cmd/go: include the go language version in cache keys

Fixes #37804

Change-Id: I4381dc5c58cfd467506d3d73fbd19c2c7257338e
Reviewed-on: https://go-review.googlesource.com/c/go/+/223139
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>

Author: Bryan C. Mills

src/cmd/go/internal/work/exec.go

@@ -213,6 +213,9 @@ func (b *Builder) buildActionID(a *Action) cache.ActionID {
 	} else if cfg.BuildTrimpath && p.Module != nil {
 		fmt.Fprintf(h, "module %s@%s\n", p.Module.Path, p.Module.Version)
 	}
+	if p.Module != nil {
+		fmt.Fprintf(h, "go %s", p.Module.GoVersion)
+	}
 	fmt.Fprintf(h, "goos %s goarch %s\n", cfg.Goos, cfg.Goarch)
 	fmt.Fprintf(h, "import %q\n", p.ImportPath)
 	fmt.Fprintf(h, "omitdebug %v standard %v local %v prefix %q\n", p.Internal.OmitDebug, p.Standard, p.Internal.Local, p.Internal.LocalPrefix)

src/cmd/go/testdata/script/mod_edit_go.txt

@@ -7,6 +7,13 @@ go mod edit -go=1.9
 grep 'go 1.9' go.mod
 go build
 
+# Reverting the version should force a rebuild and error instead of using
+# the cached 1.9 build. (https://golang.org/issue/37804)
+go mod edit -go=1.8
+! go build
+stderr 'type aliases only supported as of'
+
+
 -- go.mod --
 module m
 go 1.8