RA22-015: Fix resolution of calls to non statically resolvable fns

contrib/lkt/language/parser.py

@@ -2579,6 +2579,23 @@ def called_decl():
             ),
             # If not a generic decl, fall back on the initially found decl
             default_val=called_decl
+        )._.match(
+            # Here, if we found a declaration but it's not one of the
+            # statically callable declarations (FunDecl or TypeDecl), we
+            # return nothing, even though we might be able to statically
+            # determine a declaration, like in the example below::
+            #
+            #    val a: (Int) -> Int = null
+            #    val b: Int = a(12)
+            #
+            # That's because in language semantic terms, the actual called
+            # function is determined dynamically in the above case.
+            #
+            # TODO: Maybe introduce a base class for statically callable
+            # declarations, so we don't have to do this ugly match.
+            lambda t=TypeDecl: t,
+            lambda f=FunDecl: f,
+            lambda _: No(T.Decl.entity)
         )
 
     @langkit_property()

testsuite/tests/contrib/lkt_semantic/call_non_static_decl/test.lkt

@@ -0,0 +1,4 @@
+# Call a non static declaration
+
+val a: (Int) -> Int = null
+val b: Int = a(12)

testsuite/tests/contrib/lkt_semantic/call_non_static_decl/test.out

@@ -0,0 +1,26 @@
+Resolving test.lkt
+==================
+Id   <RefId "Int" test.lkt:3:9-3:12>
+     references <StructDecl prelude: "Int">
+
+Id   <RefId "Int" test.lkt:3:17-3:20>
+     references <StructDecl prelude: "Int">
+
+Expr <NullLit test.lkt:3:23-3:27>
+     has type <FunctionType prelude: "(Int) -> Int">
+
+Id   <RefId "Int" test.lkt:4:8-4:11>
+     references <StructDecl prelude: "Int">
+
+Id   <RefId "a" test.lkt:4:14-4:15>
+     references <ValDecl "a" test.lkt:3:1-3:27>
+
+Expr <RefId "a" test.lkt:4:14-4:15>
+     has type <FunctionType prelude: "(Int) -> Int">
+
+Expr <NumLit test.lkt:4:16-4:18>
+     has type <StructDecl prelude: "Int">
+
+Expr <CallExpr test.lkt:4:14-4:19>
+     has type <StructDecl prelude: "Int">
+

testsuite/tests/contrib/lkt_semantic/call_non_static_decl/test.yaml

@@ -0,0 +1 @@
+driver: lkt