Index: clang/include/clang/Lex/ModuleMap.h =================================================================== --- clang/include/clang/Lex/ModuleMap.h +++ clang/include/clang/Lex/ModuleMap.h @@ -413,6 +413,7 @@ /// Is this a compiler builtin header? static bool isBuiltinHeader(StringRef FileName); + bool isBuiltinHeader(const FileEntry *File); /// Add a module map callback. void addModuleMapCallbacks(std::unique_ptr Callback) { Index: clang/lib/Lex/HeaderSearch.cpp =================================================================== --- clang/lib/Lex/HeaderSearch.cpp +++ clang/lib/Lex/HeaderSearch.cpp @@ -1276,14 +1276,12 @@ // // It's common that libc++ and system modules will both define such // submodules. Make sure cached results for a builtin header won't - // prevent other builtin modules to potentially enter the builtin header. - // Note that builtins are header guarded and the decision to actually - // enter them is postponed to the controlling macros logic below. + // prevent other builtin modules from potentially entering the builtin + // header. Note that builtins are header guarded and the decision to + // actually enter them is postponed to the controlling macros logic below. bool TryEnterHdr = false; if (FileInfo.isCompilingModuleHeader && FileInfo.isModuleHeader) - TryEnterHdr = File->getDir() == ModMap.getBuiltinDir() && - ModuleMap::isBuiltinHeader( - llvm::sys::path::filename(File->getName())); + TryEnterHdr = ModMap.isBuiltinHeader(File); // Textual headers can be #imported from different modules. Since ObjC // headers find in the wild might rely only on #import and do not contain @@ -1423,8 +1421,14 @@ // If this module specifies [no_undeclared_includes], we cannot find any // file that's in a non-dependency module. - if (RequestingModule && Module && RequestingModule->NoUndeclaredIncludes) { - HS.getModuleMap().resolveUses(RequestingModule, /*Complain*/false); + // Builtin headers are a special case. Multiple modules can use the same + // builtin as a modular header (see also comment in + // ShouldEnterIncludeFile()), so the builtin header may have been "claimed" + // by an unrelated module. This shouldn't prevent us from including the + // builtin header textually in this module. + if (RequestingModule && Module && RequestingModule->NoUndeclaredIncludes && + !HS.getModuleMap().isBuiltinHeader(File)) { + HS.getModuleMap().resolveUses(RequestingModule, /*Complain*/ false); if (!RequestingModule->directlyUses(Module.getModule())) { return false; } Index: clang/lib/Lex/ModuleMap.cpp =================================================================== --- clang/lib/Lex/ModuleMap.cpp +++ clang/lib/Lex/ModuleMap.cpp @@ -387,13 +387,17 @@ .Default(false); } +bool ModuleMap::isBuiltinHeader(const FileEntry *File) { + return File->getDir() == BuiltinIncludeDir && + ModuleMap::isBuiltinHeader(llvm::sys::path::filename(File->getName())); +} + ModuleMap::HeadersMap::iterator ModuleMap::findKnownHeader(const FileEntry *File) { resolveHeaderDirectives(File); HeadersMap::iterator Known = Headers.find(File); if (HeaderInfo.getHeaderSearchOpts().ImplicitModuleMaps && - Known == Headers.end() && File->getDir() == BuiltinIncludeDir && - ModuleMap::isBuiltinHeader(llvm::sys::path::filename(File->getName()))) { + Known == Headers.end() && ModuleMap::isBuiltinHeader(File)) { HeaderInfo.loadTopLevelSystemModules(); return Headers.find(File); } Index: clang/test/Modules/Inputs/no-undeclared-includes-builtins/system_module/module.modulemap =================================================================== --- /dev/null +++ clang/test/Modules/Inputs/no-undeclared-includes-builtins/system_module/module.modulemap @@ -0,0 +1,4 @@ +module stddef [system] { + header "stddef.h" + export * +} Index: clang/test/Modules/Inputs/no-undeclared-includes-builtins/system_module/stddef.h =================================================================== --- /dev/null +++ clang/test/Modules/Inputs/no-undeclared-includes-builtins/system_module/stddef.h @@ -0,0 +1 @@ +#include_next Index: clang/test/Modules/Inputs/no-undeclared-includes-builtins/user_module/module.modulemap =================================================================== --- /dev/null +++ clang/test/Modules/Inputs/no-undeclared-includes-builtins/user_module/module.modulemap @@ -0,0 +1,4 @@ +module UserModule [no_undeclared_includes] { + header "user_module.h" + export * +} Index: clang/test/Modules/Inputs/no-undeclared-includes-builtins/user_module/user_module.h =================================================================== --- /dev/null +++ clang/test/Modules/Inputs/no-undeclared-includes-builtins/user_module/user_module.h @@ -0,0 +1 @@ +#include Index: clang/test/Modules/no-undeclared-includes-builtins.cpp =================================================================== --- /dev/null +++ clang/test/Modules/no-undeclared-includes-builtins.cpp @@ -0,0 +1,9 @@ +// Test that a [no_undeclared_headers] module can include builtin headers, even +// if these have been "claimed" by a different module that wraps these builtin +// headers. libc++ does this, for example. + +// RUN: rm -rf %t +// RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -I %S/Inputs/no-undeclared-includes-builtins/user_module -I %S/Inputs/no-undeclared-includes-builtins/system_module %s +// expected-no-diagnostics + +#include