From bf408e741c2827a45c8576dda4126fc4135ef247 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Tue, 29 Mar 2022 17:30:58 -0700
Subject: [PATCH] cmd/compile/internal/syntax: remove generic-specific parse
 modes

Generics have landed; we cannot revert the syntax anymore. Remove
ability to choose between non-generic and generic code. Also remove
mode to enable method type parameters. Adjust code accordingly.

Also remove a couple of TODOs that are not relevant anymore.

Remove tests from types2 which were focussed on method type parameters,
make types2 and go/types tests match up where there was a difference in
this regard.

Change-Id: I989bdcb19eea7414214af739187fa013a044295d
Reviewed-on: https://go-review.googlesource.com/c/go/+/396634
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---
 src/cmd/compile/internal/noder/noder.go       |   2 +-
 .../compile/internal/syntax/dumper_test.go    |   2 +-
 src/cmd/compile/internal/syntax/error_test.go |   6 +-
 src/cmd/compile/internal/syntax/parser.go     | 209 +++++++-----------
 .../compile/internal/syntax/parser_test.go    |   6 +-
 .../compile/internal/syntax/printer_test.go   |   6 +-
 src/cmd/compile/internal/syntax/syntax.go     |   2 -
 .../internal/syntax/testdata/issue47704.go    |   1 -
 .../internal/syntax/testdata/issue47704.go117 |  18 --
 .../internal/syntax/testdata/smoketest.go     |  18 +-
 src/cmd/compile/internal/types2/api_test.go   |  32 +--
 .../compile/internal/types2/builtins_test.go  |   2 +-
 src/cmd/compile/internal/types2/check_test.go |   2 +-
 src/cmd/compile/internal/types2/mono_test.go  |   2 +-
 .../compile/internal/types2/stdlib_test.go    |   2 +-
 .../types2/testdata/check/mtypeparams.go      |  52 -----
 .../types2/testdata/check/typeparams.go       |  27 +--
 .../compile/internal/types2/typeset_test.go   |   2 +-
 src/go/types/testdata/check/typeparams.go     |  25 ---
 19 files changed, 109 insertions(+), 307 deletions(-)
 delete mode 100644 src/cmd/compile/internal/syntax/testdata/issue47704.go117
 delete mode 100644 src/cmd/compile/internal/types2/testdata/check/mtypeparams.go

diff --git a/src/cmd/compile/internal/noder/noder.go b/src/cmd/compile/internal/noder/noder.go
index f8f802936b..77ca642183 100644
--- a/src/cmd/compile/internal/noder/noder.go
+++ b/src/cmd/compile/internal/noder/noder.go
@@ -27,7 +27,7 @@ import (
 func LoadPackage(filenames []string) {
 	base.Timer.Start("fe", "parse")
 
-	mode := syntax.CheckBranches | syntax.AllowGenerics
+	mode := syntax.CheckBranches
 
 	// Limit the number of simultaneously open files.
 	sem := make(chan struct{}, runtime.GOMAXPROCS(0)+10)
diff --git a/src/cmd/compile/internal/syntax/dumper_test.go b/src/cmd/compile/internal/syntax/dumper_test.go
index 033283a352..1ba85cc8d9 100644
--- a/src/cmd/compile/internal/syntax/dumper_test.go
+++ b/src/cmd/compile/internal/syntax/dumper_test.go
@@ -13,7 +13,7 @@ func TestDump(t *testing.T) {
 		t.Skip("skipping test in short mode")
 	}
 
-	ast, _ := ParseFile(*src_, func(err error) { t.Error(err) }, nil, CheckBranches|AllowGenerics)
+	ast, _ := ParseFile(*src_, func(err error) { t.Error(err) }, nil, CheckBranches)
 
 	if ast != nil {
 		Fdump(testOut(), ast)
diff --git a/src/cmd/compile/internal/syntax/error_test.go b/src/cmd/compile/internal/syntax/error_test.go
index 0900bec6ec..724ca0eb98 100644
--- a/src/cmd/compile/internal/syntax/error_test.go
+++ b/src/cmd/compile/internal/syntax/error_test.go
@@ -128,10 +128,6 @@ func testSyntaxErrors(t *testing.T, filename string) {
 	}
 	defer f.Close()
 
-	var mode Mode
-	if !strings.HasSuffix(filename, ".go117") {
-		mode = AllowGenerics
-	}
 	ParseFile(filename, func(err error) {
 		e, ok := err.(Error)
 		if !ok {
@@ -166,7 +162,7 @@ func testSyntaxErrors(t *testing.T, filename string) {
 		} else {
 			t.Errorf("%s:%s: unexpected error: %s", filename, orig, e.Msg)
 		}
-	}, nil, mode)
+	}, nil, 0)
 
 	if *print {
 		fmt.Println()
diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index a75a3b1a2e..2c53a40b2f 100644
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -87,8 +87,6 @@ func (p *parser) init(file *PosBase, r io.Reader, errh ErrorHandler, pragh Pragm
 	p.indent = nil
 }
 
-func (p *parser) allowGenerics() bool { return p.mode&AllowGenerics != 0 }
-
 // takePragma returns the current parsed pragmas
 // and clears them from the parser state.
 func (p *parser) takePragma() Pragma {
@@ -586,7 +584,7 @@ func (p *parser) typeDecl(group *Group) Decl {
 	d.Pragma = p.takePragma()
 
 	d.Name = p.name()
-	if p.allowGenerics() && p.tok == _Lbrack {
+	if p.tok == _Lbrack {
 		// d.Name "[" ...
 		// array/slice type or type parameter list
 		pos := p.pos()
@@ -762,7 +760,7 @@ func (p *parser) funcDeclOrNil() *FuncDecl {
 	f.Name = p.name()
 
 	context := ""
-	if f.Recv != nil && p.mode&AllowMethodTypeParams == 0 {
+	if f.Recv != nil {
 		context = "method" // don't permit (method) type parameters in funcType
 	}
 	f.TParamList, f.Type = p.funcType(context)
@@ -1098,45 +1096,25 @@ loop:
 
 			var i Expr
 			if p.tok != _Colon {
-				if p.mode&AllowGenerics == 0 {
-					p.xnest++
-					i = p.expr()
-					p.xnest--
-					if p.got(_Rbrack) {
-						// x[i]
-						t := new(IndexExpr)
-						t.pos = pos
-						t.X = x
-						t.Index = i
-						x = t
-						break
-					}
-				} else {
-					var comma bool
-					i, comma = p.typeList()
-					if comma || p.tok == _Rbrack {
-						p.want(_Rbrack)
-						// x[i,] or x[i, j, ...]
-						t := new(IndexExpr)
-						t.pos = pos
-						t.X = x
-						t.Index = i
-						x = t
-						break
-					}
+				var comma bool
+				i, comma = p.typeList()
+				if comma || p.tok == _Rbrack {
+					p.want(_Rbrack)
+					// x[i,] or x[i, j, ...]
+					t := new(IndexExpr)
+					t.pos = pos
+					t.X = x
+					t.Index = i
+					x = t
+					break
 				}
 			}
 
 			// x[i:...
 			// For better error message, don't simply use p.want(_Colon) here (issue #47704).
 			if !p.got(_Colon) {
-				if p.mode&AllowGenerics == 0 {
-					p.syntaxError("expecting : or ]")
-					p.advance(_Colon, _Rbrack)
-				} else {
-					p.syntaxError("expecting comma, : or ]")
-					p.advance(_Comma, _Colon, _Rbrack)
-				}
+				p.syntaxError("expecting comma, : or ]")
+				p.advance(_Comma, _Colon, _Rbrack)
 			}
 			p.xnest++
 			t := new(SliceExpr)
@@ -1418,7 +1396,7 @@ func (p *parser) funcType(context string) ([]*Field, *FuncType) {
 	typ.pos = p.pos()
 
 	var tparamList []*Field
-	if p.allowGenerics() && p.got(_Lbrack) {
+	if p.got(_Lbrack) {
 		if context != "" {
 			// accept but complain
 			p.syntaxErrorAt(typ.pos, context+" must have no type parameters")
@@ -1509,7 +1487,6 @@ func (p *parser) structType() *StructType {
 
 // InterfaceType = "interface" "{" { ( MethodDecl | EmbeddedElem | TypeList ) ";" } "}" .
 // TypeList      = "type" Type { "," Type } .
-// TODO(gri) remove TypeList syntax if we accept #45346
 func (p *parser) interfaceType() *InterfaceType {
 	if trace {
 		defer p.trace("interfaceType")()
@@ -1524,14 +1501,13 @@ func (p *parser) interfaceType() *InterfaceType {
 		switch p.tok {
 		case _Name:
 			f := p.methodDecl()
-			if f.Name == nil && p.allowGenerics() {
+			if f.Name == nil {
 				f = p.embeddedElem(f)
 			}
 			typ.MethodList = append(typ.MethodList, f)
 			return false
 
 		case _Lparen:
-			// TODO(gri) Need to decide how to adjust this restriction.
 			p.syntaxError("cannot parenthesize embedded type")
 			f := new(Field)
 			f.pos = p.pos()
@@ -1542,31 +1518,23 @@ func (p *parser) interfaceType() *InterfaceType {
 			return false
 
 		case _Operator:
-			if p.op == Tilde && p.allowGenerics() {
+			if p.op == Tilde {
 				typ.MethodList = append(typ.MethodList, p.embeddedElem(nil))
 				return false
 			}
 
 		default:
-			if p.allowGenerics() {
-				pos := p.pos()
-				if t := p.typeOrNil(); t != nil {
-					f := new(Field)
-					f.pos = pos
-					f.Type = t
-					typ.MethodList = append(typ.MethodList, p.embeddedElem(f))
-					return false
-				}
+			pos := p.pos()
+			if t := p.typeOrNil(); t != nil {
+				f := new(Field)
+				f.pos = pos
+				f.Type = t
+				typ.MethodList = append(typ.MethodList, p.embeddedElem(f))
+				return false
 			}
 		}
 
-		if p.allowGenerics() {
-			p.syntaxError("expecting method or embedded element")
-			p.advance(_Semi, _Rbrace)
-			return false
-		}
-
-		p.syntaxError("expecting method or interface name")
+		p.syntaxError("expecting method or embedded element")
 		p.advance(_Semi, _Rbrace)
 		return false
 	})
@@ -1640,7 +1608,7 @@ func (p *parser) fieldDecl(styp *StructType) {
 
 		// Careful dance: We don't know if we have an embedded instantiated
 		// type T[P1, P2, ...] or a field T of array/slice type [P]E or []E.
-		if p.allowGenerics() && len(names) == 1 && p.tok == _Lbrack {
+		if len(names) == 1 && p.tok == _Lbrack {
 			typ = p.arrayOrTArgs()
 			if typ, ok := typ.(*IndexExpr); ok {
 				// embedded type T[P1, P2, ...]
@@ -1780,79 +1748,72 @@ func (p *parser) methodDecl() *Field {
 		_, f.Type = p.funcType(context)
 
 	case _Lbrack:
-		if p.allowGenerics() {
-			// Careful dance: We don't know if we have a generic method m[T C](x T)
-			// or an embedded instantiated type T[P1, P2] (we accept generic methods
-			// for generality and robustness of parsing).
+		// Careful dance: We don't know if we have a generic method m[T C](x T)
+		// or an embedded instantiated type T[P1, P2] (we accept generic methods
+		// for generality and robustness of parsing but complain with an error).
+		pos := p.pos()
+		p.next()
+
+		// Empty type parameter or argument lists are not permitted.
+		// Treat as if [] were absent.
+		if p.tok == _Rbrack {
+			// name[]
 			pos := p.pos()
 			p.next()
-
-			// Empty type parameter or argument lists are not permitted.
-			// Treat as if [] were absent.
-			if p.tok == _Rbrack {
-				// name[]
-				pos := p.pos()
-				p.next()
-				if p.tok == _Lparen {
-					// name[](
-					p.errorAt(pos, "empty type parameter list")
-					f.Name = name
-					_, f.Type = p.funcType(context)
-				} else {
-					p.errorAt(pos, "empty type argument list")
-					f.Type = name
-				}
-				break
-			}
-
-			// A type argument list looks like a parameter list with only
-			// types. Parse a parameter list and decide afterwards.
-			list := p.paramList(nil, nil, _Rbrack, false)
-			if len(list) == 0 {
-				// The type parameter list is not [] but we got nothing
-				// due to other errors (reported by paramList). Treat
-				// as if [] were absent.
-				if p.tok == _Lparen {
-					f.Name = name
-					_, f.Type = p.funcType(context)
-				} else {
-					f.Type = name
-				}
-				break
-			}
-
-			// len(list) > 0
-			if list[0].Name != nil {
-				// generic method
+			if p.tok == _Lparen {
+				// name[](
+				p.errorAt(pos, "empty type parameter list")
 				f.Name = name
 				_, f.Type = p.funcType(context)
-				// TODO(gri) Record list as type parameter list with f.Type
-				//           if we want to type-check the generic method.
-				//           For now, report an error so this is not a silent event.
-				p.errorAt(pos, "interface method must have no type parameters")
-				break
+			} else {
+				p.errorAt(pos, "empty type argument list")
+				f.Type = name
 			}
+			break
+		}
 
-			// embedded instantiated type
-			t := new(IndexExpr)
-			t.pos = pos
-			t.X = name
-			if len(list) == 1 {
-				t.Index = list[0].Type
+		// A type argument list looks like a parameter list with only
+		// types. Parse a parameter list and decide afterwards.
+		list := p.paramList(nil, nil, _Rbrack, false)
+		if len(list) == 0 {
+			// The type parameter list is not [] but we got nothing
+			// due to other errors (reported by paramList). Treat
+			// as if [] were absent.
+			if p.tok == _Lparen {
+				f.Name = name
+				_, f.Type = p.funcType(context)
 			} else {
-				// len(list) > 1
-				l := new(ListExpr)
-				l.pos = list[0].Pos()
-				l.ElemList = make([]Expr, len(list))
-				for i := range list {
-					l.ElemList[i] = list[i].Type
-				}
-				t.Index = l
+				f.Type = name
 			}
-			f.Type = t
 			break
 		}
-		fallthrough
+
+		// len(list) > 0
+		if list[0].Name != nil {
+			// generic method
+			f.Name = name
+			_, f.Type = p.funcType(context)
+			p.errorAt(pos, "interface method must have no type parameters")
+			break
+		}
+
+		// embedded instantiated type
+		t := new(IndexExpr)
+		t.pos = pos
+		t.X = name
+		if len(list) == 1 {
+			t.Index = list[0].Type
+		} else {
+			// len(list) > 1
+			l := new(ListExpr)
+			l.pos = list[0].Pos()
+			l.ElemList = make([]Expr, len(list))
+			for i := range list {
+				l.ElemList[i] = list[i].Type
+			}
+			t.Index = l
+		}
+		f.Type = t
 
 	default:
 		// embedded type
@@ -1938,7 +1899,7 @@ func (p *parser) paramDeclOrNil(name *Name, follow token) *Field {
 			name = p.name()
 		}
 
-		if p.allowGenerics() && p.tok == _Lbrack {
+		if p.tok == _Lbrack {
 			// name "[" ...
 			f.Type = p.arrayOrTArgs()
 			if typ, ok := f.Type.(*IndexExpr); ok {
@@ -2787,7 +2748,7 @@ func (p *parser) qualifiedName(name *Name) Expr {
 		x = s
 	}
 
-	if p.allowGenerics() && p.tok == _Lbrack {
+	if p.tok == _Lbrack {
 		x = p.typeInstance(x)
 	}
 
diff --git a/src/cmd/compile/internal/syntax/parser_test.go b/src/cmd/compile/internal/syntax/parser_test.go
index ddddedc5ec..b3d4573935 100644
--- a/src/cmd/compile/internal/syntax/parser_test.go
+++ b/src/cmd/compile/internal/syntax/parser_test.go
@@ -27,11 +27,11 @@ var (
 )
 
 func TestParse(t *testing.T) {
-	ParseFile(*src_, func(err error) { t.Error(err) }, nil, AllowGenerics)
+	ParseFile(*src_, func(err error) { t.Error(err) }, nil, 0)
 }
 
 func TestVerify(t *testing.T) {
-	ast, err := ParseFile(*src_, func(err error) { t.Error(err) }, nil, AllowGenerics)
+	ast, err := ParseFile(*src_, func(err error) { t.Error(err) }, nil, 0)
 	if err != nil {
 		return // error already reported
 	}
@@ -80,7 +80,7 @@ func TestStdLib(t *testing.T) {
 				if debug {
 					fmt.Printf("parsing %s\n", filename)
 				}
-				ast, err := ParseFile(filename, nil, nil, AllowGenerics)
+				ast, err := ParseFile(filename, nil, nil, 0)
 				if err != nil {
 					t.Error(err)
 					return
diff --git a/src/cmd/compile/internal/syntax/printer_test.go b/src/cmd/compile/internal/syntax/printer_test.go
index 941af0aeb4..3eca2316a7 100644
--- a/src/cmd/compile/internal/syntax/printer_test.go
+++ b/src/cmd/compile/internal/syntax/printer_test.go
@@ -18,7 +18,7 @@ func TestPrint(t *testing.T) {
 		t.Skip("skipping test in short mode")
 	}
 
-	ast, _ := ParseFile(*src_, func(err error) { t.Error(err) }, nil, AllowGenerics)
+	ast, _ := ParseFile(*src_, func(err error) { t.Error(err) }, nil, 0)
 
 	if ast != nil {
 		Fprint(testOut(), ast, LineForm)
@@ -117,7 +117,7 @@ var stringTests = [][2]string{
 
 func TestPrintString(t *testing.T) {
 	for _, test := range stringTests {
-		ast, err := Parse(nil, strings.NewReader(test[0]), nil, nil, AllowGenerics)
+		ast, err := Parse(nil, strings.NewReader(test[0]), nil, nil, 0)
 		if err != nil {
 			t.Error(err)
 			continue
@@ -237,7 +237,7 @@ var exprTests = [][2]string{
 func TestShortString(t *testing.T) {
 	for _, test := range exprTests {
 		src := "package p; var _ = " + test[0]
-		ast, err := Parse(nil, strings.NewReader(src), nil, nil, AllowGenerics)
+		ast, err := Parse(nil, strings.NewReader(src), nil, nil, 0)
 		if err != nil {
 			t.Errorf("%s: %s", test[0], err)
 			continue
diff --git a/src/cmd/compile/internal/syntax/syntax.go b/src/cmd/compile/internal/syntax/syntax.go
index 25c8116206..e51b5538b3 100644
--- a/src/cmd/compile/internal/syntax/syntax.go
+++ b/src/cmd/compile/internal/syntax/syntax.go
@@ -16,8 +16,6 @@ type Mode uint
 // Modes supported by the parser.
 const (
 	CheckBranches Mode = 1 << iota // check correct use of labels, break, continue, and goto statements
-	AllowGenerics
-	AllowMethodTypeParams // does not support interface methods yet; ignored if AllowGenerics is not set
 )
 
 // Error describes a syntax error. Error implements the error interface.
diff --git a/src/cmd/compile/internal/syntax/testdata/issue47704.go b/src/cmd/compile/internal/syntax/testdata/issue47704.go
index 4e65857f3b..2f2e29b693 100644
--- a/src/cmd/compile/internal/syntax/testdata/issue47704.go
+++ b/src/cmd/compile/internal/syntax/testdata/issue47704.go
@@ -4,7 +4,6 @@
 
 package p
 
-// error messages for parser in generic mode
 func _() {
 	_ = m[] // ERROR expecting operand
 	_ = m[x,]
diff --git a/src/cmd/compile/internal/syntax/testdata/issue47704.go117 b/src/cmd/compile/internal/syntax/testdata/issue47704.go117
deleted file mode 100644
index 0156af7d8d..0000000000
--- a/src/cmd/compile/internal/syntax/testdata/issue47704.go117
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package p
-
-// error messages for parser in non-generic mode
-func _() {
-	_ = m[]   // ERROR expecting operand
-	_ = m[x,] // ERROR unexpected comma, expecting \: or \]
-	_ = m[x /* ERROR unexpected a */ a b c d]
-}
-
-// test case from the issue
-func f(m map[int]int) int {
-	return m[0 // ERROR expecting \: or \]
-		]
-}
diff --git a/src/cmd/compile/internal/syntax/testdata/smoketest.go b/src/cmd/compile/internal/syntax/testdata/smoketest.go
index 1eb04e3ff7..6b3593ac7a 100644
--- a/src/cmd/compile/internal/syntax/testdata/smoketest.go
+++ b/src/cmd/compile/internal/syntax/testdata/smoketest.go
@@ -38,18 +38,18 @@ var _ = T[int]{}
 type _ struct{ T[int] }
 
 // interfaces
-type _ interface{
+type _ interface {
 	m()
 	~int
 }
 
-type _ interface{
+type _ interface {
 	~int | ~float | ~string
 	~complex128
 	underlying(underlying underlying) underlying
 }
 
-type _ interface{
+type _ interface {
 	T
 	T[int]
 }
@@ -58,20 +58,16 @@ type _ interface{
 func _(T[P], T[P1, P2])
 func _(a [N]T)
 
-type _ struct{
+type _ struct {
 	T[P]
 	T[P1, P2]
-	f [N]
+	f[N]
 }
-type _ interface{
+type _ interface {
 	m()
 
-	// generic methods - disabled for now
-	// m[] /* ERROR empty type parameter list */ ()
-	// m[ /* ERROR cannot have type parameters */ P any](P)
-
 	// instantiated types
-	// T[] /* ERROR empty type argument list */ 
+	T[ /* ERROR empty type argument list */ ]
 	T[P]
 	T[P1, P2]
 }
diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index d8f7fb5eda..528beaacea 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -26,7 +26,7 @@ const brokenPkg = "package broken_"
 
 func parseSrc(path, 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, syntax.AllowGenerics|syntax.AllowMethodTypeParams)
+	return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, 0)
 }
 
 func pkgFor(path, source string, info *Info) (*Package, error) {
@@ -436,36 +436,6 @@ type T[P any] []P
 		{`package p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
 			[]testInst{{`f`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
 		},
-		// we don't know how to translate these but we can type-check them
-		{`package q0; type T struct{}; func (T) m[P any](P) {}; func _(x T) { x.m(42) }`,
-			[]testInst{{`m`, []string{`int`}, `func(int)`}},
-		},
-		{`package q1; type T struct{}; func (T) m[P any](P) P { panic(0) }; func _(x T) { x.m(42) }`,
-			[]testInst{{`m`, []string{`int`}, `func(int) int`}},
-		},
-		{`package q2; type T struct{}; func (T) m[P any](...P) P { panic(0) }; func _(x T) { x.m(42) }`,
-			[]testInst{{`m`, []string{`int`}, `func(...int) int`}},
-		},
-		{`package q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C) {}; func _(x T) { x.m(1.2, new(string), []byte{}) }`,
-			[]testInst{{`m`, []string{`float64`, `string`, `byte`}, `func(float64, *string, []byte)`}},
-		},
-		{`package q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B) {}; func _(x T) { x.m(1.2, new(byte)) }`,
-			[]testInst{{`m`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
-		},
-
-		{`package r0; type T[P1 any] struct{}; func (_ T[P2]) m[Q any](Q) {}; func _[P3 any](x T[P3]) { x.m(42) }`,
-			[]testInst{
-				{`T`, []string{`P2`}, `struct{}`},
-				{`T`, []string{`P3`}, `struct{}`},
-				{`m`, []string{`int`}, `func(int)`},
-			},
-		},
-		// TODO(gri) record method type parameters in syntax.FuncType so we can check this
-		// {`package r1; type T interface{ m[P any](P) }; func _(x T) { x.m(4.2) }`,
-		// 	`x.m`,
-		// 	[]string{`float64`},
-		// 	`func(float64)`,
-		// },
 
 		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
 			[]testInst{{`f`, []string{`string`, `*string`}, `func(x string)`}},
diff --git a/src/cmd/compile/internal/types2/builtins_test.go b/src/cmd/compile/internal/types2/builtins_test.go
index e07a7794f6..ad8873a7d4 100644
--- a/src/cmd/compile/internal/types2/builtins_test.go
+++ b/src/cmd/compile/internal/types2/builtins_test.go
@@ -159,7 +159,7 @@ func TestBuiltinSignatures(t *testing.T) {
 
 func parseGenericSrc(path, 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, syntax.AllowGenerics)
+	return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, 0)
 }
 
 func testBuiltinSignature(t *testing.T, name, src0, want string) {
diff --git a/src/cmd/compile/internal/types2/check_test.go b/src/cmd/compile/internal/types2/check_test.go
index cdf440f9be..ec242c5e22 100644
--- a/src/cmd/compile/internal/types2/check_test.go
+++ b/src/cmd/compile/internal/types2/check_test.go
@@ -135,7 +135,7 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
 		t.Fatal(err)
 	}
 
-	files, errlist := parseFiles(t, filenames, syntax.AllowGenerics|syntax.AllowMethodTypeParams)
+	files, errlist := parseFiles(t, filenames, 0)
 
 	pkgName := "<no package>"
 	if len(files) > 0 {
diff --git a/src/cmd/compile/internal/types2/mono_test.go b/src/cmd/compile/internal/types2/mono_test.go
index 19d0e95637..4511110691 100644
--- a/src/cmd/compile/internal/types2/mono_test.go
+++ b/src/cmd/compile/internal/types2/mono_test.go
@@ -16,7 +16,7 @@ import (
 
 func checkMono(t *testing.T, body string) error {
 	src := "package x; import `unsafe`; var _ unsafe.Pointer;\n" + body
-	file, err := syntax.Parse(syntax.NewFileBase("x.go"), strings.NewReader(src), nil, nil, syntax.AllowGenerics)
+	file, err := syntax.Parse(syntax.NewFileBase("x.go"), strings.NewReader(src), nil, nil, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/compile/internal/types2/stdlib_test.go b/src/cmd/compile/internal/types2/stdlib_test.go
index fda78e20d1..4e54056e74 100644
--- a/src/cmd/compile/internal/types2/stdlib_test.go
+++ b/src/cmd/compile/internal/types2/stdlib_test.go
@@ -220,7 +220,7 @@ func typecheck(t *testing.T, path string, filenames []string) {
 	var files []*syntax.File
 	for _, filename := range filenames {
 		errh := func(err error) { t.Error(err) }
-		file, err := syntax.ParseFile(filename, errh, nil, syntax.AllowGenerics)
+		file, err := syntax.ParseFile(filename, errh, nil, 0)
 		if err != nil {
 			return
 		}
diff --git a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go b/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go
deleted file mode 100644
index 1b406593f8..0000000000
--- a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// If types2.Config.AcceptMethodTypeParams is set,
-// the type checker accepts methods that have their
-// own type parameter list.
-
-package p
-
-type S struct{}
-
-func (S) m[T any](v T) {}
-
-// TODO(gri) Once we collect interface method type parameters
-//           in the parser, we can enable these tests again.
-/*
-type I interface {
-   m[T any](v T)
-}
-
-type J interface {
-   m[T any](v T)
-}
-
-var _ I = S{}
-var _ I = J(nil)
-
-type C interface{ n() }
-
-type Sc struct{}
-
-func (Sc) m[T C](v T)
-
-type Ic interface {
-   m[T C](v T)
-}
-
-type Jc interface {
-   m[T C](v T)
-}
-
-var _ Ic = Sc{}
-var _ Ic = Jc(nil)
-
-// TODO(gri) These should fail because the constraints don't match.
-var _ I = Sc{}
-var _ I = Jc(nil)
-
-var _ Ic = S{}
-var _ Ic = J(nil)
-*/
\ No newline at end of file
diff --git a/src/cmd/compile/internal/types2/testdata/check/typeparams.go b/src/cmd/compile/internal/types2/testdata/check/typeparams.go
index 68b1f0f5c5..498d6f2d26 100644
--- a/src/cmd/compile/internal/types2/testdata/check/typeparams.go
+++ b/src/cmd/compile/internal/types2/testdata/check/typeparams.go
@@ -329,9 +329,8 @@ func init[P /* ERROR func init must have no type parameters */ any]() {}
 type T struct {}
 
 func (T) m1() {}
-// The type checker accepts method type parameters if configured accordingly.
-func (T) m2[_ any]() {}
-func (T) m3[P any]() {}
+func (T) m2[ /* ERROR method must have no type parameters */ _ any]() {}
+func (T) m3[ /* ERROR method must have no type parameters */ P any]() {}
 
 // type inference across parameterized types
 
@@ -390,28 +389,6 @@ func _[T any] (x T) {
         m(S1[T]{x})
 }
 
-// type parameters in methods (generalization)
-
-type R0 struct{}
-
-func (R0) _[T any](x T) {}
-func (R0 /* ERROR invalid receiver */ ) _[R0 any]() {} // scope of type parameters starts at "func"
-
-type R1[A, B any] struct{}
-
-func (_ R1[A, B]) m0(A, B)
-func (_ R1[A, B]) m1[T any](A, B, T) T { panic(0) }
-func (_ R1 /* ERROR not a generic type */ [R1, _]) _()
-func (_ R1[A, B]) _[A /* ERROR redeclared */ any](B) {}
-
-func _() {
-        var r R1[int, string]
-        r.m1[rune](42, "foo", 'a')
-        r.m1[rune](42, "foo", 1.2 /* ERROR cannot use .* as rune .* \(truncated\) */)
-        r.m1(42, "foo", 1.2) // using type inference
-        var _ float64 = r.m1(42, "foo", 1.2)
-}
-
 type I1[A any] interface {
         m1(A)
 }
diff --git a/src/cmd/compile/internal/types2/typeset_test.go b/src/cmd/compile/internal/types2/typeset_test.go
index 68e5d8ad62..69eaff741f 100644
--- a/src/cmd/compile/internal/types2/typeset_test.go
+++ b/src/cmd/compile/internal/types2/typeset_test.go
@@ -47,7 +47,7 @@ func TestTypeSetString(t *testing.T) {
 		// parse
 		errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
 		src := "package p; type T interface" + body
-		file, err := syntax.Parse(nil, strings.NewReader(src), errh, nil, syntax.AllowGenerics)
+		file, err := syntax.Parse(nil, strings.NewReader(src), errh, nil, 0)
 		if err != nil {
 			t.Fatalf("%s: %v (invalid test case)", body, err)
 		}
diff --git a/src/go/types/testdata/check/typeparams.go b/src/go/types/testdata/check/typeparams.go
index 29a3b16cd6..199828f55f 100644
--- a/src/go/types/testdata/check/typeparams.go
+++ b/src/go/types/testdata/check/typeparams.go
@@ -389,31 +389,6 @@ func _[T any] (x T) {
         m(S1[T]{x})
 }
 
-// type parameters in methods (generalization)
-
-// Type Parameter lists are not allowed on methods, and are not produced by
-// go/parser. The test cases below are preserved for consistency with types2,
-// which produces an error but stores type parameters.
-// type R0 struct{}
-
-// func (R0) _[ /* ERROR methods cannot have type parameters */ T any](x T) {}
-// func (R0 /* ERROR invalid receiver */ ) _[ /* ERROR methods cannot have type parameters */ R0 any]() {} // scope of type parameters starts at "func"
-
-// type R1[A, B any] struct{}
-
-// func (_ R1[A, B]) m0(A, B)
-// func (_ R1[A, B]) m1[ /* ERROR methods cannot have type parameters */ T any](A, B, T) T  { panic(0) }
-// func (_ R1 /* ERROR not a generic type */ [R1, _]) _()
-// func (_ R1[A, B]) _[ /* ERROR methods cannot have type parameters */ A /* ERROR redeclared */ any](B) {}
-
-// func _() {
-//         var r R1[int, string]
-//         r.m1[rune](42, "foo", 'a')
-//         r.m1[rune](42, "foo", 1.2 /* ERROR cannot use .* as rune .* \(truncated\) */)
-//         r.m1(42, "foo", 1.2) // using type inference
-//         var _ float64 = r.m1(42, "foo", 1.2)
-// }
-
 type I1[A any] interface {
         m1(A)
 }
-- 
2.50.0