[Ada] Enable lock free protected implementation by default

In the past, the Lock_Free aspect of a protected type (including an
anonymous type) defaulted to False. In the case where an explicit
"Lock_Free => True" aspect specification would be legal, the aspect now
defaults to True (which means that a lock-free implementation is used to
implement the type's protected operations); this is like the previous
behavior of the compiler with the -gnatd9 switch specified. Support for
the Lock_Free attribute (which should not be confused with the Lock_Free
aspect) is removed.

gcc/ada/

	* debug.adb: Remove comment regarding the -gnatd9 switch.
	* doc/gnat_rm/implementation_defined_attributes.rst: Remove all
	mention of the Lock_Free attribute.
	* gnat_rm.texi, gnat_ugn.texi: Regenerate.
	* exp_attr.adb, sem_attr.adb: Remove all mention of the former
	Attribute_Lock_Free enumeration element of the Attribute_Id type.
	* sem_ch9.adb
	(Allows_Lock_Free_Implementation): Remove the Debug_Flag_9 test.
	Return False in the case of a protected function whose result type
	requires use of the secondary stack.
	(Satisfies_Lock_Free_Requirements): This functions checks for
	certain constructs and returns False if one is found. In the case
	of a protected function, there is no need to check to see if the
	protected object is being modified. So it is ok to omit *some*
	checks in the case of a protected function. But other checks which
	are required (e.g., the test for a reference to a variable that is
	not part of the protected object) were being incorrectly omitted.
	This could result in accepting "Lock_Free => True" aspect
	specifications that should be rejected.
	* snames.adb-tmpl: Name_Lock_Free no longer requires special
	treatment in Get_Pragma_Id or Is_Pragma_Name (because it is no
	longer an attribute name).
	* snames.ads-tmpl: Move the declaration of Name_Lock_Free to
	reflect the fact that it is no longer the name of an attribute.
	Delete Attribute_Lock_Free from the Attribute_Id enumeration type.

1 files changed, 1 insertions, 43 deletions

diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
index 93bb6f4..86c7d0f 100644
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -4697,19 +4697,6 @@ package body Sem_Attr is
 
          Set_Etype (N, Standard_Boolean);
 
-      ---------------
-      -- Lock_Free --
-      ---------------
-
-      when Attribute_Lock_Free =>
-         Check_E0;
-         Set_Etype (N, Standard_Boolean);
-
-         if not Is_Protected_Type (P_Type) then
-            Error_Attr_P
-              ("prefix of % attribute must be a protected object");
-         end if;
-
       ----------------
       -- Loop_Entry --
       ----------------
@@ -8338,15 +8325,6 @@ package body Sem_Attr is
 
             return;
 
-         --  For Lock_Free, we apply the attribute to the type of the object.
-         --  This is allowed since we have already verified that the type is a
-         --  protected type.
-
-         elsif Id = Attribute_Lock_Free then
-            P_Entity := Etype (P);
-
-         --  No other attributes for objects are folded
-
          else
             Check_Expressions;
             return;
@@ -8476,7 +8454,6 @@ package body Sem_Attr is
              Id = Attribute_Has_Access_Values            or else
              Id = Attribute_Has_Discriminants            or else
              Id = Attribute_Has_Tagged_Values            or else
-             Id = Attribute_Lock_Free                    or else
              Id = Attribute_Preelaborable_Initialization or else
              Id = Attribute_Type_Class                   or else
              Id = Attribute_Unconstrained_Array          or else
@@ -8595,7 +8572,7 @@ package body Sem_Attr is
       --  only the First, Last and Length attributes are possibly static.
 
       --  Atomic_Always_Lock_Free, Definite, Descriptor_Size, Has_Access_Values
-      --  Has_Discriminants, Has_Tagged_Values, Lock_Free, Type_Class, and
+      --  Has_Discriminants, Has_Tagged_Values, Type_Class, and
       --  Unconstrained_Array are again exceptions, because they apply as well
       --  to unconstrained types.
 
@@ -8614,7 +8591,6 @@ package body Sem_Attr is
             Id = Attribute_Has_Access_Values            or else
             Id = Attribute_Has_Discriminants            or else
             Id = Attribute_Has_Tagged_Values            or else
-            Id = Attribute_Lock_Free                    or else
             Id = Attribute_Preelaborable_Initialization or else
             Id = Attribute_Type_Class                   or else
             Id = Attribute_Unconstrained_Array          or else
@@ -9315,24 +9291,6 @@ package body Sem_Attr is
                True);
          end if;
 
-      ---------------
-      -- Lock_Free --
-      ---------------
-
-      when Attribute_Lock_Free => Lock_Free : declare
-         V : constant Entity_Id := Boolean_Literals (Uses_Lock_Free (P_Type));
-
-      begin
-         Rewrite (N, New_Occurrence_Of (V, Loc));
-
-         --  Analyze and resolve as boolean. Note that this attribute is a
-         --  static attribute in GNAT.
-
-         Analyze_And_Resolve (N, Standard_Boolean);
-         Static := True;
-         Set_Is_Static_Expression (N);
-      end Lock_Free;
-
       ----------
       -- Last --
       ----------