Custom compilation command fails on Windows due to slashes in paths

Question

when i type on "shell":

c:\Users\TR\Desktop\emacs-27.2-x86_64\bin\GAMES\game3>love .

works fine but when i put

(defun insert-file-name ()
 (interactive)
 (let ((compilation-ask-about-save  nil))
 (compile (concat (file-name-directory (buffer-file-name)) "love ."))))

(global-set-key (kbd "C-c C-v") #'insert-file-name)

in my initialization file using "C-c C-v" gives me the error message:

-- mode: compilation; default-directory: "c:/Users/TR/Desktop/emacs-27.2-x86_64/bin/GAMES/game3/" -- Compilation started at Sun Apr 18 23:30:16 c:/Users/TR/Desktop/emacs-27.2-x86_64/bin/GAMES/game3/love . 'c:/Users/TR/Desktop/emacs-27.2-x86_64/bin/GAMES/game3/love' is not recognized as an internal or external command, operable program or batch file.

Compilation exited abnormally with code 1 at Sun Apr 18 23:30:16

a similar code worked on Ubuntu emacs, but on Windows 7 it does not work!

How can i solve this problem?

Answer 1

Learn about backslashes in strings. And learn about manipulating file names.

The result of evaluating this is presumably the absolute file name that you want for your program:

(expand-file-name "love" "c:\\Users\\TR\\Desktop\\emacs-27.2-x86_64\\bin\\GAMES\\game3")

That is:

(expand-file-name "love" (file-name-directory (buffer-file-name)))

Answer 2

Short answer,

pass the relative file path to the cli. See documentation of file-relative-name.

Long answer,

As I can see in first paragraph. The shell is DOS shell. When current work directory is "c:\Users\TR\Desktop\emacs-27.2-x86_64\bin\GAMES\game3", you can run "love" (note it's relative path) without any problem.

But when you run M-x compile, you pass the whole path "c:/Users/TR/Desktop/emacs-27.2-x86_64/bin/GAMES/game3/love" to the DOS shell.

The DOS shell can't recognise the path.

You can convert the path by replacing the "/" with "" by (replace-regexp-in-string "/" "\\\\" "c:/hello/world.txt").

But it's better to use relative path which is portable on all environments (WSL, Cygwin, macOS, Linux ...)

In your code, instead of using full path (concat (file-name-directory (buffer-file-name)) "love ."), you should use (concat (file-name-relative (file-name-directory (buffer-file-name))) "love .").

Here is the documentation of file-relative-name,

file-relative-name is a compiled Lisp function in ‘files.el’.

(file-relative-name FILENAME &optional DIRECTORY)

Convert FILENAME to be relative to DIRECTORY (default: ‘default-directory’).
This function returns a relative file name that is equivalent to FILENAME
when used with that default directory as the default.
If FILENAME is a relative file name, it will be interpreted as existing in
‘default-directory’.

You might need set default-directory to the right working directory inside your function insert-file-name before calling compile. But looks it's correct according to the error message.