Some useful tools for binary formats

There's a similar point with libgcc: sometimes the compiler chooses to generate a call to a non-obvious implementation of a common pattern instead of a direct transformation of your source, and then the license of that implementation becomes relevant. Such things tend to be permissively licensed, so that the compiler is as widely useable as possible. On the other hand, things like regular expression libraries tend to have more runtime support and also tend to expect that a system will include the compiler and not just its output, so they don't tend to produce something that is only a derived work of the input to the compiler. So it can be a question of whether the project thinks of itself like GCC or libpcre as far as how some of the code is licensed.