[patch][pr17429] Do nothing in a null build if CLANG_ALWAYS_CHECK_VC_REV is OFF

[Jordan Rose]

Ah. The idea is that the version at least gets updated when you reconfigure, but that's already there by removing the output file.

Please don't remove HAVE_SVN_VERSION_INC, though. A slightly outdated version is still better than no version at all.

Jordan


On Oct 1, 2013, at 7:14 , Rafael Espíndola <rafael.espindola at gmail.com> wrote:

> Most of the time in a null build is spent checking the svn revision
> number. This is very wasteful in a regular development environment.
> 
> If I understand CLANG_ALWAYS_CHECK_VC_REV correctly, it is also the
> case that the version is not even always used, so we spend time for
> nothing.
> 
> The attached patch moves the entire version check under
> CLANG_ALWAYS_CHECK_VC_REV. On my machine that makes a null build of
> bin/clang 11 times faster.
> 
> Cheers,
> Rafael
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