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* [Bug c++/105518] New: [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias
@ 2022-05-07 15:21 leventyilmaz at gmail dot com
2022-11-01 23:02 ` [Bug c++/105518] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: leventyilmaz at gmail dot com @ 2022-05-07 15:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105518
Bug ID: 105518
Summary: [rejects valid] nested lambda using an outer type
alias fails with constexpr integer in that alias
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: leventyilmaz at gmail dot com
Target Milestone: ---
The following valid code is fails to compile.
https://godbolt.org/z/v1sd9snGx
// Simple run-time to compile-time integer conversion:
template<class F>
auto toStatic(int i, F f) {
switch(i) {
case 0: return f( std::integral_constant<int, 0>{} );
case 1: return f( std::integral_constant<int, 1>{} );
case 2: return f( std::integral_constant<int, 2>{} );
default: assert("too big");
}
}
// example types:
struct Base {
virtual void show() const = 0;
};
template <size_t I> struct F {
template <size_t J> struct K : Base {
void show() const override {
std::cout << I << " " << J << std::endl;
}
};
};
// nested lambda complains "I" is not captured
// even though it is only being used at compile-time
void show(int i, int j) {
return toStatic(i, [j](auto I) {
using A = F<I>;
// using A = F<decltype(I)::value>; // this works
return toStatic(j, [](auto J) {
using impl = typename A::template K<J>;
impl{}.show();
});
});
}
source>:32:19: error: 'I' is not captured
32 | using impl = typename A::template K<J>;
| ^~~~
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105518] [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias
2022-05-07 15:21 [Bug c++/105518] New: [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias leventyilmaz at gmail dot com
@ 2022-11-01 23:02 ` pinskia at gcc dot gnu.org
2022-12-15 20:54 ` cvs-commit at gcc dot gnu.org
2022-12-15 20:56 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-11-01 23:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105518
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 53819
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53819&action=edit
full testcase
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105518] [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias
2022-05-07 15:21 [Bug c++/105518] New: [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias leventyilmaz at gmail dot com
2022-11-01 23:02 ` [Bug c++/105518] " pinskia at gcc dot gnu.org
@ 2022-12-15 20:54 ` cvs-commit at gcc dot gnu.org
2022-12-15 20:56 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-12-15 20:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105518
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:be124477b38a71ba8ba0b24d859ae764bb44a4eb
commit r13-4729-gbe124477b38a71ba8ba0b24d859ae764bb44a4eb
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu Dec 15 15:54:31 2022 -0500
c++: local alias in typename in lambda [PR105518]
We substitute the qualifying scope of a TYPENAME_TYPE directly using
tsubst_aggr_type (so that we can pass entering_scope=true) instead of
going through tsubst, which means we don't properly reuse typedefs
during this substitution. This ends up causing us to reject the below
testcase because we substitute the TYPENAME_TYPE alias::type as if it
were written without the A<t> alias, and thus we expect the non-capturing
lambda to capture t.
This patch fixes this by making tsubst_aggr_type delegate typedefs
to tsubst so that get consistently reused, and then adjusting the result
appropriately if entering_scope is true. In passing, this refactors
tsubst_aggr_type into two functions, one that's intended to be called
directly and a more minimal one that's intended to be called only from
the RECORD/UNION/ENUMERAL_TYPE cases of tsubst (and contains only the
necessary bits for that call site).
PR c++/105518
gcc/cp/ChangeLog:
* pt.cc (tsubst_aggr_type): Handle typedefs by delegating to
tsubst and adjusting the result if entering_scope. Split out
the main part of the function into ...
(tsubst_aggr_type_1) ... here.
(tsubst): Use tsubst_aggr_type_1 instead of tsubst_aggr_type.
Handle TYPE_PTRMEMFUNC_P RECORD_TYPEs here instead of in
tsubst_aggr_type_1.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/lambda/lambda-alias1.C: New test.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105518] [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias
2022-05-07 15:21 [Bug c++/105518] New: [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias leventyilmaz at gmail dot com
2022-11-01 23:02 ` [Bug c++/105518] " pinskia at gcc dot gnu.org
2022-12-15 20:54 ` cvs-commit at gcc dot gnu.org
@ 2022-12-15 20:56 ` ppalka at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: ppalka at gcc dot gnu.org @ 2022-12-15 20:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105518
Patrick Palka <ppalka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |13.0
Resolution|--- |FIXED
Assignee|unassigned at gcc dot gnu.org |ppalka at gcc dot gnu.org
Status|UNCONFIRMED |RESOLVED
CC| |ppalka at gcc dot gnu.org
--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 13, thanks for the bug report.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-05-07 15:21 [Bug c++/105518] New: [rejects valid] nested lambda using an outer type alias fails with constexpr integer in that alias leventyilmaz at gmail dot com
2022-11-01 23:02 ` [Bug c++/105518] " pinskia at gcc dot gnu.org
2022-12-15 20:54 ` cvs-commit at gcc dot gnu.org
2022-12-15 20:56 ` ppalka at gcc dot gnu.org
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