[libc++] Remove the explicit Clang/LSV CI job

[ldionne]

Recent versions of Clang now enable LSV by default when building with modules enabled and C++20 and later. Since our CI job runs with the latest Standard, explicitly specifying LSV is redundant and doesn't add any additional coverage.

[llvmbot]

@llvm/pr-subscribers-libcxx

@llvm/pr-subscribers-github-workflow

Author: Louis Dionne (ldionne)

Changes

Recent versions of Clang now enable LSV by default when building with modules enabled and C++20 and later. Since our CI job runs with the latest Standard, explicitly specifying LSV is redundant and doesn't add any additional coverage.

---

Full diff: https://github.com/llvm/llvm-project/pull/131667.diff

4 Files Affected:

• (modified) .github/workflows/libcxx-build-and-test.yaml (-1)
• (removed) libcxx/cmake/caches/Generic-modules-lsv.cmake (-2)
• (modified) libcxx/utils/ci/run-buildbot (-6)
• (modified) libcxx/utils/libcxx/test/params.py (+7-8)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 8c011425abfcf..6b4e791369d50 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -137,7 +137,6 @@ jobs:
           'generic-hardening-mode-fast',
           'generic-hardening-mode-fast-with-abi-breaks',
           'generic-merged',
-          'generic-modules-lsv',
           'generic-no-exceptions',
           'generic-no-experimental',
           'generic-no-filesystem',
diff --git a/libcxx/cmake/caches/Generic-modules-lsv.cmake b/libcxx/cmake/caches/Generic-modules-lsv.cmake
deleted file mode 100644
index 395fccc217650..0000000000000
--- a/libcxx/cmake/caches/Generic-modules-lsv.cmake
+++ /dev/null
@@ -1,2 +0,0 @@
-set(LIBCXX_TEST_PARAMS "enable_modules=clang-lsv" CACHE STRING "")
-set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 947932f3802a1..6fc6c8b658ede 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -454,12 +454,6 @@ generic-modules)
     check-runtimes
     check-abi-list
 ;;
-generic-modules-lsv)
-    clean
-    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-modules-lsv.cmake"
-    check-runtimes
-    check-abi-list
-;;
 #
 # Parts removed
 #
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
index 93dc3a8be3f08..ace4630472b6b 100644
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -207,24 +207,23 @@ def getSuitableClangTidy(cfg):
     ),
     Parameter(
         name="enable_modules",
-        choices=["none", "clang", "clang-lsv"],
+        choices=["none", "clang"],
         type=str,
-        help="Whether to build the test suite with modules enabled. "
-             "Select `clang` for Clang modules, and 'clang-lsv' for Clang modules with Local Submodule Visibility.",
+        help="Whether to build the test suite with Clang modules enabled. Select `clang` for Clang modules, and "
+             "'none' for a non-modular build. Note that recent versions of Clang enable Local Submodule Visibility "
+             "by default in C++20 and later.",
         default="none",
         actions=lambda modules: filter(None, [
-            AddFeature("clang-modules-build")           if modules in ("clang", "clang-lsv") else None,
+            AddFeature("clang-modules-build")           if modules == "clang" else None,
 
             # Note: AppleClang disregards -fmodules entirely when compiling C++, so we also pass -fcxx-modules
             #       to enable modules for C++.
-            AddCompileFlag("-fmodules -fcxx-modules")   if modules in ("clang", "clang-lsv") else None,
+            AddCompileFlag("-fmodules -fcxx-modules")   if modules == "clang") else None,
 
             # Note: We use a custom modules cache path to make sure that we don't reuse
             #       the default one, which can be shared across CI builds with different
             #       configurations.
-            AddCompileFlag(lambda cfg: f"-fmodules-cache-path={cfg.test_exec_root}/ModuleCache") if modules in ("clang", "clang-lsv") else None,
-
-            AddCompileFlag("-Xclang -fmodules-local-submodule-visibility") if modules == "clang-lsv" else None,
+            AddCompileFlag(lambda cfg: f"-fmodules-cache-path={cfg.test_exec_root}/ModuleCache") if modules == "clang" else None,
         ])
     ),
     Parameter(

[ian-twilightcoder]

Should we do this? #127015 only reproduces with C++17 and LSV.

[ldionne]

No, you're right, I think we should instead switch the LSV job to use C++17 instead of C++23 to get back our coverage.