[libcxx-commits] [libcxx] [libc++] Suppress reserved module name warning for `module std` (PR #228632)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Sharadh Rajaraman (sharadhr)

<details>
<summary>Changes</summary>

Suppress the Clang reserved module identifier warning for the standard library module declarations.\n\nAdds regression coverage that promotes the warning to an error while precompiling std and std.compat.\n\nTests: filtered libc++ Lit tests for std/modules/std.pass.cpp and std/modules/std.compat.pass.cpp (pass with the change; fail without it).

---
Full diff: https://github.com/llvm/llvm-project/pull/228632.diff


6 Files Affected:

- (modified) libcxx/modules/std.compat.cppm.in (+7) 
- (modified) libcxx/modules/std.cppm.in (+7) 
- (modified) libcxx/test/std/modules/std.compat.pass.cpp (+3) 
- (modified) libcxx/test/std/modules/std.pass.cpp (+3) 
- (modified) libcxx/utils/generate_libcxx_cppm_in.py (+13-1) 
- (modified) libcxx/utils/libcxx/test/format.py (+2-2) 


``````````diff
diff --git a/libcxx/modules/std.compat.cppm.in b/libcxx/modules/std.compat.cppm.in
index ab08125c4c4e45..e69c1509a781e4 100644
--- a/libcxx/modules/std.compat.cppm.in
+++ b/libcxx/modules/std.compat.cppm.in
@@ -77,7 +77,14 @@ module;
 #  endif // __has_include(<stdfloat>)
 #endif // _WIN32
 
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wreserved-module-identifier"
+#endif
 export module std.compat;
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic pop
+#endif
 export import std;
 
 
diff --git a/libcxx/modules/std.cppm.in b/libcxx/modules/std.cppm.in
index b9a491653659af..2d2d1e655503f9 100644
--- a/libcxx/modules/std.cppm.in
+++ b/libcxx/modules/std.cppm.in
@@ -160,7 +160,14 @@ module;
 #  endif // __has_include(<stdfloat>)
 #endif // _WIN32
 
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wreserved-module-identifier"
+#endif
 export module std;
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic pop
+#endif
 
 
 @LIBCXX_MODULE_STD_INCLUDE_SOURCES@
diff --git a/libcxx/test/std/modules/std.compat.pass.cpp b/libcxx/test/std/modules/std.compat.pass.cpp
index 0d1a4ac7d89c43..22a339f7c9dc81 100644
--- a/libcxx/test/std/modules/std.compat.pass.cpp
+++ b/libcxx/test/std/modules/std.compat.pass.cpp
@@ -16,6 +16,9 @@
 // C++20 modules are incompatible with Clang modules
 // ADDITIONAL_COMPILE_FLAGS: -fno-modules
 
+// Ensure the std.compat module declaration does not trigger a reserved-name warning.
+// ADDITIONAL_COMPILE_FLAGS: -Werror=reserved-module-identifier
+
 // MODULE_DEPENDENCIES: std.compat
 
 import std.compat;
diff --git a/libcxx/test/std/modules/std.pass.cpp b/libcxx/test/std/modules/std.pass.cpp
index 4587dcb1b81784..a6ab09b4c64974 100644
--- a/libcxx/test/std/modules/std.pass.cpp
+++ b/libcxx/test/std/modules/std.pass.cpp
@@ -16,6 +16,9 @@
 // C++20 modules are incompatible with Clang modules
 // ADDITIONAL_COMPILE_FLAGS: -fno-modules
 
+// Ensure the std module declaration does not trigger a reserved-name warning.
+// ADDITIONAL_COMPILE_FLAGS: -Werror=reserved-module-identifier
+
 // MODULE_DEPENDENCIES: std
 
 import std;
diff --git a/libcxx/utils/generate_libcxx_cppm_in.py b/libcxx/utils/generate_libcxx_cppm_in.py
index fac33f74812a7f..acb3f28a2020ac 100644
--- a/libcxx/utils/generate_libcxx_cppm_in.py
+++ b/libcxx/utils/generate_libcxx_cppm_in.py
@@ -69,10 +69,22 @@ def write_file(module):
 """
             )
 
+        module_declaration = f"export module {module};"
+        if module in ("std", "std.compat"):
+            module_declaration = f"""\
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wreserved-module-identifier"
+#endif
+{module_declaration}
+#ifdef _LIBCPP_COMPILER_CLANG_BASED
+#pragma clang diagnostic pop
+#endif"""
+
         module_cpp_in.write(
             f"""#endif // _WIN32
 
-export module {module};
+{module_declaration}
 {'export import std;' if module == 'std.compat' else ''}
 
 {'@LIBCXX_MODULE_STD_INCLUDE_SOURCES@' if module == 'std' else ''}
diff --git a/libcxx/utils/libcxx/test/format.py b/libcxx/utils/libcxx/test/format.py
index 3e24e435e7c07b..7f830d7598bcc2 100644
--- a/libcxx/utils/libcxx/test/format.py
+++ b/libcxx/utils/libcxx/test/format.py
@@ -177,7 +177,7 @@ def parseScript(test, preamble):
                 0,
                 "%dbg(MODULE std.compat) %{cxx} %{flags} "
                 f"{compileFlags} "
-                "-Wno-reserved-module-identifier -Wno-reserved-user-defined-literal "
+                "-Wno-reserved-user-defined-literal "
                 "-fmodule-file=std=%{temp}/std.pcm " # The std.compat module imports std.
                 "--precompile -o %{temp}/std.compat.pcm -c %{module-dir}/std.compat.cppm",
             )
@@ -194,7 +194,7 @@ def parseScript(test, preamble):
             0,
             "%dbg(MODULE std) %{cxx} %{flags} "
             f"{compileFlags} "
-            "-Wno-reserved-module-identifier -Wno-reserved-user-defined-literal "
+            "-Wno-reserved-user-defined-literal "
             "--precompile -o %{temp}/std.pcm -c %{module-dir}/std.cppm",
         )
         moduleCompileFlags.extend(["-fmodule-file=std=%{temp}/std.pcm", "%{temp}/std.pcm"])

``````````

</details>


https://github.com/llvm/llvm-project/pull/228632