3.3.1: The point of declaration for a name is immediately after its complete declarator (clause 8) and before its initializer (if any)

3.3.2: The potential scope of a function parameter name ... begins at its point of declaration.

So this ought to be well-formed:

void f (int t, char (*buf_p)[sizeof(t)]) {}

but G++ doesn't declare 't' until after the closing paren, so name lookup fails.

This wasn't a very interesting bug until the advent of late-specified return types, which relies on naming parameters to be at all useful.