[Bug c++/110930] New: Fix-it hints suggest wrong header for names in the global namespace

[Bug c++/110930] New: Fix-it hints suggest wrong header for names in the global namespace

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

            Bug ID: 110930
           Summary: Fix-it hints suggest wrong header for names in the
                    global namespace
           Product: gcc
           Version: 13.1.1
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

Given:

uint32_t i = 0;

We say:

dcl.cc:1:1: error: 'uint32_t' does not name a type
    1 | uint32_t i = 0;
      | ^~~~~~~~
dcl.cc:1:1: note: 'uint32_t' is defined in header '<cstdint>'; this is probably
fixable by adding '#include <cstdint>'
  +++ |+#include <cstdint>
    1 | uint32_t i = 0;


But this is wrong. uint32_t is declared in <stdint.h>, std::uint32_t is
declared in <cstdint>.

We should not be encouraging reliance on the non-portable property that some
implementations of <cstdint> leak the name into the global namespace as well as
namespace std.

This is the case for every name in the C++ stdlib that comes from the C stdlib.

[Bug c++/110930] Fix-it hints suggest wrong header for names in the global namespace

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-08-07

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Maybe still OK for code using 'using std'?  I wonder if we can
check for that somehow.

[Bug c++/110930] Fix-it hints suggest wrong header for names in the global namespace

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yeah, that using-directive complicates things.

[Bug c++/110930] Fix-it hints suggest wrong header for names in the global namespace

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu.org

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I had noticed this too.

[Bug c++/110930] Fix-it hints suggest wrong header for names in the global namespace

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I see Jonathan had mentioned this issue in bug 85690 comment #1 too.

[Bug c++/110930] Fix-it hints suggest wrong header for names in the global namespace

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110930

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah yes, this is a dup of the second half of that one, but maybe worth keeping
it separate.