Add [[clang::nomerge]] attribute to ~CheckError().

To disable merging multiple ~CheckError() destructor for accurate crash logs.

Bug: 1153188
Change-Id: If6d153661667a63f13b645f6d284eb3d5ea3a300
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611331
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Zequan Wu <zequanwu@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844989}

base/check.h

@@ -85,7 +85,7 @@ class BASE_EXPORT CheckError {
   // Stream for adding optional details to the error message.
   std::ostream& stream();
 
-  ~CheckError();
+  NOMERGE ~CheckError();
 
   CheckError(const CheckError& other) = delete;
   CheckError& operator=(const CheckError& other) = delete;

base/compiler_specific.h

@@ -332,4 +332,11 @@ inline constexpr bool AnalyzerAssumeTrue(bool arg) {
 
 #endif  // defined(__clang_analyzer__)
 
+// Use nomerge attribute to disable optimization of merging multiple same calls.
+#if defined(__clang__) && __has_attribute(nomerge) && !defined(OS_CHROMEOS)
+#define NOMERGE [[clang::nomerge]]
+#else
+#define NOMERGE
+#endif
+
 #endif  // BASE_COMPILER_SPECIFIC_H_