templater: enable alias predicates to be used in "revset()" function

Before this patch, predicates defined in "[revsetalias]" can't be used
in the query specified to template function "revset()", because:

  - "revset()" uses "localrepository.revs()" to get query result, but
  - "localrepository.revs()" passes "None" as "ui" to "revset.match()", then
  - "revset.match()" can't recognize any alias predicates

To enable alias predicates to be used in "revset()" function, this
patch invokes "revset.match()" directly with "repo.ui".

This patch doesn't make "localrepository.revs()" pass "self.ui" to
"revset.match()", because this may be intentional implementation to
prevent alias predicates from shadowing built-in ones and breaking
functions internally using "localrepository.revs()".

Even if it isn't intentional one, the check for shadowing should be
implemented (maybe on default branch) before fixing it for safety.

mercurial/templater.py

@@ -8,6 +8,7 b''
 from i18n import _
 import sys, os, re
 import util, config, templatefilters, templatekw, parser, error
+import revset as revsetmod
 import types
 import minirst
 
@@ -370,16 +371,20 b' def revset(context, mapping, args):'
     ctx = mapping['ctx']
     repo = ctx._repo
 
+    def query(expr):
+        m = revsetmod.match(repo.ui, expr)
+        return m(repo, revsetmod.spanset(repo))
+
     if len(args) > 1:
         formatargs = list([a[0](context, mapping, a[1]) for a in args[1:]])
-        revs = repo.revs(raw, *formatargs)
+        revs = query(revsetmod.formatspec(raw, *formatargs))
         revs = list([str(r) for r in revs])
     else:
         revsetcache = mapping['cache'].setdefault("revsetcache", {})
         if raw in revsetcache:
             revs = revsetcache[raw]
         else:
-            revs = repo.revs(raw)
+            revs = query(raw)
             revs = list([str(r) for r in revs])
             revsetcache[raw] = revs
 

tests/test-command-template.t

@@ -1834,6 +1834,15 b' Test revset function'
   1 Parents: 0
   0 Parents: 
 
+  $ cat >> .hg/hgrc <<EOF
+  > [revsetalias]
+  > myparents(\$1) = parents(\$1)
+  > EOF
+  $ hg log --template '{rev} Parents: {revset("myparents(%s)", rev)}\n'
+  2 Parents: 1
+  1 Parents: 0
+  0 Parents: 
+
   $ hg log --template 'Rev: {rev}\n{revset("::%s", rev) % "Ancestor: {revision}\n"}\n'
   Rev: 2
   Ancestor: 0