Method PreparseVarRefs

source/script.cpp:13540–13608

ResultType Script::PreparseVarRefs()
{
	// AddLine() and ExpressionToPostfix() currently leave validation of output variables
	// and lvalues to this function, to reduce code size.  Search for "VarIsReadOnlyError".
	for (Line *line = mFirstLine; line; line = line->mNextLine)
	{
		switch (line->mActionType)
		{ // Establish context for FindOrAddVar:
		case ACT_BLOCK_BEGIN: if (line->mAttribute) g->CurrentFunc = (UserFunc *)line->mAttribute; break;
		case ACT_BLOCK_END: if (line->mAttribute) g->CurrentFunc = g->CurrentFunc->mOuterFunc; break;
		}

		for (int a = 0; a < line->mArgc; ++a)
		{
			ArgStruct &arg = line->mArg[a];
			if (!arg.is_expression)
				continue;
			for (ExprTokenType *token = arg.postfix; token->symbol != SYM_INVALID; ++token)
			{
				if (token->symbol != SYM_VAR // Not a var.
					|| VARREF_IS_WRITE(token->var_usage)) // Already resolved by ExpressionToPostfix.
					continue;
				if (  !(token->var = FindOrAddVar(token->var_deref->marker, token->var_deref->length, FINDVAR_FOR_READ))  )
					return FAIL;
				if (token->var->IsAlias()) // Upvar.
					continue;
				switch (token->var->Type())
				{
				case VAR_CONSTANT:
					// Resolve constants to their values, except in cases like IsSet(SomeClass), or when
					// the constant is a closure (which may change each time the outer function is called).
					if (!token->var->IsLocal() && token->var_usage == VARREF_READ && !token->var->IsUninitialized())
						token->var->ToToken(*token);
					continue;
				case VAR_VIRTUAL:
					if (token->var_usage == VARREF_READ)
						++arg.max_alloc; // Reserve a to_free[] slot for it in ExpandExpression().
					break;
				default:
					// Suppress any VarUnset warnings for IsSet(var) so that it can be used to determine if an
					// optionally-set global variable has been set, such as a class in an optional #Include.
					// MarkAssignedSomewhere() isn't used for this because PreprocessLocalVars() hasn't been
					// called yet, and it relies on the attribute being accurate.
					if (token->var_usage == VARREF_ISSET)
						token->var->MarkAlreadyWarned();
					// It's too early to show VarUnset warnings, since not all VARREF_ISSET references have been marked.
					// The effect of IsSet(v) for suppressing the warning shouldn't be positional since it's feasible for
					// a check in one function to guard evaluation of a VARREF_READ in some other function.
				}
			}
			if (arg.type == ARG_TYPE_INPUT_VAR)
			{
				if (arg.postfix->symbol != SYM_VAR || arg.postfix->var->Type() != VAR_NORMAL)
				{
					// Can't be ARG_TYPE_INPUT_VAR after all, as VAR_VIRTUAL and VAR_CONSTANT require ExpandExpression
					// (unless it's a constant which was converted to SYM_OBJECT above).
					arg.type = ARG_TYPE_NORMAL;
				}