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From: "mpolacek at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/111660] [14 Regression] Compilation of constexpr function
 returning enum takes exponential time with -std=c++2a since
 r14-4140-g6851e3423c2b5e
Date: Thu, 12 Oct 2023 19:17:38 +0000
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X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: compile-time-hog
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111660

--- Comment #12 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Candidate fix:

--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1072,7 +1072,7 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees,
void *data_)
       /* We're done here.  Don't clear *walk_subtrees here though: we're
called
     from cp_fold_r and we must let it recurse on the expression with
     cp_fold.  */
-      break;
+      return integer_zero_node;
     case PTRMEM_CST:
       if (TREE_CODE (PTRMEM_CST_MEMBER (stmt)) =3D=3D FUNCTION_DECL
      && DECL_IMMEDIATE_FUNCTION_P (PTRMEM_CST_MEMBER (stmt)))
@@ -1145,7 +1145,8 @@ cp_fold_immediate (tree *tp, mce_value
manifestly_const_eval)
     flags |=3D ff_mce_false;

   cp_fold_data data (flags);
-  return !!cp_walk_tree_without_duplicates (tp, cp_fold_immediate_r, &data=
);
+  tree r =3D cp_walk_tree_without_duplicates (tp, cp_fold_immediate_r, &da=
ta);
+  return r =3D=3D error_mark_node;
 }

 /* Perform any pre-gimplification folding of C++ front end trees to=