c++modules: Fix relative paths in local-arguments

Fixes: #27426

Source/cmCxxModuleMetadata.cxx

@@ -442,7 +442,7 @@ struct MetaDataProperties
   std::string MetadataDir;
   std::set<cm::string_view> AllCompileFeatures;
   std::set<cm::string_view> AllCompileOptions;
-  std::set<cm::string_view> AllIncludeDirectories;
+  std::set<std::string> AllIncludeDirectories;
   std::set<std::string> AllCompileDefinitions;
   std::set<std::string> BaseDirs;
   std::set<std::string> Sources;
@@ -473,11 +473,11 @@ MetaDataProperties CollectMetaProperties(cmCxxModuleMetadata const& meta)
 
     if (module.LocalArguments) {
       for (auto const& incDir : module.LocalArguments->IncludeDirectories) {
-        props.AllIncludeDirectories.emplace(incDir);
+        props.AllIncludeDirectories.emplace(props.NormalizePath(incDir));
       }
       for (auto const& sysIncDir :
            module.LocalArguments->SystemIncludeDirectories) {
-        props.AllIncludeDirectories.emplace(sysIncDir);
+        props.AllIncludeDirectories.emplace(props.NormalizePath(sysIncDir));
       }
       for (auto const& opt : module.LocalArguments->CompileOptions) {
         props.AllCompileOptions.emplace(opt);

Tests/RunCMake/CXXModulesCompile/RunCMakeTest.cmake

@@ -192,6 +192,7 @@ if ("named" IN_LIST CMake_TEST_MODULE_COMPILATION)
   if ("cxx_std_23" IN_LIST CMAKE_CXX_COMPILE_FEATURES AND
       "import_std23" IN_LIST CMake_TEST_MODULE_COMPILATION)
     run_cxx_module_test(imp-std)
+    run_cxx_module_test(imp-dummy-std)
     set(RunCMake_CXXModules_NO_TEST 1)
     run_cxx_module_test(imp-std-no-std-prop)
     unset(RunCMake_CXXModules_NO_TEST)

Tests/RunCMake/CXXModulesCompile/dummy-std/interface/std.cppm

@@ -0,0 +1,6 @@
+module;
+
+#include <dummy-std.hpp>
+#include <dummy-sys.hpp>
+
+export module std;

Tests/RunCMake/CXXModulesCompile/dummy-std/manifest/dummy-std.modules.json

@@ -0,0 +1,20 @@
+{
+  "version": 1,
+  "revision": 1,
+  "modules": [
+    {
+      "is-interface": true,
+      "is-std-library": true,
+      "logical-name": "std",
+      "source-path": "../interface/std.cppm",
+      "local-arguments": {
+        "include-directories": [
+          "../include"
+        ],
+        "system-include-directories": [
+          "../sysinclude"
+        ]
+      }
+    }
+  ]
+}

Tests/RunCMake/CXXModulesCompile/imp-dummy-std-stderr.txt

@@ -0,0 +1,8 @@
+CMake Warning \(dev\) at .*/Modules/Compiler/CMakeCommonCompilerMacros\.cmake:[0-9]* \(cmake_language\):
+  CMake's support for `import std;` in C\+\+23 and newer is experimental\.  It
+  is meant only for experimentation and feedback to CMake developers\.
+Call Stack \(most recent call first\):
+  .*/Modules/CMakeDetermineCompilerSupport\.cmake:[0-9]* \(cmake_cxx_find_modules_json\)
+  .*/Modules/CMakeTestCXXCompiler\.cmake:[0-9]* \(CMAKE_DETERMINE_COMPILER_SUPPORT\)
+  CMakeLists\.txt:[0-9]* \(project\)
+This warning is for project developers\.  Use -Wno-dev to suppress it\.

Tests/RunCMake/CXXModulesCompile/imp-dummy-std/CMakeLists.txt

@@ -0,0 +1,18 @@
+set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD
+  "451f2fe2-a8a2-47c3-bc32-94786d8fc91b")
+set(CMAKE_CXX_STDLIB_MODULES_JSON
+  "${CMAKE_CURRENT_LIST_DIR}/../dummy-std/manifest/dummy-std.modules.json"
+)
+
+cmake_minimum_required(VERSION 3.29)
+project(cxx_modules_import_std CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+set(CMAKE_CXX_MODULE_STD 1)
+
+add_executable(main
+  main.cxx)
+target_compile_features(main PRIVATE cxx_std_23)
+
+add_test(NAME main COMMAND main)

Tests/RunCMake/CXXModulesCompile/imp-dummy-std/main.cxx

@@ -0,0 +1,6 @@
+import std;
+
+int main(int argc, char* argv[])
+{
+  return 0;
+}