ypp | Yid Compiler | Translation library

Line breaks are essential in most computer environments. If you were given a Makefile without the line breaks and you try to cut it randomly you will have difficulties before if finally works. Try this, maybe:

You really should not be using

The code which you pasted is at the top-level of the generated file (which makes it possible to use #include directives, for example). Recall that the top-level of a C++ program can only contain declarations and definitions, not executable statements. And

There is no "correct use of %union in structs", since %union is used to declare a union. (You could, of course, declare a union with just one member, but that's almost pointless.)

The correct way of declaring a semantic type which is not a union is:

[<=|>=] is a character class, which matches just a single character, in this case if that character is one of <, =, |, or >. (Putting the same character twice — =, in this case — inside a character class is permitted, but had no effect.)

You wanted "<="|">=".

If two patterns match the same longest string, flex always returns the first one in the scanner definition. So the first token produced by flex was <, which matched RELOP1 because RELOP3 comes later in the file; then it matched = as ASSIGN because that comes earlier.

I'm sure Flex produced the warning that the RELOP3 rule cannot match anything. This warning should never be ignored; it almost always indicates an error in your patterns.

Note also that the RELOP3 rule also matches |, which is probably not what you want.

Please read the documentation on (f)lex patterns.