Martin Hořeňovský reported Jun 19, 2018 at 11:12 AM

Description

Windows recently gained support for case sensitivity in the file system, with this being the default for newly created folders from WSL. The problem is that cl.exe seems to perform case-folding on the directory part of the path, so it cannot compile files in such folder if it has an upper-case letter in the directory part.

This does not apply to files, as cl.exe does not seem to case-fold those.

Reproduction steps

1. Create a Windows-accessible folder using Bash on WSL
   1. The repro steps assume that the path is c:\ubuntu\scratch\MiXeD
2. Create a subfolder with an upper-cased letter
   1. e.g. c:\ubuntu\scratch\MiXeD\InNeR</li></ol></li><li class="">Create another subfolder with only lower-cased letters<ol><li class="">e.g. c\ubuntu\scratch\MiXeD\lower`
3. Create an empty .cpp file called CaSiNg.cpp in both of the subfolders
4. Get a cmd with cl.exe in PATH and navigate to the MiXeD folder created above
5. Try compiling the file in InNeR subfolder: cl InNeR\MiXeD.cpp
   1. The compilation will fail with c1xx: fatal error C1083: Cannot open source file: 'InNeR\MiXeD.cpp': No such file or directory
6. Try compiling the file in lower subfolder: cl lower\MiXeD.cpp
   1. The compilation will fail during the link step with LINK : fatal error LNK1561: entry point must be defined (this means that the compiler found the file properly)

This shows that

A) The compiler does not perform case-folding on filename part of path

B) The compiler does perform case-folding on directory part of path

Because of the above, compiling a file in the first case-sensitive folder works properly.

Extra Information

• Windows version: 1803 (17134.112)
  
• cl.exe version: 19.14.26430 for x86