From 5bdd4c5d3fc9c143e8edea3b10828e4b75d7a385 Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Sun, 19 Apr 2020 12:12:01 -0400
Subject: [PATCH] c++: Fix bogus -Wparentheses warning with fold-expression
[PR94505]
We issue bogus -Wparentheses warnings (3 of them!) for this fold expression:
((B && true) || ...)
Firstly, issuing a warning for a compiler-generated expression is wrong
and secondly, B && true must be wrapped in ( ) otherwise you'll get
error: binary expression in operand of fold-expression.
PR c++/94505 - bogus -Wparentheses warning with fold-expression.
* pt.c (fold_expression): Add warning_sentinel for -Wparentheses
before calling build_x_binary_op.
* g++.dg/cpp1z/fold11.C: New test.
---
gcc/cp/ChangeLog | 6 ++++++
gcc/cp/pt.c | 1 +
gcc/testsuite/ChangeLog | 5 +++++
gcc/testsuite/g++.dg/cpp1z/fold11.C | 12 ++++++++++++
4 files changed, 24 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/fold11.C
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 891ec79fcfd2..52f199d90bf3 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-20 Marek Polacek <polacek@redhat.com>
+
+ PR c++/94505 - bogus -Wparentheses warning with fold-expression.
+ * pt.c (fold_expression): Add warning_sentinel for -Wparentheses
+ before calling build_x_binary_op.
+
2020-04-20 Marek Polacek <polacek@redhat.com>
* coroutines.cc (captures_temporary): Don't assign the result of
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 4f4c04e7df89..899df9a330cf 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -12379,6 +12379,7 @@ fold_expression (tree t, tree left, tree right, tsubst_flags_t complain)
if (FOLD_EXPR_MODIFY_P (t))
return build_x_modify_expr (input_location, left, code, right, complain);
+ warning_sentinel s(warn_parentheses);
switch (code)
{
case COMPOUND_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ce31ed0cd448..33f008b9af43 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-20 Marek Polacek <polacek@redhat.com>
+
+ PR c++/94505 - bogus -Wparentheses warning with fold-expression.
+ * g++.dg/cpp1z/fold11.C: New test.
+
2020-04-20 Andreas Krebbel <krebbel@linux.ibm.com>
* g++.dg/pr94666.C: New test.
diff --git a/gcc/testsuite/g++.dg/cpp1z/fold11.C b/gcc/testsuite/g++.dg/cpp1z/fold11.C
new file mode 100644
index 000000000000..09a30555eee7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/fold11.C
@@ -0,0 +1,12 @@
+// PR c++/94505 - bogus -Wparentheses warning with fold-expression.
+// { dg-do compile { target c++17 } }
+// { dg-options "-Wparentheses" }
+
+template <bool... B>
+bool foo () {
+ return ((B && true) || ...); // { dg-bogus "suggest parentheses" }
+}
+
+int main () {
+ foo<true, false, false, true> ();
+}
--
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