1 files changed, 129 insertions, 1 deletions

diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 78bd89782aa..76f2f29578f 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -297,7 +297,17 @@ void
 insert_capture_proxy (tree var)
 {
   if (is_normal_capture_proxy (var))
-    register_local_specialization (var, DECL_CAPTURED_VARIABLE (var));
+    {
+      tree cap = DECL_CAPTURED_VARIABLE (var);
+      if (CHECKING_P)
+	{
+	  gcc_assert (!is_normal_capture_proxy (cap));
+	  tree old = retrieve_local_specialization (cap);
+	  if (old)
+	    gcc_assert (DECL_CONTEXT (old) != DECL_CONTEXT (var));
+	}
+      register_local_specialization (var, cap);
+    }
 
   /* Put the capture proxy in the extra body block so that it won't clash
      with a later local variable.  */
@@ -977,6 +987,121 @@ generic_lambda_fn_p (tree callop)
 	  && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (callop)));
 }
 
+/* Returns true iff we need to consider default capture for an enclosing
+   generic lambda.  */
+
+bool
+need_generic_capture (void)
+{
+  if (!processing_template_decl)
+    return false;
+
+  tree outer_closure = NULL_TREE;
+  for (tree t = current_class_type; t;
+       t = decl_type_context (TYPE_MAIN_DECL (t)))
+    {
+      tree lam = CLASSTYPE_LAMBDA_EXPR (t);
+      if (!lam || LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lam) == CPLD_NONE)
+	/* No default capture.  */
+	break;
+      outer_closure = t;
+    }
+
+  if (!outer_closure)
+    /* No lambda.  */
+    return false;
+  else if (dependent_type_p (outer_closure))
+    /* The enclosing context isn't instantiated.  */
+    return false;
+  else
+    return true;
+}
+
+/* A lambda-expression...is said to implicitly capture the entity...if the
+   compound-statement...names the entity in a potentially-evaluated
+   expression where the enclosing full-expression depends on a generic lambda
+   parameter declared within the reaching scope of the lambda-expression.  */
+
+static tree
+dependent_capture_r (tree *tp, int *walk_subtrees, void *data)
+{
+  hash_set<tree> *pset = (hash_set<tree> *)data;
+
+  if (TYPE_P (*tp))
+    *walk_subtrees = 0;
+
+  if (outer_automatic_var_p (*tp))
+    {
+      tree t = process_outer_var_ref (*tp, tf_warning_or_error, /*force*/true);
+      if (t != *tp
+	  && TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE
+	  && TREE_CODE (TREE_TYPE (*tp)) != REFERENCE_TYPE)
+	t = convert_from_reference (t);
+      *tp = t;
+    }
+
+  if (pset->add (*tp))
+    *walk_subtrees = 0;
+
+  switch (TREE_CODE (*tp))
+    {
+      /* Don't walk into unevaluated context or another lambda.  */
+    case SIZEOF_EXPR:
+    case ALIGNOF_EXPR:
+    case TYPEID_EXPR:
+    case NOEXCEPT_EXPR:
+    case LAMBDA_EXPR:
+      *walk_subtrees = 0;
+      break;
+
+      /* Don't walk into statements whose subexpressions we already
+	 handled.  */
+    case TRY_BLOCK:
+    case EH_SPEC_BLOCK:
+    case HANDLER:
+    case IF_STMT:
+    case FOR_STMT:
+    case RANGE_FOR_STMT:
+    case WHILE_STMT:
+    case DO_STMT:
+    case SWITCH_STMT:
+    case STATEMENT_LIST:
+    case RETURN_EXPR:
+      *walk_subtrees = 0;
+      break;
+
+    case DECL_EXPR:
+      {
+	tree decl = DECL_EXPR_DECL (*tp);
+	if (VAR_P (decl))
+	  {
+	    /* walk_tree_1 won't step in here.  */
+	    cp_walk_tree (&DECL_INITIAL (decl),
+			  dependent_capture_r, &pset, NULL);
+	    *walk_subtrees = 0;
+	  }
+      }
+      break;
+
+    default:
+      break;
+    }
+
+  return NULL_TREE;
+}
+
+tree
+do_dependent_capture (tree expr, bool force)
+{
+  if (!need_generic_capture ()
+      || (!force && !instantiation_dependent_expression_p (expr)))
+    return expr;
+
+  hash_set<tree> pset;
+  cp_walk_tree (&expr, dependent_capture_r, &pset, NULL);
+  return expr;
+}
+
 /* If the closure TYPE has a static op(), also add a conversion to function
    pointer.  */
 
@@ -1073,7 +1198,10 @@ maybe_add_lambda_conv_op (tree type)
 
 	if (generic_lambda_p)
 	  {
+	    /* Avoid capturing variables in this context.  */
+	    ++cp_unevaluated_operand;
 	    tree a = forward_parm (tgt);
+	    --cp_unevaluated_operand;
 
 	    CALL_EXPR_ARG (call, ix) = a;
 	    if (decltype_call)