Fix most GCC test failures.

This patch fixes almost all currently failing tests when
using GCC ToT.

The specific changes are:

(A) Workaround gcc.gnu.org/PR83921 which rejects variables w/o initializers
in constexpr contexts -- even when the variable is an empty class. This
bug has been worked around at all callsites by adding an initializer.
Additionally a new test, constexpr_init.pass.cpp, has been added to
test that Clang doesn't suffer from these bugs.

(B) Fix streambuf.assign/swap.pass.cpp. This test was never actually
calling the swap method as intended. In fact, the swap function it
intended to call was ill-formed when instantiated. GCC diagnosed
this ill-formedness w/o needing an instantiation.

(C) size_delete11.pass.cpp was fixed by adding c++2a to the list of
unsupported dialects.

llvm-svn: 322810

1 files changed, 2 insertions, 2 deletions

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
index 1d7db8cbc74..6c40ce368db 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
@@ -29,12 +29,12 @@ bool counting_equals ( const T &a, const T &b ) {
     }
 
 #if TEST_STD_VER > 17
-TEST_CONSTEXPR bool test_constexpr() {
+constexpr bool test_constexpr() {
     int ia[] = {0, 0, 0};
     int ib[] = {1, 1, 0};
     int ic[] = {1, 0, 1};
     int id[] = {1};
-    std::equal_to<int> c;
+    std::equal_to<int> c{};
     return !std::is_permutation(std::begin(ia), std::end(ia), std::begin(ib)              , c)
         && !std::is_permutation(std::begin(ia), std::end(ia), std::begin(ib), std::end(ib), c)
         &&  std::is_permutation(std::begin(ib), std::end(ib), std::begin(ic)              , c)