[PATCH] PR libstdc++/55917 do not handle exceptions in std::thread

[Jonathan Wakely]

Catching the exception and calling std::terminate() prevents a useful
backtrace. Letting the runtime call terminate because of an unhandled
exception gives a backtrace showing the site of the throw.

	PR libstdc++/55917
	* src/c++11/thread.cc (execute_native_thread_routine): Remove
	try-block so that exceptions propagate out of the thread and terminate
	is called by the exception-handling runtime.
	(execute_native_thread_routine_compat): Likewise.
	* testsuite/30_threads/thread/cons/terminate.cc: New.

Tested powerpc64le-linux, committed to trunk.


-------------- next part --------------
commit fb9352fda94d20ff6cfcc1370003716b7bd2c232
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Jun 12 17:11:24 2017 +0100

    PR libstdc++/55917 do not handle exceptions in std::thread
    
    	PR libstdc++/55917
    	* src/c++11/thread.cc (execute_native_thread_routine): Remove
    	try-block so that exceptions propagate out of the thread and terminate
    	is called by the exception-handling runtime.
    	(execute_native_thread_routine_compat): Likewise.
    	* testsuite/30_threads/thread/cons/terminate.cc: New.

diff --git a/libstdc++-v3/src/c++11/thread.cc b/libstdc++-v3/src/c++11/thread.cc
index 44a230a..4a94bdd 100644
--- a/libstdc++-v3/src/c++11/thread.cc
+++ b/libstdc++-v3/src/c++11/thread.cc
@@ -77,20 +77,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
     execute_native_thread_routine(void* __p)
     {
       thread::_State_ptr __t{ static_cast<thread::_State*>(__p) };
-
-      __try
-	{
-	  __t->_M_run();
-	}
-      __catch(const __cxxabiv1::__forced_unwind&)
-	{
-	  __throw_exception_again;
-	}
-      __catch(...)
-	{
-	  std::terminate();
-	}
-
+      __t->_M_run();
       return nullptr;
     }
 
@@ -104,20 +91,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
       // the thread state to a local object, breaking the reference cycle
       // created in thread::_M_start_thread.
       __local.swap(__t->_M_this_ptr);
-
-      __try
-	{
-	  __t->_M_run();
-	}
-      __catch(const __cxxabiv1::__forced_unwind&)
-	{
-	  __throw_exception_again;
-	}
-      __catch(...)
-	{
-	  std::terminate();
-	}
-
+      __t->_M_run();
       return nullptr;
     }
 #endif
diff --git a/libstdc++-v3/testsuite/30_threads/thread/cons/terminate.cc b/libstdc++-v3/testsuite/30_threads/thread/cons/terminate.cc
new file mode 100644
index 0000000..4b35b6c
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/thread/cons/terminate.cc
@@ -0,0 +1,48 @@
+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run { target *-*-freebsd* *-*-dragonfly* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* *-*-cygwin *-*-rtems* *-*-darwin* powerpc-ibm-aix* } }
+// { dg-options "-pthread" { target *-*-freebsd* *-*-dragonfly* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* powerpc-ibm-aix* } }
+// { dg-require-effective-target c++11 }
+// { dg-require-cstdint "" }
+// { dg-require-gthreads "" }
+
+#include <thread>
+#include <exception>
+#include <cstdlib>
+
+void handle_terminate()
+{
+  std::_Exit(0);
+}
+
+void f() { throw 1; }
+
+void
+test01()
+{
+  std::set_terminate(handle_terminate);
+  std::thread t(f);
+  t.join();
+  std::abort();
+}
+
+int
+main()
+{
+  test01();
+}