	pkg := NewPackage("p", f.PkgName.Value)
 	if err := NewChecker(nil, pkg, nil).Files([]*syntax.File{f}); err != nil {
 		t.Fatal(err)
diff --git a/src/cmd/compile/internal/types2/object_test.go b/src/cmd/compile/internal/types2/object_test.go
index 85b9e697ee..ef1a864ec9 100644
--- a/src/cmd/compile/internal/types2/object_test.go
+++ b/src/cmd/compile/internal/types2/object_test.go
@@ -56,7 +56,7 @@ func TestIsAlias(t *testing.T) {
 // the same Func Object as the original method. See also go.dev/issue/34421.
 func TestEmbeddedMethod(t *testing.T) {
 	const src = `package p; type I interface { error }`
-	pkg := mustTypecheck("p", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	// get original error.Error method
 	eface := Universe.Lookup("error")
@@ -110,7 +110,7 @@ func TestObjectString(t *testing.T) {
 
 	for _, test := range testObjects {
 		src := "package p; " + test.src
-		pkg, err := typecheck(filename, src, nil, nil)
+		pkg, err := typecheck(src, nil, nil)
 		if err != nil {
 			t.Errorf("%s: %s", src, err)
 			continue
diff --git a/src/cmd/compile/internal/types2/resolver_test.go b/src/cmd/compile/internal/types2/resolver_test.go
index cafbfc9af6..923712b268 100644
--- a/src/cmd/compile/internal/types2/resolver_test.go
+++ b/src/cmd/compile/internal/types2/resolver_test.go
@@ -116,8 +116,8 @@ func TestResolveIdents(t *testing.T) {
 
 	// parse package files
 	var files []*syntax.File
-	for i, src := range sources {
-		files = append(files, mustParse(fmt.Sprintf("sources[%d]", i), src))
+	for _, src := range sources {
+		files = append(files, mustParse(src))
 	}
 
 	// resolve and type-check package AST
diff --git a/src/cmd/compile/internal/types2/sizes_test.go b/src/cmd/compile/internal/types2/sizes_test.go
index f2e4a87c71..7af89583f2 100644
--- a/src/cmd/compile/internal/types2/sizes_test.go
+++ b/src/cmd/compile/internal/types2/sizes_test.go
@@ -20,7 +20,7 @@ func findStructType(t *testing.T, src string) *types2.Struct {
 
 func findStructTypeConfig(t *testing.T, src string, conf *types2.Config) *types2.Struct {
 	types := make(map[syntax.Expr]types2.TypeAndValue)
-	mustTypecheck("x", src, nil, &types2.Info{Types: types})
+	mustTypecheck(src, nil, &types2.Info{Types: types})
 	for _, tv := range types {
 		if ts, ok := tv.Type.(*types2.Struct); ok {
 			return ts
@@ -89,7 +89,7 @@ const _ = unsafe.Offsetof(struct{ x int64 }{}.x)
 		Importer: defaultImporter(),
 		Sizes:    &types2.StdSizes{WordSize: 8, MaxAlign: 8},
 	}
-	mustTypecheck("x", src, &conf, &info)
+	mustTypecheck(src, &conf, &info)
 	for _, tv := range info.Types {
 		_ = conf.Sizes.Sizeof(tv.Type)
 		_ = conf.Sizes.Alignof(tv.Type)
diff --git a/src/cmd/compile/internal/types2/typestring_test.go b/src/cmd/compile/internal/types2/typestring_test.go
index 193ee251f0..c2be40da29 100644
--- a/src/cmd/compile/internal/types2/typestring_test.go
+++ b/src/cmd/compile/internal/types2/typestring_test.go
@@ -118,7 +118,7 @@ func TestTypeString(t *testing.T) {
 
 	for _, test := range tests {
 		src := `package generic_p; import "io"; type _ io.Writer; type T ` + test.src
-		pkg, err := typecheck(filename, src, nil, nil)
+		pkg, err := typecheck(src, nil, nil)
 		if err != nil {
 			t.Errorf("%s: %s", src, err)
 			continue
@@ -136,8 +136,8 @@ func TestTypeString(t *testing.T) {
 }
 
 func TestQualifiedTypeString(t *testing.T) {
-	p := mustTypecheck("p.go", "package p; type T int", nil, nil)
-	q := mustTypecheck("q.go", "package q", nil, nil)
+	p := mustTypecheck("package p; type T int", nil, nil)
+	q := mustTypecheck("package q", nil, nil)
 
 	pT := p.Scope().Lookup("T").Type()
 	for _, test := range []struct {
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index 2d0df43263..825f30585b 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -24,21 +24,21 @@ import (
 // nopos indicates an unknown position
 var nopos token.Pos
 
-func parse(fset *token.FileSet, filename, src string) (*ast.File, error) {
-	return parser.ParseFile(fset, filename, src, 0)
+func parse(fset *token.FileSet, src string) (*ast.File, error) {
+	return parser.ParseFile(fset, pkgName(src), src, 0)
 }
 
-func mustParse(fset *token.FileSet, filename, src string) *ast.File {
-	f, err := parse(fset, filename, src)
+func mustParse(fset *token.FileSet, src string) *ast.File {
+	f, err := parse(fset, src)
 	if err != nil {
 		panic(err) // so we don't need to pass *testing.T
 	}
 	return f
 }
 
-func typecheck(path, src string, conf *Config, info *Info) (*Package, error) {
+func typecheck(src string, conf *Config, info *Info) (*Package, error) {
 	fset := token.NewFileSet()
-	f, err := parse(fset, path, src)
+	f, err := parse(fset, src)
 	if f == nil { // ignore errors unless f is nil
 		return nil, err
 	}
@@ -51,9 +51,9 @@ func typecheck(path, src string, conf *Config, info *Info) (*Package, error) {
 	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
 }
 
-func mustTypecheck(path, src string, conf *Config, info *Info) *Package {
+func mustTypecheck(src string, conf *Config, info *Info) *Package {
 	fset := token.NewFileSet()
-	f := mustParse(fset, path, src)
+	f := mustParse(fset, src)
 	if conf == nil {
 		conf = &Config{
 			Importer: importer.Default(),
@@ -66,6 +66,20 @@ func mustTypecheck(path, src string, conf *Config, info *Info) *Package {
 	return pkg
 }
 
+// pkgName extracts the package name from src, which must contain a package header.
+func pkgName(src string) string {
+	const kw = "package "
+	if i := strings.Index(src, kw); i >= 0 {
+		after := src[i+len(kw):]
+		n := len(after)
+		if i := strings.IndexAny(after, "\n\t ;/"); i >= 0 {
+			n = i
+		}
+		return after[:n]
+	}
+	panic("missing package header: " + src)
+}
+
 func TestValuesInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -149,7 +163,7 @@ func TestValuesInfo(t *testing.T) {
 		info := Info{
 			Types: make(map[ast.Expr]TypeAndValue),
 		}
-		name := mustTypecheck("ValuesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// look for expression
 		var expr ast.Expr
@@ -387,7 +401,7 @@ func TestTypesInfo(t *testing.T) {
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, broken) {
-			pkg, err := typecheck("TypesInfo", test.src, nil, &info)
+			pkg, err := typecheck(test.src, nil, &info)
 			if err == nil {
 				t.Errorf("package %s: expected to fail but passed", pkg.Name())
 				continue
@@ -396,7 +410,7 @@ func TestTypesInfo(t *testing.T) {
 				name = pkg.Name()
 			}
 		} else {
-			name = mustTypecheck("TypesInfo", test.src, nil, &info).Name()
+			name = mustTypecheck(test.src, nil, &info).Name()
 		}
 
 		// look for expression type
@@ -561,7 +575,7 @@ type T[P any] []P
 		instMap := make(map[*ast.Ident]Instance)
 		useMap := make(map[*ast.Ident]Object)
 		makePkg := func(src string) *Package {
-			pkg, _ := typecheck("p.go", src, &conf, &Info{Instances: instMap, Uses: useMap})
+			pkg, _ := typecheck(src, &conf, &Info{Instances: instMap, Uses: useMap})
 			imports[pkg.Name()] = pkg
 			return pkg
 		}
@@ -656,7 +670,7 @@ func TestDefsInfo(t *testing.T) {
 		info := Info{
 			Defs: make(map[*ast.Ident]Object),
 		}
-		name := mustTypecheck("DefsInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// find object
 		var def Object
@@ -723,7 +737,7 @@ func TestUsesInfo(t *testing.T) {
 		info := Info{
 			Uses: make(map[*ast.Ident]Object),
 		}
-		name := mustTypecheck("UsesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// find object
 		var use Object
@@ -756,7 +770,7 @@ func (r N[B]) m() { r.m(); r.n() }
 func (r *N[C]) n() {  }
 `
 	fset := token.NewFileSet()
-	f := mustParse(fset, "p.go", src)
+	f := mustParse(fset, src)
 	info := Info{
 		Defs:       make(map[*ast.Ident]Object),
 		Uses:       make(map[*ast.Ident]Object),
@@ -864,7 +878,7 @@ func TestImplicitsInfo(t *testing.T) {
 		info := Info{
 			Implicits: make(map[ast.Node]Object),
 		}
-		name := mustTypecheck("ImplicitsInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// the test cases expect at most one Implicits entry
 		if len(info.Implicits) > 1 {
@@ -992,7 +1006,7 @@ func TestPredicatesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
-		name := mustTypecheck("PredicatesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// look for expression predicates
 		got := "<missing>"
@@ -1084,7 +1098,7 @@ func TestScopesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Scopes: make(map[ast.Node]*Scope)}
-		name := mustTypecheck("ScopesInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// number of scopes must match
 		if len(info.Scopes) != len(test.scopes) {
@@ -1272,7 +1286,7 @@ func TestInitOrderInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{}
-		name := mustTypecheck("InitOrderInfo", test.src, nil, &info).Name()
+		name := mustTypecheck(test.src, nil, &info).Name()
 
 		// number of initializers must match
 		if len(info.InitOrder) != len(test.inits) {
@@ -1293,8 +1307,8 @@ func TestInitOrderInfo(t *testing.T) {
 
 func TestMultiFileInitOrder(t *testing.T) {
 	fset := token.NewFileSet()
-	fileA := mustParse(fset, "", `package main; var a = 1`)
-	fileB := mustParse(fset, "", `package main; var b = 2`)
+	fileA := mustParse(fset, `package main; var a = 1`)
+	fileB := mustParse(fset, `package main; var b = 2`)
 
 	// The initialization order must not depend on the parse
 	// order of the files, only on the presentation order to
@@ -1330,10 +1344,8 @@ func TestFiles(t *testing.T) {
 	var info Info
 	check := NewChecker(&conf, fset, pkg, &info)
 
-	for i, src := range sources {
-		filename := fmt.Sprintf("sources%d", i)
-		f := mustParse(fset, filename, src)
-		if err := check.Files([]*ast.File{f}); err != nil {
+	for _, src := range sources {
+		if err := check.Files([]*ast.File{mustParse(fset, src)}); err != nil {
 			t.Error(err)
 		}
 	}
@@ -1368,8 +1380,7 @@ func TestSelection(t *testing.T) {
 	imports := make(testImporter)
 	conf := Config{Importer: imports}
 	makePkg := func(path, src string) {
-		f := mustParse(fset, path+".go", src)
-		pkg, err := conf.Check(path, fset, []*ast.File{f}, &Info{Selections: selections})
+		pkg, err := conf.Check(path, fset, []*ast.File{mustParse(fset, src)}, &Info{Selections: selections})
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1546,9 +1557,7 @@ func TestIssue8518(t *testing.T) {
 		Importer: imports,
 	}
 	makePkg := func(path, src string) {
-		f := mustParse(fset, path, src)
-		pkg, _ := conf.Check(path, fset, []*ast.File{f}, nil) // errors logged via conf.Error
-		imports[path] = pkg
+		imports[path], _ = conf.Check(path, fset, []*ast.File{mustParse(fset, src)}, nil) // errors logged via conf.Error
 	}
 
 	const libSrc = `
@@ -1577,9 +1586,7 @@ func TestIssue59603(t *testing.T) {
 		Importer: imports,
 	}
 	makePkg := func(path, src string) {
-		f := mustParse(fset, path, src)
-		pkg, _ := conf.Check(path, fset, []*ast.File{f}, nil) // errors logged via conf.Error
-		imports[path] = pkg
+		imports[path], _ = conf.Check(path, fset, []*ast.File{mustParse(fset, src)}, nil) // errors logged via conf.Error
 	}
 
 	const libSrc = `
@@ -1664,7 +1671,7 @@ func TestLookupFieldOrMethod(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck("test", "package p;"+test.src, nil, nil)
+		pkg := mustTypecheck("package p;"+test.src, nil, nil)
 
 		obj := pkg.Scope().Lookup("a")
 		if obj == nil {
@@ -1710,7 +1717,7 @@ type Instance = *Tree[int]
 `
 
 	fset := token.NewFileSet()
-	f := mustParse(fset, "foo.go", src)
+	f := mustParse(fset, src)
 	pkg := NewPackage("pkg", f.Name.Name)
 	if err := NewChecker(nil, fset, pkg, nil).Files([]*ast.File{f}); err != nil {
 		panic(err)
@@ -1747,7 +1754,7 @@ func TestScopeLookupParent(t *testing.T) {
 		}
 	}
 
-	makePkg("lib", mustParse(fset, "", "package lib; var X int"))
+	makePkg("lib", mustParse(fset, "package lib; var X int"))
 	// Each /*name=kind:line*/ comment makes the test look up the
 	// name at that point and checks that it resolves to a decl of
 	// the specified kind and line number.  "undef" means undefined.
@@ -1791,7 +1798,7 @@ func F(){
 `
 
 	info.Uses = make(map[*ast.Ident]Object)
-	f := mustParse(fset, "", mainSrc)
+	f := mustParse(fset, mainSrc)
 	makePkg("main", f)
 	mainScope := imports["main"].Scope()
 	rx := regexp.MustCompile(`^/\*(\w*)=([\w:]*)\*/$`)
@@ -1943,7 +1950,7 @@ func TestIdentical(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck("test", "package p;"+test.src, nil, nil)
+		pkg := mustTypecheck("package p;"+test.src, nil, nil)
 		X := pkg.Scope().Lookup("X")
 		Y := pkg.Scope().Lookup("Y")
 		if X == nil || Y == nil {
@@ -2017,7 +2024,7 @@ func TestIdenticalUnions(t *testing.T) {
 func TestIssue15305(t *testing.T) {
 	const src = "package p; func f() int16; var _ = f(undef)"
 	fset := token.NewFileSet()
-	f := mustParse(fset, "issue15305.go", src)
+	f := mustParse(fset, src)
 	conf := Config{
 		Error: func(err error) {}, // allow errors
 	}
@@ -2040,7 +2047,7 @@ func TestIssue15305(t *testing.T) {
 // types for composite literal expressions and composite literal type
 // expressions.
 func TestCompositeLitTypes(t *testing.T) {
-	for _, test := range []struct {
+	for i, test := range []struct {
 		lit, typ string
 	}{
 		{`[16]byte{}`, `[16]byte`},
@@ -2053,7 +2060,7 @@ func TestCompositeLitTypes(t *testing.T) {
 		{`struct{x, y int; z complex128}{}`, `struct{x int; y int; z complex128}`},
 	} {
 		fset := token.NewFileSet()
-		f := mustParse(fset, test.lit, "package p; var _ = "+test.lit)
+		f := mustParse(fset, fmt.Sprintf("package p%d; var _ = %s", i, test.lit))
 		types := make(map[ast.Expr]TypeAndValue)
 		if _, err := new(Config).Check("p", fset, []*ast.File{f}, &Info{Types: types}); err != nil {
 			t.Fatalf("%s: %v", test.lit, err)
@@ -2108,7 +2115,7 @@ func f(x int) { y := x; print(y) }
 `
 
 	fset := token.NewFileSet()
-	f := mustParse(fset, "src", src)
+	f := mustParse(fset, src)
 
 	info := &Info{
 		Defs: make(map[*ast.Ident]Object),
@@ -2167,7 +2174,7 @@ var v T = c
 func f(x T) T { return foo.F(x) }
 `
 	fset := token.NewFileSet()
-	f := mustParse(fset, "src", src)
+	f := mustParse(fset, src)
 	files := []*ast.File{f}
 
 	// type-check using all possible importers
@@ -2222,7 +2229,7 @@ func f(x T) T { return foo.F(x) }
 func TestInstantiate(t *testing.T) {
 	// eventually we like more tests but this is a start
 	const src = "package p; type T[P any] *T[P]"
-	pkg := mustTypecheck(".", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	// type T should have one type parameter
 	T := pkg.Scope().Lookup("T").Type().(*Named)
@@ -2257,7 +2264,7 @@ func TestInstantiateErrors(t *testing.T) {
 
 	for _, test := range tests {
 		src := "package p; " + test.src
-		pkg := mustTypecheck(".", src, nil, nil)
+		pkg := mustTypecheck(src, nil, nil)
 
 		T := pkg.Scope().Lookup("T").Type().(*Named)
 
@@ -2296,7 +2303,7 @@ func TestInstanceIdentity(t *testing.T) {
 	conf := Config{Importer: imports}
 	makePkg := func(src string) {
 		fset := token.NewFileSet()
-		f := mustParse(fset, "", src)
+		f := mustParse(fset, src)
 		name := f.Name.Name
 		pkg, err := conf.Check(name, fset, []*ast.File{f}, nil)
 		if err != nil {
@@ -2353,7 +2360,7 @@ func fn() {
 		Defs: make(map[*ast.Ident]Object),
 	}
 	fset := token.NewFileSet()
-	f := mustParse(fset, "p.go", src)
+	f := mustParse(fset, src)
 	conf := Config{}
 	pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
 	if err != nil {
@@ -2485,7 +2492,7 @@ type Bad Bad // invalid type
 `
 
 	fset := token.NewFileSet()
-	f := mustParse(fset, "p.go", src)
+	f := mustParse(fset, src)
 	conf := Config{Error: func(error) {}}
 	pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
 
@@ -2580,7 +2587,7 @@ type V4 struct{}
 func (V4) M()
 `
 
-	pkg := mustTypecheck("p.go", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
 	lookup := func(name string) (*Func, bool) {
diff --git a/src/go/types/builtins_test.go b/src/go/types/builtins_test.go
index 5591fecf02..6238464f58 100644
--- a/src/go/types/builtins_test.go
+++ b/src/go/types/builtins_test.go
@@ -174,7 +174,7 @@ func testBuiltinSignature(t *testing.T, name, src0, want string) {
 
 	uses := make(map[*ast.Ident]Object)
 	types := make(map[ast.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Uses: uses, Types: types})
+	mustTypecheck(src, nil, &Info{Uses: uses, Types: types})
 
 	// find called function
 	n := 0
diff --git a/src/go/types/example_test.go b/src/go/types/example_test.go
index 37b5ea4511..1ee47bc123 100644
--- a/src/go/types/example_test.go
+++ b/src/go/types/example_test.go
@@ -35,25 +35,23 @@ func ExampleScope() {
 	// Parse the source files for a package.
 	fset := token.NewFileSet()
 	var files []*ast.File
-	for _, file := range []struct{ name, input string }{
-		{"main.go", `
-package main
+	for _, src := range []string{
+		`package main
 import "fmt"
 func main() {
 	freezing := FToC(-18)
 	fmt.Println(freezing, Boiling) }
-`},
-		{"celsius.go", `
-package main
+`,
+		`package main
 import "fmt"
 type Celsius float64
 func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
 func FToC(f float64) Celsius { return Celsius(f - 32 / 9 * 5) }
 const Boiling Celsius = 100
 func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get printed
-`},
+`,
 	} {
-		files = append(files, mustParse(fset, file.name, file.input))
+		files = append(files, mustParse(fset, src))
 	}
 
 	// Type-check a package consisting of these files.
@@ -79,13 +77,13 @@ func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get
 	// .  func temperature.FToC(f float64) temperature.Celsius
 	// .  func temperature.Unused()
 	// .  func temperature.main()
-	// .  main.go scope {
+	// .  main scope {
 	// .  .  package fmt
 	// .  .  function scope {
 	// .  .  .  var freezing temperature.Celsius
 	// .  .  }
 	// .  }
-	// .  celsius.go scope {
+	// .  main scope {
 	// .  .  package fmt
 	// .  .  function scope {
 	// .  .  .  var c temperature.Celsius
@@ -183,7 +181,7 @@ func fib(x int) int {
 	// We need a specific fileset in this test below for positions.
 	// Cannot use typecheck helper.
 	fset := token.NewFileSet()
-	f := mustParse(fset, "fib.go", input)
+	f := mustParse(fset, input)
 
 	// Type-check the package.
 	// We create an empty map for each kind of input
@@ -250,10 +248,10 @@ func fib(x int) int {
 	//   defined at -
 	//   used at 6:15
 	// func fib(x int) int:
-	//   defined at fib.go:8:6
+	//   defined at fib:8:6
 	//   used at 12:20, 12:9
 	// type S string:
-	//   defined at fib.go:4:6
+	//   defined at fib:4:6
 	//   used at 6:23
 	// type int:
 	//   defined at -
@@ -262,13 +260,13 @@ func fib(x int) int {
 	//   defined at -
 	//   used at 4:8
 	// var b S:
-	//   defined at fib.go:6:8
+	//   defined at fib:6:8
 	//   used at 6:19
 	// var c string:
-	//   defined at fib.go:6:11
+	//   defined at fib:6:11
 	//   used at 6:25
 	// var x int:
-	//   defined at fib.go:8:10
+	//   defined at fib:8:10
 	//   used at 10:10, 12:13, 12:24, 9:5
 	//
 	// Types and Values of each expression:
diff --git a/src/go/types/hilbert_test.go b/src/go/types/hilbert_test.go
index 7da2a7ded1..f530422492 100644
--- a/src/go/types/hilbert_test.go
+++ b/src/go/types/hilbert_test.go
@@ -27,7 +27,7 @@ func TestHilbert(t *testing.T) {
 		return
 	}
 
-	mustTypecheck("hilbert.go", string(src), nil, nil)
+	mustTypecheck(string(src), nil, nil)
 }
 
 func program(n int, out string) []byte {
diff --git a/src/go/types/instantiate_test.go b/src/go/types/instantiate_test.go
index 574f3aeb86..58dfa70131 100644
--- a/src/go/types/instantiate_test.go
+++ b/src/go/types/instantiate_test.go
@@ -109,7 +109,7 @@ func TestInstantiateEquality(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg := mustTypecheck(".", test.src, nil, nil)
+		pkg := mustTypecheck(test.src, nil, nil)
 
 		t.Run(pkg.Name(), func(t *testing.T) {
 			ctxt := NewContext()
@@ -135,8 +135,8 @@ func TestInstantiateEquality(t *testing.T) {
 
 func TestInstantiateNonEquality(t *testing.T) {
 	const src = "package p; type T[P any] int"
-	pkg1 := mustTypecheck(".", src, nil, nil)
-	pkg2 := mustTypecheck(".", src, nil, nil)
+	pkg1 := mustTypecheck(src, nil, nil)
+	pkg2 := mustTypecheck(src, nil, nil)
 	// We consider T1 and T2 to be distinct types, so their instances should not
 	// be deduplicated by the context.
 	T1 := pkg1.Scope().Lookup("T").Type().(*Named)
@@ -181,7 +181,7 @@ var X T[int]
 
 	for _, test := range tests {
 		src := prefix + test.decl
-		pkg := mustTypecheck(".", src, nil, nil)
+		pkg := mustTypecheck(src, nil, nil)
 		typ := NewPointer(pkg.Scope().Lookup("X").Type())
 		obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 		m, _ := obj.(*Func)
@@ -203,7 +203,7 @@ func (T[P]) m() {}
 
 var _ T[int]
 `
-	pkg := mustTypecheck(".", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 	typ := pkg.Scope().Lookup("T").Type().(*Named)
 	obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 	if obj == nil {
diff --git a/src/go/types/issues_test.go b/src/go/types/issues_test.go
index 888ca3cc70..a464659aaf 100644
--- a/src/go/types/issues_test.go
+++ b/src/go/types/issues_test.go
@@ -21,7 +21,7 @@ import (
 )
 
 func TestIssue5770(t *testing.T) {
-	_, err := typecheck("p", `package p; type S struct{T}`, nil, nil)
+	_, err := typecheck(`package p; type S struct{T}`, nil, nil)
 	const want = "undefined: T"
 	if err == nil || !strings.Contains(err.Error(), want) {
 		t.Errorf("got: %v; want: %s", err, want)
@@ -41,7 +41,7 @@ var (
 	_ = (interface{})(nil)
 )`
 	types := make(map[ast.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Types: types})
+	mustTypecheck(src, nil, &Info{Types: types})
 
 	for x, tv := range types {
 		var want Type
@@ -80,7 +80,7 @@ func f() int {
 }
 `
 	types := make(map[ast.Expr]TypeAndValue)
-	mustTypecheck("p", src, nil, &Info{Types: types})
+	mustTypecheck(src, nil, &Info{Types: types})
 
 	want := Typ[Int]
 	n := 0
@@ -104,7 +104,7 @@ package p
 func (T) m() (res bool) { return }
 type T struct{} // receiver type after method declaration
 `
-	f := mustParse(fset, "", src)
+	f := mustParse(fset, src)
 
 	var conf Config
 	defs := make(map[*ast.Ident]Object)
@@ -138,7 +138,7 @@ func _() {
 	// We need a specific fileset in this test below for positions.
 	// Cannot use typecheck helper.
 	fset := token.NewFileSet()
-	f := mustParse(fset, "", src)
+	f := mustParse(fset, src)
 
 	const want = `L3 defs func p._()
 L4 defs const w untyped int
@@ -235,7 +235,7 @@ func main() {
 `
 	f := func(test, src string) {
 		info := &Info{Uses: make(map[*ast.Ident]Object)}
-		mustTypecheck("main", src, nil, info)
+		mustTypecheck(src, nil, info)
 
 		var pkg *Package
 		count := 0
@@ -263,13 +263,13 @@ func TestIssue22525(t *testing.T) {
 
 	got := "\n"
 	conf := Config{Error: func(err error) { got += err.Error() + "\n" }}
-	typecheck("", src, &conf, nil) // do not crash
+	typecheck(src, &conf, nil) // do not crash
 	want := `
-1:27: a declared and not used
-1:30: b declared and not used
-1:33: c declared and not used
-1:36: d declared and not used
-1:39: e declared and not used
+p:1:27: a declared and not used
+p:1:30: b declared and not used
+p:1:33: c declared and not used
+p:1:36: d declared and not used
+p:1:39: e declared and not used
 `
 	if got != want {
 		t.Errorf("got: %swant: %s", got, want)
@@ -289,7 +289,7 @@ func TestIssue25627(t *testing.T) {
 		`struct { *I }`,
 		`struct { a int; b Missing; *Missing }`,
 	} {
-		f := mustParse(fset, "", prefix+src)
+		f := mustParse(fset, prefix+src)
 
 		cfg := Config{Importer: importer.Default(), Error: func(err error) {}}
 		info := &Info{Types: make(map[ast.Expr]TypeAndValue)}
@@ -326,7 +326,7 @@ func TestIssue28005(t *testing.T) {
 	// compute original file ASTs
 	var orig [len(sources)]*ast.File
 	for i, src := range sources {
-		orig[i] = mustParse(fset, "", src)
+		orig[i] = mustParse(fset, src)
 	}
 
 	// run the test for all order permutations of the incoming files
@@ -400,8 +400,8 @@ func TestIssue28282(t *testing.T) {
 }
 
 func TestIssue29029(t *testing.T) {
-	f1 := mustParse(fset, "", `package p; type A interface { M() }`)
-	f2 := mustParse(fset, "", `package p; var B interface { A }`)
+	f1 := mustParse(fset, `package p; type A interface { M() }`)
+	f2 := mustParse(fset, `package p; var B interface { A }`)
 
 	// printInfo prints the *Func definitions recorded in info, one *Func per line.
 	printInfo := func(info *Info) string {
@@ -447,10 +447,10 @@ func TestIssue34151(t *testing.T) {
 	const asrc = `package a; type I interface{ M() }; type T struct { F interface { I } }`
 	const bsrc = `package b; import "a"; type T struct { F interface { a.I } }; var _ = a.T(T{})`
 
-	a := mustTypecheck("a", asrc, nil, nil)
+	a := mustTypecheck(asrc, nil, nil)
 
 	conf := Config{Importer: importHelper{pkg: a}}
-	mustTypecheck("b", bsrc, &conf, nil)
+	mustTypecheck(bsrc, &conf, nil)
 }
 
 type importHelper struct {
@@ -488,13 +488,8 @@ func TestIssue34921(t *testing.T) {
 
 	var pkg *Package
 	for _, src := range sources {
-		f := mustParse(fset, "", src)
 		conf := Config{Importer: importHelper{pkg: pkg}}
-		res, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
-		if err != nil {
-			t.Errorf("%q failed to typecheck: %v", src, err)
-		}
-		pkg = res // res is imported by the next package in this test
+		pkg = mustTypecheck(src, &conf, nil) // pkg imported by the next package in this test
 	}
 }
 
@@ -599,7 +594,7 @@ var _ T = template /* ERRORx "cannot use.*text/template.* as T value" */.Templat
 `
 	)
 
-	a := mustTypecheck("a", asrc, nil, nil)
+	a := mustTypecheck(asrc, nil, nil)
 	imp := importHelper{pkg: a, fallback: importer.Default()}
 
 	testFiles(t, nil, []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
@@ -696,7 +691,7 @@ func TestIssue51093(t *testing.T) {
 	for _, test := range tests {
 		src := fmt.Sprintf("package p; func _[P %s]() { _ = P(%s) }", test.typ, test.val)
 		types := make(map[ast.Expr]TypeAndValue)
-		mustTypecheck("p", src, nil, &Info{Types: types})
+		mustTypecheck(src, nil, &Info{Types: types})
 
 		var n int
 		for x, tv := range types {
@@ -828,8 +823,8 @@ func (S) M5(struct {S;t}) {}
 	fset := token.NewFileSet()
 	test := func(main, b, want string) {
 		re := regexp.MustCompile(want)
-		bpkg := mustTypecheck("b", b, nil, nil)
-		mast := mustParse(fset, "main.go", main)
+		bpkg := mustTypecheck(b, nil, nil)
+		mast := mustParse(fset, main)
 		conf := Config{Importer: importHelper{pkg: bpkg}}
 		_, err := conf.Check(mast.Name.Name, fset, []*ast.File{mast}, nil)
 		if err == nil {
diff --git a/src/go/types/methodset_test.go b/src/go/types/methodset_test.go
index 3f8a0b1a10..918b51d93b 100644
--- a/src/go/types/methodset_test.go
+++ b/src/go/types/methodset_test.go
@@ -84,7 +84,7 @@ func TestNewMethodSet(t *testing.T) {
 	}
 
 	check := func(src string, methods []method, generic bool) {
-		pkg := mustTypecheck("test", "package p;"+src, nil, nil)
+		pkg := mustTypecheck("package p;"+src, nil, nil)
 
 		scope := pkg.Scope()
 		if generic {
diff --git a/src/go/types/mono_test.go b/src/go/types/mono_test.go
index a8d2acfd66..ccab846c6d 100644
--- a/src/go/types/mono_test.go
+++ b/src/go/types/mono_test.go
@@ -21,7 +21,7 @@ func checkMono(t *testing.T, body string) error {
 		Error:    func(err error) { fmt.Fprintln(&buf, err) },
 		Importer: importer.Default(),
 	}
-	typecheck("x", src, &conf, nil)
+	typecheck(src, &conf, nil)
 	if buf.Len() == 0 {
 		return nil
 	}
diff --git a/src/go/types/named_test.go b/src/go/types/named_test.go
index 55c0021398..8e00f6e0f9 100644
--- a/src/go/types/named_test.go
+++ b/src/go/types/named_test.go
@@ -32,7 +32,7 @@ func (G[P]) N() (p P) { return }
 
 type Inst = G[int]
 	`
-	pkg := mustTypecheck("p", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	var (
 		T        = pkg.Scope().Lookup("T").Type()
@@ -107,7 +107,7 @@ type Inst = *Tree[int]
 `
 
 	fset := token.NewFileSet()
-	f := mustParse(fset, "foo.go", src)
+	f := mustParse(fset, src)
 	pkg := NewPackage("p", f.Name.Name)
 	if err := NewChecker(nil, fset, pkg, nil).Files([]*ast.File{f}); err != nil {
 		t.Fatal(err)
diff --git a/src/go/types/object_test.go b/src/go/types/object_test.go
index bed8de3637..74acdaeeeb 100644
--- a/src/go/types/object_test.go
+++ b/src/go/types/object_test.go
@@ -58,7 +58,7 @@ func TestIsAlias(t *testing.T) {
 // the same Func Object as the original method. See also go.dev/issue/34421.
 func TestEmbeddedMethod(t *testing.T) {
 	const src = `package p; type I interface { error }`
-	pkg := mustTypecheck("p", src, nil, nil)
+	pkg := mustTypecheck(src, nil, nil)
 
 	// get original error.Error method
 	eface := Universe.Lookup("error")
@@ -112,7 +112,7 @@ func TestObjectString(t *testing.T) {
 
 	for _, test := range testObjects {
 		src := "package p; " + test.src
-		pkg, err := typecheck(filename, src, nil, nil)
+		pkg, err := typecheck(src, nil, nil)
 		if err != nil {
 			t.Errorf("%s: %s", src, err)
 			continue
diff --git a/src/go/types/resolver_test.go b/src/go/types/resolver_test.go
index 284ad8e998..e95af80585 100644
--- a/src/go/types/resolver_test.go
+++ b/src/go/types/resolver_test.go
@@ -119,8 +119,8 @@ func TestResolveIdents(t *testing.T) {
 	// parse package files
 	fset := token.NewFileSet()
 	var files []*ast.File
-	for i, src := range sources {
-		files = append(files, mustParse(fset, fmt.Sprintf("sources[%d]", i), src))
+	for _, src := range sources {
+		files = append(files, mustParse(fset, src))
 	}
 
 	// resolve and type-check package AST
diff --git a/src/go/types/sizes_test.go b/src/go/types/sizes_test.go
index 4964bf2cf9..f2e7e8ab2e 100644
--- a/src/go/types/sizes_test.go
+++ b/src/go/types/sizes_test.go
@@ -21,7 +21,7 @@ func findStructType(t *testing.T, src string) *types.Struct {
 
 func findStructTypeConfig(t *testing.T, src string, conf *types.Config) *types.Struct {
 	types_ := make(map[ast.Expr]types.TypeAndValue)
-	mustTypecheck("x", src, nil, &types.Info{Types: types_})
+	mustTypecheck(src, nil, &types.Info{Types: types_})
 	for _, tv := range types_ {
 		if ts, ok := tv.Type.(*types.Struct); ok {
 			return ts
@@ -90,7 +90,7 @@ const _ = unsafe.Offsetof(struct{ x int64 }{}.x)
 		Importer: importer.Default(),
 		Sizes:    &types.StdSizes{WordSize: 8, MaxAlign: 8},
 	}
-	mustTypecheck("x", src, &conf, &info)
+	mustTypecheck(src, &conf, &info)
 	for _, tv := range info.Types {
 		_ = conf.Sizes.Sizeof(tv.Type)
 		_ = conf.Sizes.Alignof(tv.Type)
diff --git a/src/go/types/typestring_test.go b/src/go/types/typestring_test.go
index d3172d6bb9..45670b7e15 100644
--- a/src/go/types/typestring_test.go
+++ b/src/go/types/typestring_test.go
@@ -119,7 +119,7 @@ func TestTypeString(t *testing.T) {
 
 	for _, test := range tests {
 		src := `package p; import "io"; type _ io.Writer; type T ` + test.src
-		pkg, err := typecheck(filename, src, nil, nil)
+		pkg, err := typecheck(src, nil, nil)
 		if err != nil {
 			t.Errorf("%s: %s", src, err)
 			continue
@@ -137,8 +137,8 @@ func TestTypeString(t *testing.T) {
 }
 
 func TestQualifiedTypeString(t *testing.T) {
-	p := mustTypecheck("p.go", "package p; type T int", nil, nil)
-	q := mustTypecheck("q.go", "package q", nil, nil)
+	p := mustTypecheck("package p; type T int", nil, nil)
+	q := mustTypecheck("package q", nil, nil)
 
 	pT := p.Scope().Lookup("T").Type()
 	for _, test := range []struct {