This patch suppresses the check for compatibility of the component types of
the formal and the corresponding actual in the instantiation of a generic
child unit, when the component type of the formal is itself a formal of an
enclosing generic unit. This removes spurious conformance errors in complex
sets of nested instantiations of generic hierarchies.
No short example available.
Tested on x86_64-pc-linux-gnu, committed on trunk
2017-09-08 Ed Schonberg <schonb...@adacore.com>
* sem_ch12.adb (Validate_Array_Type_Instance): Suppress check
for compatibility of component types of formal and actual in an
instantiation of a child unit, when the component type of the
formal is itself a formal of an enclosing generic.
Index: sem_ch12.adb
===================================================================
--- sem_ch12.adb (revision 251869)
+++ sem_ch12.adb (working copy)
@@ -12080,7 +12080,10 @@
-- for static matching has failed. The case where both the component
-- type and the array type are separate formals, and the component
-- type is a private view may also require special checking in
- -- Subtypes_Match.
+ -- Subtypes_Match. Finally, we assume that a child instance where
+ -- the component type comes from a formal of a parent instance is
+ -- correct because the generic was correct. A more precise check
+ -- seems too complex to install???
if Subtypes_Match
(Component_Type (A_Gen_T), Component_Type (Act_T))
@@ -12088,6 +12091,9 @@
Subtypes_Match
(Find_Actual_Type (Component_Type (A_Gen_T), A_Gen_T),
Component_Type (Act_T))
+ or else
+ (not Inside_A_Generic
+ and then Is_Child_Unit (Scope (Component_Type (A_Gen_T))))
then
null;
else
