In C/l-mode F1 v indent-tabs-mode prints:

indent-tabs-mode is a variable defined in `C source code'.
Its value is nil
Original value was t
Local in buffer nir_types.cpp; global value is t

But pressing the tab key still replaces the spaces used for indentation with tabs.

1 Answer 1


Turns out it was smart-tabs-mode which was making life miserable as I have it turned on by default in my init.el.

Turning it off locally for the specific project solved all my troubles. I.e. in .dir-locals.el in the source code parent folder I wrote:

  (indent-tabs-mode . nil)

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