From: "Oliver Roese" <oroese AT edina DOT xnc DOT com>
Newsgroups: comp.os.msdos.djgpp
References: <84EFC73E5BDD300C DOT 85A7FCC32BD1270B DOT F7CB654E8161FA9A AT lp DOT airnews DOT net>
Subject: Re: return type for `main' changed to `int'
Date: Sun, 17 Oct 1999 18:49:40 +0200
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To: djgpp AT delorie DOT com
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Rodeo Red <rodeored AT netstep DOT net> schrieb in im Newsbeitrag:
84EFC73E5BDD300C DOT 85A7FCC32BD1270B DOT F7CB654E8161FA9A AT lp DOT airnews DOT net...
(...)
> This command line:
>
>   gcc -c -Wall hello.cpp
>
> is supposed to produce the object file hello.o, but doesn't . Instead I
> get this message:
> hello.cpp:4: return type for `main' changed to `int'
>
> What does this mean ?
>
>
> here is hello.cpp:
>
> #include <iostream.h>
>
>    void main ()
>       {
>              cout <<"Hello world!\n";
>                 }
>
(...)

I tried to compile the program you provided, with the switches you told (vers. 2.95).
Here is what I got:
>gcc -c -Wall hello.cpp
hello.cpp:4: warning: return type for `main' changed to `int'

gcc simply omits a warning, since you told it to provide (mostly) all warnings, but compiles
your file without problems!
As you may already know, it is in C allowed but not recommend to alter the return type of  "main"
(since then the return-value is unspecified).
But is it for a cpp-program?
I searched a locale copy of an Ansi-C++ draft and here is what i found:
(...)
  This function is not predefined by the implementation,  it  cannot  be
  overloaded,    and    its   type   is   implementation-defined.    All

  implementations shall allow both of the following definitions of main:
          int main() { /* ... */ }
  and
          int main(int argc, char* argv[]) { /* ... */ }
(...)
  If  control
  reaches  the  end of main without encountering a return statement, the
  effect is that of executing
          return 0;
(...)



According to this, you were right to report this warning as an anomaly for a cpp-program.

Best Regards
Oliver Roese