[elpa] externals/xr 5b53cc9 3/5: Warn about two-character ranges like [*-+]

[Mattias Engdegård]

branch: externals/xr
commit 5b53cc9efe25b668ce0c7263c1b8cf50c999a6cb
Author: Mattias Engdegård <address@hidden>
Commit: Mattias Engdegård <address@hidden>

    Warn about two-character ranges like [*-+]
---
 xr-test.el |  5 +++++
 xr.el      | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/xr-test.el b/xr-test.el
index 8948c2a..644eedf 100644
--- a/xr-test.el
+++ b/xr-test.el
@@ -349,6 +349,7 @@
                    (10 . "Ranges `I-L' and `I-M' overlap")
                    (16 . "Ranges `a-e' and `b-d' overlap")
                    (22 . "Ranges `g-k' and `i-n' overlap")
+                   (25 . "Two-character range `s-t'")
                    (29 . "Character `3' included in range `3-7'"))))
   (should (equal (xr-lint "[a[:digit:]b[:punct:]c[:digit:]]")
                  '((22 . "Duplicated character class `[:digit:]'"))))
@@ -362,6 +363,10 @@
                  '((4 . "Suspect `[' in char alternative"))))
   (should (equal (xr-lint "[^][-].]")
                  nil))
+  (should (equal (xr-lint "[0-1]")
+                 nil))
+  (should (equal (xr-lint "[^]-][]-^]")
+                 '((6 . "Two-character range `]-^'"))))
   )
 
 (ert-deftest xr-skip-set ()
diff --git a/xr.el b/xr.el
index 4828b45..d2a65d1 100644
--- a/xr.el
+++ b/xr.el
@@ -98,6 +98,10 @@
             (push (vector ?\] end (point)) intervals)
           (xr--report warnings (point)
                       (format "Reversed range `%s' matches nothing"
+                              (xr--escape-string (match-string 0) nil))))
+        (when (eq end ?^)
+          (xr--report warnings (point)
+                      (format "Two-character range `%s'"
                               (xr--escape-string (match-string 0) nil)))))
       (goto-char (match-end 0)))
      ;; Initial ]
@@ -133,6 +137,12 @@
             (xr--report warnings (point)
                         (format "Reversed range `%s' matches nothing"
                                 (xr--escape-string (match-string 0) nil)))))
+          ;; Suppress warnings about ranges between adjacent digits,
+          ;; like [0-1], as they are common and harmless.
+          (when (and (= end (1+ start)) (not (<= ?0 start end ?9)))
+            (xr--report warnings (point)
+                        (format "Two-character range `%s'"
+                                (xr--escape-string (match-string 0) nil))))
           (goto-char (match-end 0))))
        ((looking-at (rx eos))
         (error "Unterminated character alternative"))