exp_utils.ads, [...] (Find_Optional_Prim_Op): New interface to return Empty when not found...

2015-05-22  Bob Duff  <duff@adacore.com>

	* exp_utils.ads, exp_utils.adb (Find_Optional_Prim_Op): New
	interface to return Empty when not found, so we can avoid handling
	Program_Error in that case.
	(Find_Prim_Op): Fix latent bug: raise Program_Error when there are no
	primitives.
	* exp_ch7.adb, sem_util.adb: Use Find_Optional_Prim_Op when the
	code is expecting Empty.
	* sem_ch8.adb: Use Find_Optional_Prim_Op to avoid handling
	Program_Error.

From-SVN: r223541

1 files changed, 13 insertions, 11 deletions

diff --git a/gcc/ada/exp_util.ads b/gcc/ada/exp_util.ads
index a7d8f4c..01f4377 100644
--- a/gcc/ada/exp_util.ads
+++ b/gcc/ada/exp_util.ads
@@ -471,9 +471,8 @@ package Exp_Util is
    --  Find the first primitive operation of a tagged type T with name Name.
    --  This function allows the use of a primitive operation which is not
    --  directly visible. If T is a class wide type, then the reference is to an
-   --  operation of the corresponding root type. Raises Program_Error exception
-   --  if no primitive operation is found. This is normally an internal error,
-   --  but in some cases is an expected consequence of illegalities elsewhere.
+   --  operation of the corresponding root type. It is an error if no primitive
+   --  operation with the given name is found.
 
    function Find_Prim_Op
      (T    : Entity_Id;
@@ -483,16 +482,19 @@ package Exp_Util is
    --  with the indicated suffix). This function allows use of a primitive
    --  operation which is not directly visible. If T is a class wide type,
    --  then the reference is to an operation of the corresponding root type.
-   --  Raises Program_Error exception if no primitive operation is found.
-   --  This is normally an internal error, but in some cases is an expected
-   --  consequence of illegalities elsewhere.
+
+   function Find_Optional_Prim_Op
+     (T : Entity_Id; Name : Name_Id) return Entity_Id;
+   function Find_Optional_Prim_Op
+     (T    : Entity_Id;
+      Name : TSS_Name_Type) return Entity_Id;
+   --  Same as Find_Prim_Op, except returns Empty if not found
 
    function Find_Protection_Object (Scop : Entity_Id) return Entity_Id;
-   --  Traverse the scope stack starting from Scop and look for an entry,
-   --  entry family, or a subprogram that has a Protection_Object and return
-   --  it. Raises Program_Error if no such entity is found since the context
-   --  in which this routine is invoked should always have a protection
-   --  object.
+   --  Traverse the scope stack starting from Scop and look for an entry, entry
+   --  family, or a subprogram that has a Protection_Object and return it. Must
+   --  always return a value since the context in which this routine is invoked
+   --  should always have a protection object.
 
    function Find_Protection_Type (Conc_Typ : Entity_Id) return Entity_Id;
    --  Given a protected type or its corresponding record, find the type of