[dev.typeparams] go/internal/typeparams: remove the Enabled guard

Type parameters are now always enabled. Users should guard against type
checking generic code by using the types.Config.GoVersion field.

This cleans up some differences with types2.

Change-Id: Ie3e35a549e456a90a10d6a7e158ff58653cc1394
Reviewed-on: https://go-review.googlesource.com/c/go/+/335033
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

10 files changed, 9 insertions, 54 deletions

diff --git a/src/go/internal/typeparams/typeparams.go b/src/go/internal/typeparams/typeparams.go
index e102b77ef8..3191654d4f 100644
--- a/src/go/internal/typeparams/typeparams.go
+++ b/src/go/internal/typeparams/typeparams.go
@@ -10,8 +10,6 @@ import (
 	"go/token"
 )
 
-const Enabled = true
-
 func PackIndexExpr(x ast.Expr, lbrack token.Pos, exprs []ast.Expr, rbrack token.Pos) ast.Expr {
 	switch len(exprs) {
 	case 0:
diff --git a/src/go/parser/error_test.go b/src/go/parser/error_test.go
index e22ab12451..f35ba0b501 100644
--- a/src/go/parser/error_test.go
+++ b/src/go/parser/error_test.go
@@ -189,11 +189,7 @@ func TestErrors(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			if !d.IsDir() && !strings.HasPrefix(name, ".") && (strings.HasSuffix(name, ".src") || strings.HasSuffix(name, ".go2")) {
 				mode := DeclarationErrors | AllErrors
-				if strings.HasSuffix(name, ".go2") {
-					if !typeparams.Enabled {
-						return
-					}
-				} else {
+				if !strings.HasSuffix(name, ".go2") {
 					mode |= typeparams.DisallowParsing
 				}
 				checkErrors(t, filepath.Join(testdata, name), nil, mode, true)
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index d108259171..bdc2ad308c 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -77,7 +77,7 @@ func (p *parser) init(fset *token.FileSet, filename string, src []byte, mode Mod
 }
 
 func (p *parser) parseTypeParams() bool {
-	return typeparams.Enabled && p.mode&typeparams.DisallowParsing == 0
+	return p.mode&typeparams.DisallowParsing == 0
 }
 
 // ----------------------------------------------------------------------------
diff --git a/src/go/parser/resolver_test.go b/src/go/parser/resolver_test.go
index 625c009c91..0c06c592d5 100644
--- a/src/go/parser/resolver_test.go
+++ b/src/go/parser/resolver_test.go
@@ -41,11 +41,7 @@ func TestResolution(t *testing.T) {
 			path := filepath.Join(dir, fi.Name())
 			src := readFile(path) // panics on failure
 			var mode Mode
-			if strings.HasSuffix(path, ".go2") {
-				if !typeparams.Enabled {
-					t.Skip("type params are not enabled")
-				}
-			} else {
+			if !strings.HasSuffix(path, ".go2") {
 				mode |= typeparams.DisallowParsing
 			}
 			file, err := ParseFile(fset, path, src, mode)
diff --git a/src/go/parser/short_test.go b/src/go/parser/short_test.go
index 2467ccb4a7..bfc6f6714b 100644
--- a/src/go/parser/short_test.go
+++ b/src/go/parser/short_test.go
@@ -133,9 +133,6 @@ func TestValid(t *testing.T) {
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range valids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, false)
 		}
@@ -268,9 +265,6 @@ func TestInvalid(t *testing.T) {
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range invalids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, true)
 		}
diff --git a/src/go/printer/printer_test.go b/src/go/printer/printer_test.go
index 20c97b8c08..ff8be4ae97 100644
--- a/src/go/printer/printer_test.go
+++ b/src/go/printer/printer_test.go
@@ -10,7 +10,6 @@ import (
 	"flag"
 	"fmt"
 	"go/ast"
-	"go/internal/typeparams"
 	"go/parser"
 	"go/token"
 	"io"
@@ -222,9 +221,6 @@ var data = []entry{
 func TestFiles(t *testing.T) {
 	t.Parallel()
 	for _, e := range data {
-		if !typeparams.Enabled && e.mode&allowTypeParams != 0 {
-			continue
-		}
 		source := filepath.Join(dataDir, e.source)
 		golden := filepath.Join(dataDir, e.golden)
 		mode := e.mode
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index ef248781cc..e6c209dda0 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -353,9 +353,6 @@ func TestTypesInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, broken) {
@@ -534,9 +531,6 @@ func TestDefsInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Defs: make(map[*ast.Ident]Object),
 		}
@@ -582,9 +576,6 @@ func TestUsesInfo(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Uses: make(map[*ast.Ident]Object),
 		}
diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index f0cfced97f..692004facf 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -207,10 +207,8 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
 		t.Fatal("no source files")
 	}
 
-	if strings.HasSuffix(filenames[0], ".go2") && !typeparams.Enabled {
-		t.Skip("type params are not enabled")
-	}
-	if strings.HasSuffix(filenames[0], ".go1") && typeparams.Enabled {
+	if strings.HasSuffix(filenames[0], ".go1") {
+		// TODO(rfindley): re-enable this test by using GoVersion.
 		t.Skip("type params are enabled")
 	}
 
@@ -356,14 +354,6 @@ func TestIndexRepresentability(t *testing.T) {
 	testFiles(t, &StdSizes{4, 4}, []string{"index.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
-func TestIssue46453(t *testing.T) {
-	if typeparams.Enabled {
-		t.Skip("type params are enabled")
-	}
-	const src = "package p\ntype _ comparable // ERROR \"undeclared name: comparable\""
-	testFiles(t, nil, []string{"issue46453.go"}, [][]byte{[]byte(src)}, false, nil)
-}
-
 func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDirFiles(t, "testdata/check", false) }
 func TestExamples(t *testing.T)  { testDirFiles(t, "testdata/examples", false) }
 func TestFixedbugs(t *testing.T) { testDirFiles(t, "testdata/fixedbugs", false) }
diff --git a/src/go/types/methodset_test.go b/src/go/types/methodset_test.go
index 4a373fa2c4..566356ad6d 100644
--- a/src/go/types/methodset_test.go
+++ b/src/go/types/methodset_test.go
@@ -7,7 +7,6 @@ package types_test
 import (
 	"testing"
 
-	"go/internal/typeparams"
 	. "go/types"
 )
 
@@ -101,9 +100,7 @@ func TestNewMethodSet(t *testing.T) {
 		check(src, methods, false)
 	}
 
-	if typeparams.Enabled {
-		for src, methods := range genericTests {
-			check(src, methods, true)
-		}
+	for src, methods := range genericTests {
+		check(src, methods, true)
 	}
 }
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 64a1b37cef..ea39473b51 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -263,11 +263,8 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 
 	case *ast.IndexExpr, *ast.MultiIndexExpr:
 		ix := typeparams.UnpackIndexExpr(e)
-		if typeparams.Enabled {
-			return check.instantiatedType(ix, def)
-		}
-		check.errorf(e0, _NotAType, "%s is not a type", e0)
-		check.use(ix.X)
+		// TODO(rfindley): type instantiation should require go1.18
+		return check.instantiatedType(ix, def)
 
 	case *ast.ParenExpr:
 		// Generic types must be instantiated before they can be used in any form.