[libcxx] Add LIBCXX_HAS_TERMINAL_AVAILABLE CMake option to disable print terminal checks (#99259)

Adds a new CMake option called `LIBCXX_HAS_TERMINAL_AVAILABLE` that
prevents us from checking for `isatty`.

Author: jhuber6

.github/workflows/libcxx-build-and-test.yaml

@@ -146,6 +146,7 @@ jobs:
           'generic-no-experimental',
           'generic-no-filesystem',
           'generic-no-localization',
+          'generic-no-terminal',
           'generic-no-random_device',
           'generic-no-threads',
           'generic-no-tzdb',

libcxx/CMakeLists.txt

@@ -97,6 +97,8 @@ option(LIBCXX_ENABLE_UNICODE
   "Whether to include support for Unicode in the library. Disabling Unicode can
    be useful when porting to platforms that don't support UTF-8 encoding (e.g.
    embedded)." ON)
+option(LIBCXX_HAS_TERMINAL_AVAILABLE
+  "Build libc++ with support for checking whether a stream is a terminal." ON)
 option(LIBCXX_ENABLE_WIDE_CHARACTERS
   "Whether to include support for wide characters in the library. Disabling
    wide character support can be useful when porting to platforms that don't
@@ -744,6 +746,7 @@ config_define_if(LIBCXX_ABI_FORCE_ITANIUM _LIBCPP_ABI_FORCE_ITANIUM)
 config_define_if(LIBCXX_ABI_FORCE_MICROSOFT _LIBCPP_ABI_FORCE_MICROSOFT)
 config_define_if_not(LIBCXX_ENABLE_THREADS _LIBCPP_HAS_NO_THREADS)
 config_define_if_not(LIBCXX_ENABLE_MONOTONIC_CLOCK _LIBCPP_HAS_NO_MONOTONIC_CLOCK)
+config_define_if_not(LIBCXX_HAS_TERMINAL_AVAILABLE _LIBCPP_HAS_NO_TERMINAL)
 if (NOT LIBCXX_TYPEINFO_COMPARISON_IMPLEMENTATION STREQUAL "default")
   config_define("${LIBCXX_TYPEINFO_COMPARISON_IMPLEMENTATION}" _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION)
 endif()

libcxx/cmake/caches/Generic-no-terminal.cmake

@@ -0,0 +1,5 @@
+set(LIBCXX_HAS_TERMINAL_AVAILABLE OFF CACHE BOOL "")
+
+# Speed up the CI
+set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")
+set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")

libcxx/include/__config_site.in

@@ -15,6 +15,7 @@
 #cmakedefine _LIBCPP_ABI_FORCE_MICROSOFT
 #cmakedefine _LIBCPP_HAS_NO_THREADS
 #cmakedefine _LIBCPP_HAS_NO_MONOTONIC_CLOCK
+#cmakedefine _LIBCPP_HAS_NO_TERMINAL
 #cmakedefine _LIBCPP_HAS_MUSL_LIBC
 #cmakedefine _LIBCPP_HAS_THREAD_API_PTHREAD
 #cmakedefine _LIBCPP_HAS_THREAD_API_EXTERNAL

libcxx/include/print

@@ -199,7 +199,7 @@ _LIBCPP_HIDE_FROM_ABI inline bool __is_terminal([[maybe_unused]] FILE* __stream)
   // the behavior in the test. This is not part of the public API.
 #  ifdef _LIBCPP_TESTING_PRINT_IS_TERMINAL
   return _LIBCPP_TESTING_PRINT_IS_TERMINAL(__stream);
-#  elif _LIBCPP_AVAILABILITY_HAS_PRINT == 0
+#  elif _LIBCPP_AVAILABILITY_HAS_PRINT == 0 || defined(_LIBCPP_HAS_NO_TERMINAL)
   return false;
 #  elif defined(_LIBCPP_WIN32API)
   return std::__is_windows_terminal(__stream);

libcxx/utils/ci/run-buildbot

@@ -469,6 +469,11 @@ generic-no-localization)
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-localization.cmake"
     check-runtimes
 ;;
+generic-no-terminal)
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-terminal.cmake"
+    check-runtimes
+;;
 generic-no-unicode)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-unicode.cmake"

libcxx/utils/libcxx/test/features.py

@@ -378,6 +378,7 @@ def _mingwSupportsModules(cfg):
     "_LIBCPP_HAS_NO_FILESYSTEM": "no-filesystem",
     "_LIBCPP_HAS_NO_RANDOM_DEVICE": "no-random-device",
     "_LIBCPP_HAS_NO_LOCALIZATION": "no-localization",
+    "_LIBCPP_HAS_NO_TERMINAL": "no-terminal",
     "_LIBCPP_HAS_NO_WIDE_CHARACTERS": "no-wide-characters",
     "_LIBCPP_HAS_NO_TIME_ZONE_DATABASE": "no-tzdb",
     "_LIBCPP_HAS_NO_UNICODE": "libcpp-has-no-unicode",