cmd/link, cmd/dist, internal/platform: consolidate c-archive support

Make all the tests for whether -buildmode=c-archive is supported consistent.
Base this on the historical code, on whether cmd/compile supports -shared,
and whether cmd/link permits the mode.

Change-Id: Ib996546906f698ade4c32b8e6c705838e4ad4b90
Reviewed-on: https://go-review.googlesource.com/c/go/+/463984
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index 10bca33c68d0a53cafabaf2576cbac606d93d33e..d8c59831275ad5e60cf44df1cfe74c2416624138 100644 (file)
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -1141,6 +1141,7 @@ func (t *tester) internalLinkPIE() bool {
        return false
 }
 
+// supportedBuildMode reports whether the given build mode is supported.
 func (t *tester) supportedBuildmode(mode string) bool {
        pair := goos + "-" + goarch
        switch mode {
@@ -1148,13 +1149,24 @@ func (t *tester) supportedBuildmode(mode string) bool {
                if !t.extLink() {
                        return false
                }
-               switch pair {
-               case "aix-ppc64",
-                       "darwin-amd64", "darwin-arm64", "ios-arm64",
-                       "linux-amd64", "linux-386", "linux-ppc64le", "linux-riscv64", "linux-s390x",
-                       "freebsd-amd64",
-                       "windows-amd64", "windows-386":
+               switch goos {
+               case "aix", "darwin", "ios", "windows":
                        return true
+               case "linux":
+                       switch goarch {
+                       case "386", "amd64", "arm", "armbe", "arm64", "arm64be", "ppc64", "ppc64le", "riscv64", "s390x":
+                               return true
+                       default:
+                               // Other targets do not support -shared,
+                               // per ParseFlags in
+                               // cmd/compile/internal/base/flag.go.
+                               // For c-archive the Go tool passes -shared,
+                               // so that the result is suitable for inclusion
+                               // in a PIE or shared library.
+                               return false
+                       }
+               case "freebsd":
+                       return goarch == "amd64"
                }
                return false
        case "c-shared":

diff --git a/src/cmd/link/internal/ld/config.go b/src/cmd/link/internal/ld/config.go
index 336cb33e3ba399f5871e3cc87fcbfe27c01f1138..b1774f8fd20e958451ee4895ec7f6e5df7d26cde 100644 (file)
--- a/src/cmd/link/internal/ld/config.go
+++ b/src/cmd/link/internal/ld/config.go
@@ -27,6 +27,8 @@ const (
        BuildModePlugin
 )
 
+// Set implements flag.Value to set the build mode based on the argument
+// to the -buildmode flag.
 func (mode *BuildMode) Set(s string) error {
        badmode := func() error {
                return fmt.Errorf("buildmode %s not supported on %s/%s", s, buildcfg.GOOS, buildcfg.GOARCH)

diff --git a/src/internal/platform/supported.go b/src/internal/platform/supported.go
index 86c9f07adedcd6a0fe9c1ad0f8593074ecc409c8..d8c5b7ee89a8c652666a10f29096e6bd6d14f503 100644 (file)
--- a/src/internal/platform/supported.go
+++ b/src/internal/platform/supported.go
@@ -100,9 +100,28 @@ func BuildModeSupported(compiler, buildmode, goos, goarch string) bool {
                return true
 
        case "c-archive":
-               // TODO(bcmills): This seems dubious.
-               // Do we really support c-archive mode on js/wasm‽
-               return platform != "linux/ppc64"
+               switch goos {
+               case "aix", "darwin", "ios", "windows":
+                       return true
+               case "linux":
+                       switch goarch {
+                       case "386", "amd64", "arm", "armbe", "arm64", "arm64be", "ppc64le", "riscv64", "s390x":
+                               // linux/ppc64 not supported because it does
+                               // not support external linking mode yet.
+                               return true
+                       default:
+                               // Other targets do not support -shared,
+                               // per ParseFlags in
+                               // cmd/compile/internal/base/flag.go.
+                               // For c-archive the Go tool passes -shared,
+                               // so that the result is suitable for inclusion
+                               // in a PIE or shared library.
+                               return false
+                       }
+               case "freebsd":
+                       return goarch == "amd64"
+               }
+               return false
 
        case "c-shared":
                switch platform {