This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

2793. Block-scope declaration conflicting with parameter name

[Accepted as a DR at the November, 2023 meeting.]

Consider:

  void f(int i) { extern int i; } 

According to 6.4.3 [basic.scope.block] paragraph 2, the target scope of the declaration is relevant (which would be the global scope), but not the scope in which the name is bound. That seems wrong. For comparison, template parameter names use the latter rule (13.8.2 [temp.local] paragraph 6).

Proposed resolution (approved by CWG 2023-09-15):

If a declaration that is not a name-independent declaration and whose target scope is that binds a name in the block scope S of a

• compound-statement of a lambda-expression, function-body, or function-try-block,
• substatement of a selection or iteration statement that is not itself a selection or iteration statement, or
• handler of a function-try-block

potentially conflicts with a declaration whose target scope is the parent scope of S, the program is ill-formed.