[Lldb-commits] [lldb] 0597087 - [lldb] Skip libc++ category tests on Darwin when no in-tree libc++ is built (#199262)

[via lldb-commits]

Author: Med Ismail Bennani
Date: 2026-06-01T15:54:06-07:00
New Revision: 0597087c44e493610d3f96608bef46e721201af6

URL: https://github.com/llvm/llvm-project/commit/0597087c44e493610d3f96608bef46e721201af6
DIFF: https://github.com/llvm/llvm-project/commit/0597087c44e493610d3f96608bef46e721201af6.diff

LOG: [lldb] Skip libc++ category tests on Darwin when no in-tree libc++ is built (#199262)

`canRunLibcxxTests()` previously short-circuited with "libc++ always
present" for all Darwin targets, meaning the "libc++" test category was
never skipped on macOS — even when `LLDB_HAS_LIBCXX` is `OFF` and no
`--libcxx-include-dir` / `--libcxx-library-dir` are passed to dotest.
The tests would silently run against the system libc++ instead of an
in-tree build, producing results inconsistent with what the suite is
designed to validate.

This fixes `canRunLibcxxTests()` to apply the same `libcxx_include_dir`
/ `libcxx_library_dir` guard on `Darwin` that `Linux` already uses. When
those dirs are absent (i.e. no in-tree libc++ was built), the function
returns `False` and `checkLibcxxSupport()` appends `libc++` to
`skip_categories` — skipping those tests exactly as Linux does.

On the CMake side, the `SEND_ERROR` for `LLDB_HAS_LIBCXX=OFF` is
downgraded to a `WARNING` so downstreams that intentionally skip the
runtimes build can keep `LLDB_INCLUDE_TESTS=ON` for the tests they
actually want to run. The warning is also gated on the new
`LLDB_ENABLE_LIBCXX_TESTS` option (default `ON`): setting it to OFF
acknowledges the deliberate choice and silences the warning without
requiring either an in-tree libc++ build or disabling all tests.

Signed-off-by: Med Ismail Bennani <ismail at bennani.ma>

Added: 
    

Modified: 
    lldb/CMakeLists.txt
    lldb/packages/Python/lldbsuite/test/dotest.py
    lldb/test/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/lldb/CMakeLists.txt b/lldb/CMakeLists.txt
index 0a1ca5cf391ef..c3711aac4a75c 100644
--- a/lldb/CMakeLists.txt
+++ b/lldb/CMakeLists.txt
@@ -26,6 +26,7 @@ endif()
 include(GNUInstallDirs)
 
 option(LLDB_INCLUDE_TESTS "Generate build targets for the LLDB unit tests." ${LLVM_INCLUDE_TESTS})
+option(LLDB_ENABLE_LIBCXX_TESTS "Set to OFF to acknowledge that libc++ is intentionally not built in-tree and silence the missing-libc++ warning." ON)
 
 if(LLDB_BUILT_STANDALONE)
   set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")

diff  --git a/lldb/packages/Python/lldbsuite/test/dotest.py b/lldb/packages/Python/lldbsuite/test/dotest.py
index f1abc4b63db0e..888d980e398d3 100644
--- a/lldb/packages/Python/lldbsuite/test/dotest.py
+++ b/lldb/packages/Python/lldbsuite/test/dotest.py
@@ -802,9 +802,14 @@ def canRunLibcxxTests():
 
     platform = lldbplatformutil.getPlatform()
 
-    if lldbplatformutil.target_is_android() or lldbplatformutil.platformIsDarwin():
+    if lldbplatformutil.target_is_android():
         return True, "libc++ always present"
 
+    if lldbplatformutil.platformIsDarwin():
+        if not configuration.libcxx_include_dir or not configuration.libcxx_library_dir:
+            return False, "libc++ tests require a locally built libc++"
+        return True, "libc++ present"
+
     if platform == "linux":
         if not configuration.libcxx_include_dir or not configuration.libcxx_library_dir:
             return False, "API tests require a locally built libc++."

diff  --git a/lldb/test/CMakeLists.txt b/lldb/test/CMakeLists.txt
index d5e4377648da8..0a5c3b99f0cc5 100644
--- a/lldb/test/CMakeLists.txt
+++ b/lldb/test/CMakeLists.txt
@@ -205,13 +205,15 @@ if(TARGET clang)
             "LLDB_TEST_LIBCXX_ROOT_DIR to it.")
       endif()
     else()
-      # We require libcxx for the test suite, so if we aren't building it,
-      # provide a helpful error about how to resolve the situation.
-      if(NOT LLDB_HAS_LIBCXX)
-        message(SEND_ERROR
-          "LLDB test suite requires libc++, but it is currently disabled. "
-          "Please add `libcxx` to `LLVM_ENABLE_RUNTIMES` or disable tests via "
-          "`LLDB_INCLUDE_TESTS=OFF`.")
+      # The LLDB test suite uses libc++ for many tests. If it isn't being
+      # built in-tree, tests in the "libc++" category will be skipped
+      # (same behavior as Linux).
+      if(NOT LLDB_HAS_LIBCXX AND LLDB_ENABLE_LIBCXX_TESTS)
+        message(WARNING
+          "LLDB's libc++ specific tests will be skipped. Add `libcxx` to "
+          "`LLVM_ENABLE_RUNTIMES` to get full coverage, set "
+          "`LLDB_ENABLE_LIBCXX_TESTS=OFF` to silence this warning, or disable "
+          "all tests with `LLDB_INCLUDE_TESTS=OFF`.")
       endif()
     endif()
   endif()