EricWF created this revision.
EricWF added reviewers: rsmith, manmanren, bruno.
EricWF added subscribers: cfe-commits, rsmith.
Currently libc++'s `stddef.h` is treated as a textual header by the module map,
and technically this is correct because the header is non-modular (at least
during normal compilation).
Unfortunatly this means that the stddef module doesn't own any of the
definitions it should, like `size_t` and `ptrdiff_t`. which end up getting
owned by random STL headers.
Fortunately I believe that libc++'s `stddef.h` *is* modular due to Clang
internals which handle modules containing `stddef.h` differently. Specifically
Clang translates the module definition `module stddef_h { header "stddef.h"
export *}` into
module stddef_h {
textual header "clang/builtin-includes/.../stddef.h"
header "libcxx/include/stddef.h"
}
This means that the `__need_*` macros will always be resolved and `#undef`-ed
by Clang's `stddef.h` header before processing libc++'s. Therefore we should be
able to treat libc++'s header as non-textual. This allows libc++ to actually
build a `stddef_h` module containing the correct definitions.
I've tested this change both with and without local sub-module visibility and
on both Linux and OS X.
@rsmith What do you think? Does the above rational make sense?
https://reviews.llvm.org/D27439
Files:
include/module.modulemap
test/libcxx/modules/cstddef_h_exports.sh.cpp
test/libcxx/modules/stddef_h_exports.sh.cpp
test/libcxx/modules/stdlib_h_exports.sh.cpp
Index: test/libcxx/modules/stdlib_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/stdlib_h_exports.sh.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support, verify-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %build_module
+
+#include <stdlib.h>
+
+int main() {
+ size_t x;
+}
Index: test/libcxx/modules/stddef_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/stddef_h_exports.sh.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support, verify-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %compile_module %verify
+
+#include <ciso646>
+
+int main() {
+ size_t x; // expected-error {{missing '#include <stddef.h>'}}
+}
Index: test/libcxx/modules/cstddef_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/cstddef_h_exports.sh.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %build_module
+
+#include <cstddef>
+
+int main() {
+ size_t x; ((void)x);
+ std::size_t y; ((void)y);
+}
Index: include/module.modulemap
===================================================================
--- include/module.modulemap
+++ include/module.modulemap
@@ -42,8 +42,15 @@
// <stdarg.h> provided by compiler.
// <stdbool.h> provided by compiler.
module stddef_h {
- // <stddef.h>'s __need_* macros require textual inclusion.
- textual header "stddef.h"
+ // NOTE: <stddef.h> should technically be a textual header due to the
+ // __need_* macros. However Clang transforms this module definition into:
+ // module stddef_h {
+ // textual header "clang/builtin-includes/stddef.h"
+ // header "libcxx/include/stddef.h"
+ // }
+ // Therefore Clang's stddef.h resolves the __need_* macros before
+ // building libc++'s header as a non-textual module.
+ header "stddef.h"
}
module stdint_h {
header "stdint.h"
Index: test/libcxx/modules/stdlib_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/stdlib_h_exports.sh.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support, verify-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %build_module
+
+#include <stdlib.h>
+
+int main() {
+ size_t x;
+}
Index: test/libcxx/modules/stddef_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/stddef_h_exports.sh.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support, verify-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %compile_module %verify
+
+#include <ciso646>
+
+int main() {
+ size_t x; // expected-error {{missing '#include <stddef.h>'}}
+}
Index: test/libcxx/modules/cstddef_h_exports.sh.cpp
===================================================================
--- /dev/null
+++ test/libcxx/modules/cstddef_h_exports.sh.cpp
@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-support
+
+// Test that stddef.h provides size_t
+
+// RUN: %build_module
+
+#include <cstddef>
+
+int main() {
+ size_t x; ((void)x);
+ std::size_t y; ((void)y);
+}
Index: include/module.modulemap
===================================================================
--- include/module.modulemap
+++ include/module.modulemap
@@ -42,8 +42,15 @@
// <stdarg.h> provided by compiler.
// <stdbool.h> provided by compiler.
module stddef_h {
- // <stddef.h>'s __need_* macros require textual inclusion.
- textual header "stddef.h"
+ // NOTE: <stddef.h> should technically be a textual header due to the
+ // __need_* macros. However Clang transforms this module definition into:
+ // module stddef_h {
+ // textual header "clang/builtin-includes/stddef.h"
+ // header "libcxx/include/stddef.h"
+ // }
+ // Therefore Clang's stddef.h resolves the __need_* macros before
+ // building libc++'s header as a non-textual module.
+ header "stddef.h"
}
module stdint_h {
header "stdint.h"
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