[libc++] Cleanup and enable multiple warnings.

Too many warnings are being disabled too quickly. Warnings are
important to keeping libc++ correct. This patch re-enables two
warnings: -Wconstant-evaluated and -Wdeprecated-copy.

In future, all warnings disabled for the test suite should require
an attached bug. The bug should state the plan for re-enabling that
warning, or a strong case why it should remain disabled.

5 files changed, 15 insertions, 0 deletions

diff --git a/libcxx/test/libcxx/containers/sequences/vector/asan_throw.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector/asan_throw.pass.cpp
index 443a6f2e924..235a3ffae14 100644
--- a/libcxx/test/libcxx/containers/sequences/vector/asan_throw.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/vector/asan_throw.pass.cpp
@@ -50,6 +50,7 @@ public:
             throw 0;
         }
     }
+    ThrowOnCopy& operator=(ThrowOnCopy const&) = default;
 
     bool should_throw;
 };
diff --git a/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.fail.cpp b/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.fail.cpp
index c139233b8da..2d2e0715762 100644
--- a/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.fail.cpp
+++ b/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.fail.cpp
@@ -24,6 +24,7 @@ int main(int, char**)
 #else
   // expected-error@+1 {{static_assert failed}}
   static_assert(!std::is_constant_evaluated(), "");
+  // expected-error@-1 0-1 {{'std::is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
 #endif
   return 0;
 }
diff --git a/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.pass.cpp b/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.pass.cpp
index 0f9f98e9176..e4b8a7575b0 100644
--- a/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.pass.cpp
@@ -23,6 +23,12 @@
 #endif
 #endif
 
+// Disable the tautological constant evaluation warnings for this test,
+// because it's explicitly testing those cases.
+#if TEST_HAS_WARNING("-Wconstant-evaluated") && defined(__clang__)
+#pragma clang diagnostic ignored "-Wconstant-evaluated"
+#endif
+
 template <bool> struct InTemplate {};
 
 int main(int, char**)
diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/copy.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/copy.pass.cpp
index a5ff10201c9..f14e20657d7 100644
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/copy.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/copy.pass.cpp
@@ -30,6 +30,7 @@ struct X
         if (throw_now)
             TEST_THROW(6);
     }
+    X& operator=(X const&) = default;
 };
 
 bool X::throw_now = false;
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
index f5fbedb5555..443165516b2 100644
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -47,6 +47,12 @@
 #define TEST_HAS_EXTENSION(X) 0
 #endif
 
+#ifdef __has_warning
+#define TEST_HAS_WARNING(X) __has_warning(X)
+#else
+#define TEST_HAS_WARNING(X) 0
+#endif
+
 #ifdef __has_builtin
 #define TEST_HAS_BUILTIN(X) __has_builtin(X)
 #else