Ctags: JSON output not available on OSX/Debian

I guess libjansson.so, backend library for --output-format=json, was not available on your PC or not properly linked to your ctags executable.

If the option is available, you can verify it with the other option:

[yamato@slave]$ u-ctags --help | grep -e --output-format
  --output-format=u-ctags|e-ctags|etags|xref|json

"json" is included in the help message -of --output-format.

[yamato@slave]$ u-ctags --list-features                 
#NAME             DESCRIPTION
aspell            linked with code for spell checking (internal use)
debug             TO BE WRITTEN
iconv             can convert input/output encodings
interactive       accepts source code from stdin
json              supports json format output
option-directory  TO BE WRITTEN
regex             can use regular expression based pattern matching
sandbox           linked with code for system call level sandbox
wildcards         can use glob matching
xpath             linked with library for parsing xml input
yaml              linked with library for parsing yaml input

"json" is included in the output of --list-features option.

To use the feature, you must install libjansson.so first.
The you must restart the build-procedures from "./configure ...".
If a tool run in the build-process recognizes the installation of libjansson.so properly, you will see follwoing message:

[yamato@slave]~/var/ctags-github% ./configure
...
checking for JANSSON... yes
...

I don't know well Debian (I'm using Fedora daily), however, you can install libjansson as a package.
I guess libjansson-devel or libjansson-dev package is also needed.

It seems that u-ctags debian package is also available.
https://github.com/universal-ctags/ctags/issues/1785
If --output-format=json of the executable in the binary package doesn't work, let me know.
I will try to fix it with @hnakamur.

@masatake Thank you for your support !

libjansson was indeed missing, so here is what I did :

On Debian, I installed the libjansson-dev package, then rebuilt from sources using automake :

[user@vps:~/ctags] ~$ sudo apt-get install libjansson-dev && ./autogen.sh && ./configure && make && sudo make install

And it worked properly.

On OSX, I had to use the --with-jansson option as such :

[user@macosx:~/ctags] ~$  brew install jansson
[user@macosx:~/ctags] ~$  brew install --with-jansson --HEAD universal-ctags/universal-ctags/universal-ctags

Now both binaries show :

[user@vps:~/ctags] ~$ ./ctags --list-features

#NAME                       DESCRIPTION
[...]
json                        supports json format output
[...]

Thank you so much for your help mate !

@fabiensabatie FYI, I sent the following merge requests to Debian and they were merged with some tweaks.

• Install manpages
• Add libxml2 etc

Here is the latest Build-Depends
https://salsa.debian.org/debian/universal-ctags/blob/cedf9a1c5106d371398b35031409ae09caecf3e6/debian/control#L5-13

So I think universal-ctags in the next release of Debian will have json support out of the box.