[ubsan-minimal] Switch to weak symbols for callbacks to allow overriding in client code (#119242)

Author: kstoimenov

compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp

@@ -48,7 +48,8 @@ static void format_msg(const char *kind, uintptr_t caller, char *buf,
   *buf = '\0';
 }
 
-static void report_error(const char *kind, uintptr_t caller) {
+SANITIZER_INTERFACE_WEAK_DEF(void, __ubsan_report_error, const char *kind,
+                             uintptr_t caller) {
   if (caller == 0)
     return;
   while (true) {
@@ -114,13 +115,13 @@ void NORETURN CheckFailed(const char *file, int, const char *cond, u64, u64) {
 
 #define HANDLER_RECOVER(name, kind)                                            \
   INTERFACE void __ubsan_handle_##name##_minimal() {                           \
-    report_error(kind, GET_CALLER_PC());                                       \
+    __ubsan_report_error(kind, GET_CALLER_PC());                               \
   }
 
 #define HANDLER_NORECOVER(name, kind)                                          \
   INTERFACE void __ubsan_handle_##name##_minimal_abort() {                     \
     uintptr_t caller = GET_CALLER_PC();                                        \
-    report_error(kind, caller);                                                \
+    __ubsan_report_error(kind, caller);                                        \
     abort_with_message(kind, caller);                                          \
   }
 

compiler-rt/test/ubsan_minimal/TestCases/override-callback.c

@@ -0,0 +1,15 @@
+// RUN: %clang -fsanitize=implicit-integer-sign-change %s -o %t && %run %t 0 2>&1 | FileCheck %s
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int Result;
+
+void __ubsan_report_error(const char *kind, uintptr_t caller) {
+  fprintf(stderr, "CUSTOM_CALLBACK: %s\n", kind);
+}
+
+int main(int argc, const char **argv) {
+  int32_t t0 = (~((uint32_t)0));
+  // CHECK: CUSTOM_CALLBACK: implicit-conversion
+}