Rustdoc fails on modules with reserved file names

[vihdzp]

Problem
Adding a module named con, nul, or any other reserved name on Windows causes Rustdoc to fail.

Steps

1. Add an empty module named con.
2. Run cargo doc.

Possible Solution(s)
A fix similar to #83612 should get rid of this issue.

Notes

I'm on Windows 10. I haven't tested this, but I'm almost certain this bug should exist in all other versions of Windows, and in no other operating system.

[ChrisDenton]

Full list of redirected names:

• AUX
• CON
• CONIN$
• CONOUT$
• COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, COM², COM³, COM¹
• LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9, LPT², LPT³, LPT¹
• NUL
• PRN

By default Windows will rewrite paths containing these filenames to a legacy dos device path. So, for example:

C:\path\to\docs\con.something.html

Becomes:

\\.\CON

While this behaviour can be disabled using verbatim paths (i.e. using the \\?\ prefix), this still leaves files which would be hard for the user to access.

[inquisitivecrystal]

@rustbot label +A-rustdoc +T-rustdoc

[jyn514]

This is basically #25879 - I'll leave this open so we remember to add a test case, but I expect the fixes to look very similar.