[Bug c++/94765] New: Floating point type template parameter
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94765
Bug ID: 94765
Summary: Floating point type template parameter
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: emmanuel.le-tr...@cnrs-orleans.fr
Target Milestone: ---
With C++20, non-type template parameters can now be any scalar type[0] which
include floating point types[1]. So this
template struct S {};
should compile. The rules for type equivalence are straightforward[2]
[0] http://eel.is/c++draft/temp#param-6
[1] http://eel.is/c++draft/basic.types#9
[2] http://eel.is/c++draft/temp.type#2
[Bug c++/88355] [c++20] Placeholder non-type template argument type deduction fails with custom types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88355 --- Comment #3 from Emmanuel Le Trong --- This bug has disappeared, both tests above compile with version 10.0.0 20200108.
[Bug c++/88395] ICE: Segmentation fault signal terminated program cc1plus, with -std=c++2a -fconcepts
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88395 --- Comment #2 from Emmanuel Le Trong --- (In reply to Nicholas Krause from comment #1) > First off that's just a valid snippet without a class definition so I was > unable to build it against gcc itself to even check this is a bug. Further > more can you check this is still happening and if so just report back with > the exact code that builds but is giving you a segfault on the trunk branch. I'm sorry I don't understand your requests. The compilation of this small piece of code causes the compiler (trunk 20181213) to crash, without further information.
[Bug c++/88355] [c++20] Placeholder non-type template argument type deduction fails with custom types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88355
--- Comment #2 from Emmanuel Le Trong ---
Ok I got this new snippet showing what is very probably the same bug, although
the diagnostic message is not the same at all. (And quite frankly I don't
understand it.)
$ cat bug_5.cpp
struct T {};
template
struct U {};
template
void f (U) {}
int main ()
{
constexpr T t;
f (U{});
}
$ g++-9 -std=c++2a -Wall -Wextra bug_5.cpp
bug_5.cpp: In function ‘int main()’:
bug_5.cpp:12:18: error: no matching function for call to ‘f(U)’
12 | f (U{});
| ^
bug_5.cpp:7:10: note: candidate: ‘template void
f(U<((T*)(void)0)->T::__ct_comp (((const T)t))>)’
7 | void f (U) {}
| ^
bug_5.cpp:7:10: note: template argument deduction/substitution failed:
bug_5.cpp:12:18: note: couldn't deduce template parameter ‘t’
12 | f (U{});
| ^
$ g++-9 --verbose
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9 : (reconfigured) ../gcc-9/configure
--prefix=/home/manu/system/opt/gcc-9 --program-suffix=-9 : (reconfigured)
../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9 --program-suffix=-9
--enable-languages=c,c++,fortran,lto,objc --no-create --no-recursion
Thread model: posix
gcc version 9.0.1 20190227 (experimental) (GCC)
[Bug c++/88216] New: ICE (-std=c++2a) in cxx_eval_constant_expression, at cp/constexpr.c:4602
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88216
Bug ID: 88216
Summary: ICE (-std=c++2a) in cxx_eval_constant_expression, at
cp/constexpr.c:4602
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: emmanuel.le-tr...@cnrs-orleans.fr
Target Milestone: ---
$ g++-9 -v
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9
Thread model: posix
gcc version 9.0.0 20181123 (experimental) (GCC)
$ cat bug.cpp
struct
T {};
template
struct
U {};
template
int
f (U );
$ g++-9 -std=c++2a -Wall -Wextra -c bug.cpp
bug.cpp:10:8: internal compiler error: in cxx_eval_constant_expression, at
cp/constexpr.c:4602
10 | f (U );
|^
0x5ee04a cxx_eval_constant_expression
../../gcc-9/gcc/cp/constexpr.c:4602
0x8759b6 cxx_eval_call_expression
../../gcc-9/gcc/cp/constexpr.c:1511
0x877af8 cxx_eval_constant_expression
../../gcc-9/gcc/cp/constexpr.c:4296
0x87cf3e cxx_eval_outermost_constant_expr
../../gcc-9/gcc/cp/constexpr.c:5032
0x9a9f03 get_template_parm_object
../../gcc-9/gcc/cp/pt.c:6665
0x9a9f03 convert_nontype_argument
../../gcc-9/gcc/cp/pt.c:7126
0x9a9f03 convert_template_argument
../../gcc-9/gcc/cp/pt.c:8033
0x9a9f03 convert_template_argument
../../gcc-9/gcc/cp/pt.c:7784
0x995793 coerce_template_parms
../../gcc-9/gcc/cp/pt.c:8509
0x9a115e lookup_template_class_1
../../gcc-9/gcc/cp/pt.c:9325
0x9a115e lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
../../gcc-9/gcc/cp/pt.c:9684
0x9d29db finish_template_type(tree_node*, tree_node*, int)
../../gcc-9/gcc/cp/semantics.c:3247
0x950295 cp_parser_template_id
../../gcc-9/gcc/cp/parser.c:16295
0x950406 cp_parser_class_name
../../gcc-9/gcc/cp/parser.c:22858
0x95376b cp_parser_qualifying_entity
../../gcc-9/gcc/cp/parser.c:6644
0x95376b cp_parser_nested_name_specifier_opt
../../gcc-9/gcc/cp/parser.c:6330
0x950b78 cp_parser_simple_type_specifier
../../gcc-9/gcc/cp/parser.c:17634
0x947be5 cp_parser_type_specifier
../../gcc-9/gcc/cp/parser.c:17307
0x948a8e cp_parser_decl_specifier_seq
../../gcc-9/gcc/cp/parser.c:13961
0x9618b0 cp_parser_parameter_declaration
../../gcc-9/gcc/cp/parser.c:21973
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
[Bug c++/88216] [9 Regression] ICE (-std=c++2a) in cxx_eval_constant_expression, at cp/constexpr.c:4602
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88216
--- Comment #2 from emmanuel.le-tr...@cnrs-orleans.fr ---
Valid. This snippet compiles:
struct
T {};
template
struct
U {};
T t;
U u;
[Bug c++/88355] New: [c++20] Placeholder non-type template argument type deduction fails with custom types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88355
Bug ID: 88355
Summary: [c++20] Placeholder non-type template argument type
deduction fails with custom types
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: emmanuel.le-tr...@cnrs-orleans.fr
Target Milestone: ---
Deducing the type of a non-type template parameter containing a placeholder
fails with custom types.
$ g++-9 -v
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9 : (reconfigured) ../gcc-9/configure
--prefix=/home/manu/system/opt/gcc-9 --program-suffix=-9
Thread model: posix
gcc version 9.0.0 20181127 (experimental) (GCC)
$ cat bug_2.cpp
#include // for std::is_same_v
struct T {};
template
struct U {};
template
void f (U ) {}
int main ()
{
constexpr T t;
f(U<1>{}); // OK
f (U{}); // OK
// This works:
auto x = t;
static_assert (std::is_same_v ); // OK
// This should work as well, as per [temp.arg.nontype], see below
f(U{}); // Error
}
$ g++-9 -std=c++2a -Wall -Wextrabug_2.cpp -o bug_2
bug_2.cpp: In function ‘int main()’:
bug_2.cpp:20:21: error: no matching function for call to ‘f(U)’
20 | f(U{}); // Error
| ^
bug_2.cpp:9:10: note: candidate: ‘template void f(U)’
9 | void f (U ) {}
| ^
bug_2.cpp:9:10: note: template argument deduction/substitution failed:
bug_2.cpp:20:21: note: mismatched types ‘T’ and ‘const T’
20 | f(U{}); // Error
| ^
make: *** [: bug_2] Error 1
The standardese in the latest draft is:
---8<---
12.3.2 Template non-type arguments [temp.arg.nontype]
If the type T of a template-parameter (12.1) contains a placeholder type
(9.1.7.5) or a placeholder for a deduced class type (9.1.7.6), the type of the
parameter is the type deduced for the variable x in the invented declaration
T x = template-argument ;
--->8---
[Bug c++/88092] class nontype template deduction failed when providing type to class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88092
emmanuel.le-tr...@cnrs-orleans.fr changed:
What|Removed |Added
CC||emmanuel.le-trong@cnrs-orle
||ans.fr
--- Comment #3 from emmanuel.le-tr...@cnrs-orleans.fr ---
I have a problem with this. AFAIK, nowhere in the standard is written that a
class template without argument (i.e. not a type!) can be used as the type of a
non-type template argument. [temp.param] §4 says
> A non-type template-parameter shall have one of the following (optionally
> cv-qualified) types:
> — a type that is literal, has strong structural equality (10.10.1), has no
> mutable or volatile subobjects, and in which if there is a defaulted member
> operator<=>, then it is declared public,
> — an lvalue reference type,
> — a type that contains a placeholder type (9.1.7.5), or
> — a placeholder for a deduced class type (9.1.7.6).
So
template struct A {};
template struct B {};
should not be valid IMO.
[Bug c++/88373] New: parse error in template argument list when using bitwise not with -std=c++2a switch
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88373
Bug ID: 88373
Summary: parse error in template argument list when using
bitwise not with -std=c++2a switch
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: emmanuel.le-tr...@cnrs-orleans.fr
Target Milestone: ---
Using the bitwise not in a non-type template argument produces a parse error
with the -std=c++2a switch on. It works fine without the switch. It also works
with the switch on in version 8.2.1.
$ cat bug_3.cpp
template
constexpr T value = T {};
template
struct S {};
using U = S >;
$ g++-9 -c bug_3.cpp && echo OK
OK
$ g++-9 -c -std=c++2a bug_3.cpp
bug_3.cpp:7:15: error: parse error in template argument list
7 | using U = S >;
| ^
g++-9 -v
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9
Thread model: posix
gcc version 9.0.0 20181204 (experimental) (GCC)
[Bug c++/88395] New: ICE: Segmentation fault signal terminated program cc1plus, with -std=c++2a -fconcepts
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88395
Bug ID: 88395
Summary: ICE: Segmentation fault signal terminated program
cc1plus, with -std=c++2a -fconcepts
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: emmanuel.le-tr...@cnrs-orleans.fr
Target Milestone: ---
Both trunk and 8.2.1 segfault on this valid snippet
$ cat bug_4.cpp
template
concept bool Concept2 = requires (T t, U u)
{
{ t += u } -> T&;
};
template
concept bool Concept = Concept2 ;
struct S
{
template
constexpr S& operator += (T o);
};
constexpr S operator * (S a, S b)
{
return a += b;
}
$ g++-9 -std=c++2a -fconcepts -c bug_4.cpp
g++-9: internal compiler error: Segmentation fault signal terminated program
cc1plus
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.
$ g++-9 -v
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9
Thread model: posix
gcc version 9.0.0 20181204 (experimental) (GCC)
