Avoid dialogs and generating call stacks under a debugger

base/logging.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/logging.h"
 
 #if defined(OS_WIN)
 #include <io.h>
 #include <windows.h>
 typedef HANDLE FileHandle;
@@ skipping 527 matching lines @@
                        std::string* result)
     : severity_(severity), file_(file), line_(line) {
   Init(file, line);
   stream_ << "Check failed: " << *result;
   delete result;
 }
 
 LogMessage::~LogMessage() {
 #if !defined(OFFICIAL_BUILD) && !defined(OS_NACL) && !defined(__UCLIBC__)
   if (severity_ == LOG_FATAL) {
-    // Include a stack trace on a fatal.
-    base::debug::StackTrace trace;
-    stream_ << std::endl;  // Newline to separate from log message.
-    trace.OutputToStream(&stream_);
+    if (!base::debug::BeingDebugged()) {

[Lei Zhang, 2015/09/04 22:11:31]

nit: combine with the if on the line above?

+      // Include a stack trace on a fatal, unless a debugger is attached.
+      base::debug::StackTrace trace;
+      stream_ << std::endl;  // Newline to separate from log message.
+      trace.OutputToStream(&stream_);
+    }
   }
 #endif
   stream_ << std::endl;
   std::string str_newline(stream_.str());
 
   // Give any log message handler first dibs on the message.
   if (log_message_handler &&
       log_message_handler(severity_, file_, line_,
                           message_start_, str_newline)) {
     // The handler took care of it, no further processing.
@@ skipping 70 matching lines @@
     if (log_assert_handler) {
       // Make a copy of the string for the handler out of paranoia.
       log_assert_handler(std::string(stream_.str()));
     } else {
       // Don't use the string with the newline, get a fresh version to send to
       // the debug message process. We also don't display assertions to the
       // user in release mode. The enduser can't do anything with this
       // information, and displaying message boxes when the application is
       // hosed can cause additional problems.
 #ifndef NDEBUG
-      DisplayDebugMessageInDialog(stream_.str());
+      if (!base::debug::BeingDebugged()) {
+        // Displaying a dialog is unnecessary when debugging and can complicate
+        // debugging.
+        DisplayDebugMessageInDialog(stream_.str());
+      }
 #endif
       // Crash the process to generate a dump.
       base::debug::BreakDebugger();
     }
   }
 }
 
 // writes the common header info to the stream
 void LogMessage::Init(const char* file, int line) {
   base::StringPiece filename(file);
@@ skipping 159 matching lines @@
 BASE_EXPORT void LogErrorNotReached(const char* file, int line) {
   LogMessage(file, line, LOG_ERROR).stream()
       << "NOTREACHED() hit.";
 }
 
 }  // namespace logging
 
 std::ostream& std::operator<<(std::ostream& out, const wchar_t* wstr) {
   return out << base::WideToUTF8(wstr);
 }