[PATCH] D146745: [sanitizers] Explainer about dyld and weak overrides on Darwin.

Roy Sundahl via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Mar 24 12:23:25 PDT 2023

rsundahl updated this revision to Diff 508193.
rsundahl added a comment.

Chanded order of examples to meet narrative.

  rG LLVM Github Monorepo




Index: llvm/docs/ReleaseNotes.rst
--- llvm/docs/ReleaseNotes.rst
+++ llvm/docs/ReleaseNotes.rst
@@ -231,6 +231,20 @@
 Changes to Sanitizers
+* For Darwin users that override weak symbols, note that the dynamic linker will
+  only consider symbols in other mach-o modules which themselves contain at
+  least one weak symbol. A consequence is that if your program or dylib contains
+  an intended override of a weak symbol, then it must contain at least one weak
+  symbol as well for the override to be effective. That weak symbol may be the
+  intended override itself, an otherwise usused weak symbol added solely to meet
+  the requirement, or an existing but unrelated weak symbol.
+    Examples:
+      __attribute__((weak)) const char * __asan_default_options(void) {...}
+      __attribute__((weak,unused)) unsigned __enableOverrides;
+      __attribute__((weak)) bool unrelatedWeakFlag;
 Other Changes

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