[Gm2] "hello world" is a little easier

[Gaius Mulley]

Hi,

below are the latest changes.  In summary the ISO module IOChan.mod is
complete and also an extension to allow functions to optionally return
a value has been implemented.

This allows printf to be defined in gm2/gm2-libs/libc.def as

(*
   int printf(const char *format, ...);
*)

PROCEDURE printf (format: ARRAY OF CHAR; ...) : [ INTEGER ] ;


and the infamous hello world program to be written as:

MODULE hello ;

FROM libc IMPORT printf ;

BEGIN
   printf("hello world\n")
END hello.


if we recall that before these changes one would have to declare a
temporary variable to receive the return value from printf.  Of course
this technique should be used sparingly, but the reality is that few
people want to check the return result to printf..

regards,
Gaius


        * gm2/Make-lang.in:  added entries for IOChan.mod,
          RTio.mod and ErrnoCategory.c.  Also added rule
          to build ErrnoCategory.o.
        * gm2/bnf/gm2m.bnf:  moved FIO import list before
          M2LexBuf to avoid getting the wrong definition of
          GetFileName during p2c bootstrap phase.
        * gm2/bnf/m2-2.bnf:  added OptReturnType for
          procedures (functions).  Rationalized function
          return values via OptReturnType.
        * gm2/bnf/m2-3.bnf:  added OptReturnType for
          procedures (functions).  Rationalized function
          return values via OptReturnType.  Also added
          productions to implement functions using
          an optional return type.
        * gm2/bnf/m2-h.bnf:  added OptReturnType for
          procedures (functions).  Rationalized function
          return values via OptReturnType.
        * gm2/bnf/m2.bnf:  added OptReturnType for
          procedures (functions).  Rationalized function
          return values via OptReturnType.
        * gm2/examples/server/server.mod:  modified code
          to exploit calling printf and ignoring its return
          value.
        * gm2/examples/swig/exceptions/tiny.mod:  ignore
          return result for printf.
        * gm2/gm2-compiler/M2Quads.def:  define
          CheckBuildFunction.
        * gm2/gm2-compiler/M2Quads.mod:  implement
          CheckBuildFunction.
        * gm2/gm2-compiler/P2SymBuild.def:  corrected dates.
          Added new procedure definition
          BuildOptFunction.
        * gm2/gm2-compiler/P2SymBuild.mod:  corrected dates
          and implemented BuildOptFunction.
        * gm2/gm2-compiler/SymbolTable.def:  PutOptFunction
          (new definition).  IsReturnOptional (new definition).
        * gm2/gm2-compiler/SymbolTable.mod:  ReturnOptional
          new field for ProcedureSym and ProcTypeSym.
          Implemented IsReturnOptional, SetReturnOptional,
          CheckOptFunction and PutOptFunction.
          Set ReturnOptional appropriately.
        * gm2/gm2-libs/FIO.mod:  implemented GetFileName.
          Modified names of stdin, stdout and stderr to
          <stdin>, <stdout>, <stderr> respectively.
        * gm2/gm2-libs/errno.c:  added init and finish
          functions.
        * gm2/gm2-libs/libc.def:  declare printf to have
          an optional return value.
        * gm2/gm2-libs-iso/ChanConsts.def:  fixed dates.
        * gm2/gm2-libs-iso/IOChan.mod:  fixed dates
          and reimplemented this module.
        * gm2/gm2-libs-iso/RndFile.def:  fixed dates.
        * gm2/gm2-libs-iso/TextIO.def:  fixed dates.
        * gm2/p2c/p2c-src/src/decl.c:  handle new syntax
          for optional function return value.