From 8314cf067518a24e0737ddc80cba49e7f702b5b6 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Mon, 8 Sep 2025 12:35:53 -0700
Subject: [PATCH] Fix weak symbol handling when loading multiple dynamic
 libraries.

The `currentModuleWeakSymbols` global was being set the wrong time which
would lead to the wrong set of symbols being used for a given dylib.

Also have another version of this change that removes the global
completely but this one is simpler.

Fixes: #25214
---
 src/lib/libdylink.js                          |  8 ++---
 .../code_size/test_codesize_hello_dylink.json |  4 +--
 test/test_core.py                             | 31 +++++++++++++++++++
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/src/lib/libdylink.js b/src/lib/libdylink.js
index 488eb19bfa706..637aa7f4a384d 100644
--- a/src/lib/libdylink.js
+++ b/src/lib/libdylink.js
@@ -617,14 +617,13 @@ var LibraryDylink = {
     dbg('loadWebAssemblyModule:', libName);
 #endif
     var metadata = getDylinkMetadata(binary);
-    currentModuleWeakSymbols = metadata.weakImports;
-#if ASSERTIONS
-    var originalTable = wasmTable;
-#endif
 
     // loadModule loads the wasm module after all its dependencies have been loaded.
     // can be called both sync/async.
     function loadModule() {
+#if ASSERTIONS
+      var originalTable = wasmTable;
+#endif
 #if PTHREADS
       // The first thread to load a given module needs to allocate the static
       // table and memory regions.  Later threads re-use the same table region
@@ -744,6 +743,7 @@ var LibraryDylink = {
         }
       };
       var proxy = new Proxy({}, proxyHandler);
+      currentModuleWeakSymbols = metadata.weakImports;
       var info = {
         'GOT.mem': new Proxy({}, GOTHandler),
         'GOT.func': new Proxy({}, GOTHandler),
diff --git a/test/code_size/test_codesize_hello_dylink.json b/test/code_size/test_codesize_hello_dylink.json
index 311d54f46d40c..86520d2e990cf 100644
--- a/test/code_size/test_codesize_hello_dylink.json
+++ b/test/code_size/test_codesize_hello_dylink.json
@@ -1,10 +1,10 @@
 {
   "a.out.js": 26969,
-  "a.out.js.gz": 11478,
+  "a.out.js.gz": 11479,
   "a.out.nodebug.wasm": 18567,
   "a.out.nodebug.wasm.gz": 9199,
   "total": 45536,
-  "total_gz": 20677,
+  "total_gz": 20678,
   "sent": [
     "__heap_base",
     "__indirect_function_table",
diff --git a/test/test_core.py b/test/test_core.py
index f18b81aaddfe4..6264c16263ad5 100644
--- a/test/test_core.py
+++ b/test/test_core.py
@@ -5278,6 +5278,37 @@ def test_dylink_weak(self):
   def test_dylink_weak_undef(self):
     self.dylink_testf(test_file('core/test_dylink_weak_undef.c'))
 
+  @needs_dylink
+  def test_dylink_weak_multilib(self):
+    create_file('liba.c', '''
+      #include <stdio.h>
+
+      extern int globalA __attribute__((weak));
+
+      void LibBFunc();
+
+      void LibAFunc() {
+        LibBFunc();
+        printf("globalA %p\\n", &globalA);
+      }
+    ''')
+    create_file('libb.c', '''
+     #include <stdio.h>
+
+     void LibBFunc() {
+       printf("Hello from b\\n");
+     }
+    ''')
+    create_file('main.c', '''
+      void LibAFunc();
+      int main() {
+        LibAFunc();
+      }
+    ''')
+    self.run_process([EMCC, 'libb.c', '-o', 'libb.so', '-sSIDE_MODULE'] + self.get_cflags())
+    self.run_process([EMCC, 'liba.c', '-o', 'liba.so', '-sSIDE_MODULE', 'libb.so'] + self.get_cflags())
+    self.do_runf('main.c', 'Hello from b\n', cflags=['-sMAIN_MODULE=2', '-L.', 'liba.so'])
+
   @node_pthreads
   @needs_dylink
   def test_dylink_tls(self):