go/types, types2: replace typecheck with mustTypecheck almost everywhere (cleanup)

Replace even in places where before we have a specific error message
or different control-flow (except in TestTypeString or TestObjectString)
because failing to type-check in virtually all cases represents an error
in the test itself.

Change-Id: I9f1e6d25bddd92c168353409b281b5a3f29a747c
Reviewed-on: https://go-review.googlesource.com/c/go/+/443915
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>

13 files changed, 60 insertions, 155 deletions

diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index ce05cd332e..5c56e2b7e9 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -43,12 +43,12 @@ func typecheck(path, src string, info *Info) (*Package, error) {
 	return conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
 }
 
-func mustTypecheck(path, src string, info *Info) string {
+func mustTypecheck(path, src string, info *Info) *Package {
 	pkg, err := typecheck(path, src, info)
 	if err != nil {
 		panic(err) // so we don't need to pass *testing.T
 	}
-	return pkg.Name()
+	return pkg
 }
 
 func TestValuesInfo(t *testing.T) {
@@ -134,7 +134,7 @@ func TestValuesInfo(t *testing.T) {
 		info := Info{
 			Types: make(map[syntax.Expr]TypeAndValue),
 		}
-		name := mustTypecheck("ValuesInfo", test.src, &info)
+		name := mustTypecheck("ValuesInfo", test.src, &info).Name()
 
 		// look for expression
 		var expr syntax.Expr
@@ -385,7 +385,7 @@ func TestTypesInfo(t *testing.T) {
 				name = pkg.Name()
 			}
 		} else {
-			name = mustTypecheck("TypesInfo", test.src, &info)
+			name = mustTypecheck("TypesInfo", test.src, &info).Name()
 		}
 
 		// look for expression type
@@ -644,7 +644,7 @@ func TestDefsInfo(t *testing.T) {
 		info := Info{
 			Defs: make(map[*syntax.Name]Object),
 		}
-		name := mustTypecheck("DefsInfo", test.src, &info)
+		name := mustTypecheck("DefsInfo", test.src, &info).Name()
 
 		// find object
 		var def Object
@@ -709,7 +709,7 @@ func TestUsesInfo(t *testing.T) {
 		info := Info{
 			Uses: make(map[*syntax.Name]Object),
 		}
-		name := mustTypecheck("UsesInfo", test.src, &info)
+		name := mustTypecheck("UsesInfo", test.src, &info).Name()
 
 		// find object
 		var use Object
@@ -849,7 +849,7 @@ func TestImplicitsInfo(t *testing.T) {
 		info := Info{
 			Implicits: make(map[syntax.Node]Object),
 		}
-		name := mustTypecheck("ImplicitsInfo", test.src, &info)
+		name := mustTypecheck("ImplicitsInfo", test.src, &info).Name()
 
 		// the test cases expect at most one Implicits entry
 		if len(info.Implicits) > 1 {
@@ -977,7 +977,7 @@ func TestPredicatesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
-		name := mustTypecheck("PredicatesInfo", test.src, &info)
+		name := mustTypecheck("PredicatesInfo", test.src, &info).Name()
 
 		// look for expression predicates
 		got := "<missing>"
@@ -1069,7 +1069,7 @@ func TestScopesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Scopes: make(map[syntax.Node]*Scope)}
-		name := mustTypecheck("ScopesInfo", test.src, &info)
+		name := mustTypecheck("ScopesInfo", test.src, &info).Name()
 
 		// number of scopes must match
 		if len(info.Scopes) != len(test.scopes) {
@@ -1257,7 +1257,7 @@ func TestInitOrderInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{}
-		name := mustTypecheck("InitOrderInfo", test.src, &info)
+		name := mustTypecheck("InitOrderInfo", test.src, &info).Name()
 
 		// number of initializers must match
 		if len(info.InitOrder) != len(test.inits) {
@@ -1626,11 +1626,7 @@ func TestLookupFieldOrMethod(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck("test", "package p;"+test.src, nil)
-		if err != nil {
-			t.Errorf("%s: incorrect test case: %s", test.src, err)
-			continue
-		}
+		pkg := mustTypecheck("test", "package p;"+test.src, nil)
 
 		obj := pkg.Scope().Lookup("a")
 		if obj == nil {
@@ -1912,11 +1908,7 @@ func TestIdentical(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck("test", "package p;"+test.src, nil)
-		if err != nil {
-			t.Errorf("%s: incorrect test case: %s", test.src, err)
-			continue
-		}
+		pkg := mustTypecheck("test", "package p;"+test.src, nil)
 		X := pkg.Scope().Lookup("X")
 		Y := pkg.Scope().Lookup("Y")
 		if X == nil || Y == nil {
@@ -2191,10 +2183,7 @@ 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, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck(".", src, nil)
 
 	// type T should have one type parameter
 	T := pkg.Scope().Lookup("T").Type().(*Named)
@@ -2229,14 +2218,11 @@ func TestInstantiateErrors(t *testing.T) {
 
 	for _, test := range tests {
 		src := "package p; " + test.src
-		pkg, err := typecheck(".", src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", src, nil)
 
 		T := pkg.Scope().Lookup("T").Type().(*Named)
 
-		_, err = Instantiate(nil, T, test.targs, true)
+		_, err := Instantiate(nil, T, test.targs, true)
 		if err == nil {
 			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
 		}
@@ -2552,10 +2538,7 @@ type V4 struct{}
 func (V4) M()
 `
 
-	pkg, err := typecheck("p.go", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck("p.go", src, nil)
 
 	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
 	lookup := func(name string) (*Func, bool) {
diff --git a/src/cmd/compile/internal/types2/instantiate_test.go b/src/cmd/compile/internal/types2/instantiate_test.go
index 1b66d69b47..33a34d76f3 100644
--- a/src/cmd/compile/internal/types2/instantiate_test.go
+++ b/src/cmd/compile/internal/types2/instantiate_test.go
@@ -107,10 +107,7 @@ func TestInstantiateEquality(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck(".", test.src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", test.src, nil)
 
 		t.Run(pkg.Name(), func(t *testing.T) {
 			ctxt := NewContext()
@@ -136,14 +133,8 @@ func TestInstantiateEquality(t *testing.T) {
 
 func TestInstantiateNonEquality(t *testing.T) {
 	const src = "package p; type T[P any] int"
-	pkg1, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	pkg2, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg1 := mustTypecheck(".", src, nil)
+	pkg2 := mustTypecheck(".", src, 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)
@@ -188,10 +179,7 @@ var X T[int]
 
 	for _, test := range tests {
 		src := prefix + test.decl
-		pkg, err := typecheck(".", src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", src, nil)
 		typ := NewPointer(pkg.Scope().Lookup("X").Type())
 		obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 		m, _ := obj.(*Func)
@@ -213,10 +201,7 @@ func (T[P]) m() {}
 
 var _ T[int]
 `
-	pkg, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck(".", src, 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 0daef3a795..777f7af7bf 100644
--- a/src/cmd/compile/internal/types2/issues_test.go
+++ b/src/cmd/compile/internal/types2/issues_test.go
@@ -449,10 +449,7 @@ 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, err := typecheck("a", asrc, nil)
-	if err != nil {
-		t.Fatalf("package %s failed to typecheck: %v", a.Name(), err)
-	}
+	a := mustTypecheck("a", asrc, nil)
 
 	bast := mustParse("", bsrc)
 	conf := Config{Importer: importHelper{pkg: a}}
@@ -564,16 +561,13 @@ func TestIssue43124(t *testing.T) {
 		csrc = `package c; import ("a"; "html/template"); func _() { a.G(template.Template{}) }`
 	)
 
-	a, err := typecheck("a", asrc, nil)
-	if err != nil {
-		t.Fatalf("package a failed to typecheck: %v", err)
-	}
+	a := mustTypecheck("a", asrc, nil)
 	conf := Config{Importer: importHelper{pkg: a, fallback: defaultImporter()}}
 
 	// Packages should be fully qualified when there is ambiguity within the
 	// error string itself.
 	bast := mustParse("", bsrc)
-	_, err = conf.Check(bast.PkgName.Value, []*syntax.File{bast}, nil)
+	_, err := conf.Check(bast.PkgName.Value, []*syntax.File{bast}, nil)
 	if err == nil {
 		t.Fatal("package b had no errors")
 	}
diff --git a/src/cmd/compile/internal/types2/named_test.go b/src/cmd/compile/internal/types2/named_test.go
index 1d1579b9e7..4140bca539 100644
--- a/src/cmd/compile/internal/types2/named_test.go
+++ b/src/cmd/compile/internal/types2/named_test.go
@@ -31,10 +31,7 @@ func (G[P]) N() (p P) { return }
 
 type Inst = G[int]
 	`
-	pkg, err := typecheck("p", src, nil)
-	if err != nil {
-		b.Fatal(err)
-	}
+	pkg := mustTypecheck("p", src, nil)
 
 	var (
 		T        = pkg.Scope().Lookup("T").Type()
diff --git a/src/cmd/compile/internal/types2/sizes_test.go b/src/cmd/compile/internal/types2/sizes_test.go
index 354690c9d4..a6c8468d1f 100644
--- a/src/cmd/compile/internal/types2/sizes_test.go
+++ b/src/cmd/compile/internal/types2/sizes_test.go
@@ -18,13 +18,9 @@ func findStructType(t *testing.T, src string) *types2.Struct {
 }
 
 func findStructTypeConfig(t *testing.T, src string, conf *types2.Config) *types2.Struct {
-	f := mustParse("x.go", src)
-	info := types2.Info{Types: make(map[syntax.Expr]types2.TypeAndValue)}
-	_, err := conf.Check("x", []*syntax.File{f}, &info)
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, tv := range info.Types {
+	types := make(map[syntax.Expr]types2.TypeAndValue)
+	mustTypecheck("x", src, &types2.Info{Types: types})
+	for _, tv := range types {
 		if ts, ok := tv.Type.(*types2.Struct); ok {
 			return ts
 		}
diff --git a/src/cmd/compile/internal/types2/typestring_test.go b/src/cmd/compile/internal/types2/typestring_test.go
index 076fe3751d..735b153fb2 100644
--- a/src/cmd/compile/internal/types2/typestring_test.go
+++ b/src/cmd/compile/internal/types2/typestring_test.go
@@ -135,8 +135,8 @@ func TestTypeString(t *testing.T) {
 }
 
 func TestQualifiedTypeString(t *testing.T) {
-	p, _ := typecheck("p.go", "package p; type T int", nil)
-	q, _ := typecheck("q.go", "package q", nil)
+	p := mustTypecheck("p.go", "package p; type T int", nil)
+	q := mustTypecheck("q.go", "package q", 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 6bdc2d802e..32d6634f53 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -46,12 +46,12 @@ func typecheck(path, src string, info *Info) (*Package, error) {
 	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
 }
 
-func mustTypecheck(path, src string, info *Info) string {
+func mustTypecheck(path, src string, info *Info) *Package {
 	pkg, err := typecheck(path, src, info)
 	if err != nil {
 		panic(err) // so we don't need to pass *testing.T
 	}
-	return pkg.Name()
+	return pkg
 }
 
 func TestValuesInfo(t *testing.T) {
@@ -137,7 +137,7 @@ func TestValuesInfo(t *testing.T) {
 		info := Info{
 			Types: make(map[ast.Expr]TypeAndValue),
 		}
-		name := mustTypecheck("ValuesInfo", test.src, &info)
+		name := mustTypecheck("ValuesInfo", test.src, &info).Name()
 
 		// look for expression
 		var expr ast.Expr
@@ -384,7 +384,7 @@ func TestTypesInfo(t *testing.T) {
 				name = pkg.Name()
 			}
 		} else {
-			name = mustTypecheck("TypesInfo", test.src, &info)
+			name = mustTypecheck("TypesInfo", test.src, &info).Name()
 		}
 
 		// look for expression type
@@ -642,7 +642,7 @@ func TestDefsInfo(t *testing.T) {
 		info := Info{
 			Defs: make(map[*ast.Ident]Object),
 		}
-		name := mustTypecheck("DefsInfo", test.src, &info)
+		name := mustTypecheck("DefsInfo", test.src, &info).Name()
 
 		// find object
 		var def Object
@@ -709,7 +709,7 @@ func TestUsesInfo(t *testing.T) {
 		info := Info{
 			Uses: make(map[*ast.Ident]Object),
 		}
-		name := mustTypecheck("UsesInfo", test.src, &info)
+		name := mustTypecheck("UsesInfo", test.src, &info).Name()
 
 		// find object
 		var use Object
@@ -850,7 +850,7 @@ func TestImplicitsInfo(t *testing.T) {
 		info := Info{
 			Implicits: make(map[ast.Node]Object),
 		}
-		name := mustTypecheck("ImplicitsInfo", test.src, &info)
+		name := mustTypecheck("ImplicitsInfo", test.src, &info).Name()
 
 		// the test cases expect at most one Implicits entry
 		if len(info.Implicits) > 1 {
@@ -978,7 +978,7 @@ func TestPredicatesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
-		name := mustTypecheck("PredicatesInfo", test.src, &info)
+		name := mustTypecheck("PredicatesInfo", test.src, &info).Name()
 
 		// look for expression predicates
 		got := "<missing>"
@@ -1070,7 +1070,7 @@ func TestScopesInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{Scopes: make(map[ast.Node]*Scope)}
-		name := mustTypecheck("ScopesInfo", test.src, &info)
+		name := mustTypecheck("ScopesInfo", test.src, &info).Name()
 
 		// number of scopes must match
 		if len(info.Scopes) != len(test.scopes) {
@@ -1258,7 +1258,7 @@ func TestInitOrderInfo(t *testing.T) {
 
 	for _, test := range tests {
 		info := Info{}
-		name := mustTypecheck("InitOrderInfo", test.src, &info)
+		name := mustTypecheck("InitOrderInfo", test.src, &info).Name()
 
 		// number of initializers must match
 		if len(info.InitOrder) != len(test.inits) {
@@ -1620,11 +1620,7 @@ func TestLookupFieldOrMethod(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck("test", "package p;"+test.src, nil)
-		if err != nil {
-			t.Errorf("%s: incorrect test case: %s", test.src, err)
-			continue
-		}
+		pkg := mustTypecheck("test", "package p;"+test.src, nil)
 
 		obj := pkg.Scope().Lookup("a")
 		if obj == nil {
@@ -1903,11 +1899,7 @@ func TestIdentical(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck("test", "package p;"+test.src, nil)
-		if err != nil {
-			t.Errorf("%s: incorrect test case: %s", test.src, err)
-			continue
-		}
+		pkg := mustTypecheck("test", "package p;"+test.src, nil)
 		X := pkg.Scope().Lookup("X")
 		Y := pkg.Scope().Lookup("Y")
 		if X == nil || Y == nil {
@@ -2186,10 +2178,7 @@ 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, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck(".", src, nil)
 
 	// type T should have one type parameter
 	T := pkg.Scope().Lookup("T").Type().(*Named)
@@ -2224,14 +2213,11 @@ func TestInstantiateErrors(t *testing.T) {
 
 	for _, test := range tests {
 		src := "package p; " + test.src
-		pkg, err := typecheck(".", src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", src, nil)
 
 		T := pkg.Scope().Lookup("T").Type().(*Named)
 
-		_, err = Instantiate(nil, T, test.targs, true)
+		_, err := Instantiate(nil, T, test.targs, true)
 		if err == nil {
 			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
 		}
@@ -2550,10 +2536,7 @@ type V4 struct{}
 func (V4) M()
 `
 
-	pkg, err := typecheck("p.go", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck("p.go", src, nil)
 
 	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
 	lookup := func(name string) (*Func, bool) {
diff --git a/src/go/types/instantiate_test.go b/src/go/types/instantiate_test.go
index b4ff3e4442..0b44a1a1d9 100644
--- a/src/go/types/instantiate_test.go
+++ b/src/go/types/instantiate_test.go
@@ -109,10 +109,7 @@ func TestInstantiateEquality(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		pkg, err := typecheck(".", test.src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", test.src, nil)
 
 		t.Run(pkg.Name(), func(t *testing.T) {
 			ctxt := NewContext()
@@ -139,14 +136,8 @@ func TestInstantiateEquality(t *testing.T) {
 func TestInstantiateNonEquality(t *testing.T) {
 	const src = "package p; type T[P any] int"
 
-	pkg1, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	pkg2, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg1 := mustTypecheck(".", src, nil)
+	pkg2 := mustTypecheck(".", src, nil)
 
 	// We consider T1 and T2 to be distinct types, so their instances should not
 	// be deduplicated by the context.
@@ -194,10 +185,7 @@ var X T[int]
 
 	for _, test := range tests {
 		src := prefix + test.decl
-		pkg, err := typecheck(".", src, nil)
-		if err != nil {
-			t.Fatal(err)
-		}
+		pkg := mustTypecheck(".", src, nil)
 		typ := NewPointer(pkg.Scope().Lookup("X").Type())
 		obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
 		m, _ := obj.(*Func)
@@ -219,10 +207,7 @@ func (T[P]) m() {}
 
 var _ T[int]
 `
-	pkg, err := typecheck(".", src, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	pkg := mustTypecheck(".", src, 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 27b43a0d91..5cee7a055e 100644
--- a/src/go/types/issues_test.go
+++ b/src/go/types/issues_test.go
@@ -450,10 +450,7 @@ 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, err := typecheck("a", asrc, nil)
-	if err != nil {
-		t.Fatalf("package %s failed to typecheck: %v", a.Name(), err)
-	}
+	a := mustTypecheck("a", asrc, nil)
 
 	bast := mustParse(fset, "", bsrc)
 	conf := Config{Importer: importHelper{pkg: a}}
@@ -609,10 +606,7 @@ var _ T = template /* ERROR cannot use.*text/template.* as T value */.Template{}
 `
 	)
 
-	a, err := typecheck("a", asrc, nil)
-	if err != nil {
-		t.Fatalf("package a failed to typecheck: %v", err)
-	}
+	a := mustTypecheck("a", asrc, nil)
 	imp := importHelper{pkg: a, fallback: importer.Default()}
 
 	testFiles(t, nil, []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
diff --git a/src/go/types/methodset_test.go b/src/go/types/methodset_test.go
index dba991b1d2..443994be3e 100644
--- a/src/go/types/methodset_test.go
+++ b/src/go/types/methodset_test.go
@@ -84,11 +84,7 @@ func TestNewMethodSet(t *testing.T) {
 	}
 
 	check := func(src string, methods []method, generic bool) {
-		pkg, err := typecheck("test", "package p;"+src, nil)
-		if err != nil {
-			t.Errorf("%s: incorrect test case: %s", src, err)
-			return
-		}
+		pkg := mustTypecheck("test", "package p;"+src, nil)
 
 		scope := pkg.Scope()
 		if generic {
diff --git a/src/go/types/named_test.go b/src/go/types/named_test.go
index cbfa8c7f64..92f17e5455 100644
--- a/src/go/types/named_test.go
+++ b/src/go/types/named_test.go
@@ -32,10 +32,7 @@ func (G[P]) N() (p P) { return }
 
 type Inst = G[int]
 	`
-	pkg, err := typecheck("p", src, nil)
-	if err != nil {
-		b.Fatal(err)
-	}
+	pkg := mustTypecheck("p", src, nil)
 
 	var (
 		T        = pkg.Scope().Lookup("T").Type()
diff --git a/src/go/types/sizes_test.go b/src/go/types/sizes_test.go
index c2917591d7..09ac9e2c26 100644
--- a/src/go/types/sizes_test.go
+++ b/src/go/types/sizes_test.go
@@ -21,14 +21,9 @@ func findStructType(t *testing.T, src string) *types.Struct {
 }
 
 func findStructTypeConfig(t *testing.T, src string, conf *types.Config) *types.Struct {
-	fset := token.NewFileSet()
-	f := mustParse(fset, "x.go", src)
-	info := types.Info{Types: make(map[ast.Expr]types.TypeAndValue)}
-	_, err := conf.Check("x", fset, []*ast.File{f}, &info)
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, tv := range info.Types {
+	types_ := make(map[ast.Expr]types.TypeAndValue)
+	mustTypecheck("x", src, &types.Info{Types: types_})
+	for _, tv := range types_ {
 		if ts, ok := tv.Type.(*types.Struct); ok {
 			return ts
 		}
diff --git a/src/go/types/typestring_test.go b/src/go/types/typestring_test.go
index 260a6f85af..e73f24138b 100644
--- a/src/go/types/typestring_test.go
+++ b/src/go/types/typestring_test.go
@@ -137,8 +137,8 @@ func TestTypeString(t *testing.T) {
 }
 
 func TestQualifiedTypeString(t *testing.T) {
-	p, _ := typecheck("p.go", "package p; type T int", nil)
-	q, _ := typecheck("q.go", "package q", nil)
+	p := mustTypecheck("p.go", "package p; type T int", nil)
+	q := mustTypecheck("q.go", "package q", nil)
 
 	pT := p.Scope().Lookup("T").Type()
 	for _, test := range []struct {