[Bug c++/115296] New: CTAD fails
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115296
Bug ID: 115296
Summary: CTAD fails
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
The following code compiles fine with clang and msvc, but fails with gcc.
https://godbolt.org/z/e4dP7rzar
```
#include
template
using array_view = std::span;
void fun(std::span s) {
[[maybe_unused]] auto _1 = std::span{s};
[[maybe_unused]] auto _2 = array_view{s};
}
```
Error:
```
In file included from :1:
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span: In function
'void fun(std::span)':
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span:450:5: error:
size '18446744073709551615' of array exceeds maximum object size
'9223372036854775807'
450 | span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
| ^~~~
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span:450:10:
error: size '18446744073709551615' of array exceeds maximum object size
'9223372036854775807'
450 | span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
| ^~
:8:44: error: class template argument deduction failed:
8 | [[maybe_unused]] auto _2 = array_view{s};
|^
:8:44: error: call of overloaded 'span(std::span&)' is ambiguous
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span:464:5: note:
candidate: 'std::span(_Range&&)-> span >::type> requires
__is_deducible (array_view, std::span)()))&>)())>::type,
18446744073709551615>) [with _Range = span&; typename
remove_reference >::type = int;
ranges::range_reference_t<_Range&> = int&]'
464 | span(_Range &&)
| ^~~~
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span:54:11: note:
candidate: 'span(std::span<_Type, 18446744073709551615>)-> std::span<_Type,
18446744073709551615> [with T = int]'
54 | class span;
| ^~~~
/opt/compiler-explorer/gcc-trunk-20240530/include/c++/15.0.0/span:225:7: note:
candidate: 'span(const std::span<_Type, 18446744073709551615>&)->
std::span<_Type, 18446744073709551615> [with T = int]'
225 | span(const span&) noexcept = default;
| ^~~~
Compiler returned: 1
```
[Bug c++/107652] New: c++20 gccchoses incorrect operator== overload
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107652
Bug ID: 107652
Summary: c++20 gccchoses incorrect operator== overload
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
In C++20 gcc will chose the incorrect overload for this code. The overload
should be ambiguous (see msvc).
https://godbolt.org/z/rox1z1Txa
```
namespace N {
struct C;
struct B;
struct A {
bool fun(A, B, C);
bool operator==(A const&) const;
bool operator!=(A const&) const;
};
struct B : A {};
struct C : A {
bool operator==(C const&) const;
bool operator!=(C const&) const;
C(const B&);
};
} // namespace N
namespace N {
bool A::fun(A a, B b, C c) { return b == c; }
} // namespace N
```
[Bug c++/98750] does not detect dead code
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98750 --- Comment #2 from Tiago Macarios --- Correct. I was expecting a warning there.
[Bug c++/98750] New: does not detect dead code
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98750
Bug ID: 98750
Summary: does not detect dead code
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
for the following code gcc will not detect that f() is never called. msvc
detects this correctly.
https://godbolt.org/z/Y5n78v
```
void f();
void _(int num) {
switch (num)
{
case 1:
break;
f();
}
}
```
[Bug c++/98543] New: fails to diagnose unnecessary functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98543
Bug ID: 98543
Summary: fails to diagnose unnecessary functions
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
clang diagnoses unnecessary functions, gcc fails to:
https://godbolt.org/z/vvErGh
static void f()
{
[[maybe_unused]] auto var =
}
[Bug c++/98520] New: nodiscard not diagnosed in comma operator
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98520
Bug ID: 98520
Summary: nodiscard not diagnosed in comma operator
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
https://godbolt.org/z/13j51h
struct [[nodiscard]] S{};
void f();
void _()
{
f(), S{};
}
[Bug c++/96871] New: Fails to parse templated constructor in template class
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96871
Bug ID: 96871
Summary: Fails to parse templated constructor in template class
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
Both clang and MSVC compile the below fine - gcc fails.
https://godbolt.org/z/hfPdKT
#include
template
struct S {
template
S(Arg&&... arg);
};
:6:11: error: expected ')' before '&&' token
6 | S(Arg&&... arg);
| ~ ^~
| )
[Bug c++/90473] New: gcc does not call function in comma operator
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90473
Bug ID: 90473
Summary: gcc does not call function in comma operator
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
In the code below gcc should call f() prios to calling b(), but that does not
happen.
https://godbolt.org/z/e245vi
void f();
void b(void* p = (f(), nullptr));
void z()
{
b();
}
[Bug c++/89880] New: compiles code that should not be compiled
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89880
Bug ID: 89880
Summary: compiles code that should not be compiled
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
https://godbolt.org/z/4cbr24
void f()
{
int a;
int b;
bool c;
if ((!((int(bool(a))) ^ (int(bool(b && !(c))) {}
}
[Bug c++/88162] New: GCC does not accept non-type template parameters of class type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88162
Bug ID: 88162
Summary: GCC does not accept non-type template parameters of
class type
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
Looking at http://eel.is/c++draft/temp.arg.nontype I would think that the code
below is C++17 complaint.
GCC thinks this is only available in 2a mode. clang compiles it fine in c++17
mode.
https://godbolt.org/z/PGoXwX
template struct id
{
using type = T;
};
template class T> id f( T )
{
};
constexpr struct zero_type
{
template constexpr operator T () const { return {}; }
} zero;
template class T> using nttp_t = typename decltype( f(T())
)::type;
template struct int_constant {};
template struct char_constant {};
template struct long_constant {};
template struct voidp_constant {};
void g( nttp_t, nttp_t, nttp_t,
nttp_t )
{
}
[Bug c++/88118] GCC keeps unnecessary calls to new
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88118 --- Comment #6 from Tiago Macarios --- Related clang bug: https://bugs.llvm.org/show_bug.cgi?id=39731
[Bug c++/88118] New: GCC keeps unnecessary calls to new
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88118
Bug ID: 88118
Summary: GCC keeps unnecessary calls to new
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
With the code below clang generates:
main: # @main
mov eax, 2
ret
GCC will get to the correct result, but will keep the new calls:
main:
sub rsp, 8
mov edi, 24
calloperator new(unsigned long)
mov edi, 24
calloperator new(unsigned long)
mov edi, 24
calloperator new(unsigned long)
mov eax, 2
add rsp, 8
ret
https://godbolt.org/z/Q3nV2x
namespace {
struct Node {
int value{};
Node* left{};
Node* right{};
constexpr Node(int i=0) noexcept : value(i) {};
};
auto constexpr left = ::left;
auto constexpr right = ::right;
template
constexpr Node* traverse(T np, TP... paths) noexcept
{
return (np ->* ... ->* paths);
}
}
int main()
{
Node* const root = new Node{0};
root->left = new Node{1};
root->left->right = new Node{2};
Node* const node = traverse(root, left, right);
return node->value;
}
[Bug c++/87699] New: Implement CWG 1512
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87699
Bug ID: 87699
Summary: Implement CWG 1512
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
As per http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3478.html
the below should not compile.
https://godbolt.org/z/mOpxau
bool foo(int* bar)
{
return bar > 0;
}
[Bug c++/85552] Adding curly braces to the declaration of a std::unique_ptr to a forward declared class breaks compilation
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85552 --- Comment #4 from Tiago Macarios --- Related clang bug: https://bugs.llvm.org/show_bug.cgi?id=39363
[Bug c++/87660] New: Fail to compile unique_ptr of incomplete tyoe
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87660
Bug ID: 87660
Summary: Fail to compile unique_ptr of incomplete tyoe
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
https://godbolt.org/z/zvJQ4F
For the following code GCC will fail to compile the {} and the nullptr
initializes.
#include
struct foo;
struct bar
{
#if defined(DEFAULT)
std::unique_ptr m_;
#elif defined(UNIFORM)
std::unique_ptr m_{};
#else
std::unique_ptr m_ = nullptr;
#endif
};
I would think this is a bug as per
http://eel.is/c++draft/unique.ptr#4.sentence-3
[Bug c++/87179] New: duplicate extern "C" functions in different namespaces not flagged as an error
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87179
Bug ID: 87179
Summary: duplicate extern "C" functions in different namespaces
not flagged as an error
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
Code below compiles in GCC, but is discarded by clang.
namespace A {
extern "C" int g() { return 1; }
}
namespace B {
extern "C" int g() { return 1; } // ill-formed, the function g with C
language linkage has two definitions
}
clang error:
:6:18: error: redefinition of 'g'
extern "C" int g() { return 1; } // ill-formed, the function g with C
language linkage has two definitions
^
:2:18: note: previous definition is here
extern "C" int g() { return 1; }
^
1 error generated.
Compiler returned: 1
example is a copy and paste from the standard http://eel.is/c++draft/dcl.link#6
[Bug c++/87152] New: internal compiler error: in tsubst_copy, at cp/pt.c:15484
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87152
Bug ID: 87152
Summary: internal compiler error: in tsubst_copy, at
cp/pt.c:15484
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
https://godbolt.org/z/RnO6a-
#include
#include
#include
template
constexpr int int_from_bits()
{
constexpr auto a = std::array{bits...};
int sum = 0;
for (int index = 0; bool const b : a)
{
sum += b ? exp2(index) : 0;
}
return sum;
}
int j = int_from_bits();
: In instantiation of 'constexpr int int_from_bits() [with bool ...bits
= {false, false, true}]':
:19:40: required from here
:13:25: internal compiler error: in tsubst_copy, at cp/pt.c:15486
13 | sum += b ? exp2(index) : 0;
| ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
[Bug libstdc++/86433] New: Shouldn't non const hashers also be allowed?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86433
Bug ID: 86433
Summary: Shouldn't non const hashers also be allowed?
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: tiagomacarios at gmail dot com
Target Milestone: ---
https://godbolt.org/g/Z1cqm9
#include
struct my_hash {
std::size_t operator() (int const&) /*const*/ {
return {}; // ~
}
};
std::unordered_set temp;
Shouldn't non-const hashers also be allowed?
http://eel.is/c++draft/hash.requirements#2
