[release-branch.go1.16] cmd/link: disable plugin support if cgo is disabled

Functional plugin support requires cgo to be enabled. Disable
it if the environment has disabled cgo.

This prevents unexpected linker failures when linking large
binaries with cgo disabled which use the plugin package.

Fixes #45832

Change-Id: Ib71f0e089f7373b7b3e3cd53da3612291e7bc473
Reviewed-on: https://go-review.googlesource.com/c/go/+/314449
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>
(cherry picked from commit 983dea90c169930e35721232afe39fd4e3fbe4a6)
Reviewed-on: https://go-review.googlesource.com/c/go/+/316329
Reviewed-by: Cherry Mui <cherryyz@google.com>
Trust: Dmitri Shuralyov <dmitshur@golang.org>

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 17d5040827c0e4b03f708b719bf7752c486f3cf6..18db56704152c1aa554c1551711b4046b0a4f68c 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -533,7 +533,10 @@ func (ctxt *Link) loadlib() {
        // up symbol by name may not get expected result.
 
        iscgo = ctxt.LibraryByPkg["runtime/cgo"] != nil
-       ctxt.canUsePlugins = ctxt.LibraryByPkg["plugin"] != nil
+
+       // Plugins a require cgo support to function. Similarly, plugins may require additional
+       // internal linker support on some platforms which may not be implemented.
+       ctxt.canUsePlugins = ctxt.LibraryByPkg["plugin"] != nil && iscgo
 
        // We now have enough information to determine the link mode.
        determineLinkMode(ctxt)