From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 8 Nov 2019 19:00:02 +0000 (+0100)
Subject: backport: re PR c++/92343 ([[likely]]/[[unlikely]] prevent method from being a consta... 
X-Git-Tag: releases/gcc-9.3.0~408
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1f3b59d4c6e375cb9941aa47258bb393dc38ea3a;p=thirdparty%2Fgcc.git

backport: re PR c++/92343 ([[likely]]/[[unlikely]] prevent method from being a constant expression)

	Backported from mainline
	2019-11-05  Jakub Jelinek  <jakub@redhat.com>

	PR c++/92343
	* constexpr.c (potential_constant_expression_1): Return true rather
	than false for PREDICT_EXPR.

	* g++.dg/cpp2a/attr-likely6.C: New test.

From-SVN: r277988
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 867b6e5b7f9b..c870d4a3817e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,6 +1,12 @@
 2019-11-08  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2019-11-05  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/92343
+	* constexpr.c (potential_constant_expression_1): Return true rather
+	than false for PREDICT_EXPR.
+
 	2019-10-31  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/90947
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 806a812304eb..9845416a8121 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -5925,6 +5925,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
     case LABEL_DECL:
     case LABEL_EXPR:
     case CASE_LABEL_EXPR:
+    case PREDICT_EXPR:
     case CONST_DECL:
     case SIZEOF_EXPR:
     case ALIGNOF_EXPR:
@@ -6759,7 +6760,6 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
 
     case CLEANUP_STMT:
     case EMPTY_CLASS_EXPR:
-    case PREDICT_EXPR:
       return false;
 
     case GOTO_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 161f91acf468..c3c660864bdf 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2019-11-08  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2019-11-05  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/92343
+	* g++.dg/cpp2a/attr-likely6.C: New test.
+
 	2019-10-31  Jakub Jelinek  <jakub@redhat.com>
 
 	PR preprocessor/92296
diff --git a/gcc/testsuite/g++.dg/cpp2a/attr-likely6.C b/gcc/testsuite/g++.dg/cpp2a/attr-likely6.C
new file mode 100644
index 000000000000..a04021e50375
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/attr-likely6.C
@@ -0,0 +1,14 @@
+// PR c++/92343
+// { dg-do compile { target c++14 } }
+
+constexpr bool
+foo (bool x)
+{
+  if (x)
+    [[unlikely]] return true;
+  else
+    [[likely]] return false;
+}
+
+static_assert (foo (true), "");
+static_assert (!foo (false), "");