How to safely uninstall Emacs that was installed with your emacs-27.sh?

[ianyepan]

As titled. I wish to reinstall my Emacs since the first time I forgot to pass the --with-json flag to ./configure. The current Emacs I'm using is installed with your emacs-27.sh. What is the best way to safely uninstall it so I can run the script to reinstall it again? Thanks in advance

[hubisan]

I read this before somewhere but to be sure I had a look at some files in the emacs 27 cloned git repo and that is what I found:

Emacs 27 is compiled with native JSON by default. For that reason there is actually only a --without-json flag. You can verify this by running (inside the git repo):

./autogen.sh
./configure --help | grep json
# Output:
 --without-json          don't compile with native JSON support

It is also mentioned in the configure.ac file:

dnl _ON results in a '--without' option in the --help output, so
dnl the help text should refer to "don't compile", etc.
...
OPTION_DEFAULT_ON([json], [don't compile with native JSON support])

Uninstall

If you still feel like uninstalling you need to download the git repository git clone -b emacs-27 --depth 1 git://git.sv.gnu.org/emacs.git and then:

# not sure if this is needed, but can't harm
./autogen.sh
./configure
make
# and then to uninstall
sudo make uninstall

[ianyepan]

@hubisan Thanks for getting back, I see your point. However, I do believe that I don't have native JSON support -- because when I run M-: (functionp 'json-serialize) it returns nil. I'll try to reinstall it and see how it turns out.

[ianyepan]

I just successfully reinstalled Emacs27 by passing in the --with-json flag after ./configure in the .sh file.

(funtionp 'json-serialize) now return t, indicating that I now have native JSON support.

Reference: https://emacs-lsp.github.io/lsp-mode/page/performance/

[hubisan]

@ianpan870102 Cool, that it works now.

I just noticed that I forgot to add libjansson-dev as dependency in the shell file. That might be the reason that your Emacs was not built with native JSON support.

• Please add «--with-json=yes» to confflags
• Build-depend on libjansson-dev to get faster json

[ianyepan]

@hubisan so with libjansson-dev as a dependency, one doesn't have to include the --with-json flag, yes?

[hubisan]

@ianpan870102 yeah. (functionp 'json-serialize) returns t without having used the --with-json flag.

[hubisan]

Just installed the newer Emacs 27.0.91 without the JSON flag and having libjansson-dev installed. (functionp 'json-serialize) returns t. So the flag is not needed.