test: Add test for weak ref to as-needed shared library

wild/tests/external_tests/mold_skip_tests.toml

@@ -158,6 +158,7 @@ tests = [
   "arch-x86_64-note2.sh",           # The order of sections is different.
   "arch-x86_64-plt.sh",             # We use `.got.plt`, not `.plt.got`.
   "arch-x86_64-reloc-overflow.sh",  # Different message formats
+  "as-needed-weak.sh",              # Mold-specific behaviour: GNU ld and lld do not activate --as-needed libs for weak refs
   "auxiliary.sh",                   # Different message format
   "build-id.sh",                    # Different build ID data size
   "cmdline.sh",                     # Different message formats for unknown options.
@@ -217,7 +218,6 @@ tests = [
 [skipped_groups.misc]
 reason = "Not grouped yet"
 tests = [
-  "as-needed-weak.sh",
   "bno-symbolic.sh",
   "canonical-plt.sh",
   "common-archive.sh",

wild/tests/integration_tests.rs

@@ -3618,6 +3618,7 @@ fn integration_test(
         "segment-end-syms.c",
         "linker-script-filename-match.c",
         "tls-apx-relocs.s",
+        "as-needed-weak.c",
         "linker-script-unclosed-comment.c",
         "execstack.s"
     )]

wild/tests/sources/as-needed-weak-lib.c

@@ -0,0 +1 @@
+int fn1(void) { return 1; }

wild/tests/sources/as-needed-weak.c

@@ -0,0 +1,27 @@
+//#Object:runtime.c
+//#Mode:dynamic
+//#Shared:force-dynamic-linking.c
+//#Shared:template(--push-state --as-needed $O --pop-state):as-needed-weak-lib.c
+// Tests that --as-needed shared libraries are NOT activated for weak symbol
+// references. This matches the behaviour of GNU ld and lld (mold differs).
+// If fn1 is non-null the lib was incorrectly activated; exit with fn1() (1)
+// so the test fails. If fn1 is null the lib was correctly excluded; exit 42.
+// force-dynamic-linking.c is linked without --as-needed so both Wild and GNU
+// ld produce a dynamic binary, enabling a meaningful diff.
+//#DiffIgnore:.dynamic.DT_NEEDED
+//#DiffIgnore:section.got
+//#DiffIgnore:.dynamic.DT_RELA
+//#DiffIgnore:.dynamic.DT_RELAENT
+//#DiffIgnore:rel.undefined-weak.dynamic.R_X86_64_GLOB_DAT
+
+#include "runtime.h"
+
+__attribute__((weak)) int fn1(void);
+
+void _start(void) {
+  runtime_init();
+  if (fn1) {
+    exit_syscall(fn1());
+  }
+  exit_syscall(42);
+}