[PATCH][C++] Fix PR39242

[Richard Guenther <rguenther at suse dot de>]

This avoids instantiating extern but not inline declared functions which
fixes Yast YCP compilation.

The patch has slight positive effect on memory-usage and binary size of
the set of C++ testcases run by gcc.opensuse.org.

Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk?

Thanks,
Richard.

2009-02-20  Richard Guenther  <rguenther@suse.de>

	PR c++/39242
	* pt.c (instantiate_decl): Do not instantiate extern, non-inline
	declared functions.

	* g++.dg/template/instantiate10.C: New testcase.

Index: gcc/cp/pt.c
===================================================================
*** gcc/cp/pt.c	(revision 144292)
--- gcc/cp/pt.c	(working copy)
*************** instantiate_decl (tree d, int defer_ok,
*** 15283,15291 ****
    /* In general, we do not instantiate such templates...  */
    if (external_p
        /* ... but we instantiate inline functions so that we can inline
! 	 them and ... */
        && ! (TREE_CODE (d) == FUNCTION_DECL
! 	    && possibly_inlined_p (d))
        /* ... we instantiate static data members whose values are
  	 needed in integral constant expressions.  */
        && ! (TREE_CODE (d) == VAR_DECL
--- 15283,15296 ----
    /* In general, we do not instantiate such templates...  */
    if (external_p
        /* ... but we instantiate inline functions so that we can inline
! 	 them.  An explicit instantiation declaration prohibits implicit
! 	 instantiation of non-inline functions.  With high levels of
! 	 optimization, we would normally inline non-inline functions
! 	 -- but we're not allowed to do that for "extern template" functions.
! 	 Therefore, we check DECL_DECLARED_INLINE_P, rather than
! 	 possibly_inlined_p.  And ...  */
        && ! (TREE_CODE (d) == FUNCTION_DECL
! 	    && DECL_DECLARED_INLINE_P (d))
        /* ... we instantiate static data members whose values are
  	 needed in integral constant expressions.  */
        && ! (TREE_CODE (d) == VAR_DECL
Index: gcc/testsuite/g++.dg/template/instantiate10.C
===================================================================
*** gcc/testsuite/g++.dg/template/instantiate10.C	(revision 0)
--- gcc/testsuite/g++.dg/template/instantiate10.C	(revision 0)
***************
*** 0 ****
--- 1,37 ----
+ /* PR c++/39242, xplicit instantiation declaration prohibits implicit
+    instantiation of non-inline functions.  */
+ /* { dg-do compile } */
+ /* { dg-options "-O" } */
+ 
+ class Rep {
+ public:
+     void unref() const { }
+     static void unref (const Rep * obj_r) { obj_r->unref(); }
+ };
+ template<typename _Tp, typename _Bt = _Tp>
+ class RepPtrStore {
+     _Tp * _obj;
+     void _assign( _Tp * new_r );
+ public:
+     ~RepPtrStore() { _assign( 0 ); }
+ };
+ template<typename _Tp,typename _Bt>
+ void RepPtrStore<_Tp,_Bt>::_assign( _Tp * new_r )
+ {
+   Rep::unref( _obj );
+ }
+ class RepPtrBase { };
+ template<typename _Bt> class PtrBase : public RepPtrBase { };
+ template<typename _Tp, typename _Bt = _Tp>
+ class Ptr : public PtrBase<_Bt> {
+     RepPtrStore<_Tp,_Bt> _ptr;
+ };
+ class YCode;
+ class YStatement;
+ typedef Ptr<YStatement,YCode> YStatementPtr;
+ extern template class RepPtrStore<YStatement,YCode>;
+ class ExecutionEnvironment {
+     YStatementPtr m_statement;
+     ~ExecutionEnvironment() { };
+ };
+