Give error when trying to extract a member of a constant vector/rot

[Sei-Lisa]

e.g. ZERO_VECTOR.x

Introduced in 24127a6 when constants were added to builtins.txt.

Fixes #63.

The error generated is "Invalid member .". Perhaps a syntax error would be better? llGetPos().x gives "syntax error, unexpected PERIOD". That error message would bear improvement, though.

But "Invalid member" is intended to report cases like e.g. "vec.w" so maybe it's worth reporting this as a syntax error instead.

[Sei-Lisa]

Force-pushed a minor, OCD-like style fix.

[Sei-Lisa]

Maybe an alternative error message could be: "syntax error, built-in constants don't allow member access"

The patch would look like this:

@@ -638,6 +638,9 @@ void LLScriptFunctionExpression::determine_type() {
 void LLScriptLValueExpression::determine_type() {
    LLScriptIdentifier *id = (LLScriptIdentifier *) get_child(0);
    id->resolve_symbol( SYM_VARIABLE );
+   if ( id->get_symbol() != NULL && id->get_symbol()->get_sub_type() == SYM_BUILTIN && id->get_member() != NULL ) {
+       ERROR( HERE, E_SYNTAX_ERROR, "syntax error: built-in constants don't allow member access" );
+   }
    type = id->get_type();
 }
 

and of course the new test case should be adjusted appropriately.