Adds stacktrace support from Abseil to Google Test

This change adds the ability to generate stacktraces in Google Test on
both failures of assertions/expectations and on crashes. The
stacktrace support is conditionally available only when using Abseil
with Google Test.

To use this support, run the test under Bazel with a command like this:

bazel test --define absl=1 --test_env=GTEST_INSTALL_FAILURE_SIGNAL_HANDLER=1 //path/to/your:test

The "--define absl=1" part enables stacktraces on assertion/expectation
failures.

The "--test_env=GTEST_INSTALL_FAILURE_SIGNAL_HANDLER=1" part enables
the signal handler that logs a stacktrace in the event of a crash
(this also requires the "--define absl=1" part). This is not the
default since it may interfere with existing tests.

1 files changed, 10 insertions, 0 deletions

diff --git a/googletest/src/gtest-internal-inl.h b/googletest/src/gtest-internal-inl.h
index e77c8b6..c5a4265 100644
--- a/googletest/src/gtest-internal-inl.h
+++ b/googletest/src/gtest-internal-inl.h
@@ -446,6 +446,16 @@ class OsStackTraceGetter : public OsStackTraceGetterInterface {
   virtual void UponLeavingGTest();
 
  private:
+#if GTEST_HAS_ABSL
+  Mutex mutex_;  // Protects all internal state.
+
+  // We save the stack frame below the frame that calls user code.
+  // We do this because the address of the frame immediately below
+  // the user code changes between the call to UponLeavingGTest()
+  // and any calls to the stack trace code from within the user code.
+  void* caller_frame_ = nullptr;
+#endif  // GTEST_HAS_ABSL
+
   GTEST_DISALLOW_COPY_AND_ASSIGN_(OsStackTraceGetter);
 };