bug#34338: 26.1; delete-file return codes and failures

[Boruch Baum]

Subject: 26.1; delete-file return codes and failures

Currently:

A1) When delete-file successfully deletes a file, the function returns
    nil, not t.

A2) When the file does not exist, the function returns the same
    value - nil.

A3) When the file has been chmod'ed -w, the function performs the
    operation, with no regard to any option to emulate or not emulate 'rm
    -f', and also returns the identical value - nil.

A4) When either the file's containing folder is chmod'ed -x, or the file
    is chattr'ed +i, the function crashes.


I'd like to suggest:

  delete-file FILE &optional NOERROR FORCE

B1) return t on success

B2) raise an error when (not NOERROR) and:

  B2.1) file doesn't exist

  B2.2) (and (chmod -w) (not FORCE))

  B2.3) another form of permission denial is encountered

B3) return nil when NOERROR and:

  B2.1) file doesn't exist

  B2.2)  another form of permission denial is encountered


C) maybe log the exact error or reason for nil to *Messages*.



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 of 2018-12-26, modified by Debian built on x86-ubc-01
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