https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99846
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jason at gcc dot gnu.org
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Preprocessing the attached testcase with GCC 10 (using -std=c++20) and
compiling with GCC 11 shows the error. Possibly a compiler bug (or invalid
code in the library, which gcc 10 doesn't complain about).
It started to fail on trunk with r11-2774
c++: Check satisfaction before non-dep convs. [CWG2369]
It's very hard to use concepts to protect a template from hard errors due
to
unwanted instantiation if constraints aren't checked until after doing all
substitution and checking of non-dependent conversions.
It was pretty straightforward to insert the satisfaction check into the
logic, but I needed to make the 3-parameter version of
satisfy_declaration_constraints call push_tinst_level like the 2-parameter
version already does. For simplicity, I also made it add any needed outer
template arguments from the TEMPLATE_DECL to the args.
The testsuite changes are mostly because this change causes unsatisfaction
to cause deduction to fail rather than reject the candidate later in
overload resolution.
gcc/cp/ChangeLog:
DR 2369
* cp-tree.h (push_tinst_level, push_tinst_level_loc): Declare.
* constraint.cc (satisfy_declaration_constraints):
Use add_outermost_template_args and push_tinst_level.
* pt.c (add_outermost_template_args): Handle getting
a TEMPLATE_DECL as the first argument.
(push_tinst_level, push_tinst_level_loc): No longer static.
(fn_type_unification): Check satisfaction before non-dependent
conversions.
