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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/52299] GCC warns on compile time division by zero erroneously
Date: Mon, 20 Feb 2012 19:20:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52299

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-02-20 18:27:46 UTC ---
    case COND_EXPR:
      return build_x_conditional_expr
        (RECUR (TREE_OPERAND (t, 0)),
         RECUR (TREE_OPERAND (t, 1)),
         RECUR (TREE_OPERAND (t, 2)),
         complain);

For this we'd need to first RECUR (TREE_OPERAND (t, 0)), remember that result
in some temporary, and look if it is 0, non-zero or unknown.  If 0, maybe
increment temporarily c_inhibit_evaluation_warnings around RECUR (TREE_OPERAND
(t, 1)) (dunno about cp_unevaluated_operand or fold_*defer_overflow_warnings
()), if non-zero similarly for RECUR (TREE_OPERAND (t, 1)).