[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 Marek Polacek changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #9 from Marek Polacek --- Unfortunately backporting is proving to be difficult. nontype-class28.C ICEs without r273597. That was backported to 9 in r273597, but the build_converted_constant_expr_internal bit is different. Tweaking GCC 9 so that it doesn't copy a class in a template breaks everything. I'm too nervous about messing with that now. So closing.
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 --- Comment #8 from Marek Polacek --- Fixed on trunk so far, will backport to 9 sometime soon.
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948
--- Comment #7 from CVS Commits ---
The master branch has been updated by Marek Polacek :
https://gcc.gnu.org/g:423284053ec51832bc4c823fb90dc41e632e37ac
commit r10-6329-g423284053ec51832bc4c823fb90dc41e632e37ac
Author: Marek Polacek
Date: Tue Jan 28 17:44:21 2020 -0500
c++: Fix class NTTP with template arguments [PR92948]
This PR points out an ICE with an alias template and class NTTP, but I
found that there are more issues. Trouble arise when we use a
(non-type) template parameter as an argument to the template arg list of
a template that accepts a class NTTP and a conversion to a class is
involved, e.g.
struct A { A(int) { } };
template struct B { };
template void fn () {
B b;
}
Normally for such a conversion we create a TARGET_EXPR with an
AGGR_INIT_EXPR that calls a __ct_comp with some arguments, but not in
this case: when converting X to type A in convert_nontype_argument we
are in a template and the template parameter 'X' is value-dependent, and
AGGR_INIT_EXPR don't work in templates. So it just creates a TARGET_EXPR
that contains "A::A(*this, X)", but with that overload resolution fails:
error: no matching function for call to 'A::A(A*, int)'
That happens because finish_call_expr for a BASELINK creates a dummy
object, so we have 'this' twice. I thought for the value-dependent case
we could use IMPLICIT_CONV_EXPR, as in the patch below. Note that I
only do this when we convert to a different type than the type of the
expr. The point is to avoid the call to a converting ctor.
The second issue was an ICE in tsubst_copy: when there's a conversion
like the above involved then
/* Wrapper to make a C++20 template parameter object const. */
op = tsubst_copy (op, args, complain, in_decl);
might not produce a _ZT... VAR_DECL with const type, so the assert
gcc_assert (CP_TYPE_CONST_P (TREE_TYPE (op)));
fails. Allowing IMPLICIT_CONV_EXPR there probably makes sense.
And since convert_nontype_argument uses value_dependent_expression_p
a lot, I used a dedicated bool to speed things up.
2020-01-29 Marek Polacek
PR c++/92948 - Fix class NTTP with template arguments.
* pt.c (convert_nontype_argument): Use IMPLICIT_CONV_EXPR when
converting a value-dependent expression to a class type.
(tsubst_copy) : Allow IMPLICIT_CONV_EXPR
as the result of the tsubst_copy call.
* g++.dg/cpp2a/nontype-class28.C: New test.
* g++.dg/cpp2a/nontype-class29.C: New test.
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 Marek Polacek changed: What|Removed |Added Keywords||ice-on-valid-code, patch, ||rejects-valid --- Comment #6 from Marek Polacek --- Now posted https://gcc.gnu.org/ml/gcc-patches/2020-01/msg01896.html
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 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 --- I have a patch that fixes these two issues (it uses IMPLICIT_CONV_EXPR).
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948
--- Comment #4 from Marek Polacek ---
A related test that I think should compile:
struct A {
constexpr A(int) { }
};
template
struct B {
};
template
void foo()
{
B b; // works with B<1>
}
void
fn ()
{
foo<1>();
}
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948
--- Comment #3 from Marek Polacek ---
Test I've been playing with:
struct A {
constexpr A(int) { }
};
template
struct B {
using U = unsigned;
};
template
using U = B;
//template::U> // ok
template::U> // ICE
//template::U> // error
void foo()
{
}
void
g ()
{
foo<1>();
}
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 --- Comment #2 from Marek Polacek --- Because of the alias template build_converted_constant_expr produces a TARGET_EXPR containing a TEMPLATE_PARM_INDEX which makes it value-dependent. So we don't call get_template_parm_object here 7449 /* Replace the argument with a reference to the corresponding template 7450 parameter object. */ 7451 if (!value_dependent_expression_p (expr)) 7452 expr = get_template_parm_object (expr, complain); we crash in pt.c: 16396 /* Wrapper to make a C++20 template parameter object const. */ 16397 op = tsubst_copy (op, args, complain, in_decl); ... 16405 gcc_assert (CP_TYPE_CONST_P (TREE_TYPE (op))); because tsubst_copy didn't turn op into one of those _ZT... VAR_DECLs. Poking more.
[Bug c++/92948] internal compiler error: in tsubst_copy, at cp/pt.c:15788
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92948 Marek Polacek changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2019-12-16 CC||mpolacek at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Marek Polacek --- This tsubst_copy ICE started with r267108 but before that we had another ICE: 92948.C:13:21: internal compiler error: in cxx_eval_constant_expression, at cp/constexpr.c:4594 13 | using Bbb = Bbb_; | ^ 0x8982d3 cxx_eval_constant_expression ../../gcc/cp/constexpr.c:4594 0x88b4a5 cxx_eval_call_expression ../../gcc/cp/constexpr.c:1508 0x8970c9 cxx_eval_constant_expression ../../gcc/cp/constexpr.c:4288 0x899db8 cxx_eval_outermost_constant_expr ../../gcc/cp/constexpr.c:5023 0x89a62d cxx_constant_value(tree_node*, tree_node*) ../../gcc/cp/constexpr.c:5144 0xa5be7a get_template_parm_object ../../gcc/cp/pt.c:6726 0xa5dab7 convert_nontype_argument ../../gcc/cp/pt.c:7187 0xa60ec2 convert_template_argument ../../gcc/cp/pt.c:8094 0xa62aa2 coerce_template_parms ../../gcc/cp/pt.c:8574 0xa631ac coerce_innermost_template_parms ../../gcc/cp/pt.c:8695 0xa65769 lookup_template_class_1 ../../gcc/cp/pt.c:9392 0xa67db7 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*, int, int) ../../gcc/cp/pt.c:9751 0xae8a49 finish_template_type(tree_node*, tree_node*, int) ../../gcc/cp/semantics.c:3257 0x9fabe3 cp_parser_template_id ../../gcc/cp/parser.c:16103 0xa0773f cp_parser_class_name ../../gcc/cp/parser.c:22660 0x9e74f8 cp_parser_qualifying_entity ../../gcc/cp/parser.c:6638 0x9e6598 cp_parser_nested_name_specifier_opt ../../gcc/cp/parser.c:6324 0x9fd271 cp_parser_simple_type_specifier ../../gcc/cp/parser.c:17442 0x9fc7bb cp_parser_type_specifier ../../gcc/cp/parser.c:17115 0xa05143 cp_parser_type_specifier_seq ../../gcc/cp/parser.c:21404 the second ICE started with Implement P0732R2, class types in non-type template parameters. / r265789, before that the test was rejected. So confirmed, though it may be a dup too.
