From: Nathan Sidwell <nathan@acm.org>
Date: Wed, 23 Sep 2020 14:01:10 +0000 (-0700)
Subject: c++: dependent local extern decl ICE [PR97171]
X-Git-Tag: basepoints/gcc-12~4859
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=13f7c5d504b5fe6c233f2e68acd10bd4fc9007ac;p=thirdparty%2Fgcc.git

c++: dependent local extern decl ICE [PR97171]

I'd missed the piece of substutution for the uses of a local extern
decl.  Just grab the local specialization.  We need to do this
regardless of dependentness because we always cloned the local extern.

	PR c++/97171
	gcc/cp/
	* pt.c (tsubst_copy) [FUNCTION_DECL,VAR_DECL]: Retrieve local
	specialization for DECL_LOCAL_P decls.
	gcc/testsuite/
	* g++.dg/template/local10.C: New.
---

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 314bd038c6d5..1ec039d07931 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -16531,6 +16531,14 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
     case FUNCTION_DECL:
       if (DECL_LANG_SPECIFIC (t) && DECL_TEMPLATE_INFO (t))
 	r = tsubst (t, args, complain, in_decl);
+      else if (DECL_LOCAL_DECL_P (t))
+	{
+	  /* Local specialization will have been created when we
+	     instantiated the DECL_EXPR_DECL. */
+	  r = retrieve_local_specialization (t);
+	  if (!r)
+	    r = error_mark_node;
+	}
       else if (local_variable_p (t)
 	       && uses_template_parms (DECL_CONTEXT (t)))
 	{
diff --git a/gcc/testsuite/g++.dg/template/local10.C b/gcc/testsuite/g++.dg/template/local10.C
new file mode 100644
index 000000000000..a2ffc1e73066
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/local10.C
@@ -0,0 +1,15 @@
+// PR c++/97171
+// { dg-additional-options -flto }
+
+template <typename _UnaryOperation>
+void transform(_UnaryOperation);
+
+template <typename T>
+void Apply ()
+{
+  extern T Maker (void);  // block-scope extern with dependent type
+
+  transform (Maker);
+}
+
+template void Apply<int> ();