[Bug c++/100482] New: namespaces as int in decltype expression

[Bug c++/100482] New: namespaces as int in decltype expression

[hahayes12 at tutanota dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

            Bug ID: 100482
           Summary: namespaces as int in decltype expression
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hahayes12 at tutanota dot com
  Target Milestone: ---

case:

#include <iostream>
int main() {
    decltype(std) i{1};
    std::cout << i;
}

g++ main.cpp

./a.out
1


as you can see namespaces are usable in decltype expressions and treated as
ints.

[Bug c++/100482] namespaces as int in decltype expression

[sand at rifkin dot dev]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

--- Comment #1 from Jeremy R. <sand at rifkin dot dev> ---
This appears to be valid for function return types as well but the compiler
does error when decltype is used in a function parameter

namespace std{}
int A(int a) { // fine
    decltype(std) b = a;
    return b;
}
decltype(std) B(int a) {  // fine
    decltype(std) b = a;
    return b;
}
auto C(int a) -> decltype(std) {  // fine
    decltype(std) b = a;
    return b;
}
int D(decltype(std) a) { // error: expected initializer before 'a'
    decltype(std) b = a;
    return b;
}

[Bug c++/100482] namespaces as int in decltype expression

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-05-08
             Status|UNCONFIRMED                 |NEW

[Bug c++/100482] namespaces as int in decltype expression

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
*** Bug 100481 has been marked as a duplicate of this bug. ***

[Bug c++/100482] namespaces as int in decltype expression

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:a90bd3ea6d1ba27b15476f0a768d7952c6723420

commit r14-3087-ga90bd3ea6d1ba27b15476f0a768d7952c6723420
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Tue Aug 8 12:48:43 2023 +1000

    c++: Report invalid id-expression in decltype [PR100482]

    This patch ensures that any errors raised by finish_id_expression when
    parsing a decltype expression are properly reported, rather than
    potentially going ignored and causing invalid code to be accepted.

    We can also now remove the separate check for templates without args as
    this is also checked for in finish_id_expression.

            PR c++/100482

    gcc/cp/ChangeLog:

            * parser.cc (cp_parser_decltype_expr): Report errors raised by
            finish_id_expression.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/decltype-100482.C: New test.

    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>

[Bug c++/100482] namespaces as int in decltype expression

[nshead at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100482

Nathaniel Shead <nshead at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |nshead at gcc dot gnu.org
   Target Milestone|---                         |14.0
         Resolution|---                         |FIXED

--- Comment #4 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Fixed in GCC 14.