[Bug c++/82247] New: [concepts] Name deduction in concepts fails depending on the argument type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247
Bug ID: 82247
Summary: [concepts] Name deduction in concepts fails depending
on the argument type
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mjklaim at gmail dot com
Target Milestone: ---
~~
#include
#include
template
bool concept Fooable = requires(const T& t) {
{ foo(t) }; // foo is unknown here
};
template
void foo(T&& t) {
}
template
void bar(T&& t)
{
}
class K
{
int x = 0;
};
class WTF
{
std::vector values;
};
int main() {
// int i{}; // FAIL
// K i; // SUCCEED
// float i; // FAIL
// std::string i; // FAIL?
// std::vector i; // FAIL?
// auto i =[]{}; // SUCCEED
// int i[42]; // FAIL
// int* i = nullptr;
WTF i; // SUCCEED HAHAHAHA
bar(i);
}~
~
All these lines should have succeded, but only using the custom types worked.
I have no idea what is wrong here but it seem that even for int, the deduction
of the foo function is not done at the right time.
[Bug c++/82247] [concepts] Name deduction in concepts fails depending on the argument type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247 --- Comment #1 from Joël Lamotte --- Just so that it's clear, it's on godbolt's compiler that I tried this: https://godbolt.org/g/d78J4H
[Bug c++/82247] [concepts] Name deduction in concepts fails depending on the argument type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247 --- Comment #3 from Joël Lamotte --- Sorry, I though you would see the flaga in the llink to godbolt I provided: --std=c++17 -fconcepts -O3 The code I provided in the report do compile, the problem is explained through the comments that if uncommented will not compile. All these lines, when uncommented exclusively, Should all compile.
[Bug c++/82247] [concepts] Name deduction in concepts fails depending on the argument type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247 --- Comment #5 from Joël Lamotte --- I'll have to recheck when I have access to a proper computer, but that indeed would explain this(weird) behavior. My understanding was that for basic types, ADL would still work using global namespace, which is why I didn't expect the int case to fail.
[Bug c++/82247] [concepts] Name deduction in concepts fails depending on the argument type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247 Joël Lamotte changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #6 from Joël Lamotte --- I confirm that the code is valid and my understanding of part of two-phase lookup mislead me to not understand why these lines fails compiling.
[Bug c++/67491] [meta-bug] concepts issues
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67491 Bug 67491 depends on bug 82247, which changed state. Bug 82247 Summary: [concepts] Name deduction in concepts fails depending on the argument type https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82247 What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID
