V3 PATCH: Explicitly instantiate string::npos

[Mark Mitchell <mark at codesourcery dot com>]

I'm gradually making progress with the IRIX port of V3, needed for GCC
3.0.

I ran into an infinite loop on initialization that turned out to be
caused by a semi-bug in the compiler and a semi-bug in V3.  (Fixing
either one would actually cure this problem, but both should be
fixed.)

Consider this test program:

  template <class T>
  struct U {
    static int j;
  };

  template <class T>
  struct S {
    static const int i = 7;
  };

  template <class T>
  const int S<T>::i;

  template <class T>
  int U<T>::j = S<T>::i + 5;

  template int U<double>::j;

  int main () {
  }

Compile with -fno-implicit-templates:

  bash$ g++1.sh  -fno-implicit-templates test.C
  /tmp/ccP80kVh.o: In function `__static_initialization_and_destruction_0':
  /tmp/ccP80kVh.o(.text+0x32): undefined reference to `S<double>::i'
  collect2: ld returned 1 exit status

It's pretty silly that the compiler doesn't resolve S<double>::i to
its constant intiailizer value (7).  It's not technically a bug, but
it is a quality-of-implementation issue.

In the V3 case, this resulted in basic_string::_S_Rep::_S_max_size
(whose initializer depends on basic_string::_S_Rep::npos) being
dynamically initialized when explicitly instantiated in
string-inst.cc.  That's not just a performance issue -- it's also a
correctness issue.

During start-up, some piece of the locale library creates a string
`"C"' corresponding to the current locale.  But, since _S_max_size
wasn't initialized yet, the string-creation stuff thought the
1-character string was too long, and threw an exception.  But,
initializing the exception caused the creation of a new string
(explaining that the string was too long).  This string was too long,
too, of course, and we never even get to main...

Here's the V3 fix.

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com

2000-10-28  Mark Mitchell  <mark@codesourcery.com>

	* src/string-inst.cc (basic_string<C>::npos): Explicitly
	instantiate it.

Index: src/string-inst.cc
===================================================================
RCS file: /cvs/gcc/egcs/libstdc++-v3/src/string-inst.cc,v
retrieving revision 1.9
diff -c -p -r1.9 string-inst.cc
*** string-inst.cc	2000/08/23 04:38:42	1.9
--- string-inst.cc	2000/10/28 21:21:31
*************** namespace std 
*** 48,53 ****
--- 48,54 ----
    typedef basic_string<C> S;
  
    template C S::_Rep::_S_terminal;
+   template const S::size_type S::npos;
    template S::size_type S::_Rep::_S_max_size;
    template S::size_type S::_S_empty_rep_storage[];
    template S::_Rep* S::_Rep::_S_create(size_t, S::allocator_type const&);