From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id BD79E385840C; Wed, 12 Jan 2022 16:58:40 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BD79E385840C
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/103991] [12 Regression] Bogus -Wreturn-type with constexpr
 if and local var with destructor
Date: Wed, 12 Jan 2022 16:58:40 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-103991-4-uOEGJW6iv9@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-103991-4@http.gcc.gnu.org/bugzilla/>
References: <bug-103991-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Wed, 12 Jan 2022 16:58:40 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103991

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For consteval if I guess we could do:
--- gcc/cp/cp-objcp-common.c.jj 2022-01-11 23:11:22.091294356 +0100
+++ gcc/cp/cp-objcp-common.c    2022-01-12 17:57:18.232202275 +0100
@@ -313,6 +313,13 @@ cxx_block_may_fallthru (const_tree stmt)
       return false;

     case IF_STMT:
+      if (IF_STMT_CONSTEXPR_P (stmt))
+       {
+         if (integer_nonzerop (IF_COND (stmt)))
+           return block_may_fallthru (THEN_CLAUSE (stmt));
+         if (integer_zerop (IF_COND (stmt)))
+           return block_may_fallthru (ELSE_CLAUSE (stmt));
+       }
       if (block_may_fallthru (THEN_CLAUSE (stmt)))
        return true;
       return block_may_fallthru (ELSE_CLAUSE (stmt));
--- gcc/cp/cp-gimplify.c.jj     2022-01-11 23:11:22.090294370 +0100
+++ gcc/cp/cp-gimplify.c        2022-01-12 17:53:57.431036236 +0100
@@ -166,8 +166,13 @@ genericize_if_stmt (tree *stmt_p)
      can contain unfolded immediate function calls, we have to discard
      the then_ block regardless of whether else_ has side-effects or not. =
 */
   if (IF_STMT_CONSTEVAL_P (stmt))
-    stmt =3D build3 (COND_EXPR, void_type_node, boolean_false_node,
-                  void_node, else_);
+    {
+      if (block_may_fallthru (then_))
+       stmt =3D build3 (COND_EXPR, void_type_node, boolean_false_node,
+                      void_node, else_);
+      else
+       stmt =3D else_;
+    }
   else
     stmt =3D build3 (COND_EXPR, void_type_node, cond, then_, else_);
   protected_set_expr_location_if_unset (stmt, locus);=