From 068594eb38fc550d834b7e61745177c423f2b224 Mon Sep 17 00:00:00 2001
From: Shantanu <hauntsaninja@users.noreply.github.com>
Date: Tue, 9 Jun 2020 11:02:26 -0700
Subject: [PATCH] fastparse: improve error reporting for f-string syntax errors
 (#8970)

---
 mypy/fastparse.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index 2aac8412f657..2dafbf4e1454 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -169,6 +169,11 @@ def parse(source: Union[str, bytes],
         tree.path = fnam
         tree.is_stub = is_stub_file
     except SyntaxError as e:
+        if sys.version_info < (3, 9) and e.filename == "<fstring>":
+            # In Python 3.8 and earlier, syntax errors in f-strings have lineno relative to the
+            # start of the f-string. This would be misleading, as mypy will report the error as the
+            # lineno within the file.
+            e.lineno = None
         errors.report(e.lineno if e.lineno is not None else -1, e.offset, e.msg, blocker=True,
                       code=codes.SYNTAX)
         tree = MypyFile([], [], False, {})