before-save-hook not run by 'compile'?

[Stephen Leake]

I have 'delete-trailing-whitespace' in 'before-save-hook'; the Ada
compiler I'm using complains if there is trailing whitespace.

However, sometimes when I edit a file and then invoke 'compile', the
file is save, but 'delete-trailing-whitespace' is _not_ run.

If I invoke 'save-some-buffers' directly, 'delete-trailing-whitespace'
is run.

I'm running emacs-26, built from the branch.

I've looked thru the code for compile, and it appears to call
'save-buffer', which appears to run the hook.

I've tried to instrument save-buffer for edebug, but then running
'compile' crashes emacs (with no helpful messages).

Can anyone shed any light on this?

-- 
-- Stephe