Attribute 'Valid_Scalars on private tagged types doesn't work as it
should on private tagged types. Fix most likely needs to modify three
routines. This patch document the problem with a ??? comment.
Tested on x86_64-pc-linux-gnu, committed on trunk
2020-06-19 Piotr Trojanek <troja...@adacore.com>
gcc/ada/
* exp_attr.adb (Expand_N_Attribute_Reference): Add comment.
* sem_attr.adb (Analyze_Attribute): Add ??? comment.
* sem_util.ads (Valid_Scalars): This routine is only used for
'Valid_Scalars and not for 'Valid.--- gcc/ada/exp_attr.adb
+++ gcc/ada/exp_attr.adb
@@ -7094,7 +7094,8 @@ package body Exp_Attr is
Expr := Empty;
- -- Attribute 'Valid_Scalars is not supported on private tagged types
+ -- Attribute 'Valid_Scalars is not supported on private tagged types;
+ -- see a detailed explanation where this attribute is analyzed.
if Is_Private_Type (Ptyp) and then Is_Tagged_Type (Ptyp) then
null;
--- gcc/ada/sem_attr.adb
+++ gcc/ada/sem_attr.adb
@@ -7016,6 +7016,10 @@ package body Sem_Attr is
-- types due to a code generation issue. Is_Visible_Component
-- does not allow for a component of a private tagged type to
-- be successfully retrieved.
+ -- ??? This attribute should simply ignore type privacy
+ -- (see Validated_View). It should examine components of the
+ -- tagged type extensions (if any) and recursively examine
+ -- 'Valid_Scalars of the parent's type (if any).
-- Do not use Error_Attr_P because this bypasses any subsequent
-- processing and leaves the attribute with type Any_Type. This
--- gcc/ada/sem_util.ads
+++ gcc/ada/sem_util.ads
@@ -3050,10 +3050,10 @@ package Sem_Util is
-- conversions, and unchecked conversions.
function Validated_View (Typ : Entity_Id) return Entity_Id;
- -- Obtain the "validated view" of arbitrary type Typ which is suitable
- -- for verification by attributes 'Valid and 'Valid_Scalars. This view
- -- is the type itself or its full view while stripping away concurrency,
- -- derivations, and privacy.
+ -- Obtain the "validated view" of arbitrary type Typ which is suitable for
+ -- verification by attributes 'Valid_Scalars. This view is the type itself
+ -- or its full view while stripping away concurrency, derivations, and
+ -- privacy.
function Visible_Ancestors (Typ : Entity_Id) return Elist_Id;
-- [Ada 2012:AI-0125-1]: Collect all the visible parents and progenitors
