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

3 files changed, 6 insertions, 7 deletions

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.end/find_end_pred.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.end/find_end_pred.pass.cpp
index d7427cd03de..76ac991653e 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.end/find_end_pred.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.end/find_end_pred.pass.cpp
@@ -30,14 +30,14 @@ struct count_equal
 };
 
 #if TEST_STD_VER > 17
-TEST_CONSTEXPR bool test_constexpr() {
+constexpr bool test_constexpr() {
     int ia[] = {0, 1, 2};
     int ib[] = {4, 5, 6};
     int ic[] = {0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0};
     typedef forward_iterator<int*>       FI;
     typedef bidirectional_iterator<int*> BI;
     typedef random_access_iterator<int*> RI;
-    std::equal_to<int> eq;
+    std::equal_to<int> eq{};
     return    (std::find_end(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ia)), FI(std::end(ia)), eq) == FI(ic+15))
            && (std::find_end(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ib)), FI(std::end(ib)), eq) == FI(std::end(ic)))
            && (std::find_end(BI(std::begin(ic)), BI(std::end(ic)), BI(std::begin(ia)), BI(std::end(ia)), eq) == BI(ic+15))
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.first.of/find_first_of_pred.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.first.of/find_first_of_pred.pass.cpp
index ea75e937eb7..f6f1725d6fa 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.first.of/find_first_of_pred.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find.first.of/find_first_of_pred.pass.cpp
@@ -23,15 +23,14 @@
 #include "test_iterators.h"
 
 #if TEST_STD_VER > 17
-TEST_CONSTEXPR bool test_constexpr() {
+constexpr bool test_constexpr() {
     int ia[] = {1, 2, 3};
     int ib[] = {7, 8, 9};
     int ic[] = {0, 1, 2, 3, 4, 5, 0, 1, 2, 3};
     typedef forward_iterator<int*>       FI;
     typedef bidirectional_iterator<int*> BI;
     typedef random_access_iterator<int*> RI;
-    std::equal_to<int> eq;
-    
+    std::equal_to<int> eq{};
     return    (std::find_first_of(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ia)), FI(std::end(ia)), eq) == FI(ic+1))
            && (std::find_first_of(FI(std::begin(ic)), FI(std::end(ic)), FI(std::begin(ib)), FI(std::end(ib)), eq) == FI(std::end(ic)))
            && (std::find_first_of(BI(std::begin(ic)), BI(std::end(ic)), BI(std::begin(ia)), BI(std::end(ia)), eq) == BI(ic+1))
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)