[Bug c++/106214] New: Vector template argument deduction fails for templated function element

[Bug c++/106214] New: Vector template argument deduction fails for templated function element

[henrik.nortamo at csc dot fi]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106214

            Bug ID: 106214
           Summary: Vector template argument deduction fails for templated
                    function element
           Product: gcc
           Version: 11.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: henrik.nortamo at csc dot fi
  Target Milestone: ---

Created attachment 53262
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53262&action=edit
full compiler error message

The following code fails to compile with the command
g++ -Wall -Wextra --std=c++17 minimal.cpp

minimal.cpp
"""
#include <vector>

template<typename T> 
void foo() {} 

int main(){
    std::vector V{foo<float>};
    return 0;
}
"""

The error emitted is (full error as an attachment ):

"""
minimal.cpp: In function ‘int main()’:
minimal.cpp:7:29: error: class template argument deduction failed:
     std::vector V{foo<float>};
                             ^
minimal.cpp:7:29: error: no matching function for call to ‘vector(<unresolved
overloaded function type>)’
In file included from /usr/include/c++/8/vector:64
"""

Tested to fail in the same way for the following g++ versions:

7.4.0  
8.3.0  
8.5.0  
9.1.0  
9.4.0  
11.2.0 
11.3.0 

Code compiles using Clang 13.0.0, icpc (ICC) 19.0.4 and 
"Intel(R) oneAPI DPC++/C++ Compiler 2022.1.0"

[Bug c++/106214] Vector template argument deduction fails for templated function element

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106214

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=93107
             Status|UNCONFIRMED                 |NEW
                 CC|                            |ppalka at gcc dot gnu.org
   Last reconfirmed|                            |2022-07-06
     Ever confirmed|0                           |1

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed, not a regression.  Reduced:

#include <initializer_list>

template<class T>
struct vector {
  vector(std::initializer_list<T>);
};

template<class T> void f();

vector v = {f<int>};


Seems similar to PR93107 but using CTAD instead of ordinary auto deduction.

[Bug c++/106214] Vector template argument deduction fails for templated function element

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106214

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:06ef1583d68169d1a002f5e86189462bb748963c

commit r14-578-g06ef1583d68169d1a002f5e86189462bb748963c
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon May 8 09:03:35 2023 -0400

    c++: list CTAD and resolve_nondeduced_context [PR106214]

    This extends the PR93107 fix, which made us do resolve_nondeduced_context
    on the elements of an initializer list during auto deduction, to happen for
    CTAD as well.

            PR c++/106214
            PR c++/93107

    gcc/cp/ChangeLog:

            * pt.cc (do_auto_deduction): Move up resolve_nondeduced_context
            calls to happen before do_class_deduction.  Add some
            error_mark_node tests.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp1z/class-deduction114.C: New test.

[Bug c++/106214] Vector template argument deduction fails for templated function element

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106214

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |14.0
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
         Resolution|---                         |FIXED

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 14, thanks for the bug report.