[Bug c++/115445] New: [15 Regression] ICE when repeating an export of function declared in GMF

[m.cencora at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115445

            Bug ID: 115445
           Summary: [15 Regression] ICE when repeating an export of
                    function declared in GMF
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: m.cencora at gmail dot com
  Target Milestone: ---

$ cat repeated_using.cpp

module;

namespace std
{
void make_error_code();
}

export module std;

export namespace std
{
    using std::make_error_code;
    using std::make_error_code;
}

$ g++ -Wno-global-module -fmodules-ts repeated_using.cpp

<source>:13:16: internal compiler error: tree check: expected overload, have
function_decl in lookup_maybe_add, at cp/tree.cc:2533
   13 |     using std::make_error_code;
      |                ^~~~~~~~~~~~~~~
0x26c45cc internal_error(char const*, ...)
        ???:0
0x972a48 tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        ???:0
0xbf6a6d name_lookup::add_overload(tree_node*)
        ???:0
0xbf6ce4 name_lookup::process_binding(tree_node*, tree_node*)
        ???:0
0xc00ce2 name_lookup::search_namespace(tree_node*)
        ???:0
0xc00de0 name_lookup::search_qualified(tree_node*, bool)
        ???:0
0xc0654f finish_nonmember_using_decl(tree_node*, tree_node*)
        ???:0
0xc6eb8a c_parse_file()
        ???:0
0xdc51d9 c_common_parse_file()
        ???:0

This is a recent regression - didn't occur in 20250526 snapshot.