revrange: don't parse revset aliases as hash prefixes (issue4553)

If a user has a revsetalias defined, it is their explicit wish for
this alias to be parsed as a revset and nothing else. Although the
case of the alias being short enough and only contain the letters a-f
is probably kind of rare, it may still happen.

mercurial/scmutil.py

@@ -628,12 +628,22 b' def revrange(repo, revs):'
         return repo[val].rev()
 
     seen, l = set(), revset.baseset([])
+
+    revsetaliases = [alias for (alias, _) in
+                     repo.ui.configitems("revsetalias")]
+
     for spec in revs:
         if l and not seen:
             seen = set(l)
         # attempt to parse old-style ranges first to deal with
         # things like old-tag which contain query metacharacters
         try:
+            # ... except for revset aliases without arguments. These
+            # should be parsed as soon as possible, because they might
+            # clash with a hash prefix.
+            if spec in revsetaliases:
+                raise error.RepoLookupError
+
             if isinstance(spec, int):
                 seen.add(spec)
                 l = l + revset.baseset([spec])
@@ -641,6 +651,9 b' def revrange(repo, revs):'
 
             if _revrangesep in spec:
                 start, end = spec.split(_revrangesep, 1)
+                if start in revsetaliases or end in revsetaliases:
+                    raise error.RepoLookupError
+
                 start = revfix(repo, start, 0)
                 end = revfix(repo, end, len(repo) - 1)
                 if end == nullrev and start < 0:

tests/test-revset.t

@@ -1127,6 +1127,62 b' far away.'
   3
   2
 
+issue4553: check that revset aliases override existing hash prefix
+
+  $ hg log -qr e
+  6:e0cc66ef77e8
+
+  $ hg log -qr e --config revsetalias.e="all()"
+  0:2785f51eece5
+  1:d75937da8da0
+  2:5ed5505e9f1c
+  3:8528aa5637f2
+  4:2326846efdab
+  5:904fa392b941
+  6:e0cc66ef77e8
+  7:013af1973af4
+  8:d5d0dcbdc4d9
+  9:24286f4ae135
+
+  $ hg log -qr e: --config revsetalias.e="0"
+  0:2785f51eece5
+  1:d75937da8da0
+  2:5ed5505e9f1c
+  3:8528aa5637f2
+  4:2326846efdab
+  5:904fa392b941
+  6:e0cc66ef77e8
+  7:013af1973af4
+  8:d5d0dcbdc4d9
+  9:24286f4ae135
+
+  $ hg log -qr :e --config revsetalias.e="9"
+  0:2785f51eece5
+  1:d75937da8da0
+  2:5ed5505e9f1c
+  3:8528aa5637f2
+  4:2326846efdab
+  5:904fa392b941
+  6:e0cc66ef77e8
+  7:013af1973af4
+  8:d5d0dcbdc4d9
+  9:24286f4ae135
+
+  $ hg log -qr e:
+  6:e0cc66ef77e8
+  7:013af1973af4
+  8:d5d0dcbdc4d9
+  9:24286f4ae135
+
+  $ hg log -qr :e
+  0:2785f51eece5
+  1:d75937da8da0
+  2:5ed5505e9f1c
+  3:8528aa5637f2
+  4:2326846efdab
+  5:904fa392b941
+  6:e0cc66ef77e8
+
 issue2549 - correct optimizations
 
   $ log 'limit(1 or 2 or 3, 2) and not 2'