Merge branch 'topic/resolve_overloaded_actual' into 'master'

Fix resolution of generic subprogram actuals.

Closes #1161

See merge request eng/libadalang/libadalang!1482

ada/ast.py

@@ -12422,6 +12422,26 @@ class FormalSubpDecl(ClassicSubpDecl):
         ), default_val=LogicTrue())
     )
 
+    @langkit_property(return_type=T.BasicDecl.entity, memoized=True)
+    def resolve_actual_name(name=T.Expr.entity):
+        """
+        Given the name used in the instantiation for this formal subp decl,
+        resolve it at the instantiation site to the corresponding declaration.
+        This property basically replaces ``AdaNode.resolve_generic_actual`` but
+        is more precise because we have access to the formal spec, which means
+        we can disambiguate between overloaded actuals.
+        Note that we cannot simply call ``referenced_decl`` here as this would
+        cause name resolution recursions which we want to avoid at all cost.
+        """
+        return origin.bind(name.node, name.cast(AttributeRef).then(
+            lambda attr: attr.attribute_subprogram,
+            default_val=name.cast(Name).all_env_elements.find(
+                lambda el: el.cast(BasicDecl)._.subp_decl_match_signature(
+                    Entity
+                )
+            )
+        )).cast(BasicDecl)
+
     @langkit_property(return_type=T.BasicDecl.entity)
     def corresponding_actual_impl(rb=T.EnvRebindings):
         """
@@ -12443,8 +12463,9 @@ def corresponding_actual_impl(rb=T.EnvRebindings):
                         from_rebound=False
                     )
                 )
-            ).actual_for_formal(Entity.defining_name.node)
-            ._.resolve_generic_actual.cast(BasicDecl).then(
+            ).actual_for_formal(Entity.defining_name.node).then(
+                lambda name: Entity.resolve_actual_name(name)
+            ).then(
                 lambda actual: actual.corresponding_actual
             )._or(Entity),
 

testsuite/tests/name_resolution/overloaded_generic_subp_actual/test.adb

@@ -0,0 +1,22 @@
+procedure Test is
+   generic
+      with procedure Foo (X : Integer);
+   procedure Gen;
+
+   procedure Gen is
+   begin
+      Foo (42);
+   end Gen;
+
+   --  Define three potential candidates for the actual in the instantiation
+   --  below.
+   procedure Bar (X : Boolean) is null;
+   procedure Bar (X : Integer) is null;
+   procedure Bar (X : Float) is null;
+
+   procedure My_Gen is new Gen (Foo => Bar);
+   --% gen = node.p_designated_generic_decl.p_body_part()
+   --% gen.find(lal.CallExpr).f_name.p_referenced_decl()
+begin
+   null;
+end Test;

testsuite/tests/name_resolution/overloaded_generic_subp_actual/test.out

@@ -0,0 +1,8 @@
+Working on node <GenericSubpInstantiation ["My_Gen"] test.adb:17:4-17:45>
+=========================================================================
+
+Set 'gen' to 'node.p_designated_generic_decl.p_body_part()'
+Result: <| SubpBody ["Gen"] test.adb:6:4-9:12 [test.adb:17:4] |>
+
+Eval 'gen.find(lal.CallExpr).f_name.p_referenced_decl()'
+Result: <NullSubpDecl ["Bar"] test.adb:14:4-14:40>

testsuite/tests/name_resolution/overloaded_generic_subp_actual/test.yaml

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