projectile-project-buffer-p may return incorrect result on Windows

[cshtarkov]

projectile-project-buffer-p indicates whether a buffer is part of the current project. On Windows, it can sometimes (or always?) return a false negative due to path capitalization. This happens because it uses case-sensitive string-prefix-p to check whether the project root is a prefix of the full path to the currently visited file. As a result, functions like helm-projectile and projectile-switch-to-buffer will not let the user switch to a buffer of the same project.

Expected behavior

projectile-project-buffer-p always returns t when a buffer is part of a project.

Actual behavior

It returns nil on Windows.

Steps to reproduce the problem

1. Create a directory C:\Home.
2. Create a repository under C:\Home\repo.
3. Visit a file in that repository.
4. M-: (projectile-project-buffer-p (current-buffer) (projectile-project-root)

The last step will return nil when it should be t (this buffer is surely part of the project). This happens because in projectile-project-buffer-p, project-root will evaluate to c:/Home/repo/demo.txt, while (file-truename default-directory) will be c:/home/repo/demo.txt.

Environment & Version information

Projectile version information

Projectile version: 20160526.832

Emacs version

GNU Emacs 24.5.1 (x86_64-w64-mingw32)

Operating system

Windows 7