https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110441
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2023-06-28
CC| |jason at gcc dot gnu.org,
| |ppalka at gcc dot gnu.org
--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed, this never worked. The problem seems to be that because f is
static, 'S().f()' is represented as a COMPOUND_EXPR that evaluates the
otherwise unused object argument S() followed by a TARGET_EXPR for S::f(). And
this COMPOUND_EXPR foils the copy elision check in build_special_member_call
which looks only for an outermost TARGET_EXPR and doesn't look through
COMPOUND_EXPR.
In contrast, '(S(), S::f())' (which should be equivalent) is represented as a
TARGET_EXPR of a COMPOUND_EXPR rather than a COMPOUND_EXPR of a TARGET_EXPR,
and so copy elision is correctly avoided. So perhaps we could make
keep_unused_object_arg for a TARGET_EXPR result place the COMPOUND_EXPR inside
the TARGET_EXPR_INITIAL instead of around the TARGET_EXPR?
