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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/99768] [11 Regression] Bogus -Wuninitialized diagnostic with
 type punning
Date: Thu, 25 Mar 2021 12:28:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99768

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
             Blocks|                            |24639

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think the warning is correct - there is no valid initialization of a float
entity in 'tmp' (in fact GCC removed the initialization from 'v').  It might
be misleading but then what do you expect with invalid code?

We could, in theory, do another walk to find an initialization with strict
aliasing disabled and if we then find a candidate note that there are possi=
ble
initializations (we won't be able to prove they are definite inits) but
a violation of strict-aliasing might hide them.  OTOH this would pop up a l=
ot
and likely confuse people to use -fno-strict-aliasing to simply hide the
warning but not fix the missing initialization.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D24639
[Bug 24639] [meta-bug] bug to track all Wuninitialized issues=