Add support for Passed_By_Reference attribute

ada/nodes.lkt

@@ -12647,7 +12647,13 @@ class AttributeRef: Name {
         elif rel_name == s"Result" then self.result_attr_equation()
         elif rel_name in s"Old" | s"Loop_Entry" then self.bind_to_prefix_eq()
         elif rel_name in s"Class" | s"Base" then self.prefix.sub_equation()
-        elif rel_name in s"Valid" | s"Machine_Overflows" | s"Machine_Rounds" | s"Has_Access_Values" | s"Has_Discriminants" | s"Has_Tagged_Values" | s"Definite" | s"Constrained" | s"Initialized" | s"Valid_Scalars" | s"Unconstrained_Array" | s"Library_Level" | s"Preelaborable_Initialization" | s"Denorm" | s"Signed_Zeros" | s"Fast_Math" then self.prefix.sub_equation() and %eq(node.type_var(), node.bool_type())
+        elif rel_name in s"Valid" | s"Machine_Overflows" | s"Machine_Rounds"
+            | s"Has_Access_Values" | s"Has_Discriminants" | s"Has_Tagged_Values"
+            | s"Definite" | s"Constrained" | s"Initialized" | s"Valid_Scalars"
+            | s"Unconstrained_Array" | s"Library_Level"
+            | s"Preelaborable_Initialization" | s"Denorm" | s"Signed_Zeros"
+            | s"Fast_Math" | s"Passed_By_Reference" then
+            self.prefix.sub_equation() and %eq(node.type_var(), node.bool_type())
         # In the case of the ``Enabled`` attribute, the prefix is supposed
         # to be a check name, so it's not even an entity that has source
         # existence. In that case, we just bind the type of the expr to

testsuite/tests/name_resolution/passed_by_reference_attr/test.adb

@@ -0,0 +1,6 @@
+procedure Test is
+   B : Boolean := Integer'Passed_By_Reference;
+   pragma Test_Statement;
+begin
+   null;
+end;

testsuite/tests/name_resolution/passed_by_reference_attr/test.out

@@ -0,0 +1,25 @@
+Analyzing test.adb
+##################
+
+Resolving xrefs for node <ObjectDecl ["B"] test.adb:2:4-2:47>
+*************************************************************
+
+Expr: <Id "Boolean" test.adb:2:8-2:15>
+  references:    <DefiningName "Boolean" __standard:3:8-3:15>
+  type:          None
+  expected type: None
+Expr: <AttributeRef test.adb:2:19-2:46>
+  references:    None
+  type:          <ConcreteTypeDecl ["Boolean"] __standard:3:3-3:33>
+  expected type: <ConcreteTypeDecl ["Boolean"] __standard:3:3-3:33>
+Expr: <Id "Integer" test.adb:2:19-2:26>
+  references:    <DefiningName "Integer" __standard:4:8-4:15>
+  type:          <ConcreteTypeDecl ["Integer"] __standard:4:3-4:54>
+  expected type: None
+Expr: <Id "Passed_By_Reference" test.adb:2:27-2:46>
+  references:    None
+  type:          None
+  expected type: None
+
+
+Done.

testsuite/tests/name_resolution/passed_by_reference_attr/test.yaml

@@ -0,0 +1,2 @@
+driver: name-resolution
+input_sources: [test.adb]