From aff1097d915cadf1a8c96a083230edb202082c02 Mon Sep 17 00:00:00 2001
From: LordBaryhobal <lordbaryhobal@gmail.com>
Date: Fri, 12 Jun 2026 16:55:01 +0200
Subject: [PATCH] fix(checker): update binary operation lookup

---
 midas/checker/python.py | 66 ++++++++++++++++++++---------------------
 1 file changed, 32 insertions(+), 34 deletions(-)

diff --git a/midas/checker/python.py b/midas/checker/python.py
index f1cecb8..1e57d35 100644
--- a/midas/checker/python.py
+++ b/midas/checker/python.py
@@ -324,47 +324,36 @@ class PythonTyper(
         left: Type = self.type_of(expr.left)
         right: Type = self.type_of(expr.right)
 
-        operations: list[Operation] = self.types.get_operations_by_name(method)
-        valid_operations: list[Operation] = []
-        for op in operations:
-            sig: Operation.CallSignature = op.signature
-            if self.is_subtype(left, sig.left) and self.is_subtype(right, sig.right):
-                valid_operations.append(op)
-
-        if len(valid_operations) == 0:
+        operation: Optional[Type] = self.types.lookup_member(left, method)
+        if operation is None:
             self.reporter.error(
                 expr.location,
                 f"Undefined operation {method} between {left} and {right}",
             )
             return UnknownType()
-        elif len(valid_operations) == 1:
-            self.logger.debug(f"Unique operation {method} between {left} and {right}")
-            return valid_operations[0].result
 
-        for i, op1 in enumerate(valid_operations):
-            sig1: Operation.CallSignature = op1.signature
-            best_match: bool = True
-            for j, op2 in enumerate(valid_operations):
-                if i == j:
-                    continue
-                sig2: Operation.CallSignature = op2.signature
+        match operation:
+            case Function() as function:
+                if not self._is_binary_function(function):
+                    self.reporter.error(
+                        expr.location,
+                        f"Wrong definition of binary operation. Expected function with 2 positional-only parameters, got {function}",
+                    )
+                    return UnknownType()
 
-                # If op1 is not a full overload of op2 (i.e. operands of op1 are subtypes of op2's)
-                # ambiguity -> not best match
-                if not self.is_subtype(sig1.left, sig2.left) or not self.is_subtype(
-                    sig1.right, sig2.right
-                ):
-                    best_match = False
-                    break
-                self.logger.debug(f"{op1} is a full overload of {op2}")
-            if best_match:
-                return op1.result
-
-        self.reporter.error(
-            expr.location,
-            f"Ambiguous operation {method} between {left} and {right}, multiple matching overloads: {', '.join(map(str, valid_operations))}",
-        )
-        return UnknownType()
+                rhs: Function.Argument = function.pos_args[0]
+                if not self.is_subtype(right, rhs.type):
+                    self.reporter.error(
+                        expr.location,
+                        f"Wrong type for right-hand side, expected {rhs.type}, got {right}",
+                    )
+                    return UnknownType()
+                return function.returns
+            case _:
+                self.reporter.warning(
+                    expr.location, f"Unsupported operation {operation}"
+                )
+                return UnknownType()
 
     def visit_compare_expr(self, expr: p.CompareExpr) -> Type:
         method: Optional[str] = COMPARATOR_METHODS.get(expr.operator.__class__)
@@ -617,3 +606,12 @@ class PythonTyper(
             )
 
         return mapped
+
+    def _is_binary_function(self, function: Function) -> bool:
+        if len(function.pos_args) != 1:
+            return False
+        if len(function.args) != 0:
+            return False
+        if len(function.kw_args) != 0:
+            return False
+        return True