From 39d989022dd0eacf1a7b95b7b20621acbe717d70 Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Mon, 12 Feb 2024 14:53:24 -0500
Subject: [PATCH] c++: ICE with reinterpret_cast and switch [PR113545]
Jason, this is the patch you proposed for PR113545. It looks very safe
so I'm posting it here so that it's not forgotten.
PR c++/113545
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_switch_expr): If the condition doesn't reduce
to an INTEGER_CST, consider it non-constant.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-reinterpret3.C: Remove dg-ice.
---
gcc/cp/constexpr.cc | 10 ++++++++++
gcc/testsuite/g++.dg/cpp1y/constexpr-reinterpret3.C | 4 +---
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 2ebb1470dd5e..fa346fe01c9c 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -7106,6 +7106,16 @@ cxx_eval_switch_expr (const constexpr_ctx *ctx, tree t,
cond = cxx_eval_constant_expression (ctx, cond, vc_prvalue,
non_constant_p, overflow_p);
VERIFY_CONSTANT (cond);
+ if (TREE_CODE (cond) != INTEGER_CST)
+ {
+ /* If the condition doesn't reduce to an INTEGER_CST it isn't a usable
+ switch condition even if it's constant enough for other things
+ (c++/113545). */
+ gcc_checking_assert (ctx->quiet);
+ *non_constant_p = true;
+ return t;
+ }
+
*jump_target = cond;
tree body
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-reinterpret3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-reinterpret3.C
index 51feb2e558e7..adc0b418df91 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-reinterpret3.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-reinterpret3.C
@@ -1,7 +1,5 @@
// PR c++/113545
-// { dg-do compile { target c++14 } }
-// Please change the above "dg-do compile" to "dg-do run" when the ICE is resolved.
-// { dg-ice "PR112545 - constexpr function with switch called for reinterpret_cast" }
+// { dg-do run { target c++14 } }
char foo;
--
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