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From: "zhaoweiliew at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/25689] missed diagnostic about assignment used as truth
 value.
Date: Wed, 09 Feb 2022 17:24:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D25689

--- Comment #3 from Zhao Wei Liew <zhaoweiliew at gmail dot com> ---
Created attachment 52395
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D52395&action=3Dedit
Test patch (seeking feedback)

Hi! I wrote a small patch to fix this issue, but I think that it has much r=
oom
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=3D(int);
  operator bool();
};

void f(A a, A b)
{
  if (a =3D 0); // GCC warns after patch (correct)
  if (a.operator=3D(0)) {} // GCC warns after patch (incorrect, but doesn't=
 sound
like a major issue)
  if (a =3D b) {} // GCC does not warn before & after patch (incorrect)
}

Specifically, there are 2 issues:
1. GCC warns for `if (a.operator=3D(0))`
2. GCC does not warn for `if (a =3D b)` where the default copy/move assignm=
ent
operator is used.

Thanks!=