4 ms·

Why is it undefined behaviour?

• IainIreland 6y ago
  You aren't allowed to goto a label in a different function. From the C standard: > The identifier in a goto statement shall name a label located somewhere in the enclosing function. `Shall` is a term of art here: > If a "shall" or "shall not" requirement that appears outside of a constraint is violated, the behavior is undefined. (Sections 6.8.6.1.1 and 4.2, respectively: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf)
  • jpcooper 6y ago
    Appreciated.
  • jhoechtl 6y ago
    It's undefined in the C standard. That doesn't mean its insecure or undefined as seen from the machine code. nothin is hilding you back to do your own code generation and clearly define this behaviour.
    • MaxBarraclough 6y ago
      They weren't doing their own code-generation, BEAM/C treated C as the target language, and then relied on a standard C compiler. From the article: > it is undefined behavior even in GCC. It happened to work with GCC on Sparc, but not on GCC for X86.
    • deleted 6y ago
      [deleted]