C89 had a questionable feature where the compiler would implicitly
declare a function that the user called but was never previously
declared. The resulting function would be globally declared as
extern int func(); -- a function without a prototype which accepts zero
or more arguments.
C99 removed support for this questionable feature due to severe
security concerns. However, there was no deprecation period; C89 had
the feature, C99 didn't. So Clang (and GCC) both supported the
functionality as an extension in C99 and later modes.
C2x no longer supports that function signature as it now requires all
functions to have a prototype, and given the known security issues with
the feature, continuing to support it as an extension is not tenable.
This patch changes the diagnostic behavior for the
-Wimplicit-function-declaration warning group depending on the language
mode in effect. We continue to warn by default in C89 mode (due to the
feature being dangerous to use). However, because this feature will not
be supported in C2x mode, we've diagnosed it as being invalid for so
long, the security concerns with the feature, and the trivial
workaround for users (declare the function), we now default the
extension warning to an error in C99-C17 mode. This still gives users
an easy workaround if they are extensively using the extension in those
modes (they can disable the warning or use -Wno-error to downgrade the
error), but the new diagnostic makes it more clear that this feature is
not supported and should be avoided. In C2x mode, we no longer allow an
implicit function to be defined and treat the situation the same as any
other lookup failure.
Differential Revision: https://reviews.llvm.org/D122983
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 advertise private modules to be declared as submodules
(Foo.Private). This has proven to not scale well since private headers
might carry several dependencies, introducing unwanted content into the
main module and often causing dep cycles.
Change the canonical way to name it to Foo_Private, forcing private
modules as top level ones, and provide warnings under -Wprivate-module
to suggest fixes for other private naming. Update documentation to
reflect that.
rdar://problem/31173501
llvm-svn: 321337
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
This would cause frameworks to have spurious "redefinition" errors if
they had both a (legacy) "module.map" and a (new) "module.modulemap" file and we
happened to do a sub-directory search in that directory using a
non-framework include path (e.g. -Ifoo/ -Ffoo/). For migration
purposes it's very handy that the compiler will prefer the new spelling
of the filename and not look at the old one if it doesn't need to.
llvm-svn: 230308
This name, while more verbose, plays more nicely with tools that use
file extensions to determine file types. The existing spelling
'module.map' will continue to work, but the new spelling will take
precedence.
In frameworks, this new filename will only go in a new 'Modules'
sub-directory.
Similarly, add a module.private.modulemap corresponding to
module_private.map.
llvm-svn: 204261
Aaron Ballman