[PATCH] implement -Winfinite-recursion [PR88232]

[Martin Sebor]

On 11/24/21 3:16 AM, Thomas Schwinge wrote:
> Hi!
> 
> On 2021-11-09T21:28:43-0700, Martin Sebor via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>> The attached patch adds support to the middle end for detecting
>> infinitely recursive calls.  The warning is controlled by the new
>> -Winfinite-recursion option.  The option name is the same as
>> Clang's.
> 
> Thanks!
> 
>> The warning detects a superset of problems detected by Clang
>> (based on its tests).  It detects the problem in PR88232
>> (the feature request) as well as the one in PR 87742,
>> an unrelated problem report that was root-caused to bug due
>> to infinite recursion.
> 
> ... and I'm thus confirming that it also would have caught
> PR101204 "infinite recursion in gtype-desc.c since
> r12-1801-g7036e9ef462fde8181bece4ac4e03f3aa27204dc":

I'd hoped it would pick it up but didn't take the time to verify
it did.  Thanks for double-checking that!

Martin

> 
>      [...]
>      gtype-desc.c: In function ‘void gt_pch_nx(int_hash<unsigned int, 0, 4294967295>*, gt_pointer_operator, void*)’:
>      gtype-desc.c:11311:1: error: infinite recursion detected [-Werror=infinite-recursion]
>      11311 | gt_pch_nx (int_hash<location_t,0,UINT_MAX>* x ATTRIBUTE_UNUSED,
>            | ^~~~~~~~~
>      gtype-desc.c:11315:15: note: recursive call
>      11315 |     gt_pch_nx (&((*x)), op, cookie);
>            |     ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
>      cc1plus: all warnings being treated as errors
>      make[3]: *** [gtype-desc.o] Error 1
>      make[3]: Leaving directory `[...]/build-gcc/gcc'
>      make[2]: *** [all-stage2-gcc] Error 2
>      make[2]: Leaving directory `[...]/build-gcc'
>      make[1]: *** [stage2-bubble] Error 2
>      make[1]: Leaving directory `[...]/build-gcc'
>      make: *** [all] Error 2
> 
> That's with recent fix-up commit c71cb26a9e841888f52e4bfcaad94c8f8ecb4fdb
> "Get rid of infinite recursion for 'typedef' used with GTY-marked
> 'gcc/diagnostic-spec.h:nowarn_map' [PR101204, PR103157]" temporarily
> reverted (and commit f861ed8b29a5eb6164d1ddbcfbb6232dddae713f
> "Use 'location_hash' for 'gcc/diagnostic-spec.h:nowarn_map'" as a
> prerequisite, too).
> 
> 
> Grüße
>   Thomas
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