cmd/dist: require Go 1.22.6 as minimum bootstrap toolchain

This is a minimal change to start to require the new minimum bootstrap.
Taking advantage of the newer bootstap to simplify and improve code is
left to be done in separate CLs.

For #64751.

Change-Id: I1d4f883fae3026354a199174d51e79a36cd2dc53
Reviewed-on: https://go-review.googlesource.com/c/go/+/606156
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

doc/next/5-toolchain.md

@@ -4,4 +4,9 @@
 
 ## Linker {#linker}
 
+## Bootstrap {#bootstrap}
 
+<!-- go.dev/issue/64751 -->
+As mentioned in the [Go 1.22 release notes](/doc/go1.22#bootstrap), Go 1.24 now requires
+Go 1.22.6 or later for bootstrap.
+We expect that Go 1.26 will require a point release of Go 1.24 or later for bootstrap.

src/cmd/dist/README

@@ -4,16 +4,16 @@ As of Go 1.5, dist and other parts of the compiler toolchain are written
 in Go, making bootstrapping a little more involved than in the past.
 The approach is to build the current release of Go with an earlier one.
 
-The process to install Go 1.x, for x ≥ 22, is:
+The process to install Go 1.x, for x ≥ 24, is:
 
-1. Build cmd/dist with Go 1.20.6.
-2. Using dist, build Go 1.x compiler toolchain with Go 1.20.6.
+1. Build cmd/dist with Go 1.22.6.
+2. Using dist, build Go 1.x compiler toolchain with Go 1.22.6.
 3. Using dist, rebuild Go 1.x compiler toolchain with itself.
 4. Using dist, build Go 1.x cmd/go (as go_bootstrap) with Go 1.x compiler toolchain.
 5. Using go_bootstrap, build the remaining Go 1.x standard library and commands.
 
-Because of backward compatibility, although the steps above say Go 1.20.6,
-in practice any release ≥ Go 1.20.6 but < Go 1.x will work as the bootstrap base.
+Because of backward compatibility, although the steps above say Go 1.22.6,
+in practice any release ≥ Go 1.22.6 but < Go 1.x will work as the bootstrap base.
 Releases ≥ Go 1.x are very likely to work as well.
 
 See https://go.dev/s/go15bootstrap for more details about the original bootstrap

src/cmd/dist/notgo122.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 1.22 and later requires Go 1.20 as the bootstrap toolchain.
+// Go 1.24 and later requires Go 1.22.6 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_20_6_or_later (notgo120.go) in /Users/rsc/go/src/cmd/dist
+// found packages main (build.go) and building_Go_requires_Go_1_22_6_or_later (notgo122.go) in /Users/rsc/go/src/cmd/dist
 // %
 //
 // which is the best we can do under the circumstances.
@@ -16,6 +16,6 @@
 // See go.dev/issue/44505 for more background on
 // why Go moved on from Go 1.4 for bootstrap.
 
-//go:build !go1.20
+//go:build !go1.22
 
-package building_Go_requires_Go_1_20_6_or_later
+package building_Go_requires_Go_1_22_6_or_later

src/make.bash

@@ -64,14 +64,14 @@
 # timing information to this file. Useful for profiling where the
 # time goes when these scripts run.
 #
-# GOROOT_BOOTSTRAP: A working Go tree >= Go 1.20.6 for bootstrap.
+# GOROOT_BOOTSTRAP: A working Go tree >= Go 1.22.6 for bootstrap.
 # If $GOROOT_BOOTSTRAP/bin/go is missing, $(go env GOROOT) is
-# tried for all "go" in $PATH. By default, one of $HOME/go1.20.6,
-# $HOME/sdk/go1.20.6, or $HOME/go1.4, whichever exists, in that order.
+# tried for all "go" in $PATH. By default, one of $HOME/go1.22.6,
+# $HOME/sdk/go1.22.6, or $HOME/go1.4, whichever exists, in that order.
 # We still check $HOME/go1.4 to allow for build scripts that still hard-code
 # that name even though they put newer Go toolchains there.
 
-bootgo=1.20.6
+bootgo=1.22.6
 
 set -e
 

src/make.bat

@@ -85,7 +85,7 @@ for /f "tokens=*" %%g in ('where go 2^>nul') do (
 	)
 )
 
-set bootgo=1.20.6
+set bootgo=1.22.6
 if "x%GOROOT_BOOTSTRAP%"=="x" if exist "%HOMEDRIVE%%HOMEPATH%\go%bootgo%" set GOROOT_BOOTSTRAP=%HOMEDRIVE%%HOMEPATH%\go%bootgo%
 if "x%GOROOT_BOOTSTRAP%"=="x" if exist "%HOMEDRIVE%%HOMEPATH%\sdk\go%bootgo%" set GOROOT_BOOTSTRAP=%HOMEDRIVE%%HOMEPATH%\sdk\go%bootgo%
 if "x%GOROOT_BOOTSTRAP%"=="x" set GOROOT_BOOTSTRAP=%HOMEDRIVE%%HOMEPATH%\Go1.4

src/make.rc

@@ -48,7 +48,7 @@ fn bootstrapenv {
 	GOROOT=$GOROOT_BOOTSTRAP GO111MODULE=off GOENV=off GOOS=() GOARCH=() GOEXPERIMENT=() GOFLAGS=() $*
 }
 
-bootgo = 1.20.6
+bootgo = 1.22.6
 GOROOT = `{cd .. && pwd}
 goroot_bootstrap_set = 'true'
 if(! ~ $#GOROOT_BOOTSTRAP 1){