Fix gopackagesdriver for Go 1.18 by replicating stdlib

go/tools/builders/stdliblist.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"flag"
+	"fmt"
 	"go/build"
 	"os"
 	"path/filepath"
@@ -145,6 +146,42 @@ func flatPackageForStd(execRoot string, pkg *goListPackage) *flatPackage {
 	return newPkg
 }
 
+// In Go 1.18, the standard library started using go:embed directives.
+// When Bazel runs this action, it does so inside a sandbox where GOROOT points
+// to an external/go_sdk directory that contains a symlink farm of all files in
+// the Go SDK.
+// If we run "go list" with that GOROOT, this action will fail because those
+// go:embed directives will refuse to include the symlinks in the sandbox.
+//
+// To work around this, cloneRoot creates a copy of external/go_sdk into a new
+// directory "root" while retaining its path relative to the root directory.
+// So "$OUTPUT_BASE/external/go_sdk" becomes
+// "$OUTPUT_BASE/root/external/go_sdk".
+// This ensures that file paths in the generated JSON are still valid.
+//
+// cloneRoot returns the new root directory and the new GOROOT we should run
+// under.
+func cloneRoot(execRoot, goroot string) (newRoot string, newGoroot string, err error) {
+	relativeGoroot, err := filepath.Rel(abs(execRoot), abs(goroot))
+	if err != nil {
+		// GOROOT has to be a subdirectory of execRoot.
+		// Otherwise we're breaking the sandbox.
+		return "", "", fmt.Errorf("GOROOT %q is not relative to execution root %q: %v", goroot, execRoot)
+	}
+
+	newRoot = filepath.Join(execRoot, "root")
+	newGoroot = filepath.Join(newRoot, relativeGoroot)
+	if err := os.MkdirAll(newGoroot, 01755); err != nil {
+		return "", "", err
+	}
+
+	if err := replicate(goroot, newGoroot, replicatePaths("src", "pkg/tool", "pkg/include")); err != nil {
+		return "", "", err
+	}
+
+	return newRoot, newGoroot, nil
+}
+
 // stdliblist runs `go list -json` on the standard library and saves it to a file.
 func stdliblist(args []string) error {
 	// process the args
@@ -158,19 +195,22 @@ func stdliblist(args []string) error {
 		return err
 	}
 
+	execRoot, goroot, err := cloneRoot(".", os.Getenv("GOROOT"))
+	if err != nil {
+		return err
+	}
+
 	// Ensure paths are absolute.
 	absPaths := []string{}
 	for _, path := range filepath.SplitList(os.Getenv("PATH")) {
 		absPaths = append(absPaths, abs(path))
 	}
 	os.Setenv("PATH", strings.Join(absPaths, string(os.PathListSeparator)))
-	os.Setenv("GOROOT", abs(os.Getenv("GOROOT")))
+	os.Setenv("GOROOT", goroot)
 	// Make sure we have an absolute path to the C compiler.
 	// TODO(#1357): also take absolute paths of includes and other paths in flags.
 	os.Setenv("CC", abs(os.Getenv("CC")))
 
-	execRoot := abs(".")
-
 	cachePath := abs(*out + ".gocache")
 	defer os.RemoveAll(cachePath)
 	os.Setenv("GOCACHE", cachePath)

tests/core/stdlib/stdlib_files.bzl

@@ -27,10 +27,11 @@ pure_transition = transition(
 def _stdlib_files_impl(ctx):
     # When a transition is used, ctx.attr._stdlib is a list of Target instead
     # of a Target. Possibly a bug?
-    libs = ctx.attr._stdlib[0][GoStdLib].libs
+    stdlib = ctx.attr._stdlib[0][GoStdLib]
+    libs = stdlib.libs
     runfiles = ctx.runfiles(files = libs)
     return [DefaultInfo(
-        files = depset(libs),
+        files = depset(libs + [stdlib._list_json]),
         runfiles = runfiles,
     )]