[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870
Marek Polacek changed:
What|Removed |Added
Resolution|--- |FIXED
Status|ASSIGNED|RESOLVED
--- Comment #7 from Marek Polacek ---
commit d417b4f5414d9076300ab41974a14424f722688c
Author: Marek Polacek
Date: Fri Feb 28 16:57:04 2020 -0500
c++: Fix convert_like in template [PR91465, PR93870, PR92031, PR94068]
The point of this patch is to fix the recurring problem of trees
generated by convert_like while processing a template that break when
substituting. For instance, when convert_like creates a CALL_EXPR
while in a template, substituting such a call breaks in finish_call_expr
because we have two 'this' arguments. Another problem is that we
can create &TARGET_EXPR<> and then fail when substituting because we're
taking the address of an rvalue. I've analyzed some of the already fixed
PRs and also some of the currently open ones:
In c++/93870 we create EnumWrapper::operator E(&operator~(E)).
In c++/87145 we create S::operator int (&{N}).
In c++/92031 we create &TARGET_EXPR <0>.
The gist of the problem is when convert_like_real creates a call for
a ck_user or wraps a TARGET_EXPR in & in a template. So in these cases
use IMPLICIT_CONV_EXPR. In a template we shouldn't need to perform the
actual conversion, we only need it's result type.
perform_direct_initialization_if_possible and
perform_implicit_conversion_flags can also create an IMPLICIT_CONV_EXPR.
Given the change above, build_converted_constant_expr can return an
IMPLICIT_CONV_EXPR so call fold_non_dependent_expr rather than
maybe_constant_value to deal with that.
To avoid the problem of instantiating something twice in a row I'm
removing a call to instantiate_non_dependent_expr_sfinae in
compute_array_index_type_loc. And the build_converted_constant_expr
pattern can now be simplified.
2020-03-09 Marek Polacek
PR c++/92031 - bogus taking address of rvalue error.
PR c++/91465 - ICE with template codes in check_narrowing.
PR c++/93870 - wrong error when converting template non-type arg.
PR c++/94068 - ICE with template codes in check_narrowing.
* call.c (convert_like_real): Return IMPLICIT_CONV_EXPR
in a template when not ck_identity and we're dealing with a class.
(convert_like_real) : Return IMPLICIT_CONV_EXPR
in a template if we need a temporary.
* decl.c (compute_array_index_type_loc): Remove
instantiate_non_dependent_expr_sfinae call. Call
fold_non_dependent_expr instead of maybe_constant_value.
(build_explicit_specifier): Don't instantiate or create a sentinel
before converting the expression.
* except.c (build_noexcept_spec): Likewise.
* pt.c (convert_nontype_argument): Don't build IMPLICIT_CONV_EXPR.
Set IMPLICIT_CONV_EXPR_NONTYPE_ARG if that's what
build_converted_constant_expr returned.
* typeck2.c (check_narrowing): Call fold_non_dependent_expr instead
of maybe_constant_value.
* g++.dg/cpp0x/conv-tmpl2.C: New test.
* g++.dg/cpp0x/conv-tmpl3.C: New test.
* g++.dg/cpp0x/conv-tmpl4.C: New test.
* g++.dg/cpp0x/conv-tmpl5.C: New test.
* g++.dg/cpp0x/conv-tmpl6.C: New test.
* g++.dg/cpp1z/conv-tmpl1.C: New test.
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 Jakub Jelinek changed: What|Removed |Added Target Milestone|8.4 |8.5 --- Comment #6 from Jakub Jelinek --- GCC 8.4.0 has been released, adjusting target milestone.
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 Marek Polacek changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org --- Comment #5 from Marek Polacek --- Mine but it occurs to me I should get back to bug 91465 before attacking this one. This one might even be fixed for free by the previous one.
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 --- Comment #4 from Marek Polacek --- Actually perhaps we should create an IMPLICIT_CONV_EXPR for *any* value-dependent argument.
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870
--- Comment #3 from Marek Polacek ---
Completely untested:
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -7082,7 +7082,7 @@ convert_nontype_argument (tree type, tree expr,
tsubst_flags_t complain)
create a TARGET_EXPR, but in a template we can't
use AGGR_INIT_EXPR, and the TARGET_EXPR would lead
to a bogus error. */
- || (val_dep_p && MAYBE_CLASS_TYPE_P (type
+ || val_dep_p))
{
expr = build1 (IMPLICIT_CONV_EXPR, type, expr);
IMPLICIT_CONV_EXPR_NONTYPE_ARG (expr) = true;
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 Marek Polacek changed: What|Removed |Added Priority|P3 |P2
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 --- Comment #2 from Marek Polacek --- Clearly we're trying to take the address of a TARGET_EXPR: TARGET_EXPR That's bad and we've had PRs about this in the past, e.g. Bug 87145. I suspect the fix might be along the same lines.
[Bug c++/93870] [8/9/10 Regression] User-defined conversion function not working in evaluation of template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93870 Marek Polacek changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2020-02-27 CC||mpolacek at gcc dot gnu.org Target Milestone|--- |8.4 Summary|User-defined conversion |[8/9/10 Regression] |function not working in |User-defined conversion |evaluation of template |function not working in |argument|evaluation of template ||argument Ever confirmed|0 |1 --- Comment #1 from Marek Polacek --- Confirmed. Started with r7-4012-g16b61424dd309f61326f577a6deb8487c6c1f291.
