Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!giza.cis.ohio-state.edu!george
From: george@giza.cis.ohio-state.edu (George M. Jones)
Newsgroups: comp.lang.c
Subject: forward references in typedefs
Message-ID: <55480@tut.cis.ohio-state.edu>
Date: 19 Jul 89 20:53:44 GMT
Sender: news@tut.cis.ohio-state.edu
Reply-To: George M. Jones <george@cis.ohio-state.edu>
Organization: The Ohio Stat<e University Dept of Computer & Information Science
Lines: 47

I have noticed what I consider anomolous behavior when using forward references
in structs & typedefs and would would like to know whether things behave as
they do because (a) that's just the way the compilers choose to implement
a fuzzy point or (b) there is some definition (ansi, K&R) that say this is
[in]correct behavior.


The following code compiles (Sun, GCC, Green Hills) just fine as expected:

  struct one
    {
      struct two_t *foo;
    } one_t;
  
  struct two
    {
      struct one_t *bar;
    } two_t;


However all the compilers I tried appear to be choaking on the forward 
reference to two_t in the following chunk of code

  typedef struct one
    {
      two_t *foo;
    } one_t;
  
  typedef struct two
    {
      one_t *bar;
    } two_t;
  4:35pm> cc -c bad.c
  "bad.c", line 3: syntax error at or near variable name "two_t"
  "bad.c", line 4: zero sized structure

Any definitive answers from the knowledgable clientel of this newsgroup ?

Thanks,
---George Jones



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