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[Ada] Spurious error on actual array type in generic child instantiation.

Message ID 20170908092307.GA4711@adacore.com
State New
Headers show
Series [Ada] Spurious error on actual array type in generic child instantiation. | expand

Commit Message

Arnaud Charlet Sept. 8, 2017, 9:23 a.m. UTC 
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  <schonberg@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.
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Patch

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