[libc++][CI] Reenables clang-tidy.

[mordante]

The patch does several things:

• fixes module exports
• disables clang-tidy with Clang-17 due to known issues
• disabled clang-tidy on older libstdc++ versions since it lacks C++20 features used
• fixes the CMake dependency

The issue why clang-tidy was not used in the CI was the last issue; the plugin was not a
dependency of the tests. Without a plugin the tests disable clang-tidy.

This was noticed while investigating #89898

[github-actions]

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You can test this locally with the following command:

darker --check --diff -r 1a2a1fbd7c03381fe5e4f459f7081bef13366ef4...0bac7e0819fcfa767ee1447469c92b6138e3eb6a libcxx/test/libcxx/clang_tidy.gen.py

View the diff from darker here.

--- clang_tidy.gen.py	2024-05-08 15:24:03.000000 +0000
+++ clang_tidy.gen.py	2024-05-08 15:26:41.250489 +0000
@@ -16,11 +16,12 @@
 import sys
 sys.path.append(sys.argv[1])
 from libcxx.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
-  print(f"""\
+    print(
+        f"""\
 //--- {header}.sh.cpp
 
 // REQUIRES: has-clang-tidy
 
 // The GCC compiler flags are not always compatible with clang-tidy.
@@ -34,6 +35,7 @@
 // TODO: run clang-tidy with modules enabled once they are supported
 // RUN: %{{clang-tidy}} %s --warnings-as-errors=* -header-filter=.* --checks='-*,libcpp-*' --load=%{{test-tools-dir}}/clang_tidy_checks/libcxx-tidy.plugin -- %{{compile_flags}} -fno-modules
 // RUN: %{{clang-tidy}} %s --warnings-as-errors=* -header-filter=.* --config-file=%{{libcxx-dir}}/.clang-tidy -- -Wweak-vtables %{{compile_flags}} -fno-modules
 
 #include <{header}>
-""")
+"""
+    )

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Mark de Wever (mordante)

Changes

This is currently a test patch; locally clang-tidy seems to be used in the Docker image.

This was noticed while investigating #89898

---

Full diff: https://github.com/llvm/llvm-project/pull/90077.diff

5 Files Affected:

• (modified) libcxx/modules/std/chrono.inc (+5-1)
• (modified) libcxx/modules/std/ranges.inc (+4-3)
• (modified) libcxx/test/CMakeLists.txt (+6)
• (modified) libcxx/test/libcxx/clang_tidy.gen.py (+3)
• (modified) libcxx/test/tools/clang_tidy_checks/CMakeLists.txt (+20-2)

diff --git a/libcxx/modules/std/chrono.inc b/libcxx/modules/std/chrono.inc
index 1265e21dc54ef..aa275a112e0f0 100644
--- a/libcxx/modules/std/chrono.inc
+++ b/libcxx/modules/std/chrono.inc
@@ -213,11 +213,15 @@ export namespace std {
     using std::chrono::ambiguous_local_time;
     using std::chrono::nonexistent_local_time;
 #    endif // if 0
+#endif   //  !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&
+         //  !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
     // [time.zone.info], information classes
     using std::chrono::local_info;
     using std::chrono::sys_info;
 
+#if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                              \
+    !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #    if 0
     // [time.zone.timezone], class time_zone
     using std::chrono::choose;
@@ -248,7 +252,7 @@ export namespace std {
 #    endif
 #  endif // _LIBCPP_ENABLE_EXPERIMENTAL
 #endif   //  !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&
-         //    !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+         //  !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
   } // namespace chrono
 
diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index 80f31c79a1a40..f71efe948ede1 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -138,9 +138,6 @@ export namespace std {
     }
 #endif // _LIBCPP_HAS_NO_LOCALIZATION
 
-#if _LIBCPP_STD_VER >= 23
-    // [range.adaptor.object], range adaptor objects
-    using std::ranges::range_adaptor_closure;
     // Note: This declaration not in the synopsis or explicitly in the wording.
     // However it is needed for the range adaptors.
     // [range.adaptor.object]/3
@@ -151,7 +148,11 @@ export namespace std {
     //   involving an object of type cv D as an operand to the | operator is
     //   undefined if overload resolution selects a program-defined operator|
     //   function.
+    // This is used internally in C++20 mode.
     using std::ranges::operator|;
+#if _LIBCPP_STD_VER >= 23
+    // [range.adaptor.object], range adaptor objects
+    using std::ranges::range_adaptor_closure;
 #endif
 
     // [range.all], all view
diff --git a/libcxx/test/CMakeLists.txt b/libcxx/test/CMakeLists.txt
index e0d3a0dbc4003..fd57aa9fe8b37 100644
--- a/libcxx/test/CMakeLists.txt
+++ b/libcxx/test/CMakeLists.txt
@@ -1,5 +1,11 @@
 include(HandleLitArguments)
 add_subdirectory(tools)
+# When the tools add clang-tidy support, the dependencies need to be updated.
+# This cannot be done in the tools CMakeLists.txt since that does not update
+# the status in this (a parent) directory.
+if(TARGET cxx-tidy)
+  list(APPEND LIBCXX_TEST_DEPS cxx-tidy)
+endif()
 
 # By default, libcxx and libcxxabi share a library directory.
 if (NOT LIBCXX_CXX_ABI_LIBRARY_PATH)
diff --git a/libcxx/test/libcxx/clang_tidy.gen.py b/libcxx/test/libcxx/clang_tidy.gen.py
index 19b6a999df607..8419a6f4637c5 100644
--- a/libcxx/test/libcxx/clang_tidy.gen.py
+++ b/libcxx/test/libcxx/clang_tidy.gen.py
@@ -24,6 +24,9 @@
 // The GCC compiler flags are not always compatible with clang-tidy.
 // UNSUPPORTED{BLOCKLIT}: gcc
 
+// Clang 17 has false positives.
+// UNSUPPORTED{BLOCKLIT}: clang-17
+
 {lit_header_restrictions.get(header, '')}
 
 // TODO: run clang-tidy with modules enabled once they are supported
diff --git a/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt b/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
index 28eed61445833..aa5c2a0a1d900 100644
--- a/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
+++ b/libcxx/test/tools/clang_tidy_checks/CMakeLists.txt
@@ -64,6 +64,26 @@ if(NOT HAS_CLANG_TIDY_HEADERS)
                  "clang-tidy headers are not present.")
   return()
 endif()
+
+# The clangTidy plugin uses C++20, when using stdlibc++ verify the version is correct.
+# Note it has not been tested whether version 11 works.
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/test.cpp" "
+#include <version>
+#if defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 12
+  # error The stdlibc++ version is too old.
+#endif
+int main(){}
+")
+try_compile(HAS_NEWER_STANDARD_LIBRARY
+  "${CMAKE_CURRENT_BINARY_DIR}"
+  "${CMAKE_CURRENT_BINARY_DIR}/test.cpp"
+   LINK_LIBRARIES clangTidy)
+
+if(NOT HAS_NEWER_STANDARD_LIBRARY)
+  message(STATUS "Clang-tidy tests are disabled due to using "
+                 "stdlibc++ older than version 12")
+  return()
+endif()
 message(STATUS "Clang-tidy tests are enabled.")
 
 set(SOURCES
@@ -88,5 +108,3 @@ set_target_properties(cxx-tidy PROPERTIES
 
 set_target_properties(cxx-tidy PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 set(CMAKE_SHARED_MODULE_SUFFIX_CXX .plugin) # Use a portable suffix to simplify how we can find it from Lit
-
-list(APPEND LIBCXX_TEST_DEPS cxx-tidy)

[ldionne]

LGTM w/ some comments.