Re: [PATCH 16/16] fix handling of integer constant expressions

[Al Viro <viro@ftp.linux.org.uk>]

On Sun, Jun 24, 2007 at 12:04:44PM -0700, Linus Torvalds wrote:
> 
> 
> On Sun, 24 Jun 2007, Al Viro wrote:
> > 
> > Why?  I'd say it's not better than BUILD_BUG_ON_ZERO() use
> > instead of that ?:
> 
> Oh, _that_ part I have no problem with. It's more that it seems that the 
> gcc optimization is ok at least as an extension.

gcc logs:
	* expressions of form <....> can be reduced to cheaper form
	  by <....>.  Tested and merged.

gcc logs a year later:
	* revert commit <...>, it causes subtle problems (see PR<....>,
	  <....> and <....>).  Proposed replacement is too intrusive
	  for stable branch.

gcc logs a month later:
	* tested and merged the real fix for PR<....>; will go into the
	  next release.

foobar logs a year later:
	* gcc versions between <...> and <...> refuse to compile baz.c,
	  complain about non-constant index in initializer.  Waded through
	  the sewers of macros we have in barf.h and blah.h, found what
	  had been causing that.  Fixed.

Ain't fun...