From: Cherry Mui <cherryyz@google.com>
Date: Fri, 24 May 2024 22:04:11 +0000 (-0400)
Subject: cmd/link: don't include deadcoded function symbols in shared build mode
X-Git-Tag: go1.23rc1~68
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=98529a8e7cf1cc0b561f26a4bd3ddf8f6dbd2f8a;p=gostls13.git

cmd/link: don't include deadcoded function symbols in shared build mode

In shared build mode, we include all symbols. This includes
function symbols that are deadcoded by the compiler. They don't
really get compiled, and their metadata may be missing, causing
linker failures. Skip them.

Fixes #67635.

Change-Id: Ic0e64bd032be499cca26da5e9e3ffbe9998bac05
Reviewed-on: https://go-review.googlesource.com/c/go/+/588316
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/cmd/cgo/internal/testshared/testdata/depBase/dep.go b/src/cmd/cgo/internal/testshared/testdata/depBase/dep.go
index a143fe2ff1..6a8bf49c58 100644
--- a/src/cmd/cgo/internal/testshared/testdata/depBase/dep.go
+++ b/src/cmd/cgo/internal/testshared/testdata/depBase/dep.go
@@ -51,3 +51,8 @@ func F() int {
 	defer func() {}()
 	return V
 }
+
+func H() {
+	// Issue 67635: deadcoded closures causes linker crash.
+	func() { F() }()
+}
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 241cf603db..20609ed7bf 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -50,6 +50,12 @@ func (d *deadcodePass) init() {
 		n := d.ldr.NDef()
 		for i := 1; i < n; i++ {
 			s := loader.Sym(i)
+			if d.ldr.SymType(s) == sym.STEXT && d.ldr.SymSize(s) == 0 {
+				// Zero-sized text symbol is a function deadcoded by the
+				// compiler. It doesn't really get compiled, and its
+				// metadata may be missing.
+				continue
+			}
 			d.mark(s, 0)
 		}
 		d.mark(d.ctxt.mainInittasks, 0)