Fix PR39749 - Headers containing just #error harm __has_include.

This patch changes <experimental/foo> to use #warning instead of
is harmful to common feature detection idioms.

We should also consider only emitting the warning when __DEPRECATED is
defined, like we do in the <ext/foo> headers. Users may want to specify
"-Werror=-W#warnings" while still ignoring the libc++ warnings.

16 files changed, 312 insertions, 0 deletions

diff --git a/libcxx/test/libcxx/experimental/diagnostics/syserr/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/diagnostics/syserr/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..074a9c58c61
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/diagnostics/syserr/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/system_error>
+
+#include <experimental/system_error>
+
+// expected-error@experimental/system_error:* {{"<experimental/system_error> has been removed. Use <system_error> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/diagnostics/syserr/version.pass.cpp b/libcxx/test/libcxx/experimental/diagnostics/syserr/version.pass.cpp
new file mode 100644
index 00000000000..c4fb9593a9e
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/diagnostics/syserr/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/system_error>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/system_error>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/numerics/numeric.ops/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/numerics/numeric.ops/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..32fd0527d48
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/numerics/numeric.ops/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/numeric>
+
+#include <experimental/numeric>
+
+// expected-error@experimental/numeric:* {{"<experimental/numeric> has been removed. Use <numeric> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/numerics/numeric.ops/version.pass.cpp b/libcxx/test/libcxx/experimental/numerics/numeric.ops/version.pass.cpp
new file mode 100644
index 00000000000..37ac584a7cd
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/numerics/numeric.ops/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/numeric>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/numeric>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/strings/string.view/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/strings/string.view/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..64f73742099
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/strings/string.view/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/string_view>
+
+#include <experimental/string_view>
+
+// expected-error@experimental/string_view:* {{"<experimental/string_view> has been removed. Use <string_view> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/strings/string.view/version.pass.cpp b/libcxx/test/libcxx/experimental/strings/string.view/version.pass.cpp
new file mode 100644
index 00000000000..417982e3669
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/strings/string.view/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/string_view>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/string_view>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/any/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/utilities/any/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..0bcda7056b4
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/any/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/any>
+
+#include <experimental/any>
+
+// expected-error@experimental/any:* {{"<experimental/any> has been removed. Use <any> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/any/version.pass.cpp b/libcxx/test/libcxx/experimental/utilities/any/version.pass.cpp
new file mode 100644
index 00000000000..bc37d8b4dbf
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/any/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/any>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/any>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/optional/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/utilities/optional/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..1711d2f0374
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/optional/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/optional>
+
+#include <experimental/optional>
+
+// expected-error@experimental/optional:* {{"<experimental/optional> has been removed. Use <optional> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/optional/version.pass.cpp b/libcxx/test/libcxx/experimental/utilities/optional/version.pass.cpp
new file mode 100644
index 00000000000..ef011bbe450
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/optional/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/optional>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/optional>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/ratio/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/utilities/ratio/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..d9a01337a93
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/ratio/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/ratio>
+
+#include <experimental/ratio>
+
+// expected-error@experimental/ratio:* {{"<experimental/ratio> has been removed. Use <ratio> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/ratio/version.pass.cpp b/libcxx/test/libcxx/experimental/utilities/ratio/version.pass.cpp
new file mode 100644
index 00000000000..8ebb347a44b
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/ratio/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/ratio>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/ratio>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/time/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/utilities/time/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..9f3d679fc2a
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/time/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/chrono>
+
+#include <experimental/chrono>
+
+// expected-error@experimental/chrono:* {{"<experimental/chrono> has been removed. Use <chrono> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/time/version.pass.cpp b/libcxx/test/libcxx/experimental/utilities/time/version.pass.cpp
new file mode 100644
index 00000000000..5544a3f0e14
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/time/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/chrono>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/chrono>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/tuple/use_header_warning.fail.cpp b/libcxx/test/libcxx/experimental/utilities/tuple/use_header_warning.fail.cpp
new file mode 100644
index 00000000000..520e9fbb42f
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/tuple/use_header_warning.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: verify-support
+
+// <experimental/tuple>
+
+#include <experimental/tuple>
+
+// expected-error@experimental/tuple:* {{"<experimental/tuple> has been removed. Use <tuple> instead."}}
+
+int main() {}
diff --git a/libcxx/test/libcxx/experimental/utilities/tuple/version.pass.cpp b/libcxx/test/libcxx/experimental/utilities/tuple/version.pass.cpp
new file mode 100644
index 00000000000..c7c9e572856
--- /dev/null
+++ b/libcxx/test/libcxx/experimental/utilities/tuple/version.pass.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <experimental/tuple>
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-W#warnings"
+#endif
+#include <experimental/tuple>
+
+#ifndef _LIBCPP_VERSION
+#error _LIBCPP_VERSION not defined
+#endif
+
+int main() {}