const void as return type

crewchill

I found this code a little confusing. Due to proprietary nature of the original source, I have to abstract this out. What does const void return value mean? I can understand the intent of "const void*" return value, but "const void" seems to be just a typo? Am I missing anything fancy with the construct here?

#include typedef const void (*hello)();

const void x()
{
printf("x() is called\n");
}

int main()
{
hello test=x;
test();
}

Stuart Dootson

I don't believe you're missing anything - it does seem odd. In fact, gcc raises a warning on a function returning const void:

a.c:2: warning: function definition has qualified void return type

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

led mike

crewchill wrote:

I found this code a little confusing.

Yes. Working with legacy code I often find confusing items or constructs. My initial reaction is, like yours:

crewchill wrote:

Am I missing anything fancy with the construct here?

Then later it becomes apparent that the author was just stupid. :sigh: On the bright side, tomorrow is FRIDAY! :beer: :jig:

crewchill

Hm... which gcc are you using? Mine doesn't even complain about it.

~
$ cat x.c
#include <stdio.h>

typedef const void (*hello)();

const void x()
{
printf("x() is called\n");
}

int main()
{
hello test=x;
test();
}

~
$ gcc x.c

~
$ ./a.exe
x() is called

~
$ gcc --ver
Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs
Configured with: /usr/build/package/orig/test.respin/gcc-3.4.4-3/configure --ver
bose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib --libe
xecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --enable-langu
ages=c,ada,c++,d,f77,pascal,java,objc --enable-nls --without-included-gettext --
enable-version-specific-runtime-libs --without-x --enable-libgcj --disable-java-
awt --with-system-zlib --enable-interpreter --disable-libgcj-debug --enable-thre
ads=posix --enable-java-gc=boehm --disable-win32-registry --enable-sjlj-exceptio
ns --enable-hash-synchronization --enable-libstdcxx-debug
Thread model: posix
gcc version 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)

crewchill

Amen to Friday. My head is about to explode already. You know the scariest part was, this is quite recent code. The older version didn't have this and somehow the extra "const" appeared after it's being code reviewed :( Not by me, mind you.

Stuart Dootson

i686-apple-darwin9-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5490)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p