[Bug analyzer/108524] New: -Wanalyzer-infinite-recursion false positives seen in qemu's JSON parser

[Bug analyzer/108524] New: -Wanalyzer-infinite-recursion false positives seen in qemu's JSON parser

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108524

            Bug ID: 108524
           Summary: -Wanalyzer-infinite-recursion false positives seen in
                    qemu's JSON parser
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: dmalcolm at gcc dot gnu.org
  Target Milestone: ---

Created attachment 54338
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54338&action=edit
Reproducer

Attached reproducer reports 4 warnings from GCC 13's new
-Wanalyzer-infinite-recursion on qemu's JSON parser. 

All of them seem to be false positives, in that tokens are being consumed
during the recursion:
  https://godbolt.org/z/KWbPTcMEd

[Bug analyzer/108524] -Wanalyzer-infinite-recursion false positives seen in qemu's JSON parser

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108524

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-01-25

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
I'm testing a fix for this.

[Bug analyzer/108524] -Wanalyzer-infinite-recursion false positives seen in qemu's JSON parser

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108524

--- Comment #2 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:7bffea89f1f164efc10dd37d979a83c4c5fbfa7e

commit r13-5388-g7bffea89f1f164efc10dd37d979a83c4c5fbfa7e
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Thu Jan 26 09:12:21 2023 -0500

    analyzer: fix false positives from -Wanalyzer-infinite-recursion [PR108524]

    Reject -Wanalyzer-infinite-recursion diagnostics in which control flow
    has been affected by conjured_svalues between the initial call to a
    function and the subsequent entry to that function.  This prevents false
    positives such as in qemu's recursive JSON parser where function calls are
    changing state in the rest of the program (e.g. consuming tokens), despite
    the modelled state being effectively identical at both nested entrypoints.

    gcc/analyzer/ChangeLog:
            PR analyzer/108524
            * analyzer.h (class feasible_node): New forward decl.
            * diagnostic-manager.cc (epath_finder::get_best_epath): Add "pd"
            param.
            (epath_finder::explore_feasible_paths): Likewise.
            (epath_finder::process_worklist_item): Likewise.  Use it to call
            pending_diagnostic::check_valid_fpath_p on the final fpath to
            give pending_diagnostic a way to add additional restrictions on
            feasibility.
            (saved_diagnostic::calc_best_epath): Pass pending_diagnostic to
            epath_finder::get_best_epath.
            * infinite-recursion.cc: Include "analyzer/feasible-graph.h".
            (infinite_recursion_diagnostic::check_valid_fpath_p): New.
            (infinite_recursion_diagnostic::fedge_uses_conjured_svalue_p): New.
            (infinite_recursion_diagnostic::expr_uses_conjured_svalue_p): New.
            * pending-diagnostic.h (pending_diagnostic::check_valid_fpath_p):
            New vfunc.

    gcc/testsuite/ChangeLog:
            PR analyzer/108524
            * gcc.dg/analyzer/infinite-recursion-pr108524-1.c: New test.
            * gcc.dg/analyzer/infinite-recursion-pr108524-2.c: New test.
            *
gcc.dg/analyzer/infinite-recursion-pr108524-qobject-json-parser.c:
            New test.

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

[Bug analyzer/108524] -Wanalyzer-infinite-recursion false positives seen in qemu's JSON parser

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108524

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Should be fixed by the above commit.