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Re: [Patch] Fix localedata test builds with latest GCC


On Wed, 19 Jul 2017, Steve Ellcey wrote:

> While testing the latest glibc sources with the latest (ToT) GCC, I ran
> into some build failures (during testing, not during the glibc build).
> This patch fixes the build failures in the localedata subdirectory.  I
> believe these started failing with this GCC patch:
> 
> 	https://gcc.gnu.org/ml/gcc-patches/2017-06/msg00537.html

The warnings you quoted look very much like false positives to me, i.e. 
something that should be fixed in GCC not worked around in glibc.

Specifically, they look quite like the issue described in 
<https://gcc.gnu.org/ml/gcc-patches/2017-07/msg01827.html>.  Does that 
patch avoid the need for these -Wno- options?  If so, that indicates these 
-Wno- options should be removed.  If not, that indicates engaging with 
that thread would be appropriate to explain how the glibc case differs 
(unless there are cases in glibc that can be shown *not* to be false 
positives, i.e. where the code suggests a macro expansion is entirely 
within an "if" etc. but only part of it is).

> +# These tests use multistatement macros from tests-mbwc/tst_funcs.h
> +# and will not compile with GCC 8.1 without the warning turned off.

A comment referencing GCC 8.1 can't possibly be correct here yet; that's 
making a prediction about a version of GCC from April 2018, and so is 
misleading by suggesting something applies to a future release that may or 
may not apply to that release.  All GCC 8 development versions at present 
are 8.0.

-- 
Joseph S. Myers
joseph@codesourcery.com


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