[pushed] c++: DMI in template with virtual base [PR106890]

[Jason Merrill <jason@redhat.com>]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

When parsing a default member init we just build a CONVERT_EXPR for
converting to a virtual base, and then expand that into the more complex
form when we actually use the DMI in a constructor.  But that wasn't working
for the template case where we are considering the conversion at the point
that the constructor needs the DMI instantiation, so it seemed like we were
in a constructor already.  And then when the other constructor tries to
reuse the instantiation, it sees uses of the first constructor's parameters,
and dies.  So ensure that we get the CONVERT_EXPR in this case, too.

	PR c++/106890

gcc/cp/ChangeLog:

	* init.cc (maybe_instantiate_nsdmi_init): Don't leave
	current_function_decl set to a constructor.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/nsdmi-template25.C: New test.
---
 gcc/cp/init.cc                                | 14 ++++++++++++++
 gcc/testsuite/g++.dg/cpp0x/nsdmi-template25.C | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template25.C

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 90302372340..c5a55dae563 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -613,6 +613,18 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 	      pushed = true;
 	    }
 
+	  /* If we didn't push_to_top_level, still step out of constructor
+	     scope so build_base_path doesn't try to use its __in_chrg.  */
+	  tree cfd = current_function_decl;
+	  auto cbl = current_binding_level;
+	  if (at_function_scope_p ())
+	    {
+	      current_function_decl
+		= decl_function_context (current_function_decl);
+	      while (current_binding_level->kind != sk_class)
+		current_binding_level = current_binding_level->level_chain;
+	    }
+
 	  inject_this_parameter (ctx, TYPE_UNQUALIFIED);
 
 	  start_lambda_scope (member);
@@ -629,6 +641,8 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 	  if (init != error_mark_node)
 	    hash_map_safe_put<hm_ggc> (nsdmi_inst, member, init);
 
+	  current_function_decl = cfd;
+	  current_binding_level = cbl;
 	  if (pushed)
 	    {
 	      pop_deferring_access_checks ();
diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template25.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template25.C
new file mode 100644
index 00000000000..368e745540e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template25.C
@@ -0,0 +1,18 @@
+// PR c++/106890
+// { dg-do compile { target c++11 } }
+
+struct A
+{
+  int p;
+};
+
+template<typename T>
+struct B : virtual public A
+{
+  B() { }
+  B(int) { }
+
+  int k = this->p;
+};
+
+template struct B<int>;

base-commit: 0a846340b99675d57fc2f2923a0412134eed09d3
-- 
2.31.1