[PATCH] D19218: [sanitizer] Fix 'dyld: Symbol not found: _dyldVersionNumber' link error on old Darwin systems.

[Maxim Ostapenko via llvm-commits]

m.ostapenko created this revision.
m.ostapenko added reviewers: kcc, samsonov, dvyukov, kubabrecka.
m.ostapenko added subscribers: llvm-commits, ygribov.
m.ostapenko set the repository for this revision to rL LLVM.

This patch fixes https://github.com/google/sanitizers/issues/669. On older Darwin systems (in particular, Darwin 10), dyld doesn't export **_dyldVersionNumber** symbol so we would have 'undefined reference' error in sanitzer library. Although sanitizers support was added to LLVM on OS X 10.7+ where **_dyldVersionNumber** symbol is already exported, GCC users still may want use them on older systems.

Repository:
  rL LLVM

http://reviews.llvm.org/D19218

Files:
  lib/sanitizer_common/sanitizer_mac.cc

Index: lib/sanitizer_common/sanitizer_mac.cc
===================================================================
--- lib/sanitizer_common/sanitizer_mac.cc
+++ lib/sanitizer_common/sanitizer_mac.cc
@@ -560,10 +560,14 @@
   reexec_disabled = true;
 }
 
-extern "C" double dyldVersionNumber;
+extern "C" SANITIZER_WEAK_ATTRIBUTE double dyldVersionNumber;
 static const double kMinDyldVersionWithAutoInterposition = 360.0;
 
 bool DyldNeedsEnvVariable() {
+  // Although sanitizer support was added to LLVM on OS X 10.7+, GCC users
+  // still may want use them on older systems. On older Darwin platforms, dyld
+  // doesn't export dyldVersionNumber symbol and we simply return true.
+  if (!&dyldVersionNumber) return true;
   // If running on OS X 10.11+ or iOS 9.0+, dyld will interpose even if
   // DYLD_INSERT_LIBRARIES is not set. However, checking OS version via
   // GetMacosVersion() doesn't work for the simulator. Let's instead check


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