[sanitizer] Don't call dlerror() after swift_demangle lookup through dlsym

Because the call to `dlerror()` may actually want to print something, which turns into a deadlock
as showcased in #49223.

Instead rely on further call to dlsym to clear `dlerror` internal state if they
need to check the return status.

Differential Revision: https://reviews.llvm.org/D128992

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
index 8be7709..b223f6c 100644 (file)
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
@@ -72,7 +72,6 @@ static swift_demangle_ft swift_demangle_f;
 // symbolication.
 static void InitializeSwiftDemangler() {
   swift_demangle_f = (swift_demangle_ft)dlsym(RTLD_DEFAULT, "swift_demangle");
-  (void)dlerror(); // Cleanup error message in case of failure
 }
 
 // Attempts to demangle a Swift name. The demangler will return nullptr if a