Fixed GCC elides lambdas

See
  http://code.google.com/p/android/issues/detail?id=35933
  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54170

Backport of r194098 to both GCC 4.6 and 4.7

    /cp
    2012-12-03  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/54170
	* cvt.c (cp_convert_to_pointer): Don't discard side-effects from
	expressions of nullptr_t.
	* typeck.c (build_ptrmemfunc): Likewise.

    /testsuite
    2012-12-03  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/54170
	* g++.dg/cpp0x/lambda/lambda-nullptr.C: New.

Change-Id: I4c90f9e06262a54796302773b36eb5bac7b4f1fa

1 files changed, 47 insertions, 0 deletions

diff --git a/gcc-4.6/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-nullptr.C b/gcc-4.6/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-nullptr.C
new file mode 100644
index 000000000..1aadbb490
--- /dev/null
+++ b/gcc-4.6/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-nullptr.C
@@ -0,0 +1,47 @@
+// PR c++/54170
+// { dg-do run { target c++11 } }
+
+#include <cassert> 
+
+struct A;
+typedef A* ptr;
+typedef int (A::*pmf) (int);
+typedef int (A::*pdm);
+
+int total;
+
+void add(int n)
+{
+  total += n;
+}
+
+template <typename RType, typename Callable>
+RType Call(Callable native_func, int arg)
+{
+  return native_func(arg);
+}
+
+template <typename RType>
+RType do_test(int delta)
+{
+  return Call<RType>([=](int delta) { add(delta); return nullptr; }, delta);
+}
+
+template <typename RType>
+void test()
+{
+  total = 0;
+  assert (!do_test<RType>(5));
+  assert (total == 5);
+  assert (!do_test<RType>(20));
+  assert (total == 25);
+  assert (!do_test<RType>(-256));
+  assert (total == -231);
+}
+
+int main()
+{
+  test<ptr>();
+  test<pdm>();
+  test<pmf>();
+}