[CLN-list] patch for cln with gcc-4

[Ralf Wildenhues]

Hi Richard,

* Richard B. Kreckel wrote on Fri, Apr 15, 2005 at 11:31:09PM CEST:
> On Fri, 15 Apr 2005, Ralf Wildenhues wrote:
> > This trivial patch is necessary for cln to compile with gcc-4
> > prerelease.  Without it, the friend declarations below are marked as
> > erroneous.
> 
> I'ld either have to read the standard to be convinced that they are really
> erroneous...
> ...or be able to reproduce a failure, because over here it works with
> gcc-4.0.0-20050410 even with -Werror...
> ...or be in a good mood and just apply the patch.
> 
> Seriously: where did you see the failure?

$ /tmp/gcc-test/bin/g++ -g -O3 -march=nocona -W -Wall -I../include -I../../cln/include -I../../cln/src/base -c ../../cln/src/base/output/cl_prin_globals.cc  -fPIC -DPIC -o .libs/cl_prin_globals.o
../../cln/include/cln/string.h:30: error: ISO C++ forbids declaration of 'cl_string' with no type
../../cln/include/cln/string.h:30: error: 'cl_string' is neither function nor member function; cannot be declared friend
../../cln/include/cln/string.h:30: error: expected ';' before 'operator'
../../cln/include/cln/string.h:31: error: ISO C++ forbids declaration of 'cl_string' with no type
../../cln/include/cln/string.h:31: error: 'cl_string' is neither function nor member function; cannot be declared friend
../../cln/include/cln/string.h:31: error: expected ';' before 'operator'
../../cln/include/cln/string.h:32: error: ISO C++ forbids declaration of 'cl_string' with no type
../../cln/include/cln/string.h:32: error: 'cl_string' is neither function nor member function; cannot be declared friend
../../cln/include/cln/string.h:32: error: expected ';' before 'operator'

$ /tmp/gcc-test/bin/g++ --version
g++ (GCC) 4.1.0 20050415 (experimental)
Copyright (C) 2005 Free Software Foundation, Inc.

This compiler is straight from CVS HEAD (that day).  Sorry for not
noticing that I had left 4.0.0 CVS now.  So, again CLN brings out
another compiler issue (ok, we don't know yet who is at fault :).
The only related change a cursory search gives me is this:
http://gcc.gnu.org/ml/gcc-patches/2005-04/msg01244.html


So, let's look at this simple test case:

class X {
  friend class Y;
  friend int foo(const Y&);
};

is marked as erroneous:
a.cc:3: error: expected ‘,’ or ‘...’ before ‘&’ token
a.cc:3: error: ISO C++ forbids declaration of ‘Y’ with no type

while this, for example,

class X {
  class Y;
  friend class Y;
  friend int foo(const Y&);
};

is ok.  With this patch instead:

--- include/cln/string.h	23 Jun 2004 21:11:21 -0000	1.4
+++ include/cln/string.h	18 Apr 2005 09:26:42 -0000
@@ -23,6 +23,7 @@
 	cl_heap_string ();
 private:
 // Friend declarations. They are for the compiler. Just ignore them.
+	class cl_string;
 	friend class cl_string;
 	friend cl_heap_string* cl_make_heap_string (unsigned long len);
 	friend cl_heap_string* cl_make_heap_string (const char * s);

I get these errors:

$ /tmp/gcc-test/bin/g++ -g -O3 -march=nocona -W -Wall -I../include -I../../cln/include -I../../cln/src/base -c ../../cln/src/base/output/cl_prin_globals.cc  -fPIC -DPIC -o .libs/cl_prin_globals.o
../../cln/include/cln/string.h: In member function 'const char* cln::cl_string::asciz() const':
../../cln/include/cln/string.h:17: error: 'char cln::cl_heap_string::data [1]' is private
../../cln/include/cln/string.h:44: error: within this context
../../cln/include/cln/string.h: In member function 'long unsigned int cln::cl_string::length() const':
../../cln/include/cln/string.h:16: error: 'long unsigned int cln::cl_heap_string::length' is private
../../cln/include/cln/string.h:49: error: within this context
../../cln/include/cln/string.h: In member function 'char cln::cl_string::operator[](long unsigned int) const':
../../cln/include/cln/string.h:17: error: 'char cln::cl_heap_string::data [1]' is private
../../cln/include/cln/string.h:55: error: within this context


but with this patch:

--- include/cln/string.h	23 Jun 2004 21:11:21 -0000	1.4
+++ include/cln/string.h	18 Apr 2005 09:28:07 -0000
@@ -24,6 +24,7 @@
 private:
 // Friend declarations. They are for the compiler. Just ignore them.
 	friend class cl_string;
+	struct cl_string;
 	friend cl_heap_string* cl_make_heap_string (unsigned long len);
 	friend cl_heap_string* cl_make_heap_string (const char * s);
 	friend cl_heap_string* cl_make_heap_string (const char * ptr, unsigned long len);

it all compiles fine.

I am by no means a C++ expert.  You decide what to do.  :)
(I can ask on one of the gcc lists if you want to, but only if someone
explains to me why gcc should be wrong.)

Regards,
Ralf