Make --pretty work better on multi-line issues

mypy/errors.py

@@ -1003,6 +1003,9 @@ def format_messages(
                     marker = "^"
                     if end_line == line and end_column > column:
                         marker = f'^{"~" * (end_column - column - 1)}'
+                    elif end_line != line:
+                        # just highlight the first line instead
+                        marker = f'^{"~" * (len(source_line_expanded) - column - 1)}'
                     a.append(" " * (DEFAULT_SOURCE_OFFSET + column) + marker)
         return a
 

test-data/unit/check-unreachable-code.test

@@ -1619,3 +1619,14 @@ reveal_type(bar().attr)  # N: Revealed type is "Never"
 1  # not unreachable
 reveal_type(foo().attr)  # N: Revealed type is "Never"
 1  # E: Statement is unreachable
+
+[case testUnreachableStatementPrettyHighlighting]
+# flags: --warn-unreachable --pretty
+def x() -> None:
+    assert False
+    if 5:
+        pass
+[out]
+main:4: error: Statement is unreachable
+        if 5:
+        ^~~~~

test-data/unit/daemon.test

@@ -122,7 +122,7 @@ Daemon stopped
 Daemon started
 foo.py:1: error: Function is missing a return type annotation
     def f():
-    ^
+    ^~~~~~~~
 foo.py:1: note: Use "-> None" if function does not return a value
 Found 1 error in 1 file (checked 1 source file)
 == Return code: 1