all: update build tags to require/assume Go 1.20

Updates #54265.

Change-Id: Ia1c9486484c73c565bb4f78234dedff6d929ed42
Reviewed-on: https://go-review.googlesource.com/c/go/+/511656
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

src/cmd/compile/internal/base/mapfile_mmap.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
 
 package base
 

src/cmd/compile/internal/base/mapfile_read.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20)
+//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !solaris
 
 package base
 

src/cmd/dist/exec.go

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.19
-// +build go1.19
-
 package main
 
 import (

src/cmd/dist/exec_118.go

@@ -1,47 +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.
-
-//go:build !go1.19
-// +build !go1.19
-
-package main
-
-import (
-	"os"
-	"os/exec"
-	"strings"
-)
-
-// setDir sets cmd.Dir to dir, and also adds PWD=dir to cmd's environment.
-func setDir(cmd *exec.Cmd, dir string) {
-	cmd.Dir = dir
-	setEnv(cmd, "PWD", dir)
-}
-
-// setEnv sets cmd.Env so that key = value.
-func setEnv(cmd *exec.Cmd, key, value string) {
-	kv := key + "=" + value
-	if cmd.Env == nil {
-		cmd.Env = os.Environ()
-	}
-	cmd.Env = append(cmd.Env, kv)
-}
-
-// unsetEnv sets cmd.Env so that key is not present in the environment.
-func unsetEnv(cmd *exec.Cmd, key string) {
-	if cmd.Env == nil {
-		cmd.Env = os.Environ()
-	}
-
-	prefix := key + "="
-	newEnv := []string{}
-	for _, entry := range cmd.Env {
-		if strings.HasPrefix(entry, prefix) {
-			continue
-		}
-		newEnv = append(newEnv, entry)
-		// key may appear multiple times, so keep going.
-	}
-	cmd.Env = newEnv
-}

src/cmd/dist/notgo120.go

@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Go 1.20 and later requires Go 1.17 as the bootstrap toolchain.
+// Go 1.22 and later requires Go 1.20 as the bootstrap toolchain.
 // If cmd/dist is built using an earlier Go version, this file will be
 // included in the build and cause an error like:
 //
 // % GOROOT_BOOTSTRAP=$HOME/sdk/go1.16 ./make.bash
 // Building Go cmd/dist using /Users/rsc/sdk/go1.16. (go1.16 darwin/amd64)
-// found packages main (build.go) and building_Go_requires_Go_1_17_13_or_later (notgo117.go) in /Users/rsc/go/src/cmd/dist
+// found packages main (build.go) and building_Go_requires_Go_1_20_6_or_later (notgo120.go) in /Users/rsc/go/src/cmd/dist
 // %
 //
 // which is the best we can do under the circumstances.
@@ -16,7 +16,7 @@
 // See go.dev/issue/44505 for more background on
 // why Go moved on from Go 1.4 for bootstrap.
 
-//go:build !go1.17
+//go:build !go1.20
-// +build !go1.17
+// +build !go1.20
 
-package building_Go_requires_Go_1_17_13_or_later
+package building_Go_requires_Go_1_20_6_or_later

src/cmd/internal/bio/buf_mmap.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
 
 package bio
 

src/cmd/internal/bio/buf_nommap.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20)
+//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !solaris
 
 package bio
 

src/cmd/link/internal/ld/msync_darwin_libc.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build darwin && go1.20
+//go:build darwin
 
 package ld
 

src/cmd/link/internal/ld/msync_darwin_syscall.go

@@ -1,24 +0,0 @@
-// Copyright 2022 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.
-
-//go:build darwin && !go1.20
-
-package ld
-
-import (
-	"syscall"
-	"unsafe"
-)
-
-func msync(b []byte, flags int) (err error) {
-	var p unsafe.Pointer
-	if len(b) > 0 {
-		p = unsafe.Pointer(&b[0])
-	}
-	_, _, errno := syscall.Syscall(syscall.SYS_MSYNC, uintptr(p), uintptr(len(b)), uintptr(flags))
-	if errno != 0 {
-		return errno
-	}
-	return nil
-}

src/cmd/link/internal/ld/outbuf_mmap.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
 
 package ld
 

src/cmd/link/internal/ld/outbuf_nommap.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20) && !windows
+//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !solaris && !windows
 
 package ld
 

src/internal/abi/type.go

@@ -179,7 +179,7 @@ func (t *Type) IsDirectIface() bool {
 }
 
 func (t *Type) GcSlice(begin, end uintptr) []byte {
-	return unsafeSliceFor(t.GCData, int(end))[begin:]
+	return unsafe.Slice(t.GCData, int(end))[begin:]
 }
 
 // Method on non-interface type
@@ -660,7 +660,7 @@ func (n Name) Name() string {
 		return ""
 	}
 	i, l := n.ReadVarint(1)
-	return unsafeStringFor(n.DataChecked(1+i, "non-empty string"), l)
+	return unsafe.String(n.DataChecked(1+i, "non-empty string"), l)
 }
 
 // Tag returns the tag string for n, or empty if there is none.
@@ -670,7 +670,7 @@ func (n Name) Tag() string {
 	}
 	i, l := n.ReadVarint(1)
 	i2, l2 := n.ReadVarint(1 + i + l)
-	return unsafeStringFor(n.DataChecked(1+i+l+i2, "non-empty string"), l2)
+	return unsafe.String(n.DataChecked(1+i+l+i2, "non-empty string"), l2)
 }
 
 func NewName(n, tag string, exported, embedded bool) Name {

src/internal/abi/unsafestring_go119.go

@@ -1,32 +0,0 @@
-// Copyright 2023 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.
-
-//go:build !go1.20
-// +build !go1.20
-
-package abi
-
-import "unsafe"
-
-type (
-	stringHeader struct {
-		Data *byte
-		Len  int
-	}
-	sliceHeader struct {
-		Data *byte
-		Len  int
-		Cap  int
-	}
-)
-
-func unsafeStringFor(b *byte, l int) string {
-	h := stringHeader{Data: b, Len: l}
-	return *(*string)(unsafe.Pointer(&h))
-}
-
-func unsafeSliceFor(b *byte, l int) []byte {
-	h := sliceHeader{Data: b, Len: l, Cap: l}
-	return *(*[]byte)(unsafe.Pointer(&h))
-}

src/internal/abi/unsafestring_go120.go

@@ -1,18 +0,0 @@
-// Copyright 2023 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.
-
-//go:build go1.20
-// +build go1.20
-
-package abi
-
-import "unsafe"
-
-func unsafeStringFor(b *byte, l int) string {
-	return unsafe.String(b, l)
-}
-
-func unsafeSliceFor(b *byte, l int) []byte {
-	return unsafe.Slice(b, l)
-}