fix: preserving resolution of integer type sign to reduce warning messages in variadic functions

src/resolver.rs

@@ -24,7 +24,6 @@ use plc_ast::{
 use plc_source::source_location::SourceLocation;
 use plc_util::convention::internal_type_name;
 
-use crate::index::{FxIndexMap, FxIndexSet, InterfaceIndexEntry};
 use crate::typesystem::VOID_INTERNAL_NAME;
 use crate::{
     builtins::{self, BuiltIn},
@@ -35,6 +34,10 @@ use crate::{
         REAL_TYPE, TIME_OF_DAY_TYPE, TIME_TYPE, VOID_TYPE, WORD_TYPE,
     },
 };
+use crate::{
+    index::{FxIndexMap, FxIndexSet, InterfaceIndexEntry},
+    typesystem::UDINT_TYPE,
+};
 
 pub mod const_evaluator;
 pub mod generics;
@@ -427,10 +430,16 @@ impl TypeAnnotator<'_> {
                     get_bigger_type(data_type, self.index.get_type_or_panic(LREAL_TYPE), self.index)
                         .get_name()
                 }
-                DataTypeInformation::Integer { .. }
+                DataTypeInformation::Integer { signed, .. }
                     if !data_type.information.is_bool() && !data_type.information.is_character() =>
                 {
-                    get_bigger_type(data_type, self.index.get_type_or_panic(DINT_TYPE), self.index).get_name()
+                    let right_type = if *signed {
+                        self.index.get_type_or_panic(DINT_TYPE)
+                    } else {
+                        self.index.get_type_or_panic(UDINT_TYPE)
+                    };
+
+                    get_bigger_type(data_type, right_type, self.index).get_name()
                 }
                 // Enum types need to be promoted based on their underlying integer type
                 DataTypeInformation::Enum { referenced_type, .. } => self

src/resolver/tests/resolve_expressions_tests.rs

@@ -20,7 +20,7 @@ use crate::{
     test_utils::tests::{annotate_with_ids, index_with_ids},
     typesystem::{
         DataTypeInformation, Dimension, TypeSize, BOOL_TYPE, BYTE_TYPE, DINT_TYPE, DWORD_TYPE, INT_TYPE,
-        LINT_TYPE, LREAL_TYPE, REAL_TYPE, SINT_TYPE, UINT_TYPE, USINT_TYPE, VOID_TYPE, WORD_TYPE,
+        LINT_TYPE, LREAL_TYPE, REAL_TYPE, SINT_TYPE, UDINT_TYPE, UINT_TYPE, USINT_TYPE, VOID_TYPE, WORD_TYPE,
     },
 };
 
@@ -3847,7 +3847,7 @@ fn undeclared_varargs_type_hint_promoted_correctly() {
         assert_type_and_hint!(&annotations, &index, parameters[0], REAL_TYPE, Some(LREAL_TYPE));
         assert_type_and_hint!(&annotations, &index, parameters[1], LREAL_TYPE, Some(LREAL_TYPE));
         assert_type_and_hint!(&annotations, &index, parameters[2], BOOL_TYPE, None);
-        assert_type_and_hint!(&annotations, &index, parameters[3], USINT_TYPE, Some(DINT_TYPE));
+        assert_type_and_hint!(&annotations, &index, parameters[3], USINT_TYPE, Some(UDINT_TYPE));
         assert_type_and_hint!(&annotations, &index, parameters[4], INT_TYPE, Some(DINT_TYPE));
         assert_type_and_hint!(&annotations, &index, parameters[5], DINT_TYPE, Some(DINT_TYPE));
         assert_type_and_hint!(&annotations, &index, parameters[6], LINT_TYPE, Some(LINT_TYPE));

src/validation/tests/statement_validation_tests.rs

@@ -2712,3 +2712,36 @@ fn division_by_zero_variable_must_not_result_in_error() {
 
     assert_snapshot!(diagnostics, @"");
 }
+
+#[test]
+fn function_call_with_variadics_should_not_produce_downcast_warnings() {
+    let diagnostics = parse_and_validate_buffered(
+        "
+        TYPE LogLevel :
+        (
+            LOG_LEVEL_INFO := 0,
+        );
+        END_TYPE
+
+        FUNCTION Log_Print : ErrorCode
+        VAR_INPUT
+            Priority : LogLevel;
+            Format : STRING[1023];
+            Args : ...;
+        END_VAR
+            // Do nothing
+        END_FUNCTION
+
+        FUNCTION main
+            VAR
+                x : UDINT := 21;
+                y : LREAL := 42;
+            END_VAR
+
+            Log_Print(LOG_LEVEL_INFO, 'X(%u): Y = %f', x, y);
+        END_FUNCTION
+        ",
+    );
+
+    assert_snapshot!(diagnostics, @"");
+}

tests/lit/single/variadics/implicit_types_passed_correctly.st

@@ -0,0 +1,10 @@
+// RUN: (%COMPILE %s && %RUN) | %CHECK %s
+FUNCTION main: DINT
+    VAR
+        x : UDINT := 21;
+        y : LREAL := 42;
+    END_VAR
+
+    // CHECK: X(21): Y = 42.000000
+    printf('X(%u): Y = %f', x, y);
+END_FUNCTION