fnovtmpl.txt

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Overloading in the presence of templates:

Question:
=========
    Is this allowed:
	template<class T> T foo( T, int );
	template<class T> T foo( int, T );
    which implies that:
	int foo( int, int );
    is ambiguous.  But these
	char foo( char, int );
	char foo( int, char );
    are fine.

ARM states:
===========
1.  look for an exact match on existing functions. (i.e. functions currently
    in the symbol table) (exact match == FNOV_RANK_SAME)
2.  look for a function template that can be used to create a template
    function that is an exact match.
3.  look for an ordinary function overload match on existing functions in
    the symbol table.

Notes:
======
1.  For function template:
	``template<class T> T foo( T );''
    the declaration:
        ``int foo( int );''
    causes an entry to be added to the symbol table.  This entry can be
    used in step 1 during future overloading.  Whereas the usage:
	``char c = foo( 'q' );''
    generates a reference to the template function but does not cause an
    entry to be added to the symbol table for use in future overloading.
2.  Step 2 is not clear on whether the exact match applies only to
    the template-arguments of the function template or to all arguments
    of the function template.
    i.e.
	template<class T> T foo( T, int );
	int a = foo( 1, 2 );	// ok
	int b = foo( 3, 'c' );	// not clear (my guess is: NO_MATCH )

ARM states:
===========
pg347
Declaring a function with the same name as a function template with a
matching type constitutes a declaration of a specific template function.
pg348
The definition of a (nontemplate) function with a type that exactly matches
the type of a function template declaration is a definition of that specific
template function. (i.e. the template definition is over-ridden)

--> These sections imply a change to the distinct function checking.
    When a function declaration is checked for uniqueness it must also be
    considered in terms of templates.

Proposed Overloading Algorithm for Function Resolution:
=======================================================
while building list of functions, note any SC_TEMPLATE entries
o_result = existing overload
if( o_result <= FNOV_RANK_SAME ) {
    if( unique ) {
	return symbol
    } else {
	return ambiguous
    }
} else {
    if( there are SC_TEMPLATE entries ) {
	t_result = make template function with provided args
	if( t_result = OK ) {
	    return created symbol
	} else if( t_result == AMBIGUOUS ) {
	    return ambiguous
	}
    }
    if( o_result < NO_MATCH ) {
	if( unique ) {
	    return symbol
	} else {
	    return ambiguous
	}
    }
    return NO_MATCH
}