cmd/go: make sure the linker for shared doesn't include tempdir path

This is similar to CL 478196 and CL 477296,
but this is for -buildmode=shared.

When using "go install -buildmode=shared std",
because the gold linker is used by default on Linux arm64,
it will cause temporary paths to be included in libstd.so.

Based on the changes of CL 478196,
I speculate that this may also have issues on other platforms.
So, this change is for all platform.

Fixes #69464

Change-Id: I4493c82be030186e61aef597ea0e6f43bcf95a32
GitHub-Last-Rev: ee40cf81acf70f553bfc63a21a41ce0174857043
GitHub-Pull-Request: golang/go#69394
Reviewed-on: https://go-review.googlesource.com/c/go/+/612396
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 1fbd267e09571e6b6c20578d7191ad1fb99d712e..a04794bbe5cb7864a7c0b29e9602c0bb01756e48 100644 (file)
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -714,7 +714,21 @@ func (gcToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action,
                }
                ldflags = append(ldflags, d.Package.ImportPath+"="+d.Target)
        }
-       return b.Shell(root).run(".", targetPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", targetPath, "-importcfg", importcfg, ldflags)
+
+       // On OS X when using external linking to build a shared library,
+       // the argument passed here to -o ends up recorded in the final
+       // shared library in the LC_ID_DYLIB load command.
+       // To avoid putting the temporary output directory name there
+       // (and making the resulting shared library useless),
+       // run the link in the output directory so that -o can name
+       // just the final path element.
+       // On Windows, DLL file name is recorded in PE file
+       // export section, so do like on OS X.
+       // On Linux, for a shared object, at least with the Gold linker,
+       // the output file path is recorded in the .gnu.version_d section.
+       dir, targetPath := filepath.Split(targetPath)
+
+       return b.Shell(root).run(dir, targetPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", targetPath, "-importcfg", importcfg, ldflags)
 }
 
 func (gcToolchain) cc(b *Builder, a *Action, ofile, cfile string) error {

diff --git a/src/cmd/go/testdata/script/build_shared_reproducible.txt b/src/cmd/go/testdata/script/build_shared_reproducible.txt
new file mode 100644 (file)
index 0000000..7e3bb34
--- /dev/null
+++ b/src/cmd/go/testdata/script/build_shared_reproducible.txt
@@ -0,0 +1,10 @@
+[!buildmode:shared] skip
+[short] skip
+[!cgo] skip '-buildmode=shared requires external linking'
+[!GOOS:linux] skip
+
+env GO111MODULE=off
+env CGO_ENABLED=1
+go install -a -trimpath -buildvcs=false -buildmode=shared -pkgdir=pkgdir1 runtime
+go install -a -trimpath -buildvcs=false -buildmode=shared -pkgdir=pkgdir2 runtime
+[GOOS:linux] cmp -q pkgdir1/libruntime.so pkgdir2/libruntime.so