------- Additional Comments From smcpeak at cs dot berkeley dot edu 2005-02-21 02:41 ------- I question the apparent conclusion reached in this discussion. The reporter's testcase refers to
n::f(a) where 'a' has dependent type. The conclusion so far is that 'f' is not dependent because it is qualified. The primary justification offered is that 14.6.2p1 mentions exactly two syntactic cases of dependent names: - function call with a simple 'identifier' as the function - operator in an expression However, as discussed here and elsewhere (e.g., http://gcc.gnu.org/onlinedocs/gcc/Name-lookup.html), there is general consensus that the following forms also make 'f' dependent: - x->f(a) // when x is a type-dependent expression - C::f(a) // when C is a dependent type Therefore, my interpretation is that the two cases given in 14.6.2 are *not* exhaustive, but rather merely examples. 14.6.2 first gives some general properties of dependent names (e.g., "... semantics which may differ from one instantiation to another.") that clearly apply to more situations. And 14.6.4.2 singles out unqualified names as a special case---why would they be a special case if only unqualified names could be dependent? Now, it is true that the two additional generally-agreed-upon cases above are "doubly" dependent: not only do they have arguments of dependent type, but their receiver object or qualifier is also of dependent type. Consequently, the expressions are type-dependent (14.6.2.2 p1, p3 resp.); but the standard never says that being part of a type-dependent expression automatically makes the name dependent! On the contrary, 14.6.2.2p4 gives several counterexamples. Moreover, in the simple case "f(a)", 'f' is not a type-dependent expression, and yet it is clearly a dependent name. Extrapolating from the first few sentences of 14.6.2, it seems to me that the following are exhaustive representatives of cases where the name 'foo' is dependent: A. Cases where function overload resolution is performed, and influenced by some type that might be dependent: A1. foo(a,b,c) A2. C::foo(a,b,c) A3. x->foo(a,b,c) A4. x->C::foo(a,b,c) when a or b or c is a type-dependent expression. B. Cases where lookup involves traversing a class with dependent type: B1. C::foo B2. x->foo B3. x->C::foo when C is a dependent type, or x is a type-dependent expression. C. Cases when the address of an overloaded function is matched to a target type (13.4) that is dependent. This would include all variations of C. [&][x->][C::]foo where by brackets ([]) I mean optional component. In all cases (except case C, I *think*) 'foo' could be a template-id, and would still be dependent. (Plus the case of operators in expressions where an operand is a type-dependent expr.) -- What |Removed |Added ---------------------------------------------------------------------------- CC| |smcpeak at cs dot berkeley | |dot edu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11828
