https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101194
Bug ID: 101194
Summary: 7.2 Regression
Product: gcc
Version: 7.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: yannick.lepennec+gcc at live dot fr
Target Milestone: ---
Dear Maintainers,
Obligatory godbolt: https://godbolt.org/z/KnMnc7P57
Since GCC 7.2:
$ g++ -std=c++17 -Wall -Wextra -pedantic-errors
#include
struct nodefault {
nodefault(int) {}
};
int main() {
std::array arr1{ nodefault{1} }; // OK
std::array arr2{ arr1[0] }; // Error???
}
Gives:
main.cpp: In function 'int main()':
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:9:44: error: no matching function for call to 'nodefault::nodefault()'
std::array arr2{ arr1[0] }; // Error???
^
main.cpp:4:5: note: candidate: nodefault::nodefault(int)
nodefault(int) {}
^
main.cpp:4:5: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(const nodefault&)
struct nodefault {
^
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
main.cpp:3:8: note: candidate: constexpr nodefault::nodefault(nodefault&&)
main.cpp:3:8: note: candidate expects 1 argument, 0 provided
---
GCC 7.2 and above accept the same code with -std=c++14. GCC 7.1 accepts it with
either. The error message seems to have gotten shorter in more recent GCC, but
is still present. I have bisected this to
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=0634d9fe36e8ced1c6046759f9ce1d2655c8d731