function resolvableAliases( ast ) {
		var substr;
		var alias;
		var match;
		var line;
		var pos;

		match = RE_OUTSIDE_ALIAS.exec( ast.raw );
		while ( !isNull( match ) ) {
			alias = pkg2alias( match[ 1 ] );
			if ( !alias ) {
				substr = ast.raw.substring( 0, RE_OUTSIDE_ALIAS.lastIndex );
				line = countLines( substr );
				pos = {
					'start': line,
					'end': line
				};
				context.report( match[ 1 ]+' does not map to any REPL alias', pos );
			}
			match = RE_OUTSIDE_ALIAS.exec( ast.raw );
		}
	}
Checks that all packages in aliases are resolvable.

@private
@param {Object} ast - full AST