[clang] [llvm] [clang][unittests] Build the libclang unit tests on Windows (PR #232809)

[via cfe-commits]

https://github.com/UebelAndre updated https://github.com/llvm/llvm-project/pull/232809

>From 240a83b45b7b462dd74d843bd6416948eb608575 Mon Sep 17 00:00:00 2001
From: UebelAndre <github at uebelandre.com>
Date: Fri, 16 Oct 2026 07:49:26 -0700
Subject: [PATCH 1/2] [clang][unittests] Build the libclang unit tests on
 Windows

The remaining Windows failures are the VirtualFileOverlay tests, which
assume POSIX paths; those are skipped at runtime in a follow-up.
---
 clang/unittests/CMakeLists.txt | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/clang/unittests/CMakeLists.txt b/clang/unittests/CMakeLists.txt
index b2fee01649abc6..91e1890e6b427b 100644
--- a/clang/unittests/CMakeLists.txt
+++ b/clang/unittests/CMakeLists.txt
@@ -97,9 +97,7 @@ add_subdirectory(CodeGen)
 if(HAVE_CLANG_REPL_SUPPORT)
   add_subdirectory(Interpreter)
 endif()
-# FIXME: libclang unit tests are disabled on Windows due
-# to failures, mostly in libclang.VirtualFileOverlay_*.
-if(NOT WIN32 AND CLANG_TOOL_LIBCLANG_BUILD) 
+if(CLANG_TOOL_LIBCLANG_BUILD)
   add_subdirectory(libclang)
 endif()
 add_subdirectory(DirectoryWatcher)

>From 9f763a0f484ebfdb235c62acd9aba797aeeecd5a Mon Sep 17 00:00:00 2001
From: UebelAndre <github at uebelandre.com>
Date: Fri, 16 Oct 2026 07:49:27 -0700
Subject: [PATCH 2/2] [libclang][test] Skip the VirtualFileOverlay tests on
 Windows

They assume POSIX paths. Move them to a fixture that skips on Windows
and drop the equivalent gtest filter from the Bazel target.
---
 clang/unittests/libclang/LibclangTest.cpp     | 27 ++++++++++++-------
 .../clang/unittests/BUILD.bazel               |  8 ------
 2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/clang/unittests/libclang/LibclangTest.cpp b/clang/unittests/libclang/LibclangTest.cpp
index 7ca90547379d9f..981a37fe3f22e2 100644
--- a/clang/unittests/libclang/LibclangTest.cpp
+++ b/clang/unittests/libclang/LibclangTest.cpp
@@ -78,9 +78,18 @@ struct TestVFO {
     clang_VirtualFileOverlay_dispose(VFO);
   }
 };
+
+class VirtualFileOverlayTest : public ::testing::Test {
+protected:
+  void SetUp() override {
+#ifdef _WIN32
+    GTEST_SKIP() << "VirtualFileOverlay tests assume POSIX paths";
+#endif
+  }
+};
 }
 
-TEST(libclang, VirtualFileOverlay_Basic) {
+TEST_F(VirtualFileOverlayTest, Basic) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -102,7 +111,7 @@ TEST(libclang, VirtualFileOverlay_Basic) {
   T.map("/path/virtual/foo.h", "/real/foo.h");
 }
 
-TEST(libclang, VirtualFileOverlay_Unicode) {
+TEST_F(VirtualFileOverlayTest, Unicode) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -124,13 +133,13 @@ TEST(libclang, VirtualFileOverlay_Unicode) {
   T.map("/path/♫/☂.h", "/real/☂.h");
 }
 
-TEST(libclang, VirtualFileOverlay_InvalidArgs) {
+TEST_F(VirtualFileOverlayTest, InvalidArgs) {
   TestVFO T(nullptr);
   T.mapError("/path/./virtual/../foo.h", "/real/foo.h",
              CXError_InvalidArguments);
 }
 
-TEST(libclang, VirtualFileOverlay_RemapDirectories) {
+TEST_F(VirtualFileOverlayTest, RemapDirectories) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -182,7 +191,7 @@ TEST(libclang, VirtualFileOverlay_RemapDirectories) {
   T.map("/path/virtual/dir/in/subdir/foo4.h", "/real/foo4.h");
 }
 
-TEST(libclang, VirtualFileOverlay_CaseInsensitive) {
+TEST_F(VirtualFileOverlayTest, CaseInsensitive) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -206,7 +215,7 @@ TEST(libclang, VirtualFileOverlay_CaseInsensitive) {
   clang_VirtualFileOverlay_setCaseSensitivity(T.VFO, false);
 }
 
-TEST(libclang, VirtualFileOverlay_SharedPrefix) {
+TEST_F(VirtualFileOverlayTest, SharedPrefix) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -258,7 +267,7 @@ TEST(libclang, VirtualFileOverlay_SharedPrefix) {
   T.map("/path/foobarbaz.h", "/real/foobarbaz.h");
 }
 
-TEST(libclang, VirtualFileOverlay_AdjacentDirectory) {
+TEST_F(VirtualFileOverlayTest, AdjacentDirectory) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -304,7 +313,7 @@ TEST(libclang, VirtualFileOverlay_AdjacentDirectory) {
   T.map("/path/dir2/baz.h", "/real/baz.h");
 }
 
-TEST(libclang, VirtualFileOverlay_TopLevel) {
+TEST_F(VirtualFileOverlayTest, TopLevel) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
@@ -326,7 +335,7 @@ TEST(libclang, VirtualFileOverlay_TopLevel) {
   T.map("/foo.h", "/real/foo.h");
 }
 
-TEST(libclang, VirtualFileOverlay_Empty) {
+TEST_F(VirtualFileOverlayTest, Empty) {
   const char *contents =
       "{\n"
       "  'version': 0,\n"
diff --git a/utils/bazel/llvm-project-overlay/clang/unittests/BUILD.bazel b/utils/bazel/llvm-project-overlay/clang/unittests/BUILD.bazel
index e5a749e160f02d..8fb365ee025801 100644
--- a/utils/bazel/llvm-project-overlay/clang/unittests/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/clang/unittests/BUILD.bazel
@@ -580,14 +580,6 @@ cc_test(
     ) + [
         "libclang/TestUtils.h",
     ],
-    args = select({
-        "@platforms//os:windows": [
-            # Need to disable the VFS tests that don't use Windows friendly
-            # paths. These are also disabled on Windows in the CMake build.
-            "--gtest_filter=-*VirtualFileOverlay*",
-        ],
-        "//conditions:default": [],
-    }),
     deps = [
         "//clang:libclang",
         "//llvm:Support",