Does emacs have an option or some internal command that displays build time settings and whatever features it supports?

A good example is the nginx -V command which lists the ./configure options it was compiled with.


Take a look at the system-configuration-options variable.

Here's an example, which is the result of running C-h v system-configuration-options

system-configuration-options is a variable defined in `C source code'.
Its value is
"--prefix=/usr/local/emacs 'CFLAGS=-O2 -march=native -pipe
-falign-functions=64 -fomit-frame-pointer -ftracer -funit-at-a-time
-fweb -fforce-addr -fpeel-loops -funswitch-loops -frename-registers
-mfpmath=sse -ffast-math -fno-finite-math-only -fstack-check'

String containing the configuration options Emacs was built with.

For more information check the manuals.

Dunno about a command-line switch, but:

  1. If you use library emacsbug+.el, which enhances standard library emacsbug.el, then you can use command ebp-insert-version with a prefix arg, to insert the complete version info, including some build info, in the current buffer. This is the same version info that is included when you use command report-emacs-bug. For example:

     In GNU Emacs 25.2.1 (x86_64-w64-mingw32)
      of 2017-04-24
     Windowing system distributor `Microsoft Corp.', version 6.1.7601
     Configured using:
      `configure --without-dbus --without-compress-install 'CFLAGS=-O2
      -static -g3''
  2. Without library emacsbug+.el, you can use standard command emacs-version, to give you a subset of that info. With a prefix arg it inserts the info in the current buffer. For example:

    GNU Emacs 25.2.1 (x86_64-w64-mingw32) of 2017-04-24

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