drop Go 1.21 and start using go/version

Needing to awkwardly treat Go versions as if they were semver
is no longer necessary thanks to go/version being in Go 1.22.0 now.

.github/workflows/test.yml

@@ -25,7 +25,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.21.x, 1.22.x]
+        go-version: [1.22.x]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:

go.mod

@@ -1,6 +1,6 @@
 module mvdan.cc/garble
 
-go 1.21
+go 1.22
 
 require (
 	github.com/bluekeyes/go-gitdiff v0.7.1

main.go

@@ -20,6 +20,7 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"go/version"
 	"io"
 	"io/fs"
 	"log"
@@ -40,7 +41,6 @@ import (
 	"golang.org/x/exp/maps"
 	"golang.org/x/exp/slices"
 	"golang.org/x/mod/module"
-	"golang.org/x/mod/semver"
 	"golang.org/x/tools/go/ast/astutil"
 	"golang.org/x/tools/go/ssa"
 	"mvdan.cc/garble/internal/ctrlflow"
@@ -267,28 +267,21 @@ type errJustExit int
 func (e errJustExit) Error() string { return fmt.Sprintf("exit: %d", e) }
 
 func goVersionOK() bool {
-	// TODO(mvdan): use go/version once we can require Go 1.22 or later: https://go.dev/issue/62039
-	const (
-		minGoVersionSemver = "v1.21.0"
-		suggestedGoVersion = "1.21"
-	)
+	const minGoVersion = "go1.22"
 
-	// rxVersion looks for a version like "go1.2" or "go1.2.3"
+	// rxVersion looks for a version like "go1.2" or "go1.2.3" in `go env GOVERSION`.
 	rxVersion := regexp.MustCompile(`go\d+\.\d+(?:\.\d+)?`)
 
 	toolchainVersionFull := sharedCache.GoEnv.GOVERSION
-	toolchainVersion := rxVersion.FindString(toolchainVersionFull)
-	if toolchainVersion == "" {
-		// Go 1.15.x and older do not have GOVERSION yet.
-		// We could go the extra mile and fetch it via 'go toolchainVersion',
-		// but we'd have to error anyway.
-		fmt.Fprintf(os.Stderr, "Go version is too old; please upgrade to Go %s or newer\n", suggestedGoVersion)
+	sharedCache.GoVersion = rxVersion.FindString(toolchainVersionFull)
+	if sharedCache.GoVersion == "" {
+		// Go 1.15.x and older did not have GOVERSION yet; they are too old anyway.
+		fmt.Fprintf(os.Stderr, "Go version is too old; please upgrade to %s or newer\n", minGoVersion)
 		return false
 	}
 
-	sharedCache.GoVersionSemver = "v" + strings.TrimPrefix(toolchainVersion, "go")
-	if semver.Compare(sharedCache.GoVersionSemver, minGoVersionSemver) < 0 {
-		fmt.Fprintf(os.Stderr, "Go version %q is too old; please upgrade to Go %s or newer\n", toolchainVersionFull, suggestedGoVersion)
+	if version.Compare(sharedCache.GoVersion, minGoVersion) < 0 {
+		fmt.Fprintf(os.Stderr, "Go version %q is too old; please upgrade to %s or newer\n", toolchainVersionFull, minGoVersion)
 		return false
 	}
 
@@ -304,10 +297,9 @@ func goVersionOK() bool {
 		// Fall back to not performing the check against the toolchain version.
 		return true
 	}
-	builtVersionSemver := "v" + strings.TrimPrefix(builtVersion, "go")
-	if semver.Compare(builtVersionSemver, sharedCache.GoVersionSemver) < 0 {
+	if version.Compare(builtVersion, sharedCache.GoVersion) < 0 {
 		fmt.Fprintf(os.Stderr, `
-garble was built with %q and is being used with %q; rebuild it with a command like:
+garble was built with %q and can't be used with the newer %q; rebuild it with a command like:
     go install mvdan.cc/garble@latest
 `[1:], builtVersionFull, toolchainVersionFull)
 		return false

scripts/gen-go-std-tables.sh

@@ -46,8 +46,8 @@ var runtimeLinknamed = []string{
 $(for path in ${runtime_linknamed}; do
 	echo "\"${path}\"",
 done)
-	// Existed in Go 1.21; removed in Go 1.22.
-	"math/rand",
+	// The net package linknames to the runtime, not the other way around.
+	// TODO: support this automatically via our script.
 	"net",
 }
 
@@ -58,7 +58,6 @@ done)
 }
 
 var compilerIntrinsicsFuncs = map[string]bool{
-	"runtime.mulUintptr": true, // Existed in Go 1.21; removed in Go 1.22.
 $(while read path name; do
 	echo "\"${path}.${name}\": true,"
 done <<<"${compiler_intrinsics_table}")

shared.go

@@ -18,7 +18,6 @@ import (
 	"time"
 
 	"golang.org/x/mod/module"
-	"golang.org/x/mod/semver"
 )
 
 //go:generate ./scripts/gen-go-std-tables.sh
@@ -50,12 +49,12 @@ type sharedCacheType struct {
 
 	GOGARBLE string
 
-	// GoVersionSemver is a semver-compatible version of the Go toolchain
-	// currently being used, as reported by "go env GOVERSION".
+	// GoVersion is a version of the Go toolchain currently being used,
+	// as reported by "go env GOVERSION" and compatible with go/version.
 	// Note that the version of Go that built the garble binary might be newer.
 	// Also note that a devel version like "go1.22-231f290e51" is
-	// currently represented as "v1.22".
-	GoVersionSemver string
+	// currently represented as "go1.22", as the suffix is ignored by go/version.
+	GoVersion string
 
 	// Filled directly from "go env".
 	// Keep in sync with fetchGoEnv.
@@ -267,8 +266,6 @@ func appendListedPackages(packages []string, mainBuild bool) error {
 				// Some packages in runtimeLinknamed need a build tag to be importable,
 				// like crypto/internal/boring/fipstls with boringcrypto,
 				// so any pkg.Error should be ignored when the build tag isn't set.
-			} else if pkg.ImportPath == "math/rand/v2" && semver.Compare(sharedCache.GoVersionSemver, "v1.22") < 0 {
-				// added in Go 1.22, so Go 1.21 runs into a "not found" error.
 			} else {
 				if pkgErrors.Len() > 0 {
 					pkgErrors.WriteString("\n")

testdata/script/asm.txtar

@@ -33,7 +33,7 @@ binsubstr main$exe 'addJmp' 'AddImpl'
 -- go.mod --
 module test/with.many.dots/main
 
-go 1.21
+go 1.22
 -- main.go --
 package main
 

testdata/script/atomic.txtar

@@ -18,7 +18,7 @@ cmp stderr main.stderr
 -- go.mod --
 module test/main
 
-go 1.21
+go 1.22
 -- main.go --
 package main
 

testdata/script/basic.txtar

@@ -59,7 +59,7 @@ binsubstr main$exe 'garble_main.go' 'globalVar' 'globalFunc' $gofullversion
 -- go.mod --
 module test/mainfoo
 
-go 1.21
+go 1.22
 -- garble_main.go --
 package main
 

testdata/script/cache.txtar

@@ -28,7 +28,7 @@ cmp stderr main.stderr
 -- go.mod --
 module test/main
 
-go 1.21
+go 1.22
 -- main.go --
 package main
 

testdata/script/cgo.txtar

@@ -29,7 +29,7 @@ binsubstr main$exe 'privateAdd'
 -- go.mod --
 module test/main
 
-go 1.21
+go 1.22
 -- main.go --
 package main
 

testdata/script/crossbuild.txtar

@@ -31,7 +31,7 @@ exec garble build
 -- go.mod --
 module test/main
 
-go 1.21
+go 1.22
 -- main.go --
 package main
 

testdata/script/ctrlflow.txtar

@@ -30,7 +30,7 @@ grep 'func\(int\) int' $WORK/debug/test/main/GARBLE_controlflow.go
 -- go.mod --
 module test/main
 
-go 1.21
+go 1.22
 -- garble_main.go --
 package main