[elpa] externals/xr 549cbc5 3/3: Detect duplicated branches in alternatives

[Mattias Engdegård]

branch: externals/xr
commit 549cbc55fa3160e4246fefdead4130c85a91b608
Author: Mattias Engdegård <address@hidden>
Commit: Mattias Engdegård <address@hidden>

    Detect duplicated branches in alternatives
    
    Eg. "A\\|A". Sometimes indication of deeper mistake, always wasteful.
---
 xr-test.el | 2 ++
 xr.el      | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/xr-test.el b/xr-test.el
index c90258a..c1c9b31 100644
--- a/xr-test.el
+++ b/xr-test.el
@@ -349,6 +349,8 @@
                    (29 . "Character `3' included in range `3-7'"))))
   (should (equal (xr-lint "[a[:digit:]b[:punct:]c[:digit:]]")
                  '((22 . "Duplicated character class `[:digit:]'"))))
+  (should (equal (xr-lint "a*\\|b+\\|\\(?:a\\)*")
+                 '((8 . "Duplicated alternative branch"))))
   )
 
 (provide 'xr-test)
diff --git a/xr.el b/xr.el
index 5f644bb..d287165 100644
--- a/xr.el
+++ b/xr.el
@@ -545,7 +545,11 @@
     (push (xr--parse-seq warnings) alternatives)
     (while (not (looking-at (rx (or "\\)" eos))))
       (forward-char 2)                  ; skip \|
-      (push (xr--parse-seq warnings) alternatives))
+      (let ((pos (point))
+            (seq (xr--parse-seq warnings)))
+        (when (and warnings (member seq alternatives))
+          (xr--report warnings pos "Duplicated alternative branch"))
+        (push seq alternatives)))
     (if (cdr alternatives)
         ;; Simplify (or nonl "\n") to anything
         (if (or (equal alternatives '(nonl "\n"))