r174560 - Introduce -fmodules-ignore-macro=NNN to ignore a macro when building/loading modules.

[Jordan Rose]

On Feb 6, 2013, at 16:21 , Douglas Gregor <dgregor at apple.com> wrote:

> Author: dgregor
> Date: Wed Feb  6 18:21:12 2013
> New Revision: 174560
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=174560&view=rev
> Log:
> Introduce -fmodules-ignore-macro=NNN to ignore a macro when building/loading modules.
> 
> The use of this flag enables a modules optimization where a given set
> of macros can be labeled as "ignored" by the modules
> system. Definitions of those macros will be completely ignored when
> building the module hash and will be stripped when actually building
> modules. The overall effect is that this flag can be used to
> drastically reduce the number of

…of…?

> Eventually, we'll want modules to tell us what set of macros they
> respond to (the "configuration macros"), and anything not in that set
> will be excluded. However, that requires a lot of per-module
> information that must be accurate, whereas this option can be used
> more readily.
> 
> Fixes the rest of <rdar://problem/13165109>.
>