Add xref support in erlang.el

In GNU Emacs 25 xref will be introduced.  It is a framework for cross
referencing commands, in particular commands for finding definitions.
It does not replace etags.  It rather resides on top of it and
provides user-friendly commands.  The idea is that the user commands
should be the same regardless of what back-end does the actual finding
of definitions.

Add to the xref commands awareness of the module:tag syntax in a
similar way that is already done for the old etags commands.

Xref completion support is not included in this commit.

Remove all compilation warnings for GNU Emacs 24.5 and current 25
(4ffec91).

Remove XEmacs incompatibility in
erlang-font-lock-exported-function-name-face.

Add file erlang-test.el with a single unit test.

Add TAGS to .gitignore.

1 files changed, 107 insertions, 0 deletions

diff --git a/lib/tools/emacs/erlang-test.el b/lib/tools/emacs/erlang-test.el
new file mode 100644
index 0000000000..a5aab04953
--- /dev/null
+++ b/lib/tools/emacs/erlang-test.el
@@ -0,0 +1,107 @@
+;;; erlang-test.el -*- lexical-binding: t; coding: utf-8-unix -*-
+
+;;; Unit tests for erlang.el.
+
+;; Author:   Johan Claesson
+;; Created: 2016-05-07
+;; Keywords: erlang, languages
+
+;; %CopyrightBegin%
+;;
+;; Copyright Ericsson AB 2016. All Rights Reserved.
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;;     http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+;;
+;; %CopyrightEnd%
+
+
+;;; Commentary:
+
+;; This library require GNU Emacs 25 or later.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(defvar erlang-test-code
+  '((nil . "-module(erlang_test).")
+    (nil . "-import(lists, [map/2]).")
+    (nil . "-compile(export_all).")
+    ("SYMBOL" . "-define(SYMBOL, value).")
+    ("MACRO" . "-define(MACRO(X), X + X).")
+    ("struct" . "-record(struct, {until,maps,are,everywhere}).")
+    ("function". "function() -> #struct{}."))
+  "Alist of erlang test code.
+Each entry have the format (TAGNAME . ERLANG_CODE).  If TAGNAME
+is nil there is no definitions in the ERLANG_CODE.  The
+ERLANG_CODE is a single line of erlang code.  These lines will be
+concatenated to form an erlang file to test on.")
+
+
+(ert-deftest erlang-test-tags ()
+  (let* ((dir (make-temp-file "erlang-test" t))
+         (erlang-file (expand-file-name "erlang_test.erl" dir))
+         (tags-file (expand-file-name "TAGS" dir))
+         tags-file-name tags-table-list erlang-buffer)
+    (unwind-protect
+        (progn
+          (erlang-test-create-erlang-file erlang-file)
+          (erlang-test-compile-tags erlang-file tags-file)
+          (setq erlang-buffer (find-file-noselect erlang-file))
+          (with-current-buffer erlang-buffer
+            (setq-local tags-file-name tags-file))
+          ;; PENDING - setting global tags-file-name is a workaround
+          ;; for GNU Emacs bug23164.
+          (setq tags-file-name tags-file)
+          (erlang-test-xref-find-definitions erlang-file erlang-buffer))
+      (when (buffer-live-p erlang-buffer)
+        (kill-buffer erlang-buffer))
+      (let ((tags-buffer (find-buffer-visiting tags-file)))
+        (when (buffer-live-p tags-buffer)
+          (kill-buffer tags-buffer)))
+      (when (file-exists-p dir)
+        (delete-directory dir t)))))
+
+(defun erlang-test-create-erlang-file (erlang-file)
+  (with-temp-file erlang-file
+    (cl-loop for (_ . code) in erlang-test-code
+             do (insert code "\n"))))
+
+(defun erlang-test-compile-tags (erlang-file tags-file)
+  (should (zerop (call-process "etags" nil nil nil
+                               "-o" tags-file
+                               erlang-file))))
+
+(defun erlang-test-xref-find-definitions (erlang-file erlang-buffer)
+  (cl-loop for (tagname . code) in erlang-test-code
+           for line = 1 then (1+ line)
+           do (when tagname
+                (switch-to-buffer erlang-buffer)
+                (xref-find-definitions tagname)
+                (erlang-test-verify-pos erlang-file line)
+                (xref-find-definitions (concat "erlang_test:" tagname))
+                (erlang-test-verify-pos erlang-file line)))
+  (xref-find-definitions "erlang_test:")
+  (erlang-test-verify-pos erlang-file 1))
+
+(defun erlang-test-verify-pos (expected-file expected-line)
+  (should (string-equal (file-truename expected-file)
+                        (file-truename (buffer-file-name))))
+  (should (eq expected-line (line-number-at-pos)))
+  (should (= (point-at-bol) (point))))
+
+
+(provide 'erlang-test)
+
+;;; erlang-test.el ends here