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* [Bug c++/25689] missed diagnostic about assignment used as truth value.
[not found] <bug-25689-4@http.gcc.gnu.org/bugzilla/>
@ 2021-08-10 0:44 ` pinskia at gcc dot gnu.org
2022-02-09 17:24 ` zhaoweiliew at gmail dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-10 0:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25689
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2014-10-12 00:00:00 |2021-8-9
Severity|minor |enhancement
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25689] missed diagnostic about assignment used as truth value.
[not found] <bug-25689-4@http.gcc.gnu.org/bugzilla/>
2021-08-10 0:44 ` [Bug c++/25689] missed diagnostic about assignment used as truth value pinskia at gcc dot gnu.org
@ 2022-02-09 17:24 ` zhaoweiliew at gmail dot com
2022-04-29 2:59 ` cvs-commit at gcc dot gnu.org
2022-07-22 13:54 ` ppalka at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: zhaoweiliew at gmail dot com @ 2022-02-09 17:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25689
--- Comment #3 from Zhao Wei Liew <zhaoweiliew at gmail dot com> ---
Created attachment 52395
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52395&action=edit
Test patch (seeking feedback)
Hi! I wrote a small patch to fix this issue, but I think that it has much room
for improvement, though I'm not very sure how. Could anyone take a look and
give me feedback on how I could improve the patch?
Here's an example code snippet. I've commented the expected and actual
diagnostic results beside the lines of code.
struct A {
A& operator=(int);
operator bool();
};
void f(A a, A b)
{
if (a = 0); // GCC warns after patch (correct)
if (a.operator=(0)) {} // GCC warns after patch (incorrect, but doesn't sound
like a major issue)
if (a = b) {} // GCC does not warn before & after patch (incorrect)
}
Specifically, there are 2 issues:
1. GCC warns for `if (a.operator=(0))`
2. GCC does not warn for `if (a = b)` where the default copy/move assignment
operator is used.
Thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25689] missed diagnostic about assignment used as truth value.
[not found] <bug-25689-4@http.gcc.gnu.org/bugzilla/>
2021-08-10 0:44 ` [Bug c++/25689] missed diagnostic about assignment used as truth value pinskia at gcc dot gnu.org
2022-02-09 17:24 ` zhaoweiliew at gmail dot com
@ 2022-04-29 2:59 ` cvs-commit at gcc dot gnu.org
2022-07-22 13:54 ` ppalka at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-04-29 2:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25689
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:
https://gcc.gnu.org/g:654f6978cdc85a3970ff2c478d4df3e55cf4d3ab
commit r13-23-g654f6978cdc85a3970ff2c478d4df3e55cf4d3ab
Author: Zhao Wei Liew <zhaoweiliew@gmail.com>
Date: Tue Feb 15 17:44:29 2022 +0800
c++: Add diagnostic when operator= is used as truth cond [PR25689]
When compiling the following code with g++ -Wparentheses, GCC does not
warn on the if statement. For example, there is no warning for this code:
struct A {
A& operator=(int);
operator bool();
};
void f(A a) {
if (a = 0); // no warning
}
This is because a = 0 is a call to operator=, which GCC does not handle.
This patch fixes this issue by handling calls to operator= when deciding
to warn.
Bootstrapped and regression tested on x86_64-pc-linux-gnu.
PR c++/25689
gcc/cp/ChangeLog:
* call.cc (extract_call_expr): Return a NULL_TREE on failure
instead of asserting.
(build_new_method_call): Suppress -Wparentheses diagnostic for
MODIFY_EXPR.
* semantics.cc (is_assignment_op_expr_p): Add function to check
if an expression is a call to an op= operator expression.
(maybe_convert_cond): Handle the case of a op= operator expression
for the -Wparentheses diagnostic.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wparentheses-31.C: New test.
Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25689] missed diagnostic about assignment used as truth value.
[not found] <bug-25689-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2022-04-29 2:59 ` cvs-commit at gcc dot gnu.org
@ 2022-07-22 13:54 ` ppalka at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: ppalka at gcc dot gnu.org @ 2022-07-22 13:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25689
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ppalka at gcc dot gnu.org
Status|NEW |RESOLVED
Target Milestone|--- |13.0
Resolution|--- |FIXED
--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 13 I think?
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25689] New: missed diagnostic about assignment used as truth value.
@ 2006-01-06 9:45 pluto at agmk dot net
2006-01-06 12:32 ` [Bug c++/25689] " pinskia at gcc dot gnu dot org
0 siblings, 1 reply; 5+ messages in thread
From: pluto at agmk dot net @ 2006-01-06 9:45 UTC (permalink / raw)
To: gcc-bugs
[ foo.cpp ]
struct Var {
operator int() const;
Var& operator = (int);
bool operator == (int);
};
bool operator == (int, Var&);
void foo(Var var)
{
if (var = 0); // if (var.operator=(0))
}
[ foo.cpp.t03.gimple ]
void foo(Var) (var)
{
bool retval.0;
struct Var & D.1768;
int D.1769;
D.1768 = operator= (&var, 0);
D.1769 = operator 1 (D.1768);
retval.0 = D.1769 != 0;
}
--
Summary: missed diagnostic about assignment used as truth value.
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pluto at agmk dot net
GCC build triplet: i686-pld-linux
GCC host triplet: i686-pld-linux
GCC target triplet: i686-pld-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25689
^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <bug-25689-4@http.gcc.gnu.org/bugzilla/>
2021-08-10 0:44 ` [Bug c++/25689] missed diagnostic about assignment used as truth value pinskia at gcc dot gnu.org
2022-02-09 17:24 ` zhaoweiliew at gmail dot com
2022-04-29 2:59 ` cvs-commit at gcc dot gnu.org
2022-07-22 13:54 ` ppalka at gcc dot gnu.org
2006-01-06 9:45 [Bug c++/25689] New: " pluto at agmk dot net
2006-01-06 12:32 ` [Bug c++/25689] " pinskia at gcc dot gnu dot org
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