[gcc r14-6394] c++: Clear uninstantiated template friend when instantiating [PR104234]

[Nathaniel Shead]

https://gcc.gnu.org/g:ab3daffcbf35566d468c3028e48068a481048baf

commit r14-6394-gab3daffcbf35566d468c3028e48068a481048baf
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Thu Nov 23 23:15:19 2023 +1100

    c++: Clear uninstantiated template friend when instantiating [PR104234]
    
    Otherwise attempting to get the originating module declaration ICEs
    because the DECL_CHAIN of an instantiated friend template is no longer
    its context.
    
            PR c++/104234
            PR c++/112580
    
    gcc/cp/ChangeLog:
    
            * pt.cc (tsubst_template_decl): Clear
            DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/modules/pr104234.C: New test.
    
    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>

Diff:
---
 gcc/cp/pt.cc                            |  2 ++
 gcc/testsuite/g++.dg/modules/pr104234.C | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 669d2ad65c3..e9dcdb32c6c 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -14790,6 +14790,8 @@ tsubst_template_decl (tree t, tree args, tsubst_flags_t complain,
   if (PRIMARY_TEMPLATE_P (t))
     DECL_PRIMARY_TEMPLATE (r) = r;
 
+  DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P (r) = false;
+
   if (!lambda_fntype && !class_p)
     {
       /* Record this non-type partial instantiation.  */
diff --git a/gcc/testsuite/g++.dg/modules/pr104234.C b/gcc/testsuite/g++.dg/modules/pr104234.C
new file mode 100644
index 00000000000..d81f0d435bc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr104234.C
@@ -0,0 +1,16 @@
+// PR c++/104234
+// { dg-additional-options "-fmodules-ts" }
+
+template <typename> struct _Node_handle_common {
+  template <typename> friend class _Rb_tree;
+};
+struct _Hashtable {
+  using node_type = _Node_handle_common<int>;
+  node_type __trans_tmp_1;
+};
+template <typename> class _Rb_tree {
+  struct _Rb_tree_impl {
+    _Rb_tree_impl();
+  } _M_impl;
+};
+_Rb_tree<int> _M_tmap_;