From: Marek Polacek <polacek@redhat.com>
To: Jason Merrill <jason@redhat.com>, GCC Patches <gcc-patches@gcc.gnu.org>
Subject: [PATCH] c++: Quash bogus -Wunused-value with new [PR107797]
Date: Thu, 19 Jan 2023 21:03:39 -0500 [thread overview]
Message-ID: <20230120020339.1025075-1-polacek@redhat.com> (raw)
We shouldn't emit "right operand of comma operator has no effect"
when that comma operator was created by the compiler for "new int{}".
convert_to_void/COMPOUND_EXPR already checks warning_suppressed_p so
we can just suppress -Wunused-value.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
PR c++/107797
gcc/cp/ChangeLog:
* cvt.cc (ocp_convert): copy_warning when creating a new
COMPOUND_EXPR.
* init.cc (build_new_1): Suppress -Wunused-value on
compiler-generated COMPOUND_EXPRs.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wunused-value-1.C: New test.
---
gcc/cp/cvt.cc | 6 ++++--
gcc/cp/init.cc | 2 ++
gcc/testsuite/g++.dg/warn/Wunused-value-1.C | 12 ++++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wunused-value-1.C
diff --git a/gcc/cp/cvt.cc b/gcc/cp/cvt.cc
index 0cbfd8060cb..17827d06a4a 100644
--- a/gcc/cp/cvt.cc
+++ b/gcc/cp/cvt.cc
@@ -711,8 +711,10 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
return error_mark_node;
if (e == TREE_OPERAND (expr, 1))
return expr;
- return build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (e),
- TREE_OPERAND (expr, 0), e);
+ e = build2_loc (EXPR_LOCATION (expr), COMPOUND_EXPR, TREE_TYPE (e),
+ TREE_OPERAND (expr, 0), e);
+ copy_warning (e, expr);
+ return e;
}
complete_type (type);
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index f816c474cef..52e96fbe590 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -3800,6 +3800,8 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
if (cookie_expr)
rval = build2 (COMPOUND_EXPR, TREE_TYPE (rval), cookie_expr, rval);
+ suppress_warning (rval, OPT_Wunused_value);
+
if (rval == data_addr && TREE_CODE (alloc_expr) == TARGET_EXPR)
/* If we don't have an initializer or a cookie, strip the TARGET_EXPR
and return the call (which doesn't need to be adjusted). */
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-value-1.C b/gcc/testsuite/g++.dg/warn/Wunused-value-1.C
new file mode 100644
index 00000000000..2ba5587fce0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-value-1.C
@@ -0,0 +1,12 @@
+// PR c++/107797
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused" }
+
+void
+g ()
+{
+ (long) new int{};
+ long(new int{});
+ (long) new int();
+ long(new int());
+}
base-commit: 86caab6c5d1e26e1c54c3dceacc873d6e27bfc09
--
2.39.0
next reply other threads:[~2023-01-20 2:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 2:03 Marek Polacek [this message]
2023-01-20 19:37 ` Jason Merrill
2023-01-23 21:28 ` Marek Polacek
2023-01-23 21:34 ` Jason Merrill
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230120020339.1025075-1-polacek@redhat.com \
--to=polacek@redhat.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jason@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).