c++: don't wrap cleanups that can't throw

Since C++11, the vast majority of destructors are noexcept, so
wrap_temporary_cleanups adds a bunch of useless TRY_CATCH_EXPR to be removed
later in the optimizers.  It's simple to avoid adding them in the first
place.

gcc/cp/ChangeLog:

	* decl.c (wrap_cleanups_r): Don't wrap if noexcept.

gcc/testsuite/ChangeLog:

	* g++.dg/eh/cleanup6.C: New test.

1 files changed, 13 insertions, 0 deletions

diff --git a/gcc/testsuite/g++.dg/eh/cleanup6.C b/gcc/testsuite/g++.dg/eh/cleanup6.C
new file mode 100644
index 0000000..e27563f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/eh/cleanup6.C
@@ -0,0 +1,13 @@
+// Test that we don't wrap the non-throwing A cleanup with a B cleanup.
+
+// { dg-do compile { target c++11 } }
+// { dg-additional-options -fdump-tree-gimple }
+// { dg-final { scan-tree-dump-times "B::~B" 1 "gimple" } }
+
+struct A { A(); ~A(); };
+struct B { B(const A& = A()); ~B(); };
+
+int main()
+{
+  B b;
+}