[Bug c++/106276] Missing -Wpessimizing-move warning
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Aug 17 16:38:35 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106276
--- Comment #8 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:8d22c7cb8b1a6f9b67c54a798dd5504244614e51
commit r13-2095-g8d22c7cb8b1a6f9b67c54a798dd5504244614e51
Author: Marek Polacek <polacek@redhat.com>
Date: Mon Aug 1 17:02:23 2022 -0400
c++: Extend -Wpessimizing-move to other contexts
In my recent patch which enhanced -Wpessimizing-move so that it warns
about class prvalues too I said that I'd like to extend it so that it
warns in more contexts where a std::move can prevent copy elision, such
as:
T t = std::move(T());
T t(std::move(T()));
T t{std::move(T())};
T t = {std::move(T())};
void foo (T);
foo (std::move(T()));
This patch does that by adding two maybe_warn_pessimizing_move calls.
These must happen before we've converted the initializers otherwise the
std::move will be buried in a TARGET_EXPR.
PR c++/106276
gcc/cp/ChangeLog:
* call.cc (build_over_call): Call maybe_warn_pessimizing_move.
* cp-tree.h (maybe_warn_pessimizing_move): Declare.
* decl.cc (build_aggr_init_full_exprs): Call
maybe_warn_pessimizing_move.
* typeck.cc (maybe_warn_pessimizing_move): Handle TREE_LIST and
CONSTRUCTOR. Add a bool parameter and use it. Adjust a diagnostic
message.
(check_return_expr): Adjust the call to
maybe_warn_pessimizing_move.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/Wpessimizing-move7.C: Add dg-warning.
* g++.dg/cpp0x/Wpessimizing-move8.C: New test.
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