4 ms·

What happens if a header file declares a function to return auto, does the compiler have to wait until link time to find out what the type is?

• missblit 12y ago
  No, types are completely determined before link time. An auto return type means the type is inferred from the type of the expression that the function returns, so it's known from that.
  • seccess 12y ago
    Interesting, could you elaborate on this a bit more? Say I have a header file "foo.h" with an "auto foo();" declaration. Another file (eg, "bar.h") imports foo.h. How can the compiler do type checking when compiling bar.cc without also parsing foo.cc to determine the return type of foo()?
    • mkup 12y ago
      If there's no function body in header (non-inline function), then it won't compile.
    • deleted 12y ago
      [deleted]
    • nanofortnight 12y ago
      Inferrence isn't magic and has sensible limits. To quote: > Of course, this requires the function body to be visible. https://isocpp.org/wiki/faq/cpp14-language#generalized-return https://isocpp.org/wiki/faq/cpp14-language#generalized-retur...