Re: older gccs and case labels producing integer constants

[Jakub Jelinek]

On Tue, Apr 05, 2022 at 12:36:58PM +0200, Borislav Petkov wrote:
> On Tue, Apr 05, 2022 at 12:06:45PM +0200, Richard Biener wrote:
> > Wird auch mit gcc 11 rejected.  Kanns sein dass mit gcc 7 andere
> > compiler flags genommen werden?
> 
> Found it:
> 
> $ gcc -fsanitize=shift -c switch.c
> switch.c: In function ‘foo’:
> switch.c:10:7: error: case label does not reduce to an integer constant
>        case (((0xfc08) << 16) | (0x0101)):;
> 
> $ gcc --version
> gcc (SUSE Linux) 7.4.1 20190905 [gcc-7-branch revision 275407]
> Copyright (C) 2017 Free Software Foundation, Inc.
> 
> Something not fully backported?

That is rejected with -fsanitize=shift even on current trunk (in C, C++ is
fine).
C++ constexpr code has cases for ubsan builtins and internal functions,
but C just doesn't handle those apparently.

	Jakub