[libcxx] r249738 - Split <ctype.h> out of <cctype>.

[Richard Smith via cfe-commits]

On Mon, Oct 24, 2016 at 4:58 PM, Bruno Cardoso Lopes via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> On Mon, Oct 24, 2016 at 4:17 PM, Richard Smith <richard at metafoo.co.uk>
> wrote:
> > On Mon, Oct 24, 2016 at 3:30 PM, Bruno Cardoso Lopes
> > <bruno.cardoso at gmail.com> wrote:
> >>
> >> > Sure, go ahead.
> >>
> >> I committed in r284797 and r284801 (libcxx). There's one minor issue
> >> I've found: the changes for the builtins affecting non submodule local
> >> visibility broke current users of plain "-fmodules" against our
> >> frameworks in public SDKs, in 10.11 & 10.12. I've attached a patch to
> >> work around that for the time being: make the new behavior dependent
> >> on local vis. Can you take a look?
> >
> >
> > What's the nature of the breakage? Generally I'd be fine with your patch,
> > but I wonder if there's something better we could do here.
>
> I haven't entirely isolated the problem, but they are all related to
> definitions from stdint.h. In one example below, uint32_t doesn't
> leak, requiring an explicit "#include <stdint.h>" to make it work.
>
> -- example.m
> #import <IOKit/IODataQueueClient.h>
> --
> $ clang -arch x86_64 -isysroot
> /Applications/Xcode.app/Contents/Developer/Platforms/
> MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk
> -fmodules-cache-path=tmpcache example.m -E -o /dev/null  -fmodules
>
> While building module 'IOKit' imported from example.m:1:
> In file included from <module-includes>:2:
> /Applications/Xcode.app/Contents/Developer/Platforms/
> MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/System/
> Library/Frameworks/IOKit.framework/Headers/IODataQueueClient.h:62:71:
> error: de
>       'Darwin.POSIX._types._uint32_t' before it is required
> IOReturn IODataQueueDequeue(IODataQueueMemory *dataQueue, void *data,
> uint32_t *dataSize);
>                                                                       ^
> /Applications/Xcode.app/Contents/Developer/Platforms/
> MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/
> include/_types/_uint32_t.h:31:22:
> note: previous declaration is here
> typedef unsigned int uint32_t;
>                      ^
> bot.m:1:9: fatal error: could not build module 'IOKit'
> #import <IOKit/IODataQueueClient.h>
>  ~~~~~~~^


This change also broke local submodule visibility builds with modular glibc
(see PR30778 for details). I have an idea for how to fix this; running it
through bootstrap now.

>> > Hmm. Ideally, we should try to pick something that captures the spirit
> >> > of
> >> > "only non-modular headers and headers from used modules". Something
> like
> >> > "ignore_modules_not_declared_used", but less wordy?
> >>
> >> Right. It's gonna be hard to shrink this to a meaningful short name.
> >> What about a more generic "no_escape"?  "no_undeclared_headers"?
> >
> >
> > Hmm. Maybe we could allow the existing [exhaustive] attribute to be
> > specified on a use-declaration:
> >
> >   use [exhaustive] a, b, c
>
> I don't understand, the 'Darwin' module map doesn't use the 'use'
> keyword in any of its modules, how do you suggest we would use that to
> express the 'ignore_modules_not_declared_used' idea?


Hah, right, this would only work if your module has dependencies. Maybe an
[exhaustive_uses] attribute on the module itself then?
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