[Bug c++/85043] -Wuseless-cast false positive for temporary objects; add separate -Wcast-to-the-same-type to cover that case instead
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Oct 19 19:30:33 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85043
--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:
https://gcc.gnu.org/g:b3c98d6a59a6dcd5b0b52bd5676b586ef4fe785f
commit r13-3388-gb3c98d6a59a6dcd5b0b52bd5676b586ef4fe785f
Author: Marek Polacek <polacek@redhat.com>
Date: Tue Oct 18 12:20:14 2022 -0400
c++: Mitigate -Wuseless-cast with classes [PR85043]
-Wuseless-cast (not part of -Wall/-Wextra) warns here:
struct S { };
void g (S&&);
void f (S&& arg)
{
g (S(arg)); // warning: useless cast to type 'struct S'
}
which is wrong: the code will not compile without the cast because
"arg" is an lvalue which cannot bind to S&&.
This patch disables the warning when an object that isn't a prvalue
is cast to a non-reference type. Therefore we still warn about the
useless cast in "X(X{})".
PR c++/85043
gcc/cp/ChangeLog:
* typeck.cc (maybe_warn_about_useless_cast): Don't warn when
a glvalue is cast to a non-reference type.
gcc/ChangeLog:
* doc/invoke.texi: Update documentation of -Wuseless-cast.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wuseless-cast.C: Remove dg-warning.
* g++.dg/warn/Wuseless-cast3.C: New test.
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