Re: Traditional C chokes on struct/union initialization in new cpplex.c

[Jeffrey A Law <law at cygnus dot com>]

  In message <200007052059.QAA26992@caip.rutgers.edu>you write:
  > Hi Zack,
  > 
  > 	I had some trouble compiling the overhauled cpplex.c on sunos4
  > using its K&R cc compiler.  I get:
  > 
  >  > "../../egcs-CVS20000705/gcc/cpplex.c", line 1938: operands of = have
  >  > 				       incompatible types
  >  > "../../egcs-CVS20000705/gcc/cpplex.c", line 1939: operands of = have
  >  > 				       incompatible types
  > 
  > 
  > The problem occurs on these two lines from cpplex.c:
  > 
  >  > static const cpp_token placemarker_token = {0, 0, CPP_PLACEMARKER, 0, {0
  > }};
  >  > static const cpp_token eof_token = {0, 0, CPP_EOF, 0, {0}};
  > 
  > Based on some experimentation, it appears to me that traditional C
  > cannot initialize a union member of a struct.  I tried getting it to
  > work by playing with braces, etc., but no luck.
  > 
  > If I take out the {0} entirely, then default initialization to zero
  > works.  However I still want to have the {0} appear for gcc so we
  > don't get missing member initialization warnings.
  > 
  > I hacked up this patch and got midway through stage2 so far.  Assuming
  > bootstrap succeeds, ok to install?
  > 
  > 		--Kaveh
  > 
  > 
  > 2000-07-05  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
  > 
  > 	* cpplex.c (placemarker_token, eof_token): Don't initialize struct
  > 	union member in traditional C.
The way this has been handled in BFD and elsewhere is to simply omit the
union initialization when ___STDC__.

See this change in BFD as an example.

1999-08-06  Ian Lance Taylor  <ian@zembu.com>

        * section.c (global_syms): Only initialize union field if
        __STDC__.

Unless there is significant benefit, we should adopt the same conventions
as other GNU projects.




  > 
  > diff -rup ../egcs-CVS20000705/gcc/cpplex.c egcs-CVS20000705/gcc/cpplex.c
  > --- ../egcs-CVS20000705/gcc/cpplex.c	Wed Jul  5 05:43:15 2000
  > +++ egcs-CVS20000705/gcc/cpplex.c	Wed Jul  5 16:05:21 2000
  > @@ -1935,8 +1935,15 @@ spell_token (pfile, token, buffer)
  >  
  >  /* Macro expansion algorithm.  TODO.  */
  >  
  > -static const cpp_token placemarker_token = {0, 0, CPP_PLACEMARKER, 0, {0}}
  > ;
  > -static const cpp_token eof_token = {0, 0, CPP_EOF, 0, {0}};
  > +/* Traditional C cannot initialize union members of structs.  */
  > +#ifdef ANSI_PROTOTYPES
  > +#define UNION_INIT , {0}
  > +#else
  > +#define UNION_INIT
  > +#endif
  > +
  > +static const cpp_token placemarker_token = {0, 0, CPP_PLACEMARKER, 0 UNION
  > _INIT};
  > +static const cpp_token eof_token = {0, 0, CPP_EOF, 0 UNION_INIT};
  >  
  >  #define IS_ARG_CONTEXT(c) ((c)->flags & CONTEXT_ARG)
  >  #define CURRENT_CONTEXT(pfile) ((pfile)->contexts + (pfile)->cur_context)
  >