* [Ada] Reject 'Valid_Scalars on Unchecked_Union regardless of privacy
@ 2022-09-12 8:19 Marc Poulhiès
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From: Marc Poulhiès @ 2022-09-12 8:19 UTC (permalink / raw)
To: gcc-patches; +Cc: Piotr Trojanek
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Attribute Valid_Scalars applied to prefix with an unchecked union
component causes a legitimate crash in the backend. It was already
rejected in the frontend for prefixes of a public type; now it is
rejected in the frontend regardless of the type privacy.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_attr.adb (Analyze_Attribute [Valid_Scalars]): Move check for
unchecked union before checks for private and public types.
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diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -7399,10 +7399,19 @@ package body Sem_Attr is
if Comes_From_Source (N) then
Check_Object_Reference (P);
+ -- Attribute 'Valid_Scalars is illegal on unchecked union types
+ -- regardles of the privacy, because it is not always guaranteed
+ -- that the components are retrievable based on whether the
+ -- discriminants are inferable.
+
+ if Has_Unchecked_Union (Validated_View (P_Type)) then
+ Error_Attr_P
+ ("attribute % not allowed for Unchecked_Union type");
+
-- Do not emit any diagnostics related to private types to avoid
-- disclosing the structure of the type.
- if Is_Private_Type (P_Type) then
+ elsif Is_Private_Type (P_Type) then
-- Attribute 'Valid_Scalars is not supported on private tagged
-- types due to a code generation issue. Is_Visible_Component
@@ -7432,15 +7441,6 @@ package body Sem_Attr is
("??attribute % always True, no scalars to check", P);
Set_Boolean_Result (N, True);
end if;
-
- -- Attribute 'Valid_Scalars is illegal on unchecked union types
- -- because it is not always guaranteed that the components are
- -- retrievable based on whether the discriminants are inferable
-
- if Has_Unchecked_Union (P_Type) then
- Error_Attr_P
- ("attribute % not allowed for Unchecked_Union type");
- end if;
end if;
end if;
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2022-09-12 8:19 [Ada] Reject 'Valid_Scalars on Unchecked_Union regardless of privacy Marc Poulhiès
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