[libc++][CI] Tests the no RTTI configuration.

There are a few drive-by fixes: - Since the combination RTTI disabled and exceptions enabled do not work, this combination is prohibited. - A small NFC in any fixing clang-tidy. The code in the Buildkite configuration is prepared for using the std module. There are more fixes needed for that configuration which will be done in a separate commit.

Author: mordante

libcxx/CMakeLists.txt

@@ -279,7 +279,9 @@ endif()
 
 # Feature options -------------------------------------------------------------
 option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
-option(LIBCXX_ENABLE_RTTI "Use run time type information." ON)
+option(LIBCXX_ENABLE_RTTI
+ "Use run time type information.
+ This option may only be set to OFF when LIBCXX_ENABLE_EXCEPTIONS=OFF." ON)
 option(LIBCXX_ENABLE_THREADS "Build libc++ with support for threads." ON)
 option(LIBCXX_ENABLE_MONOTONIC_CLOCK
  "Build libc++ with support for a monotonic clock.
@@ -370,6 +372,11 @@ if (LIBCXX_HAS_PTHREAD_API)
  endif()
 endif()
 
+if (NOT LIBCXX_ENABLE_RTTI AND LIBCXX_ENABLE_EXCEPTIONS)
+ message(FATAL_ERROR "The option LIBCXX_ENABLE_RTTI can not be turned off"
+ " when LIBCXX_ENABLE_EXCEPTIONS is turned on.")
+endif()
+
 # Ensure LLVM_USE_SANITIZER is not specified when LIBCXX_GENERATE_COVERAGE
 # is ON.
 if (LLVM_USE_SANITIZER AND LIBCXX_GENERATE_COVERAGE)

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

@@ -0,0 +1,4 @@
+set(LIBCXX_ENABLE_RTTI OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(LIBCXXABI_ENABLE_RTTI OFF CACHE BOOL "")
+set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")

libcxx/docs/BuildingLibcxx.rst

@@ -378,6 +378,7 @@ libc++ Feature Options
  **Default**: ``ON``
 
  Build libc++ with run time type information.
+ This option may only be set to OFF when LIBCXX_ENABLE_EXCEPTIONS=OFF.
 
 .. option:: LIBCXX_INCLUDE_TESTS:BOOL
 

libcxx/include/any

@@ -196,9 +196,7 @@ namespace __any_imp
  if (__id && *__id == typeid(_Tp))
  return true;
 #endif
- if (!__id && __fallback_id == __any_imp::__get_fallback_typeid<_Tp>())
- return true;
- return false;
+ return !__id && __fallback_id == __any_imp::__get_fallback_typeid<_Tp>();
  }
 
  template <class _Tp>

libcxx/utils/ci/buildkite-pipeline.yml

@@ -741,6 +741,27 @@ steps:
  limit: 2
  timeout_in_minutes: 120
 
+ - label: "No RTTI"
+ command: "libcxx/utils/ci/run-buildbot generic-no-rtti"
+ artifact_paths:
+ - "**/test-results.xml"
+ - "**/*.abilist"
+ env:
+ # Note: Modules require and absolute path for clang-scan-deps
+ # https://github.com/llvm/llvm-project/issues/61006
+ CC: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang"
+ CXX: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang++"
+ CMAKE: "/opt/bin/cmake"
+ ENABLE_CLANG_TIDY: "On"
+ agents:
+ queue: "libcxx-builders"
+ os: "linux"
+ retry:
+ automatic:
+ - exit_status: -1 # Agent was lost
+ limit: 2
+ timeout_in_minutes: 120
+
  - label: "Unstable ABI"
  command: "libcxx/utils/ci/run-buildbot generic-abi-unstable"
  artifact_paths:

libcxx/utils/ci/run-buildbot

@@ -476,6 +476,11 @@ generic-no-exceptions)
  check-runtimes
  check-abi-list
 ;;
+generic-no-rtti)
+ clean
+ generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-rtti.cmake"
+ check-runtimes
+;;
 #
 # Other miscellaneous jobs
 #