From f50d3582b4844b86ad86372028e44b52c560ec7d Mon Sep 17 00:00:00 2001 From: Ian Anderson Date: Wed, 13 Mar 2024 11:15:41 -0700 Subject: [clang][modules] giving the __stddef_ headers their own modules can cause redeclaration errors with -fbuiltin-headers-in-system-modules (#84127) On Apple platforms, some of the stddef.h types are also declared in system headers. In particular NULL has a conflicting declaration in . When that's in a different module from <__stddef_null.h>, redeclaration errors can occur. Make the \_\_stddef_ headers be non-modular in -fbuiltin-headers-in-system-modules and restore them back to not respecting their header guards. Still define the header guards though. __stddef_max_align_t.h was in _Builtin_stddef_max_align_t prior to the addition of _Builtin_stddef, and it needs to stay in a module because struct's can't be type merged. __stddef_wint_t.h didn't used to have a module, but leave it in it current module since it doesn't really belong to stddef.h. --- clang/lib/Lex/ModuleMap.cpp | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'clang/lib/Lex/ModuleMap.cpp') diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp index afb2948..10c475f 100644 --- a/clang/lib/Lex/ModuleMap.cpp +++ b/clang/lib/Lex/ModuleMap.cpp @@ -2498,9 +2498,12 @@ void ModuleMapParser::parseHeaderDecl(MMToken::TokenKind LeadingToken, } bool NeedsFramework = false; - // Don't add the top level headers to the builtin modules if the builtin headers - // belong to the system modules. - if (!Map.LangOpts.BuiltinHeadersInSystemModules || ActiveModule->isSubModule() || !isBuiltInModuleName(ActiveModule->Name)) + // Don't add headers to the builtin modules if the builtin headers belong to + // the system modules, with the exception of __stddef_max_align_t.h which + // always had its own module. + if (!Map.LangOpts.BuiltinHeadersInSystemModules || + !isBuiltInModuleName(ActiveModule->getTopLevelModuleName()) || + ActiveModule->fullModuleNameIs({"_Builtin_stddef", "max_align_t"})) Map.addUnresolvedHeader(ActiveModule, std::move(Header), NeedsFramework); if (NeedsFramework) -- cgit v1.1