Make top level modules for all the C standard library headers.
The `__stddef` implementation headers need header guards now that they're all modular. stdarg.h and stddef.h will be textual headers in the builtin modules, and so need to be repeatedly included in both the system and builtin module case. Define their header guards for consistency, but ignore them when building with modules.
`__stddef_null.h` needs to ignore its header guard when modules aren't being used to fulfill its redefinition obligation.
`__stddef_nullptr_t.h` needs to add a guard for C23 so that `_Builtin_stddef` can compile in C17 and earlier modes. `_Builtin_stddef.nullptr_t` can't require C23 because it also needs to be usable from C++.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D159064
Including select builtin headers in system modules is a workaround for module cycles, primarily in Apple's Darwin module that includes all of its C standard library headers. The workaround is problematic because it doesn't include all of the builtin headers (inttypes.h is notably absent), and it also doesn't include C++ headers. The straightforward for for this is to make top level modules for all of the C standard library headers and unwind.h in C++, clang, and the OS.
However, doing so in clang before the OS modules are ready re-introduces the module cycles. Add a -fbuiltin-headers-in-system-modules option to control if the special builtin headers belong to system modules or builtin modules. Pass the option by default for Apple.
Reviewed By: ChuanqiXu, Bigcheese, benlangmuir
Differential Revision: https://reviews.llvm.org/D159483
A significant number of our tests in C accidentally use functions
without prototypes. This patch converts the function signatures to have
a prototype for the situations where the test is not specific to K&R C
declarations. e.g.,
void func();
becomes
void func(void);
This is the seventh batch of tests being updated (there are a
significant number of other tests left to be updated).
We used to have a flag to enable module maps, and two more flags to enable
implicit module maps. This is all redundant; we don't need any flag for
enabling module maps in the abstract, and we don't usually have -fno- flags for
-cc1. We now have just a single flag, -fimplicit-module-maps, that enables
implicitly searching the file system for module map files and loading them.
The driver interface is unchanged for now. We should probably rename
-fmodule-maps to -fimplicit-module-maps at some point.
llvm-svn: 239789
Clang's <stddef.h> provides definitions for the C standard library
types size_t, ptrdiff_t, and wchar_t. However, the system's C standard
library headers tend to provide the same typedefs, and the two
generally avoid each other using the macros
_SIZE_T/_PTRDIFF_T/_WCHAR_T. With modules, however, we need to see
*all* of the places where these types are defined, so provide the
typedefs (ignoring the macros) when modules are enabled.
llvm-svn: 177686
