Implement P0018R3, C++17 lambda capture of *this by value as [=,*this]

	Implement P0018R3, C++17 lambda capture of *this by value as [=,*this]
	* parser.c (cp_parser_lambda_introducer): Formatting fix.  Pass
	true instead of false as by_reference_p to add_capture for 'this'.
	Parse '*this' simple-capture.
	* lambda.c (build_capture_proxy): Handle '*this' capture by value.
	(add_capture): Adjust function comment.  For id == this_identifier,
	treat by_reference_p as capturing '*this' by reference, i.e. 'this'
	by value, and !by_reference_p as capturing '*this' by value.
	(add_default_capture): For implicit 'this' capture, always pass
	by_reference_p true rather than false.

	* g++.dg/cpp1z/lambda-this1.C: New test.
	* g++.dg/cpp1z/lambda-this2.C: New test.

From-SVN: r240556

3 files changed, 49 insertions, 5 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 75c9d36..1a1f186 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,16 @@
 2016-09-27  Jakub Jelinek  <jakub@redhat.com>
 
+	Implement P0018R3, C++17 lambda capture of *this by value as [=,*this]
+	* parser.c (cp_parser_lambda_introducer): Formatting fix.  Pass
+	true instead of false as by_reference_p to add_capture for 'this'.
+	Parse '*this' simple-capture.
+	* lambda.c (build_capture_proxy): Handle '*this' capture by value.
+	(add_capture): Adjust function comment.  For id == this_identifier,
+	treat by_reference_p as capturing '*this' by reference, i.e. 'this'
+	by value, and !by_reference_p as capturing '*this' by value.
+	(add_default_capture): For implicit 'this' capture, always pass
+	by_reference_p true rather than false.
+
 	PR c++/77722
 	* cp-gimplify.c (cp_ubsan_maybe_instrument_return): Instrument also
 	functions that have just a STATEMENT_LIST instead of BIND_EXPR, or
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index d511185..cd32226 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -380,6 +380,13 @@ build_capture_proxy (tree member)
 
   type = lambda_proxy_type (object);
 
+  if (name == this_identifier && !POINTER_TYPE_P (type))
+    {
+      type = build_pointer_type (type);
+      type = cp_build_qualified_type (type, TYPE_QUAL_CONST);
+      object = build_fold_addr_expr_with_type (object, type);
+    }
+
   if (DECL_VLA_CAPTURE_P (member))
     {
       /* Rebuild the VLA type from the pointer and maxindex.  */
@@ -440,7 +447,8 @@ vla_capture_type (tree array_type)
 
 /* From an ID and INITIALIZER, create a capture (by reference if
    BY_REFERENCE_P is true), add it to the capture-list for LAMBDA,
-   and return it.  */
+   and return it.  If ID is `this', BY_REFERENCE_P says whether
+   `*this' is captured by reference.  */
 
 tree
 add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,
@@ -499,7 +507,14 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,
       type = lambda_capture_field_type (initializer, explicit_init_p);
       if (type == error_mark_node)
 	return error_mark_node;
-      if (by_reference_p)
+      if (id == this_identifier && !by_reference_p)
+	{
+	  gcc_assert (POINTER_TYPE_P (type));
+	  type = TREE_TYPE (type);
+	  initializer = cp_build_indirect_ref (initializer, RO_NULL,
+					       tf_warning_or_error);
+	}
+      if (id != this_identifier && by_reference_p)
 	{
 	  type = build_reference_type (type);
 	  if (!dependent_type_p (type) && !lvalue_p (initializer))
@@ -628,8 +643,8 @@ add_default_capture (tree lambda_stack, tree id, tree initializer)
                             id,
                             initializer,
                             /*by_reference_p=*/
-			    (!this_capture_p
-			     && (LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lambda)
+			    (this_capture_p
+			     || (LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lambda)
 				 == CPLD_REFERENCE)),
 			    /*explicit_init_p=*/false);
       initializer = convert_from_reference (var);
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 5ec8b1b..f672b8d 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -9899,7 +9899,25 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
 	  cp_lexer_consume_token (parser->lexer);
 	  add_capture (lambda_expr,
 		       /*id=*/this_identifier,
-		       /*initializer=*/finish_this_expr(),
+		       /*initializer=*/finish_this_expr (),
+		       /*by_reference_p=*/true,
+		       explicit_init_p);
+	  continue;
+	}
+
+      /* Possibly capture `*this'.  */
+      if (cp_lexer_next_token_is (parser->lexer, CPP_MULT)
+	  && cp_lexer_nth_token_is_keyword (parser->lexer, 2, RID_THIS))
+	{
+	  location_t loc = cp_lexer_peek_token (parser->lexer)->location;
+	  if (cxx_dialect < cxx1z)
+	    pedwarn (loc, 0, "%<*this%> capture only available with "
+			     "-std=c++1z or -std=gnu++1z");
+	  cp_lexer_consume_token (parser->lexer);
+	  cp_lexer_consume_token (parser->lexer);
+	  add_capture (lambda_expr,
+		       /*id=*/this_identifier,
+		       /*initializer=*/finish_this_expr (),
 		       /*by_reference_p=*/false,
 		       explicit_init_p);
 	  continue;