Fix specific_type in case of discrete base subtype

ada/ast.py

@@ -6132,7 +6132,12 @@ def specific_type():
             # Recurse on the class-wide type because it could be a subtype
             # renaming a class-wide type itself.
             lambda cw=T.ClasswideTypeDecl: cw.type_decl.specific_type,
-            lambda bt=T.BaseSubtypeDecl: bt.base_subtype.specific_type,
+            lambda bt=T.BaseSubtypeDecl: Let(
+                lambda bt=bt.base_subtype:
+                # Check if the base subtype is Self, to not do an infinite
+                # recursion.
+                If(bt == Entity, Entity, bt.specific_type)
+            ),
             lambda _: Entity
         )
 

testsuite/tests/properties/specific_type/test.adb

@@ -0,0 +1,6 @@
+procedure Test is
+   subtype P is Integer'Base;
+   --% node.f_subtype.p_designated_type_decl.p_specific_type
+begin
+   null;
+end Test;

testsuite/tests/properties/specific_type/test.out

@@ -0,0 +1,5 @@
+Working on node <SubtypeDecl ["P"] test.adb:2:4-2:30>
+=====================================================
+
+Eval 'node.f_subtype.p_designated_type_decl.p_specific_type'
+Result: <DiscreteBaseSubtypeDecl ["Integer"] __standard:4:3-4:54>

testsuite/tests/properties/specific_type/test.yaml

@@ -0,0 +1,2 @@
+driver: inline-playground
+input_sources: [test.adb]