Failed to find exact letter case of module name when relative import on Windows OS

[trlaitioer]

Bug Report

Failed to find exact letter case of module name when relative import on Windows OS.

To Reproduce

ModuleName
├─ __init__.py
├─ file.py
├─ main.py

# main.py
from .file import *

Everything is fine when the path is correct with letter case.

mypy .\ModuleName\main.py
Success: no issues found in 1 source file

But if the path of files is wrong with letter case,

mypy .\moduleName\main.py

but there will be an [import-not-found] error.

moduleName\main.py:1: error: Cannot find implementation or library stub for module named "moduleName.file"  [import-not-found]

Your Environment

• Mypy version used: mypy 1.14.1 (compiled: yes)

[trlaitioer]

I think it may be the same question with #12880

Edit:
It's more difficult for this one,

• os.path.normcase always return lowercase
• os.path.normpath do not normalize case
• pathlib.Path(...).resolve() will return the abs path, and make drive name uppercase, but do not change the case of directory

It seems no simple solution for this one.

This may help #12880:
replace

mypy/mypy/find_sources.py

Line 36 in 1affabe

path = os.path.normpath(path)

with

path = os.path.normpath(path)
drive, root, path = os.path.splitroot(path)
if drive.endswith(":"):
    drive = drive.upper()
path = os.path.join(drive, root, path)