From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Redelings I <bredelin@ucsd.edu>
To: egcs@cygnus.com
Subject: New c++ bug with conversion operators?
Date: Wed, 06 May 1998 16:13:00 -0000
Message-id: <3550C34B.B5D0BAA3@ucsd.edu>
X-SW-Source: 1998-05/msg00210.html

Hi!, I recently went from the 980315 snapshot to 19980502.  gcc still
compiles the kernel OK with -mpentiumpro -O12 -fstrength-reduce, but I
have a new problem with one of my C++ projects.

g++ now appears not to want 'const' conversion operators any more...
Here is my sample code:
---------------test.C------------------
struct string
{
  char* location;
  int length;

  operator const char*() const{return location;}
  /*  operator const char*() {return location;} */
  operator char*() {return location;}
};

main() {
  int i;
  string s1;
  const string s2=s1;

  i=strlen(s1);
  i=strlen(s2);
}
--------------end test.C--------------
Here is the text of the warnings:
telomere:~/devel/Psh.0.4.6.8> make test
g++ -fno-rtti -fno-exceptions -Wall -g -O13 -DNDEBUG -mpentiumpro
-I../include -fno-rtti -fno-exceptions   test.C   -o test
test.C: In function `int main()':
test.C:16: warning: choosing `string::operator char *()' over
`string::operator const char *() const'
test.C:16: warning:   for conversion from `string' to `const char *'
test.C:16: warning:   because conversion sequence for `this' argument is
better
test.C:16: warning: choosing `string::operator char *()' over
`string::operator const char *() const'
test.C:16: warning:   for conversion from `string' to `const char *'
test.C:16: warning:   because conversion sequence for `this' argument is
better


	This seems rather strange to me...the second 'const' in the declaration
of
'operator const char*()' just means that "*this" will not be changed
during the conversion (nor will be changed afterwards, with the info
provided by the conversion).  But g++ is saying that it won't use this
operator on 's1' because 's1' wasn't declared const!  That is
irrelevant.
	If it is possible to consider the type that s1 is being cast to by
strlen, then it should consider that instead and convert to 'const
char*'.

If you uncomment the second operator definition, the warning goes away. 
Wierd.  Am I perhaps coding this in the wrong way?  That DOES seem likea
strange way to code, but AFAIK C++ requires it.

-BenRI