[libc++][modules] Removes module testing. (#76083)

This removes the entire modules testing infrastructure.

The current infrastructure uses CMake to generate the std and std.compat
module. This requires quite a bit of plumbing and uses CMake. Since
CMake introduced module support in CMake 3.26, modules have a higher
CMake requirement than the rest of the LLVM project. (The LLVM project
requires 3.20.) The main motivation for this approach was how libc++
generated its modules. Every header had its own module partition. This
was changed to improve performance and now only two modules remain. The
code to build these can be manually crafted.

A followup patch will reenable testing modules, using a different
approach.

5 files changed, 2 insertions, 25 deletions

diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
index e4bda4f..225de93 100644
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -152,17 +152,6 @@ RUN <<EOF
     wget https://github.com/Kitware/CMake/releases/download/v3.21.1/cmake-3.21.1-linux-x86_64.sh -O /tmp/install-cmake.sh
     sudo bash /tmp/install-cmake.sh --prefix=/usr --exclude-subdir --skip-license
     rm /tmp/install-cmake.sh
-
-    # Install a newer CMake for modules
-    # TODO Remove the duplicated installation when all runtimes can be build with CMake 3.28.
-    wget https://github.com/Kitware/CMake/releases/download/v3.27.1/cmake-3.27.1-linux-x86_64.sh -O /tmp/install-cmake.sh
-    sudo bash /tmp/install-cmake.sh --prefix=/opt --exclude-subdir --skip-license
-    rm /tmp/install-cmake.sh
-
-    wget https://github.com/Kitware/CMake/releases/download/v3.28.0-rc4/cmake-3.28.0-rc4-linux-x86_64.sh -O /tmp/install-cmake.sh
-    sudo mkdir /opt/cmake-3.28
-    sudo bash /tmp/install-cmake.sh --prefix=/opt/cmake-3.28 --exclude-subdir --skip-license
-    rm /tmp/install-cmake.sh
 EOF
 
 # ===----------------------------------------------------------------------===##
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
index a48f852..a7c44da 100644
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -48,7 +48,6 @@ environment_definitions:
       CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
       CC: clang-${LLVM_HEAD_VERSION}
       CXX: clang++-${LLVM_HEAD_VERSION}
-      CMAKE: /opt/bin/cmake
 
   _absolute_path_clang: &absolute_path_clang
     # Note modules require and absolute path for clang-scan-deps
@@ -262,7 +261,6 @@ steps:
     env:
       CC: clang16
       CXX: clang++16
-      ENABLE_STD_MODULES: 'Off'
     agents:
       queue: libcxx-builders
       os: freebsd
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 221b497..ddfe53d 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -47,11 +47,6 @@ CLANG_FORMAT        The clang-format binary to use when generating the format
 ENABLE_CLANG_TIDY   Whether to compile and run clang-tidy checks. This variable
                     is optional.
 
-ENABLE_STD_MODULES  Whether to enable or disable building the C++23 std
-                    modules. This variable is optional.
-                    TODO MODULES remove when all supported compilers support
-                    modules.
-
 EOF
 }
 
@@ -120,10 +115,6 @@ if [ -z "${ENABLE_CLANG_TIDY}" ]; then
     ENABLE_CLANG_TIDY=Off
 fi
 
-if [ -n "${ENABLE_STD_MODULES}" ]; then
-    ENABLE_STD_MODULES="-DLIBCXX_ENABLE_STD_MODULES=${ENABLE_STD_MODULES}"
-fi
-
 function generate-cmake-base() {
     echo "--- Generating CMake"
     ${CMAKE} \
@@ -136,7 +127,6 @@ function generate-cmake-base() {
           -DLIBCXXABI_ENABLE_WERROR=YES \
           -DLIBUNWIND_ENABLE_WERROR=YES \
           -DLIBCXX_ENABLE_CLANG_TIDY=${ENABLE_CLANG_TIDY} \
-          ${ENABLE_STD_MODULES} \
           -DLLVM_LIT_ARGS="-sv --xunit-xml-output test-results.xml --timeout=1500 --time-tests" \
           "${@}"
 }
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
index 461e134..1570a6b 100644
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -343,7 +343,6 @@ macros = {
     "_LIBCPP_HAS_NO_WIDE_CHARACTERS": "no-wide-characters",
     "_LIBCPP_HAS_NO_TIME_ZONE_DATABASE": "no-tzdb",
     "_LIBCPP_HAS_NO_UNICODE": "libcpp-has-no-unicode",
-    "_LIBCPP_HAS_NO_STD_MODULES":  "libcpp-has-no-std-modules",
     "_LIBCPP_PSTL_CPU_BACKEND_LIBDISPATCH": "libcpp-pstl-cpu-backend-libdispatch",
 }
 for macro, feature in macros.items():
diff --git a/libcxx/utils/libcxx/test/modules.py b/libcxx/utils/libcxx/test/modules.py
index bd19fac..9362d52 100644
--- a/libcxx/utils/libcxx/test/modules.py
+++ b/libcxx/utils/libcxx/test/modules.py
@@ -118,9 +118,10 @@ class module_test_generator:
         print(
             f"""\
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// UNSUPPORTED: libcpp-has-no-std-modules
 // UNSUPPORTED: clang-modules-build
 
+// XFAIL: *
+
 // REQUIRES: has-clang-tidy
 
 // The GCC compiler flags are not always compatible with clang-tidy.