[release-branch.go1.23] go1.23.0

Change-Id: I2b0514157b85ca61f9f6b8931df6ac874598a045
Reviewed-on: https://go-review.googlesource.com/c/go/+/605215
Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Gopher Robot <gobot@golang.org>
Auto-Submit: Carlos Amedee <carlos@golang.org>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

VERSION

@@ -0,0 +1,2 @@
+go1.23.0
+time 2024-08-07T19:21:44Z

codereview.cfg

@@ -1 +1,2 @@
-branch: master
+branch: release-branch.go1.23
+parent-branch: master

src/cmd/compile/internal/importer/ureader.go

@@ -9,6 +9,7 @@ import (
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/types2"
 	"cmd/internal/src"
+	"internal/buildcfg"
 	"internal/pkgbits"
 )
 
@@ -411,6 +412,14 @@ func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types2.Package, string) {
 			panic("weird")
 
 		case pkgbits.ObjAlias:
+			if buildcfg.Experiment.AliasTypeParams && len(r.dict.bounds) > 0 {
+				// Temporary work-around for issue #68526: rather than panicking
+				// with an non-descriptive index-out-of-bounds panic when trying
+				// to access a missing type parameter, instead panic with a more
+				// descriptive error. Only needed for Go 1.23; Go 1.24 will have
+				// the correct implementation.
+				panic("importing generic type aliases is not supported in Go 1.23 (see issue #68526)")
+			}
 			pos := r.pos()
 			typ := r.typ()
 			return newAliasTypeName(pr.enableAlias, pos, objPkg, objName, typ)

src/cmd/compile/internal/types2/alias.go

@@ -134,10 +134,10 @@ func (check *Checker) newAlias(obj *TypeName, rhs Type) *Alias {
 // newAliasInstance creates a new alias instance for the given origin and type
 // arguments, recording pos as the position of its synthetic object (for error
 // reporting).
-func (check *Checker) newAliasInstance(pos syntax.Pos, orig *Alias, targs []Type, ctxt *Context) *Alias {
+func (check *Checker) newAliasInstance(pos syntax.Pos, orig *Alias, targs []Type, expanding *Named, ctxt *Context) *Alias {
 	assert(len(targs) > 0)
 	obj := NewTypeName(pos, orig.obj.pkg, orig.obj.name, nil)
-	rhs := check.subst(pos, orig.fromRHS, makeSubstMap(orig.TypeParams().list(), targs), nil, ctxt)
+	rhs := check.subst(pos, orig.fromRHS, makeSubstMap(orig.TypeParams().list(), targs), expanding, ctxt)
 	res := check.newAlias(obj, rhs)
 	res.orig = orig
 	res.tparams = orig.tparams

src/cmd/compile/internal/types2/instantiate.go

@@ -11,6 +11,7 @@ import (
 	"cmd/compile/internal/syntax"
 	"errors"
 	"fmt"
+	"internal/buildcfg"
 	. "internal/types/errors"
 )
 
@@ -126,8 +127,9 @@ func (check *Checker) instance(pos syntax.Pos, orig genericType, targs []Type, e
 		res = check.newNamedInstance(pos, orig, targs, expanding) // substituted lazily
 
 	case *Alias:
-		// TODO(gri) is this correct?
+		if !buildcfg.Experiment.AliasTypeParams {
 			assert(expanding == nil) // Alias instances cannot be reached from Named types
+		}
 
 		tparams := orig.TypeParams()
 		// TODO(gri) investigate if this is needed (type argument and parameter count seem to be correct here)
@@ -138,7 +140,7 @@ func (check *Checker) instance(pos syntax.Pos, orig genericType, targs []Type, e
 			return orig // nothing to do (minor optimization)
 		}
 
-		return check.newAliasInstance(pos, orig, targs, ctxt)
+		return check.newAliasInstance(pos, orig, targs, expanding, ctxt)
 
 	case *Signature:
 		assert(expanding == nil) // function instances cannot be reached from Named types

src/cmd/compile/internal/types2/subst.go

@@ -115,7 +115,7 @@ func (subst *subster) typ(typ Type) Type {
 		// that has a type argument for it.
 		targs, updated := subst.typeList(t.TypeArgs().list())
 		if updated {
-			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.ctxt)
+			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.expanding, subst.ctxt)
 		}
 
 	case *Array:

src/crypto/tls/handshake_test.go

@@ -491,9 +491,10 @@ func testHandshake(t *testing.T, clientConfig, serverConfig *Config) (serverStat
 		if got := string(buf); got != sentinel {
 			t.Errorf("read %q from TLS connection, but expected %q", got, sentinel)
 		}
-		if err := cli.Close(); err != nil {
-			t.Errorf("failed to call cli.Close: %v", err)
-		}
+		// We discard the error because after ReadAll returns the server must
+		// have already closed the connection. Sending data (the closeNotify
+		// alert) can cause a reset, that will make Close return an error.
+		cli.Close()
 	}()
 	server := Server(s, serverConfig)
 	err = server.Handshake()

src/go/types/alias.go

@@ -137,10 +137,10 @@ func (check *Checker) newAlias(obj *TypeName, rhs Type) *Alias {
 // newAliasInstance creates a new alias instance for the given origin and type
 // arguments, recording pos as the position of its synthetic object (for error
 // reporting).
-func (check *Checker) newAliasInstance(pos token.Pos, orig *Alias, targs []Type, ctxt *Context) *Alias {
+func (check *Checker) newAliasInstance(pos token.Pos, orig *Alias, targs []Type, expanding *Named, ctxt *Context) *Alias {
 	assert(len(targs) > 0)
 	obj := NewTypeName(pos, orig.obj.pkg, orig.obj.name, nil)
-	rhs := check.subst(pos, orig.fromRHS, makeSubstMap(orig.TypeParams().list(), targs), nil, ctxt)
+	rhs := check.subst(pos, orig.fromRHS, makeSubstMap(orig.TypeParams().list(), targs), expanding, ctxt)
 	res := check.newAlias(obj, rhs)
 	res.orig = orig
 	res.tparams = orig.tparams

src/go/types/instantiate.go

@@ -14,6 +14,7 @@ import (
 	"errors"
 	"fmt"
 	"go/token"
+	"internal/buildcfg"
 	. "internal/types/errors"
 )
 
@@ -129,8 +130,9 @@ func (check *Checker) instance(pos token.Pos, orig genericType, targs []Type, ex
 		res = check.newNamedInstance(pos, orig, targs, expanding) // substituted lazily
 
 	case *Alias:
-		// TODO(gri) is this correct?
+		if !buildcfg.Experiment.AliasTypeParams {
 			assert(expanding == nil) // Alias instances cannot be reached from Named types
+		}
 
 		tparams := orig.TypeParams()
 		// TODO(gri) investigate if this is needed (type argument and parameter count seem to be correct here)
@@ -141,7 +143,7 @@ func (check *Checker) instance(pos token.Pos, orig genericType, targs []Type, ex
 			return orig // nothing to do (minor optimization)
 		}
 
-		return check.newAliasInstance(pos, orig, targs, ctxt)
+		return check.newAliasInstance(pos, orig, targs, expanding, ctxt)
 
 	case *Signature:
 		assert(expanding == nil) // function instances cannot be reached from Named types

src/go/types/subst.go

@@ -118,7 +118,7 @@ func (subst *subster) typ(typ Type) Type {
 		// that has a type argument for it.
 		targs, updated := subst.typeList(t.TypeArgs().list())
 		if updated {
-			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.ctxt)
+			return subst.check.newAliasInstance(subst.pos, t.orig, targs, subst.expanding, subst.ctxt)
 		}
 
 	case *Array:

src/os/dir.go

@@ -132,15 +132,17 @@ func ReadDir(name string) ([]DirEntry, error) {
 // CopyFS copies the file system fsys into the directory dir,
 // creating dir if necessary.
 //
-// Newly created directories and files have their default modes
-// where any bits from the file in fsys that are not part of the
-// standard read, write, and execute permissions will be zeroed
-// out, and standard read and write permissions are set for owner,
-// group, and others while retaining any existing execute bits from
-// the file in fsys.
+// Files are created with mode 0o666 plus any execute permissions
+// from the source, and directories are created with mode 0o777
+// (before umask).
 //
-// Symbolic links in fsys are not supported, a *PathError with Err set
-// to ErrInvalid is returned on symlink.
+// CopyFS will not overwrite existing files, and returns an error
+// if a file name in fsys already exists in the destination.
+//
+// Symbolic links in fsys are not supported. A *PathError with Err set
+// to ErrInvalid is returned when copying from a symbolic link.
+//
+// Symbolic links in dir are followed.
 //
 // Copying stops at and returns the first error encountered.
 func CopyFS(dir string, fsys fs.FS) error {

src/os/example_test.go

@@ -61,7 +61,7 @@ func ExampleFileMode() {
 		log.Fatal(err)
 	}
 
-	fmt.Printf("permissions: %#o\n", fi.Mode().Perm()) // 0400, 0777, etc.
+	fmt.Printf("permissions: %#o\n", fi.Mode().Perm()) // 0o400, 0o777, etc.
 	switch mode := fi.Mode(); {
 	case mode.IsRegular():
 		fmt.Println("regular file")

src/os/file.go

@@ -366,7 +366,7 @@ func Open(name string) (*File, error) {
 }
 
 // Create creates or truncates the named file. If the file already exists,
-// it is truncated. If the file does not exist, it is created with mode 0666
+// it is truncated. If the file does not exist, it is created with mode 0o666
 // (before umask). If successful, methods on the returned File can
 // be used for I/O; the associated file descriptor has mode O_RDWR.
 // If there is an error, it will be of type *PathError.
@@ -602,11 +602,11 @@ func UserHomeDir() (string, error) {
 // On Unix, the mode's permission bits, ModeSetuid, ModeSetgid, and
 // ModeSticky are used.
 //
-// On Windows, only the 0200 bit (owner writable) of mode is used; it
+// On Windows, only the 0o200 bit (owner writable) of mode is used; it
 // controls whether the file's read-only attribute is set or cleared.
 // The other bits are currently unused. For compatibility with Go 1.12
-// and earlier, use a non-zero mode. Use mode 0400 for a read-only
-// file and 0600 for a readable+writable file.
+// and earlier, use a non-zero mode. Use mode 0o400 for a read-only
+// file and 0o600 for a readable+writable file.
 //
 // On Plan 9, the mode's permission bits, ModeAppend, ModeExclusive,
 // and ModeTemporary are used.

test/fixedbugs/issue68580.go

@@ -0,0 +1,15 @@
+// compile -goexperiment aliastypeparams
+
+// Copyright 2024 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 main
+
+type A[P any] = struct{ _ P }
+
+type N[P any] A[P]
+
+func f[P any](N[P]) {}
+
+var _ = f[int]