clang import std

llvm/llvm-project#75741

Author: huangqinjin

import-std/CMakeLists.txt

@@ -35,4 +35,23 @@ elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
         BASE_DIRS ${modules}
         FILES ${modules}/std.ixx
     )
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    include(CheckCXXSymbolExists)
+    check_cxx_symbol_exists(_LIBCPP_VERSION version libcxx)
+    if(libcxx)
+        find_path(modules REQUIRED
+            NAMES
+              std.cppm
+            PATH_SUFFIXES
+              share/libc++/v1
+            PATHS
+              "${CMAKE_CXX_COMPILER}/../.."
+            NO_DEFAULT_PATH
+        )
+        target_sources(${PROJECT_NAME} PUBLIC FILE_SET CXX_MODULES
+            BASE_DIRS ${modules}
+            FILES ${modules}/std.cppm
+        )
+        target_compile_options(${PROJECT_NAME} PRIVATE -Wno-reserved-module-identifier)
+    endif()
 endif()

import-std/Makefile.clang

@@ -0,0 +1,16 @@
+CLANG_DIR_CMD = $(PREFIX)clang++ -print-resource-dir
+STD_CPPM_LOC = /../../../share/libc++/v1/std.cppm
+
+hello.exe: main.cpp std.o std.pcm
+	$(PREFIX)clang++ -stdlib=libc++ -std=c++23 -fprebuilt-module-path=. main.cpp std.o -o hello.exe
+
+std.o std.pcm: std.cppm.o
+	$(PREFIX)clang++ -stdlib=libc++ -std=c++23 -fmodule-output=std.pcm -c @std.cppm.o -Wno-reserved-module-identifier
+
+std.cppm.o:
+	-FOR /F "delims=" %%i IN ('$(CLANG_DIR_CMD)') DO @echo %%i$(STD_CPPM_LOC) >> std.cppm.o
+	-printf `$(CLANG_DIR_CMD)`$(STD_CPPM_LOC) >> std.cppm.o
+
+clean:
+	-rm  *.pcm *.o *.exe
+	-del *.pcm *.o *.exe

import-std/main.cpp

@@ -1,6 +1,17 @@
+#include <version>
+
+// https://github.com/llvm/llvm-project/issues/89579
+#ifdef _LIBCPP_VERSION
+#define __cpp_lib_modules 202207L
+#endif
+
+#ifdef __cpp_lib_modules
 import std;
+#endif
 
 int main()
 {
+#ifdef __cpp_lib_modules
     std::println("{}", "Hello, World!");
+#endif
 }