feat(checker): handle overloaded function calls

midas/checker/python.py

@@ -12,12 +12,16 @@ from midas.checker.reporter import FileReporter, Reporter
 from midas.checker.resolver import Resolver
 from midas.checker.types import (
     Function,
+    OverloadedFunction,
     Type,
     UnitType,
     UnknownType,
+    unfold_type,
 )
 from midas.parser.python import PythonParser
 
+TypedExpr = tuple[p.Expr, Type]
+
 
 class ReturnException(Exception):
     pass
@@ -354,26 +358,7 @@ class PythonTyper(
             )
             return UnknownType()
 
-        match operation:
-            case Function() as function:
-                if not self._check_arity(function, 1, 0, 0):
-                    self.reporter.error(
-                        location,
-                        f"Wrong definition of binary operation. Expected function with 1 positional-only parameters, got {function}",
-                    )
-                    return UnknownType()
-
-                rhs: Function.Argument = function.pos_args[0]
-                if not self.is_subtype(right, rhs.type):
-                    self.reporter.error(
-                        location,
-                        f"Wrong type for right-hand side, expected {rhs.type}, got {right}",
-                    )
-                    return UnknownType()
-                return function.returns
-            case _:
-                self.reporter.warning(location, f"Unsupported operation {operation}")
-                return UnknownType()
+        return self._get_call_result(location, operation, [(right_expr, right)], {})
 
     def visit_unary_expr(self, expr: p.UnaryExpr) -> Type:
         method: Optional[str] = UNARY_METHODS.get(expr.operator.__class__)
@@ -393,35 +378,24 @@ class PythonTyper(
             )
             return UnknownType()
 
-        match operation:
-            case Function() as function:
-                if not self._check_arity(function, 0, 0, 0):
-                    self.reporter.error(
-                        expr.location,
-                        f"Wrong definition of unary operation. Expected function with 0 parameters, got {function}",
-                    )
-                    return UnknownType()
-                return function.returns
-            case _:
-                self.reporter.warning(
-                    expr.location, f"Unsupported operation {operation}"
-                )
-                return UnknownType()
+        return self._get_call_result(
+            expr.location, operation, [(expr.right, operand)], {}
+        )
 
     def visit_call_expr(self, expr: p.CallExpr) -> Type:
         callee: Type = self.type_of(expr.callee)
-        if not isinstance(callee, Function):
-            self.reporter.error(expr.callee.location, "Callee is not a function")
-            return UnknownType()
-        function: Function = callee
-        mapped: list[MappedArgument] = self.map_call_arguments(function, expr)
-        for arg in mapped:
-            if not self.is_subtype(arg.type, arg.argument.type):
-                self.reporter.error(
-                    arg.expr.location,
-                    f"Wrong type for argument '{arg.argument.name}', expected {arg.argument.type}, got {arg.type}",
-                )
-        return function.returns
+        positional: list[TypedExpr] = [
+            (arg, self.type_of(arg)) for arg in expr.arguments
+        ]
+        keywords: dict[str, TypedExpr] = {
+            name: (arg, self.type_of(arg)) for name, arg in expr.keywords.items()
+        }
+        return self._get_call_result(
+            location=expr.location,
+            callee=callee,
+            positional=positional,
+            keywords=keywords,
+        )
 
     def visit_get_expr(self, expr: p.GetExpr) -> Type:
         object: Type = self.type_of(expr.object)
@@ -572,9 +546,105 @@ class PythonTyper(
         self.reporter.warning(node.location, "FrameType not yet supported")
         return UnknownType()
 
+    def _get_call_result(
+        self,
+        location: Location,
+        callee: Type,
+        positional: list[TypedExpr],
+        keywords: dict[str, TypedExpr],
+    ) -> Type:
+        match callee:
+            case Function() as function:
+                valid: bool
+                mapped: list[MappedArgument]
+                valid, mapped = self.map_call_arguments(
+                    function, location, positional, keywords
+                )
+                valid = valid and self._are_arguments_valid(mapped)
+                if not valid:
+                    return UnknownType()
+                return function.returns
+
+            case OverloadedFunction(overloads=overloads):
+                function = self._match_overload(
+                    overloads, location, positional, keywords
+                )
+                if function is None:
+                    return UnknownType()
+                return function.returns
+            case _:
+                self.reporter.error(location, f"{callee} is not callable")
+                return UnknownType()
+
+    def _are_arguments_valid(
+        self,
+        arguments: list[MappedArgument],
+        report_errors: bool = True,
+    ) -> bool:
+        valid: bool = True
+        for arg in arguments:
+            if not self.is_subtype(arg.type, arg.argument.type):
+                if report_errors:
+                    self.reporter.error(
+                        arg.expr.location,
+                        f"Wrong type for argument '{arg.argument.name}', expected {arg.argument.type}, got {arg.type}",
+                    )
+                valid = False
+        return valid
+
+    def _match_overload(
+        self,
+        overloads: list[Type],
+        location: Location,
+        positional: list[TypedExpr],
+        keywords: dict[str, TypedExpr],
+    ) -> Optional[Function]:
+        candidates: list[Function] = []
+        for overload in overloads:
+            function: Type = unfold_type(overload)
+            if not isinstance(function, Function):
+                self.logger.error(
+                    f"Overload is not a function: {overload} is {function}"
+                )
+                continue
+            valid, mapped = self.map_call_arguments(
+                function=function,
+                location=location,
+                positional=positional,
+                keywords=keywords,
+                report_errors=False,
+            )
+            if valid and self._are_arguments_valid(mapped, report_errors=False):
+                candidates.append(function)
+
+        pos_types: str = ", ".join(str(type) for _, type in positional)
+        kw_types: str = ", ".join(
+            f"{name}: {type}" for name, (_, type) in keywords.items()
+        )
+        for_args: str = f"for arguments pos=[{pos_types}] and kw={{{kw_types}}}"
+
+        if len(candidates) == 0:
+            self.reporter.error(
+                location,
+                f"No matching overload in {overloads} {for_args}",
+            )
+            return None
+        if len(candidates) > 1:
+            self.reporter.error(
+                location,
+                f"Multiple matching overloads {for_args}: {', '.join(map(str, candidates))}",
+            )
+            return None
+        return candidates[0]
+
     def map_call_arguments(
-        self, function: Function, call: p.CallExpr
-    ) -> list[MappedArgument]:
+        self,
+        function: Function,
+        location: Location,
+        positional: list[TypedExpr],
+        keywords: dict[str, TypedExpr],
+        report_errors: bool = True,
+    ) -> tuple[bool, list[MappedArgument]]:
         """Map call arguments to function parameters as defined in its signature
 
         This method maps positional-only, keyword-only and mixed parameter definitions
@@ -589,12 +659,6 @@ class PythonTyper(
         Returns:
             list[MappedArgument]: the list of mapped arguments
         """
-        positional: list[tuple[p.Expr, Type]] = [
-            (arg, self.type_of(arg)) for arg in call.arguments
-        ]
-        keywords: dict[str, tuple[p.Expr, Type]] = {
-            name: (arg, self.type_of(arg)) for name, arg in call.keywords.items()
-        }
         set_args: set[str] = set()
 
         required_positional: list[str] = [
@@ -612,6 +676,8 @@ class PythonTyper(
             arg.name: arg for arg in function.kw_args
         }
 
+        valid_call: bool = True
+
         # TODO: handle *args and **kwargs sinks
         for arg in positional:
             param: Function.Argument
@@ -620,7 +686,11 @@ class PythonTyper(
             elif len(mixed_params) != 0:
                 param = mixed_params.pop(0)
             else:
-                self.reporter.error(arg[0].location, "Too many positional arguments")
+                if report_errors:
+                    self.reporter.error(
+                        arg[0].location, "Too many positional arguments"
+                    )
+                valid_call = False
                 break
             name: str = param.name
             if name in required_positional:
@@ -640,14 +710,16 @@ class PythonTyper(
         for name, arg in keywords.items():
             param: Function.Argument
             if name not in kw_params:
-                if name in set_args:
-                    self.reporter.error(
-                        arg[0].location, f"Multiple values for argument '{name}'"
-                    )
-                else:
-                    self.reporter.error(
-                        arg[0].location, f"Unknown keyword argument '{name}'"
-                    )
+                if report_errors:
+                    if name in set_args:
+                        self.reporter.error(
+                            arg[0].location, f"Multiple values for argument '{name}'"
+                        )
+                    else:
+                        self.reporter.error(
+                            arg[0].location, f"Unknown keyword argument '{name}'"
+                        )
+                valid_call = False
                 continue
             param = kw_params.pop(name)
             if name in required_positional:
@@ -674,20 +746,24 @@ class PythonTyper(
         if len(required_positional) != 0:
             plural: str = "" if len(required_positional) == 1 else "s"
             args: str = join_args(required_positional)
-            self.reporter.error(
-                call.location,
-                f"Missing required positional argument{plural}: {args}",
-            )
+            if report_errors:
+                self.reporter.error(
+                    location,
+                    f"Missing required positional argument{plural}: {args}",
+                )
+            valid_call = False
 
         if len(required_keyword) != 0:
             plural: str = "" if len(required_keyword) == 1 else "s"
             args: str = join_args(required_keyword)
-            self.reporter.error(
-                call.location,
-                f"Missing required keyword argument{plural}: {args}",
-            )
+            if report_errors:
+                self.reporter.error(
+                    location,
+                    f"Missing required keyword argument{plural}: {args}",
+                )
+            valid_call = False
 
-        return mapped
+        return valid_call, mapped
 
     def _check_arity(
         self,