cmake_path command: path management

Fixes: #19568, #20922

2 files changed, 40 insertions, 8 deletions

diff --git a/Source/Checks/cm_cxx_features.cmake b/Source/Checks/cm_cxx_features.cmake
index e726fc72b4..5c1593db40 100644
--- a/Source/Checks/cm_cxx_features.cmake
+++ b/Source/Checks/cm_cxx_features.cmake
@@ -1,6 +1,7 @@
 include(${CMAKE_CURRENT_LIST_DIR}/cm_message_checks_compat.cmake)
 
 function(cm_check_cxx_feature name)
+  set(TRY_RUN_FEATURE "${ARGN}")
   string(TOUPPER ${name} FEATURE)
   if(NOT DEFINED CMake_HAVE_CXX_${FEATURE})
     cm_message_checks_compat(
@@ -12,12 +13,26 @@ function(cm_check_cxx_feature name)
     else()
       set(maybe_cxx_standard "")
     endif()
-    try_compile(CMake_HAVE_CXX_${FEATURE}
-      ${CMAKE_CURRENT_BINARY_DIR}
-      ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
-      CMAKE_FLAGS ${maybe_cxx_standard}
-      OUTPUT_VARIABLE OUTPUT
-      )
+    if (TRY_RUN_FEATURE)
+      try_run(CMake_RUN_CXX_${FEATURE} CMake_COMPILE_CXX_${FEATURE}
+        ${CMAKE_CURRENT_BINARY_DIR}
+        ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
+        CMAKE_FLAGS ${maybe_cxx_standard}
+        OUTPUT_VARIABLE OUTPUT
+        )
+      if (CMake_RUN_CXX_${FEATURE} EQUAL "0" AND CMake_COMPILE_CXX_${FEATURE})
+        set(CMake_HAVE_CXX_${FEATURE} ON CACHE INTERNAL "TRY_RUN" FORCE)
+      else()
+        set(CMake_HAVE_CXX_${FEATURE} OFF CACHE INTERNAL "TRY_RUN" FORCE)
+      endif()
+    else()
+      try_compile(CMake_HAVE_CXX_${FEATURE}
+        ${CMAKE_CURRENT_BINARY_DIR}
+        ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
+        CMAKE_FLAGS ${maybe_cxx_standard}
+        OUTPUT_VARIABLE OUTPUT
+        )
+    endif()
     set(check_output "${OUTPUT}")
     # Filter out MSBuild output that looks like a warning.
     string(REGEX REPLACE " +0 Warning\\(s\\)" "" check_output "${check_output}")
@@ -64,7 +79,7 @@ if(CMake_HAVE_CXX_MAKE_UNIQUE)
 endif()
 cm_check_cxx_feature(unique_ptr)
 if (NOT CMAKE_CXX_STANDARD LESS "17")
-  cm_check_cxx_feature(filesystem)
+  cm_check_cxx_feature(filesystem TRY_RUN)
 else()
   set(CMake_HAVE_CXX_FILESYSTEM FALSE)
 endif()
diff --git a/Source/Checks/cm_cxx_filesystem.cxx b/Source/Checks/cm_cxx_filesystem.cxx
index e508d1c969..ae8acc56a6 100644
--- a/Source/Checks/cm_cxx_filesystem.cxx
+++ b/Source/Checks/cm_cxx_filesystem.cxx
@@ -3,8 +3,25 @@
 
 int main()
 {
+  std::filesystem::path p0(L"/a/b/c");
+
   std::filesystem::path p1("/a/b/c");
   std::filesystem::path p2("/a/b/c");
+  if (p1 != p2) {
+    return 1;
+  }
+
+#if defined(_WIN32)
+  std::filesystem::path p3("//host/a/b/../c");
+  if (p3.lexically_normal().generic_string() != "//host/a/c") {
+    return 1;
+  }
+
+  std::filesystem::path p4("c://a/.///b/../");
+  if (p4.lexically_normal().generic_string() != "c:/a/") {
+    return 1;
+  }
+#endif
 
-  return p1 == p2 ? 0 : 1;
+  return 0;
 }