c++/10551: Failure to emit explicitly instantiated template w/--no-implicit-templates

c++/10551: Failure to emit explicitly instantiated template w/--no-implicit-templates

[snyder]

>Number:         10551
>Category:       c++
>Synopsis:       Failure to emit explicitly instantiated template w/--no-implicit-templates
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 29 19:06:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     scott snyder
>Release:        3.4 20030429 (experimental)
>Organization:
<organization of PR author (multiple lines)>
>Environment:
System: Linux karma 2.4.19-emp_2419p5a829i #1 Tue Sep 3 17:42:17 EST 2002 i686 i686 i386 GNU/Linux
Architecture: i686

	<machine, os, target, libraries (multiple lines)>
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long --enable-languages=c,c++,f77 : (reconfigured) 
>Description:

The source below does not link if --no-implicit-templates is used,
because JTCHandleT<JTCThreadGroup>::~JTCHandleT isn't emitted:

$ g++ -o x --no-implicit-templates x.cc
/tmp/ccUf5Tw9.o: In function `__static_initialization_and_destruction_0(int, int)':
/tmp/ccUf5Tw9.o(.text+0x3e): undefined reference to `JTCHandleT<JTCThreadGroup>::~JTCHandleT [in-charge]()'
collect2: ld returned 1 exit status
$

It does work if implicit instantiation is used.

I see this both in 3.3 and 3.4; it seems to be related to this patch:

2003-04-25  Mark Mitchell  <mark@codesourcery.com>

	* decl2.c (finish_file): Don't call import_export_decl for
	functions that are not defined.
	(handle_class_head): Robustify.

If i revert this patch in 3.3, the problem goes away.



>How-To-Repeat:

--------------------------------------------------
template <class T> class JTCHandleT;

class JTCThreadGroup;
typedef JTCHandleT<JTCThreadGroup> JTCThreadGroupHandle;

template <class T>
struct JTCHandleT
{
  ~JTCHandleT();
};
template <class T> JTCHandleT<T>::~JTCHandleT() {}


struct JTCThreadGroup
{
  struct JTCThreadGroupSet
  {
    JTCThreadGroupHandle* handles_;
    ~JTCThreadGroupSet() { delete [] handles_; }
  };
};

template class JTCHandleT<JTCThreadGroup>;
JTCHandleT<JTCThreadGroup> x;

int main () { return 0; }
--------------------------------------------------

>Fix:
	<how to correct or work around the problem, if known (multiple lines)>
>Release-Note:
>Audit-Trail:
>Unformatted: