From 6d1556ecfae3eff010ef7dc15f3da998403fa196 Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Sat, 23 May 2020 14:39:28 -0400
Subject: [PATCH] c++: Avoid concept evaluation when uid-sensitive [PR94038]
Concept evaluation may entail DECL_UID generation and/or template
instantiation, so in general we can't perform it during uid-sensitive
constexpr evaluation.
gcc/cp/ChangeLog:
PR c++/94038
* constexpr.c (cxx_eval_constant_expression)
<case TEMPLATE_ID_EXPR>: Don't evaluate the concept when
constexpr evaluation is uid-sensitive.
gcc/testsuite/ChangeLog:
PR c++/94038
* g++.dg/warn/pr94038-3.C: New test.
---
gcc/cp/ChangeLog | 7 +++++++
gcc/cp/constexpr.c | 3 ++-
gcc/testsuite/ChangeLog | 5 +++++
gcc/testsuite/g++.dg/warn/pr94038-3.C | 15 +++++++++++++++
4 files changed, 29 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/warn/pr94038-3.C
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 385bfcd72db4..2feeb12bcb02 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-23 Patrick Palka <ppalka@redhat.com>
+
+ PR c++/94038
+ * constexpr.c (cxx_eval_constant_expression)
+ <case TEMPLATE_ID_EXPR>: Don't evaluate the concept when
+ constexpr evaluation is uid-sensitive.
+
2020-05-21 Patrick Palka <ppalka@redhat.com>
PR c++/94038
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 98c974e657f6..4e441ac8d2fa 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -6486,7 +6486,8 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
break;
}
- if (!processing_template_decl)
+ if (!processing_template_decl
+ && !uid_sensitive_constexpr_evaluation_p ())
r = evaluate_concept_check (t, tf_warning_or_error);
else
*non_constant_p = true;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9711a27e29c0..80fd33dac18d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-23 Patrick Palka <ppalka@redhat.com>
+
+ PR c++/94038
+ * g++.dg/warn/pr94038-3.C: New test.
+
2020-05-22 Mark Wielaard <mark@klomp.org>
* gcc.dg/spellcheck-stdint.c: New test.
diff --git a/gcc/testsuite/g++.dg/warn/pr94038-3.C b/gcc/testsuite/g++.dg/warn/pr94038-3.C
new file mode 100644
index 000000000000..49b6d133f085
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/pr94038-3.C
@@ -0,0 +1,15 @@
+// PR c++/94038
+// { dg-do compile { target c++20 } }
+// { dg-additional-options "-Wall" }
+
+template<typename T>
+constexpr int foo() {
+ return T::x;
+}
+
+constexpr bool bar(bool a) { return a; }
+
+template<typename T>
+concept C = foo<T>() == 0;
+
+static_assert(decltype(bar(C<int>)){} == false);
--
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