PR c++/84160 - ICE with nested variadic capture.

	* lambda.c (is_capture_proxy_with_ref): New.
	(insert_capture_proxy): Don't set DECL_CAPTURED_VARIABLE from a
	COMPONENT_REF.
	* expr.c (mark_use): Use is_capture_proxy_with_ref.
	* constexpr.c (potential_constant_expression_1): Likewise.
	* semantics.c (process_outer_var_ref): Likewise.

From-SVN: r257325

1 files changed, 26 insertions, 6 deletions

diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index e1caaef..ff8236a 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -290,13 +290,24 @@ is_normal_capture_proxy (tree decl)
   return DECL_NORMAL_CAPTURE_P (val);
 }
 
+/* Returns true iff DECL is a capture proxy for which we can use
+   DECL_CAPTURED_VARIABLE.  In effect, this is a normal proxy other than a
+   nested capture of a function parameter pack.  */
+
+bool
+is_capture_proxy_with_ref (tree var)
+{
+  return (is_normal_capture_proxy (var) && DECL_LANG_SPECIFIC (var)
+	  && DECL_CAPTURED_VARIABLE (var));
+}
+
 /* VAR is a capture proxy created by build_capture_proxy; add it to the
    current function, which is the operator() for the appropriate lambda.  */
 
 void
 insert_capture_proxy (tree var)
 {
-  if (is_normal_capture_proxy (var))
+  if (is_capture_proxy_with_ref (var))
     {
       tree cap = DECL_CAPTURED_VARIABLE (var);
       if (CHECKING_P)
@@ -443,11 +454,20 @@ build_capture_proxy (tree member, tree init)
 	    init = TREE_OPERAND (init, 0);
 	  STRIP_NOPS (init);
 	}
-      gcc_assert (VAR_P (init) || TREE_CODE (init) == PARM_DECL);
-      while (is_normal_capture_proxy (init))
-	init = DECL_CAPTURED_VARIABLE (init);
-      retrofit_lang_decl (var);
-      DECL_CAPTURED_VARIABLE (var) = init;
+
+      if (TREE_CODE (init) == COMPONENT_REF)
+	/* We're capturing a capture of a function parameter pack, and have
+	   lost track of the original variable.  It's not important to have
+	   DECL_CAPTURED_VARIABLE in this case, since a function parameter pack
+	   isn't a constant variable, so don't bother trying to set it.  */;
+      else
+	{
+	  gcc_assert (VAR_P (init) || TREE_CODE (init) == PARM_DECL);
+	  while (is_normal_capture_proxy (init))
+	    init = DECL_CAPTURED_VARIABLE (init);
+	  retrofit_lang_decl (var);
+	  DECL_CAPTURED_VARIABLE (var) = init;
+	}
     }
 
   if (name == this_identifier)