[Bug c++/94101] New: Variadic template deduction guide issue - error: 'In instantiation of'

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94101

Bug ID: 94101
   Summary: Variadic template deduction guide issue - error: 'In
instantiation of'
   Product: gcc
   Version: 9.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: rosemberg at ymail dot com
  Target Milestone: ---

The gcc9.2 (I tested with gcc7) return the follow error due the deduction guide
declaration:

In instantiation of 'Merged::Merged(T&& ...) (with T = {const main()::&, const
main()::&, main()::}; B = {}]':

#include 

template
struct Merged : B ... {
   template
   Merged(T&& ... t) : B(std::forward(t))... {}

using B::operator()...;
};

template
Merged(T...) -> Merged...>;

int main() {
const auto l1 = []() { return 4; };
const auto l2 = [](const int i) { return i * 10; };

Merged merged(l1,
  l2,
  [](const double d) { return d * 3.2; });

return 0;
}

Just to clarify, the work around to solve it was to add the follow deduction
guide:

template 
Merged (T0, T ...) 
   -> Merged, std::decay_t...>;

[Bug c++/94102] New: Variadic template deduction guide issue - error: 'In instantiation of'

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94102

Bug ID: 94102
   Summary: Variadic template deduction guide issue - error: 'In
instantiation of'
   Product: gcc
   Version: 9.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: rosemberg at ymail dot com
  Target Milestone: ---

The gcc9.2 (I tested with gcc7) return the follow error due the deduction guide
declaration:

In instantiation of 'Merged::Merged(T&& ...) (with T = {const main()::&, const
main()::&, main()::}; B = {}]':

#include 

template
struct Merged : B ... {
   template
   Merged(T&& ... t) : B(std::forward(t))... {}

using B::operator()...;
};

template
Merged(T...) -> Merged...>;

int main() {
const auto l1 = []() { return 4; };
const auto l2 = [](const int i) { return i * 10; };

Merged merged(l1,
  l2,
  [](const double d) { return d * 3.2; });

return 0;
}

[Bug c++/94102] Variadic template deduction guide issue - error: 'In instantiation of'

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94102

--- Comment #1 from rosemberg at ymail dot com ---
The work around to solve it was to add the follow deduction guide:

template 
Merged (T0, T ...) 
   -> Merged, std::decay_t...>;

[Bug c++/94102] Variadic template deduction guide issue - error: 'In instantiation of'

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94102

--- Comment #2 from rosemberg at ymail dot com ---
*** Bug 94101 has been marked as a duplicate of this bug. ***

[Bug c++/94101] Variadic template deduction guide issue - error: 'In instantiation of'

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94101

rosemberg at ymail dot com changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution|--- |DUPLICATE

--- Comment #1 from rosemberg at ymail dot com ---
.

*** This bug has been marked as a duplicate of bug 94102 ***

[Bug c++/78080] New: chown command (sys/stat.h) fail to change the owner directory if the return value is not attributed to a variable.

[rosemberg at ymail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78080

Bug ID: 78080
   Summary: chown command (sys/stat.h) fail to change the owner
directory if the return value is not attributed to a
variable.
   Product: gcc
   Version: 5.4.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: rosemberg at ymail dot com
  Target Milestone: ---

Hi,
chown command (sys/stat.h) fail to change the owner directory if the return
value is not attributed to a variable.

Supposed the directory /home/user/tochange exists and the program is running
with administrator rights and tochange owner and group is not the same like its
parent directory .

example of success code:

#include 
#include 
#include 

int main()
{

string sPath("/home/user/tochange");
struct stat info;

stat("/home/user",&info);

int iA = chown(sPath.c_str(), info.st_uid, info.st_gid);
cout << iA << endl;

return 0;
}


The result to iA will be 0 (success)

If I change the last 2 lines (before return 0;) to the follow code, the chown
command failed and cout will return -1 (nothing was changed):

cout << chown(sPath.c_str(), info.st_uid, info.st_gid) << endl;


it also happened with if statement.

Best regards,
M.Rosemberg