8 files changed, 17 insertions, 24 deletions
diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 8f31687e9f..3adf9e5d11 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -50,9 +50,8 @@ func checkFiles(m posMap, noders []*noder) (*types2.Package, *types2.Info) {
 			}
 			base.ErrorfAt(m.makeXPos(terr.Pos), terr.Code, "%s", msg)
 		},
-		Importer:                   &importer,
-		Sizes:                      &gcSizes{},
-		EnableReverseTypeInference: true,
+		Importer: &importer,
+		Sizes:    &gcSizes{},
 	}
 	info := &types2.Info{
 		StoreTypesInSyntax: true,
diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index 0ee9a4bd06..b798f2c888 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -169,13 +169,6 @@ type Config struct {
 	// If DisableUnusedImportCheck is set, packages are not checked
 	// for unused imports.
 	DisableUnusedImportCheck bool
-
-	// If EnableReverseTypeInference is set, uninstantiated and
-	// partially instantiated generic functions may be assigned
-	// (incl. returned) to variables of function type and type
-	// inference will attempt to infer the missing type arguments.
-	// See proposal go.dev/issue/59338.
-	EnableReverseTypeInference bool
 }
 
 func srcimporter_setUsesCgo(conf *Config) {
diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 8a11dd9a49..3fa8782930 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -594,10 +594,7 @@ type T[P any] []P
 
 	for _, test := range tests {
 		imports := make(testImporter)
-		conf := Config{
-			Importer:                   imports,
-			EnableReverseTypeInference: true,
-		}
+		conf := Config{Importer: imports}
 		instMap := make(map[*syntax.Name]Instance)
 		useMap := make(map[*syntax.Name]Object)
 		makePkg := func(src string) *Package {
diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index bd8ca953ef..ac5efad93d 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -496,7 +496,7 @@ func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []T
 
 	// collect type parameters from generic function arguments
 	var genericArgs []int // indices of generic function arguments
-	if check.conf.EnableReverseTypeInference {
+	if enableReverseTypeInference {
 		for i, arg := range args {
 			// generic arguments cannot have a defined (*Named) type - no need for underlying type below
 			if asig, _ := arg.typ.(*Signature); asig != nil && asig.TypeParams().Len() > 0 {
diff --git a/src/cmd/compile/internal/types2/check_test.go b/src/cmd/compile/internal/types2/check_test.go
index 382d1ad19e..26bb1aed9e 100644
--- a/src/cmd/compile/internal/types2/check_test.go
+++ b/src/cmd/compile/internal/types2/check_test.go
@@ -133,7 +133,6 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
 	flags := flag.NewFlagSet("", flag.PanicOnError)
 	flags.StringVar(&conf.GoVersion, "lang", "", "")
 	flags.BoolVar(&conf.FakeImportC, "fakeImportC", false, "")
-	flags.BoolVar(&conf.EnableReverseTypeInference, "reverseTypeInference", false, "")
 	if err := parseFlags(filenames[0], nil, flags); err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index 295c497054..19e3b9bc98 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -1291,7 +1291,7 @@ func (check *Checker) nonGeneric(T Type, x *operand) {
 		}
 	case *Signature:
 		if t.tparams != nil {
-			if check.conf.EnableReverseTypeInference && T != nil {
+			if enableReverseTypeInference && T != nil {
 				if tsig, _ := under(T).(*Signature); tsig != nil {
 					check.funcInst(tsig, x.Pos(), x, nil)
 					return
@@ -1617,7 +1617,7 @@ func (check *Checker) exprInternal(T Type, x *operand, e syntax.Expr, hint Type)
 	case *syntax.IndexExpr:
 		if check.indexExpr(x, e) {
 			var tsig *Signature
-			if check.conf.EnableReverseTypeInference && T != nil {
+			if enableReverseTypeInference && T != nil {
 				tsig, _ = under(T).(*Signature)
 			}
 			check.funcInst(tsig, e.Pos(), x, e)
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index 1028924c32..ce6bb91e96 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -13,6 +13,13 @@ import (
 	"strings"
 )
 
+// If enableReverseTypeInference is set, uninstantiated and
+// partially instantiated generic functions may be assigned
+// (incl. returned) to variables of function type and type
+// inference will attempt to infer the missing type arguments.
+// Available with go1.21.
+const enableReverseTypeInference = true // disable for debugging
+
 // infer attempts to infer the complete set of type arguments for generic function instantiation/call
 // based on the given type parameters tparams, type arguments targs, function parameters params, and
 // function arguments args, if any. There must be at least one type parameter, no more type arguments
diff --git a/src/cmd/compile/internal/types2/stdlib_test.go b/src/cmd/compile/internal/types2/stdlib_test.go
index d9db545dc6..404e1636ae 100644
--- a/src/cmd/compile/internal/types2/stdlib_test.go
+++ b/src/cmd/compile/internal/types2/stdlib_test.go
@@ -139,9 +139,8 @@ func testTestDir(t *testing.T, path string, ignore ...string) {
 		file, err := syntax.ParseFile(filename, nil, nil, 0)
 		if err == nil {
 			conf := Config{
-				GoVersion:                  goVersion,
-				Importer:                   stdLibImporter,
-				EnableReverseTypeInference: true,
+				GoVersion: goVersion,
+				Importer:  stdLibImporter,
 			}
 			_, err = conf.Check(filename, []*syntax.File{file}, nil)
 		}
@@ -254,9 +253,8 @@ func typecheckFiles(t *testing.T, path string, filenames []string) {
 
 	// typecheck package files
 	conf := Config{
-		Error:                      func(err error) { t.Error(err) },
-		Importer:                   stdLibImporter,
-		EnableReverseTypeInference: true,
+		Error:    func(err error) { t.Error(err) },
+		Importer: stdLibImporter,
 	}
 	info := Info{Uses: make(map[*syntax.Name]Object)}
 	conf.Check(path, files, &info)