make cli overload error have newline

conformance/third_party/conformance.exp

@@ -5019,7 +5019,7 @@
       "code": -2,
       "column": 12,
       "concise_description": "`+` is not supported between `AnyStr` and `AnyStr`",
-      "description": "`+` is not supported between `AnyStr` and `AnyStr`\n  No matching overload found for function `str.__add__` called with arguments: (AnyStr)\n  Possible overloads:\n  (value: LiteralString, /) -> LiteralString\n  (value: str, /) -> str [closest match]",
+      "description": "`+` is not supported between `AnyStr` and `AnyStr`\n  No matching overload found for function `str.__add__` called with arguments: (AnyStr)\n  Possible overloads:\n  def (value: LiteralString, /) -> LiteralString:\n    ...\n  def (value: str, /) -> str:# [closest match]\n    ...",
       "line": 34,
       "name": "unsupported-operation",
       "severity": "error",
@@ -8265,7 +8265,7 @@
       "code": -2,
       "column": 1,
       "concise_description": "Cannot index into `Bytes`",
-      "description": "Cannot index into `Bytes`\n  No matching overload found for function `Bytes.__getitem__` called with arguments: (Literal[''])\n  Possible overloads:\n  (__i: int, /) -> int [closest match]\n  (__s: slice[Any, Any, Any], /) -> bytes",
+      "description": "Cannot index into `Bytes`\n  No matching overload found for function `Bytes.__getitem__` called with arguments: (Literal[''])\n  Possible overloads:\n  def (__i: int, /) -> int:# [closest match]\n    ...\n  def (__s: slice[Any, Any, Any], /) -> bytes:\n    ...",
       "line": 39,
       "name": "bad-index",
       "severity": "error",
@@ -8447,7 +8447,7 @@
       "code": -2,
       "column": 11,
       "concise_description": "No matching overload found for function `example1_1` called with arguments: ()",
-      "description": "No matching overload found for function `example1_1` called with arguments: ()\n  Possible overloads:\n  (x: int, y: str) -> int\n  (x: str) -> str [closest match]",
+      "description": "No matching overload found for function `example1_1` called with arguments: ()\n  Possible overloads:\n  def (\n    x: int,\n    y: str\n) -> int:\n    ...\n  def (x: str) -> str:# [closest match]\n    ...",
       "line": 38,
       "name": "no-matching-overload",
       "severity": "error",
@@ -8458,7 +8458,7 @@
       "code": -2,
       "column": 11,
       "concise_description": "No matching overload found for function `example1_1` called with arguments: (Literal[1], Literal[1])",
-      "description": "No matching overload found for function `example1_1` called with arguments: (Literal[1], Literal[1])\n  Possible overloads:\n  (x: int, y: str) -> int [closest match]\n  (x: str) -> str",
+      "description": "No matching overload found for function `example1_1` called with arguments: (Literal[1], Literal[1])\n  Possible overloads:\n  def (\n    x: int,\n    y: str\n) -> int:# [closest match]\n    ...\n  def (x: str) -> str:\n    ...",
       "line": 46,
       "name": "no-matching-overload",
       "severity": "error",
@@ -8469,7 +8469,7 @@
       "code": -2,
       "column": 11,
       "concise_description": "No matching overload found for function `example1_1` called with arguments: (Literal[1])",
-      "description": "No matching overload found for function `example1_1` called with arguments: (Literal[1])\n  Possible overloads:\n  (x: int, y: str) -> int [closest match]\n  (x: str) -> str",
+      "description": "No matching overload found for function `example1_1` called with arguments: (Literal[1])\n  Possible overloads:\n  def (\n    x: int,\n    y: str\n) -> int:# [closest match]\n    ...\n  def (x: str) -> str:\n    ...",
       "line": 51,
       "name": "no-matching-overload",
       "severity": "error",
@@ -8480,7 +8480,7 @@
       "code": -2,
       "column": 13,
       "concise_description": "No matching overload found for function `example2` called with arguments: (int | str, int | str, Literal[1])",
-      "description": "No matching overload found for function `example2` called with arguments: (int | str, int | str, Literal[1])\n  Possible overloads:\n  (x: int, y: str, z: int) -> str [closest match]\n  (x: int, y: int, z: int) -> int",
+      "description": "No matching overload found for function `example2` called with arguments: (int | str, int | str, Literal[1])\n  Possible overloads:\n  def (\n    x: int,\n    y: str,\n    z: int\n) -> str:# [closest match]\n    ...\n  def (\n    x: int,\n    y: int,\n    z: int\n) -> int:\n    ...",
       "line": 115,
       "name": "no-matching-overload",
       "severity": "error",
@@ -11302,7 +11302,7 @@
       "code": -2,
       "column": 10,
       "concise_description": "No matching overload found for function `A.update` called with arguments: (TypedDict[A])",
-      "description": "No matching overload found for function `A.update` called with arguments: (TypedDict[A])\n  Possible overloads:\n  (m: Partial[A], /) -> None [closest match]\n  (m: Iterable[tuple[Literal['y'], int]], /) -> None\n  (*, y: int = ...) -> None",
+      "description": "No matching overload found for function `A.update` called with arguments: (TypedDict[A])\n  Possible overloads:\n  def (m: Partial[A], /) -> None:# [closest match]\n    ...\n  def (m: Iterable[tuple[Literal['y'], int]], /) -> None:\n    ...\n  def (*, y: int = ...) -> None:\n    ...",
       "line": 23,
       "name": "no-matching-overload",
       "severity": "error",

conformance/third_party/conformance.result

@@ -133,7 +133,7 @@
     "Line 98: Expected 1 errors"
   ],
   "generics_basic.py": [
-    "Line 34: Unexpected errors ['`+` is not supported between `AnyStr` and `AnyStr`\\n  Argument `AnyStr` is not assignable to parameter `value` with type `Buffer` in function `bytes.__add__`\\n  Protocol `Buffer` requires attribute `__buffer__`', '`+` is not supported between `AnyStr` and `AnyStr`\\n  No matching overload found for function `str.__add__` called with arguments: (AnyStr)\\n  Possible overloads:\\n  (value: LiteralString, /) -> LiteralString\\n  (value: str, /) -> str [closest match]', 'Returned type `bytes | Unknown` is not assignable to declared return type `AnyStr`']",
+    "Line 34: Unexpected errors ['`+` is not supported between `AnyStr` and `AnyStr`\\n  Argument `AnyStr` is not assignable to parameter `value` with type `Buffer` in function `bytes.__add__`\\n  Protocol `Buffer` requires attribute `__buffer__`', '`+` is not supported between `AnyStr` and `AnyStr`\\n  No matching overload found for function `str.__add__` called with arguments: (AnyStr)\\n  Possible overloads:\\n  def (value: LiteralString, /) -> LiteralString:\\n    ...\\n  def (value: str, /) -> str:# [closest match]\\n    ...', 'Returned type `bytes | Unknown` is not assignable to declared return type `AnyStr`']",
     "Line 67: Unexpected errors ['assert_type(MyStr, str) failed']",
     "Line 68: Unexpected errors ['assert_type(MyStr, str) failed', 'Argument `str` is not assignable to parameter `y` with type `MyStr` in function `concat`']"
   ],

pyrefly/lib/alt/overload.rs

@@ -368,7 +368,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
             ];
             for overload in overloads {
                 let suffix = if overload.1.signature == closest_overload.func.1.signature {
-                    " [closest match]"
+                    "# [closest match]"
                 } else {
                     ""
                 };
@@ -384,7 +384,8 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
                 let signature = self
                     .solver()
                     .for_display(Type::Callable(Box::new(signature)));
-                msg.push(format!("{signature}{suffix}"));
+                let signature = signature.as_hover_string();
+                msg.push(format!("def {signature}:{suffix}\n    ..."));
             }
             // We intentionally discard closest_overload.call_errors. When no overload matches,
             // there's a high likelihood that the "closest" one by our heuristic isn't the right

pyrefly/lib/test/overload.rs

@@ -895,7 +895,7 @@ def f(x: int, y: int) -> int: ...
 def f(x: int, y: int = 0) -> int:
     return x + y
 
-f(0, 1, 2)  # E: (x: int, y: int) -> int [closest match]
+f(0, 1, 2)  # E: (\n    x: int,\n    y: int\n) -> int:# [closest match]
     "#,
 );