https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116306
Bug ID: 116306
Summary: Compiler halts during negative case in requires
statement when defining concept (unpacking variadic
arguments)
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rekerner at gmail dot com
Target Milestone: ---
When defining a concept to constrain volatile-qualified member functions, the
concept fails with an error in the negative case only. Investigating, the
situation occurs when a tuple representing the arguments list is unpacked and
passed to a lambda through the std::apply function.
I believe the error may be related to the compiler and not to the library.
(https://godbolt.org/z/MWT3Mbvjx)
I reviewed the bug list and did not find an existing occurrence of this issue.
---------------------------------------------------------------------------------
template <typename F>
concept Volatile = requires (F mf, Args<F> a){
std::apply([a](auto ... arg){
using C = ClassType<F>;
volatile C c;
F f;
(c.*f)(arg...);
},a);
};
Output:
---------------------------------------------------------------------------------
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)
COLLECT_GCC_OPTIONS='-Wall' '-Wextra' '-v' '-save-temps' '-std=c++20'
'-mtune=generic' '-march=x86-64' '-dumpdir' 'a-'
/usr/lib/gcc/x86_64-linux-gnu/11/cc1plus -E -quiet -v -imultiarch
x86_64-linux-gnu -D_GNU_SOURCE save.cpp -mtune=generic -march=x86-64 -std=c++20
-Wall -Wextra -fpch-preprocess -fasynchronous-unwind-tables
-fstack-protector-strong -Wformat-security -fstack-clash-protection
-fcf-protection -o a-save.ii
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/11"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/11
/usr/include/x86_64-linux-gnu/c++/11
/usr/include/c++/11/backward
/usr/lib/gcc/x86_64-linux-gnu/11/include
/usr/local/include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-Wall' '-Wextra' '-v' '-save-temps' '-std=c++20'
'-mtune=generic' '-march=x86-64' '-dumpdir' 'a-'
/usr/lib/gcc/x86_64-linux-gnu/11/cc1plus -fpreprocessed a-save.ii -quiet
-dumpdir a- -dumpbase save.cpp -dumpbase-ext .cpp -mtune=generic -march=x86-64
-Wall -Wextra -std=c++20 -version -fasynchronous-unwind-tables
-fstack-protector-strong -Wformat-security -fstack-clash-protection
-fcf-protection -o a-save.s
GNU C++20 (Ubuntu 11.4.0-1ubuntu1~22.04) version 11.4.0 (x86_64-linux-gnu)
compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++20 (Ubuntu 11.4.0-1ubuntu1~22.04) version 11.4.0 (x86_64-linux-gnu)
compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: d591828bb4d392ae8b7b160e5bb0b95f
save.cpp: In instantiation of '<lambda(auto:11 ...)> [with auto:11 = {int,
float}]':
/usr/include/c++/11/type_traits:2530:26: required by substitution of
'template<class _Fn, class ... _Args> static std::__result_of_success<decltype
(declval<_Fn>()((declval<_Args>)()...)), std::__invoke_other>
std::__result_of_other_impl::_S_test(int) [with _Fn = <lambda(auto:11 ...)>;
_Args = {int&, float&}]'
/usr/include/c++/11/type_traits:2541:55: required from 'struct
std::__result_of_impl<false, false, <lambda(auto:11 ...)>, int&, float&>'
/usr/include/c++/11/type_traits:152:12: recursively required by substitution
of 'template<class _Result, class _Ret> struct
std::__is_invocable_impl<_Result, _Ret, true, std::__void_t<typename
_CTp::type> > [with _Result = std::__invoke_result<<lambda(auto:11 ...)>, int&,
float&>; _Ret = void]'
/usr/include/c++/11/type_traits:152:12: required from 'struct
std::__and_<std::__is_invocable_impl<std::__invoke_result<<lambda(auto:11
...)>, int&, float&>, void, true, void>,
std::__call_is_nothrow<std::__invoke_result<<lambda(auto:11 ...)>, int&,
float&>, <lambda(auto:11 ...)>, int&, float&> >'
/usr/include/c++/11/type_traits:3046:12: required from 'struct
std::is_nothrow_invocable<<lambda(auto:11 ...)>, int&, float&>'
/usr/include/c++/11/tuple:1838:31: required from 'constexpr const bool
std::__unpack_std_tuple<template<class _Fn, class ... _ArgTypes> struct
std::is_nothrow_invocable, <lambda(auto:11 ...)>, std::tuple<int, float>&>'
/usr/include/c++/11/tuple:1861:14: required from 'constexpr decltype(auto)
std::apply(_Fn&&, _Tuple&&) [with _Fn = <lambda(auto:11 ...)>; _Tuple =
std::tuple<int, float>&]'
save.cpp:26:19: required by substitution of 'template<class F> requires
!(Volatile<F>) void checkIfVolatile() [with F = void (Bar<int, float>::*)(int,
float)]'
save.cpp:48:65: required from here
save.cpp:29:13: error: invalid conversion from 'volatile C*' {aka 'volatile
Bar<int, float>*'} to 'Bar<int, float>*' [-fpermissive]
29 | (c.*f)(arg...);
| ^
| |
| volatile C* {aka volatile Bar<int, float>*}
