From 5922333d5c52226cdae4f3346a0843211040f9bb Mon Sep 17 00:00:00 2001
From: Spandan Das <spandandas@google.com>
Date: Thu, 15 Aug 2024 21:54:09 +0000
Subject: [PATCH] Skip `-Wl,--version-script` on libclang_rt.* stubs (temp
 hack)

The checked-in libclang_rt.* prebuilts do not contain versioned symbols,
but the autogenerated map.txt file for these libraries contain versions
e.g.
LIBCLANG_RT_ASAN {
  global:
...
}
```

This causes a discrepancy between the symbols in the stubs and impl
variants of these libraries. After https://r.android.com/3236596 is
submitted and a new set of libclang_rt.* prebuilts are generated, this
discrepancy will go away.

For now, skip `-Wl,version-script` when generating the stub
variants of these libraries to prevent link errors at build time.

Test: lunch aosp_panther_hwasan-trunk_staging-userdebug && m crash_dump
Bug: 3222365
Change-Id: Ic1e06cb58ec33b761136ac325f191da7ac900151
---
 cc/prebuilt.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/cc/prebuilt.go b/cc/prebuilt.go
index 1c98aed87..299fb5148 100644
--- a/cc/prebuilt.go
+++ b/cc/prebuilt.go
@@ -16,6 +16,7 @@ package cc
 
 import (
 	"path/filepath"
+	"strings"
 
 	"github.com/google/blueprint/proptools"
 
@@ -118,6 +119,22 @@ func (p *prebuiltLibraryLinker) link(ctx ModuleContext,
 	// Stub variants will create a stub .so file from stub .c files
 	if p.buildStubs() && objs.objFiles != nil {
 		// TODO (b/275273834): Make objs.objFiles == nil a hard error when the symbol files have been added to module sdk.
+
+		// The map.txt files of libclang_rt.* contain version information, but the checked in .so files do not.
+		// e.g. libclang_rt.* libs impl
+		// $ nm -D prebuilts/../libclang_rt.hwasan-aarch64-android.so
+		// __hwasan_init
+
+		// stubs generated from .map.txt
+		// $ nm -D out/soong/.intermediates/../<stubs>/libclang_rt.hwasan-aarch64-android.so
+		// __hwasan_init@@LIBCLANG_RT_ASAN
+
+		// Special-case libclang_rt.* libs to account for this discrepancy.
+		// TODO (spandandas): Remove this special case https://r.android.com/3236596 has been submitted, and a new set of map.txt
+		// files of libclang_rt.* libs have been generated.
+		if strings.Contains(ctx.ModuleName(), "libclang_rt.") {
+			p.versionScriptPath = android.OptionalPathForPath(nil)
+		}
 		return p.linkShared(ctx, flags, deps, objs)
 	}