[Bug analyzer/107565] [12 Regression] -Wanalyzer-use-of-uninitialized-value false positive with rdrand

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107565

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:

https://gcc.gnu.org/g:56572a08ec4a0fc1a7802d3737cd7f7cc9089c4b

commit r13-6466-g56572a08ec4a0fc1a7802d3737cd7f7cc9089c4b
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Fri Mar 3 17:59:21 2023 -0500

    analyzer: provide placeholder implementation of sprintf

    Previously, the analyzer lacked a known_function implementation of
    sprintf, and thus would handle calls to sprintf with the "anything could
    happen" fallback.

    Whilst working on PR analyzer/107565 I noticed that this was preventing
    a lot of genuine memory leaks from being reported for Doom; fixing
    thusly.

    Integration testing of the effect of the patch shows a big increase in
    true positives due to the case mentioned in Doom, and one new false
    positive (in pcre2), which I'm tracking as PR analyzer/109014.

    Comparison:
      GOOD:  67 -> 123 (+56); 10.91% -> 18.33%
       BAD: 547 -> 548 (+1)

    where the affected warnings/projects are:

      -Wanalyzer-malloc-leak:
        GOOD:  0 -> 56 (+56);  0.00% -> 41.48%
         BAD: 79
          True positives: 0 -> 56 (+56)
            (all in Doom)

      -Wanalyzer-use-of-uninitialized-value:
        GOOD: 0;  0.00%
         BAD: 80 -> 81 (+1)
          False positives:
            pcre2-10.42: 0 -> 1 (+1)

    gcc/analyzer/ChangeLog:
            * kf.cc (class kf_sprintf): New.
            (register_known_functions): Register it.

    gcc/testsuite/ChangeLog:
            * gcc.dg/analyzer/doom-d_main-IdentifyVersion.c: New test.
            * gcc.dg/analyzer/sprintf-1.c: New test.
            * gcc.dg/analyzer/sprintf-concat.c: New test.

    Signed-off-by: David Malcolm <dmalcolm@redhat.com>