Assertion failure: '0' on line 872 in file 'constfold.c'

[long]

void main(){}

char[] ctfe_lower(char[] s){
	char[] res	;
	foreach(int i, c;s){
		if( c >= 'A' && c <='Z' ){
			res	~= c + 32 ;
		}else{
			res	~= c;
		}
	}
	return res;
}

char[] ctfe_remove(char[] _if, char[] remove){
	_if		= ctfe_lower(_if.dup);
	char[] limit	= ctfe_lower(remove.dup);
	int len	= limit.length;
	char[] _if2	= null;
	foreach(int i, c; _if){
		if( _if.length - i > len ){
			if( _if[i..i+len] == limit ){
				if( _if[i+len] is ' ' ){
					_if2	= _if[0..i].dup;
					break;
				}
			}
		}
	}
	if( _if2 is null ){
		_if2	= _if.dup;
	}
	return _if2;
}

pragma(msg, ctfe_remove("1234 5", "34") );