Use appropriate coding system when unzipping jars

in `cider-find-file`. This prevents CRLF encoded files from appearing with ^M
characters at the end of each line, which, in turn, avoids confusing
`clojure-find-ns` and breaking `cider-find-var`.
`clojure-find-ns` uses Emacs' `(thing-at-point 'symbol)` as part of identifying
a file's namespace, and when a file isn't decoded properly, namespaces can be
reported as `my.lib^M` which `cider-find-var` won't know what to do with.

Author: pdbrown

CHANGELOG.md

@@ -15,8 +15,9 @@
 * [#2953](https://github.com/clojure-emacs/cider/issues/2953): Don't font-lock function/macro vars as generic vars.
 * [#2964](https://github.com/clojure-emacs/cider/issues/2964): Fix issue with `cider-company-enable-fuzzy-completion` and Helm.
 * [#2937](https://github.com/clojure-emacs/cider/issues/2937): Green fringe produced for extra line in rich comment block.
-* [#2996]((https://github.com/clojure-emacs/cider/issues/2937)): Fix debugger incorrectly locating `#_` ignored forms.
+* [#2996](https://github.com/clojure-emacs/cider/issues/2937): Fix debugger incorrectly locating `#_` ignored forms.
 * Bump the injected `cider-nrepl` to 0.25.6. This should fix a compatibility issue with Java 15 and fetching fresh ClojureDocs data.
+* [#3004](https://github.com/clojure-emacs/cider/pull/3004): Use appropriate coding system when unzipping jars
 
 ### Changes
 

cider-common.el

@@ -382,7 +382,18 @@ found."
             (t
              (with-current-buffer (generate-new-buffer
                                    (file-name-nondirectory entry))
-               (archive-zip-extract path entry)
+               ;; Use appropriate coding system for bytes read from unzip cmd to
+               ;; display Emacs native newlines regardless of whether the file
+               ;; uses unix LF or dos CRLF line endings.
+               ;; It's important to avoid spurious CR characters, which may
+               ;; appear as `^M', because they can confuse clojure-mode's symbol
+               ;; detection, e.g. `clojure-find-ns', and break `cider-find-var'.
+               ;; `clojure-find-ns' uses Emacs' (thing-at-point 'symbol) as
+               ;; part of identifying a file's namespace, and when a file
+               ;; isn't decoded properly, namespaces can be reported as
+               ;; `my.lib^M' which `cider-find-var' won't know what to do with.
+               (let ((coding-system-for-read 'prefer-utf-8))
+                 (archive-zip-extract path entry))
                (set-visited-file-name name)
                (setq-local default-directory (file-name-directory path))
                (setq-local buffer-read-only t)