conformtest: Support xfail markers on individual assertions [committed]

[Joseph Myers]

On Fri, 19 Jun 2015, Roland McGrath wrote:

> I like the intent.  I noticed that almost all of the instances in the -data
> files use a consistent convention for the comment:
> 	// Bug NNNNN: ...
> 
> My first impulse was to ask that the convention be stated somewhere and
> followed uniformly.  But it occurs to me it would be nice to have this be
> more formal than a comment convention.  How about instead of:
> 	// Bug NNNNN: explanatory comment
> 	xfail-foo ...
> we make it:
> 	// explanatory comment
> 	xfail {NNNNN} foo ...
> 
> This makes it completely explicit that you can't have an XFAIL without
> having a bug filed for it.  It also makes it marginally easier than a
> comment convention to have scripts that do something or other with the bug
> number.

There are cases where it's not clear having bugs filed is useful.  (For 
example: XPG4 specifies st_blksize and st_blocks as of type long, where 
subsequent standards change them to blksize_t and blkcnt_t.  So when 
properly reviewed for XPG4, the data should reflect this - but should also 
have xfail markers, given that those types aren't always long.  And as 
that's simply a limitation in the level of support for an old standard - 
much like we have the varargs.h tests XFAILed at makefile level - I don't 
see a use in a bug for it.)

I did wonder about making the syntax include somewhere for a condition 
under which the xfail applies - to allow for architecture-specific xfails 
(hard-to-fix issues with types can often be architecture-specific) - but 
that didn't seem necessary at this point.

-- 
Joseph S. Myers
joseph@codesourcery.com