Closes#26777
This PR fixes a panic when a file name contains a newline and a
multi-byte character like 👋 (4 bytes in UTF-8). The issue was in the
regex not considering newlines in file names, causing it to match only
the latter part of the file name.
For example:
```
left: PathWithPosition { path: "ab", row: None, column: None } // matched
right: PathWithPosition { path: "ab\ncd", row: None, column: None } // actual file name
```
This resulted in incorrect index calculation later in the code, which
went unnoticed until now due to the lack of tests with file names
containing newlines.
We discovered this issue when a panic occurred due to incorrect index
calculation while trying to get the index of a multi-byte character.
After the newline fix, the index calculation is always correct, even in
the case of multi-byte characters.
Release Notes:
- Fixed an issue where file names with newlines and multi-byte
characters could cause a crash in certain cases.
ae017c3f96