It's hard to tell why exactly that's the choice they took. Only an Apple
employee would be able to help us in explaining this. However, I don't
think it's an explicit exclusion of conceal
by itself.
When you compile Vim, the configure script accepts an option called
--with-features
which controls a set of features to be enabled or
disabled.
--with-features=TYPE. tiny, small, normal, big or huge (default: huge)
from src/auto/configure L1532
The conceal
feature is only enabled with big or huge, and
dependent on +syntax
:
/*
* +conceal 'conceal' option. Needs syntax highlighting
* as this is how the concealed text is defined.
*/
#if defined(FEAT_BIG) && defined(FEAT_SYN_HL)
# define FEAT_CONCEAL
#endif
from src/feature.h L496-502
You can see a handy list of what is included in each feature set by
checking :h +feature-list
. Thus, judging by the other features, I'd
say conceal
is disabled just because they are compiling with the
feature set option --with-features=normal
.
It's highly recommended to install a newer and more complete Vim.
Replacing the system program might not be optimal, but that's exactly
why there are plenty of alternatives which take care of doing it right
and keeping Vim updated and complete. If you have Homebrew
installed, a simple command will do:
$ brew install vim
Alternatively, if you have MacVim you can also use its internal
executable by making an alias on your shell or something similar.