From 3f5cd050b6cb5e124e1663c0e8292ecd231e8295 Mon Sep 17 00:00:00 2001
From: Adam Turner <turner@hudson-trading.com>
Date: Tue, 3 Feb 2026 22:46:18 +0000
Subject: [PATCH] Emit end line/column in JSON format for span tracking

---
 mypy/error_formatter.py               |  2 ++
 mypy/errors.py                        | 21 ++++++++++++++++++---
 test-data/unit/check-incremental.test |  2 +-
 test-data/unit/outputjson.test        |  8 ++++----
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/mypy/error_formatter.py b/mypy/error_formatter.py
index ffc6b67475962..ea79affbddd0e 100644
--- a/mypy/error_formatter.py
+++ b/mypy/error_formatter.py
@@ -26,6 +26,8 @@ def report_error(self, error: "MypyError") -> str:
                 "file": error.file_path,
                 "line": error.line,
                 "column": error.column,
+                "end_line": error.end_line,
+                "end_column": error.end_column,
                 "message": error.message,
                 "hint": None if len(error.hints) == 0 else "\n".join(error.hints),
                 "code": None if error.errorcode is None else error.errorcode.code,
diff --git a/mypy/errors.py b/mypy/errors.py
index 4cdeb0534f2e8..750b7c746c4b1 100644
--- a/mypy/errors.py
+++ b/mypy/errors.py
@@ -1480,6 +1480,8 @@ def __init__(
         file_path: str,
         line: int,
         column: int,
+        end_line: int,
+        end_column: int,
         message: str,
         errorcode: ErrorCode | None,
         severity: Literal["error", "note"],
@@ -1487,6 +1489,8 @@ def __init__(
         self.file_path = file_path
         self.line = line
         self.column = column
+        self.end_line = end_line
+        self.end_column = end_column
         self.message = message
         self.errorcode = errorcode
         self.severity = severity
@@ -1502,7 +1506,7 @@ def create_errors(error_tuples: list[ErrorTuple]) -> list[MypyError]:
     latest_error_at_location: dict[_ErrorLocation, MypyError] = {}
 
     for error_tuple in error_tuples:
-        file_path, line, column, _, _, severity, message, errorcode = error_tuple
+        file_path, line, column, end_line, end_column, severity, message, errorcode = error_tuple
         if file_path is None:
             continue
 
@@ -1512,14 +1516,25 @@ def create_errors(error_tuples: list[ErrorTuple]) -> list[MypyError]:
             error = latest_error_at_location.get(error_location)
             if error is None:
                 # This is purely a note, with no error correlated to it
-                error = MypyError(file_path, line, column, message, errorcode, severity="note")
+                error = MypyError(
+                    file_path,
+                    line,
+                    column,
+                    end_line,
+                    end_column,
+                    message,
+                    errorcode,
+                    severity="note",
+                )
                 errors.append(error)
                 continue
 
             error.hints.append(message)
 
         else:
-            error = MypyError(file_path, line, column, message, errorcode, severity="error")
+            error = MypyError(
+                file_path, line, column, end_line, end_column, message, errorcode, severity="error"
+            )
             errors.append(error)
             error_location = (file_path, line, column)
             latest_error_at_location[error_location] = error
diff --git a/test-data/unit/check-incremental.test b/test-data/unit/check-incremental.test
index 1698a51a975d9..52e3f8b9aa84c 100644
--- a/test-data/unit/check-incremental.test
+++ b/test-data/unit/check-incremental.test
@@ -7655,7 +7655,7 @@ def wrong() -> int:
 [out]
 main:2: error: Missing return statement
 [out2]
-{"file": "main", "line": 2, "column": 0, "message": "Missing return statement", "hint": null, "code": "return", "severity": "error"}
+{"file": "main", "line": 2, "column": 0, "end_line": 4, "end_column": 16, "message": "Missing return statement", "hint": null, "code": "return", "severity": "error"}
 
 [case testReExportAllInStubIncremental]
 from m1 import C
diff --git a/test-data/unit/outputjson.test b/test-data/unit/outputjson.test
index 43649b7b781d3..51a49c64530ac 100644
--- a/test-data/unit/outputjson.test
+++ b/test-data/unit/outputjson.test
@@ -18,7 +18,7 @@ def foo() -> None:
 
 foo(1)
 [out]
-{"file": "main", "line": 5, "column": 0, "message": "Too many arguments for \"foo\"", "hint": null, "code": "call-arg", "severity": "error"}
+{"file": "main", "line": 5, "column": 0, "end_line": 5, "end_column": 6, "message": "Too many arguments for \"foo\"", "hint": null, "code": "call-arg", "severity": "error"}
 
 [case testOutputJsonWithHint]
 # flags: --output=json
@@ -39,6 +39,6 @@ foo('42')
 def bar() -> None: ...
 bar('42')
 [out]
-{"file": "main", "line": 12, "column": 12, "message": "Revealed type is \"Overload(def (), def (x: builtins.int))\"", "hint": null, "code": "misc", "severity": "note"}
-{"file": "main", "line": 14, "column": 0, "message": "No overload variant of \"foo\" matches argument type \"str\"", "hint": "Possible overload variants:\n    def foo() -> None\n    def foo(x: int) -> None", "code": "call-overload", "severity": "error"}
-{"file": "main", "line": 17, "column": 0, "message": "Too many arguments for \"bar\"", "hint": null, "code": "call-arg", "severity": "error"}
+{"file": "main", "line": 12, "column": 12, "end_line": 12, "end_column": 15, "message": "Revealed type is \"Overload(def (), def (x: builtins.int))\"", "hint": null, "code": "misc", "severity": "note"}
+{"file": "main", "line": 14, "column": 0, "end_line": 14, "end_column": 9, "message": "No overload variant of \"foo\" matches argument type \"str\"", "hint": "Possible overload variants:\n    def foo() -> None\n    def foo(x: int) -> None", "code": "call-overload", "severity": "error"}
+{"file": "main", "line": 17, "column": 0, "end_line": 17, "end_column": 9, "message": "Too many arguments for \"bar\"", "hint": null, "code": "call-arg", "severity": "error"}