This is a report from this emacs-devel post:

    https://lists.gnu.org/archive/html/emacs-devel/2016-09/msg00414.html

Making a bug report to keep track of this question. The original
message:

I've been working with Makefiles recently, and discovered that $ has
word syntax. This results in odd behaviors. For instance, if you have

    asdf-$(xyz)

in your buffer with the point on 'a', then commands like M-s . or
C-M-SPC select "asdf-$", which makes no sense. Shouldn't $ have
punctuation syntax (attached patch)? Am I missing something obvious
here?