--- a/hgext/churn.py	Thu Sep 10 17:14:03 2020 +0900
+++ b/hgext/churn.py	Thu Sep 10 18:01:43 2020 +0900
@@ -23,7 +23,6 @@
     patch,
     pycompat,
     registrar,
-    scmutil,
 )
 from mercurial.utils import dateutil
 
@@ -76,8 +75,6 @@
     if opts.get(b'date'):
         df = dateutil.matchdate(opts[b'date'])
 
-    m = scmutil.match(repo[None], pats, opts)
-
     def prep(ctx, fmatch):
         rev = ctx.rev()
         if df and not df(ctx.date()[0]):  # doesn't match date format
@@ -99,7 +96,15 @@
 
         progress.increment()
 
-    for ctx in cmdutil.walkchangerevs(repo, m, opts, prep):
+    wopts = logcmdutil.walkopts(
+        pats=pats,
+        opts=opts,
+        revspec=opts[b'rev'],
+        include_pats=opts[b'include'],
+        exclude_pats=opts[b'exclude'],
+    )
+    revs, makefilematcher = logcmdutil.makewalker(repo, wopts)
+    for ctx in cmdutil.walkchangerevs(repo, revs, makefilematcher, prep):
         continue
 
     progress.complete()

--- a/mercurial/cmdutil.py	Thu Sep 10 17:14:03 2020 +0900
+++ b/mercurial/cmdutil.py	Thu Sep 10 18:01:43 2020 +0900
@@ -2428,8 +2428,8 @@
         return False
 
 
-def walkchangerevs(repo, match, opts, prepare):
-    '''Iterate over files and the revs in which they changed.
+def walkchangerevs(repo, revs, makefilematcher, prepare):
+    '''Iterate over files and the revs in a "windowed" way.
 
     Callers most commonly need to iterate backwards over the history
     in which they are interested. Doing so has awful (quadratic-looking)
@@ -2443,107 +2443,11 @@
     yielding each context, the iterator will first call the prepare
     function on each context in the window in forward order.'''
 
-    allfiles = opts.get(b'all_files')
-    follow = opts.get(b'follow') or opts.get(b'follow_first')
-    revs = _walkrevs(repo, opts)
     if not revs:
         return []
-    wanted = set()
-    slowpath = match.anypats() or (not match.always() and opts.get(b'removed'))
-    fncache = {}
     change = repo.__getitem__
 
-    # First step is to fill wanted, the set of revisions that we want to yield.
-    # When it does not induce extra cost, we also fill fncache for revisions in
-    # wanted: a cache of filenames that were changed (ctx.files()) and that
-    # match the file filtering conditions.
-
-    if match.always() or allfiles:
-        # No files, no patterns.  Display all revs.
-        wanted = revs
-    elif not slowpath:
-        # We only have to read through the filelog to find wanted revisions
-
-        try:
-            wanted = walkfilerevs(repo, match, follow, revs, fncache)
-        except FileWalkError:
-            slowpath = True
-
-            # We decided to fall back to the slowpath because at least one
-            # of the paths was not a file. Check to see if at least one of them
-            # existed in history, otherwise simply return
-            for path in match.files():
-                if path == b'.' or path in repo.store:
-                    break
-            else:
-                return []
-
-    if slowpath:
-        # We have to read the changelog to match filenames against
-        # changed files
-
-        if follow:
-            raise error.Abort(
-                _(b'can only follow copies/renames for explicit filenames')
-            )
-
-        # The slow path checks files modified in every changeset.
-        # This is really slow on large repos, so compute the set lazily.
-        class lazywantedset(object):
-            def __init__(self):
-                self.set = set()
-                self.revs = set(revs)
-
-            # No need to worry about locality here because it will be accessed
-            # in the same order as the increasing window below.
-            def __contains__(self, value):
-                if value in self.set:
-                    return True
-                elif not value in self.revs:
-                    return False
-                else:
-                    self.revs.discard(value)
-                    ctx = change(value)
-                    if allfiles:
-                        matches = list(ctx.manifest().walk(match))
-                    else:
-                        matches = [f for f in ctx.files() if match(f)]
-                    if matches:
-                        fncache[value] = matches
-                        self.set.add(value)
-                        return True
-                    return False
-
-            def discard(self, value):
-                self.revs.discard(value)
-                self.set.discard(value)
-
-        wanted = lazywantedset()
-
-    # it might be worthwhile to do this in the iterator if the rev range
-    # is descending and the prune args are all within that range
-    for rev in opts.get(b'prune', ()):
-        rev = repo[rev].rev()
-        ff = _followfilter(repo)
-        stop = min(revs[0], revs[-1])
-        for x in pycompat.xrange(rev, stop - 1, -1):
-            if ff.match(x):
-                wanted = wanted - [x]
-
-    # Now that wanted is correctly initialized, we can iterate over the
-    # revision range, yielding only revisions in wanted.
     def iterate():
-        if follow and match.always():
-            ff = _followfilter(repo, onlyfirst=opts.get(b'follow_first'))
-
-            def want(rev):
-                return ff.match(rev) and rev in wanted
-
-        else:
-
-            def want(rev):
-                return rev in wanted
-
         it = iter(revs)
         stopiteration = False
         for windowsize in increasingwindows():
@@ -2553,28 +2457,10 @@
                 if rev is None:
                     stopiteration = True
                     break
-                elif want(rev):
-                    nrevs.append(rev)
+                nrevs.append(rev)
             for rev in sorted(nrevs):
-                fns = fncache.get(rev)
                 ctx = change(rev)
-                if not fns:
-
-                    def fns_generator():
-                        if allfiles:
-
-                            def bad(f, msg):
-                                pass
-
-                            for f in ctx.matches(matchmod.badmatch(match, bad)):
-                                yield f
-                        else:
-                            for f in ctx.files():
-                                if match(f):
-                                    yield f
-
-                    fns = fns_generator()
-                prepare(ctx, scmutil.matchfiles(repo, fns))
+                prepare(ctx, makefilematcher(ctx))
             for rev in nrevs:
                 yield change(rev)
 

--- a/mercurial/commands.py	Thu Sep 10 17:14:03 2020 +0900
+++ b/mercurial/commands.py	Thu Sep 10 18:01:43 2020 +0900
@@ -3579,7 +3579,6 @@
 
     skip = set()
     revfiles = {}
-    match = scmutil.match(repo[None], pats, opts)
     found = False
     follow = opts.get(b'follow')
 
@@ -3654,9 +3653,21 @@
                     if pfn not in matches[parent] and pfn in pctx:
                         grepbody(pfn, parent, readfile(pctx, pfn))
 
+    wopts = logcmdutil.walkopts(
+        pats=pats,
+        opts=opts,
+        revspec=opts[b'rev'],
+        include_pats=opts[b'include'],
+        exclude_pats=opts[b'exclude'],
+        follow=follow,
+        force_changelog_traversal=all_files,
+        filter_revisions_by_pats=not all_files,
+    )
+    revs, makefilematcher = logcmdutil.makewalker(repo, wopts)
+
     ui.pager(b'grep')
     fm = ui.formatter(b'grep', opts)
-    for ctx in cmdutil.walkchangerevs(repo, match, opts, prep):
+    for ctx in cmdutil.walkchangerevs(repo, revs, makefilematcher, prep):
         rev = ctx.rev()
         parent = ctx.p1().rev()
         for fn in sorted(revfiles.get(rev, [])):

--- a/tests/test-grep.t	Thu Sep 10 17:14:03 2020 +0900
+++ b/tests/test-grep.t	Thu Sep 10 18:01:43 2020 +0900
@@ -990,7 +990,6 @@
   1: A add0-cp1, A add0-cp1-mod1, A add0-cp1-mod1-rm3, M add0-mod1, R add0-rm1
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history
  BROKEN: should not abort because of removed file
   $ hg grep --diff -fr'wdir()' data
   add0-cp4-mod4:2147483647:+:data4
@@ -1063,10 +1062,12 @@
   1: A add0-cp1, A add0-cp1-mod1, A add0-cp1-mod1-rm3, M add0-mod1, R add0-rm1
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should include the revision 1
   $ hg grep --diff -fr'1+2' data
   add0-cp2-mod2:2:+:data2
   add0-mod2:2:+:data2
+  add0-cp1-mod1:1:+:data1
+  add0-cp1-mod1-rm3:1:+:data1
+  add0-mod1:1:+:data1
   add0:0:+:data0
   add0-mod1:0:+:data0
   add0-mod2:0:+:data0
@@ -1076,7 +1077,6 @@
   add0-rm2:0:+:data0
   add0-rm4:0:+:data0
 
- BROKEN: should include the revision 1
   $ hg grep -fr'1+2' data
   add0:2:data0
   add0-cp2:2:data0
@@ -1089,6 +1089,19 @@
   add0-mod4:2:data0
   add0-rm1:2:data0
   add0-rm4:2:data0
+  add0:1:data0
+  add0-cp1:1:data0
+  add0-cp1-mod1:1:data0
+  add0-cp1-mod1:1:data1
+  add0-cp1-mod1-rm3:1:data0
+  add0-cp1-mod1-rm3:1:data1
+  add0-mod1:1:data0
+  add0-mod1:1:data1
+  add0-mod2:1:data0
+  add0-mod3:1:data0
+  add0-mod4:1:data0
+  add0-rm2:1:data0
+  add0-rm4:1:data0
   add0:0:data0
   add0-mod1:0:data0
   add0-mod2:0:data0
@@ -1108,11 +1121,9 @@
   add0-mod3:3:+:data3
   add0-mod3:0:+:data0
 
- BROKEN: should not include the revision 2
   $ hg grep -f data add0-mod3
   add0-mod3:3:data0
   add0-mod3:3:data3
-  add0-mod3:2:data0
   add0-mod3:1:data0
   add0-mod3:0:data0
 
@@ -1124,10 +1135,8 @@
   $ hg grep --diff -f data add0-mod4
   add0-mod4:0:+:data0
 
- BROKEN: should not include the revision 2
   $ hg grep -f data add0-mod4
   add0-mod4:3:data0
-  add0-mod4:2:data0
   add0-mod4:1:data0
   add0-mod4:0:data0
 
@@ -1170,7 +1179,7 @@
   [255]
 
   $ hg grep --diff -f data add0-cp4
-  abort: cannot follow file not in parent revision: "add0-cp4"
+  abort: cannot follow nonexistent file: "add0-cp4"
   [255]
 
  BROKEN: maybe better to abort
@@ -1199,7 +1208,7 @@
   [255]
 
   $ hg grep --diff -fr. data add0-cp1-mod1-rm3
-  abort: cannot follow file not in parent revision: "add0-cp1-mod1-rm3"
+  abort: cannot follow file not in any of the specified revisions: "add0-cp1-mod1-rm3"
   [255]
 
  BROKEN: should abort
@@ -1213,14 +1222,13 @@
   abort: cannot follow file not in parent revision: "add0-rm4"
   [255]
 
- BROKEN: may be okay, but different behavior from "hg log"
   $ hg grep --diff -f data add0-rm4
-  add0-rm4:0:+:data0
+  abort: cannot follow file not in parent revision: "add0-rm4"
+  [255]
 
- BROKEN: should not include the revision 2, and maybe better to abort
+ BROKEN: should abort
   $ hg grep -f data add0-rm4
   add0-rm4:3:data0
-  add0-rm4:2:data0
   add0-rm4:1:data0
   add0-rm4:0:data0
 
@@ -1250,14 +1258,12 @@
   add0:0:+:data0
   add0-mod3:0:+:data0
 
- BROKEN: should not include the revision 2
  BROKEN: should follow history across renames
   $ hg grep -f data add0-mod3 add0-cp1-mod1
   add0-cp1-mod1:3:data0
   add0-cp1-mod1:3:data1
   add0-mod3:3:data0
   add0-mod3:3:data3
-  add0-mod3:2:data0
   add0-cp1-mod1:1:data0
   add0-cp1-mod1:1:data1
   add0-mod3:1:data0
@@ -1269,8 +1275,8 @@
   2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should include the revision 2
   $ hg grep --diff -fr2 data add0-mod2
+  add0-mod2:2:+:data2
   add0-mod2:0:+:data0
 
   $ hg grep -fr2 data add0-mod2
@@ -1284,10 +1290,8 @@
   2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history from the specified revision
   $ hg grep --diff -fr2 data add0-cp2
-  abort: cannot follow file not in parent revision: "add0-cp2"
-  [255]
+  add0:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr2 data add0-cp2
@@ -1299,10 +1303,9 @@
   2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history from the specified revision
   $ hg grep --diff -fr2 data add0-cp2-mod2
-  abort: cannot follow file not in parent revision: "add0-cp2-mod2"
-  [255]
+  add0-cp2-mod2:2:+:data2
+  add0:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr2 data add0-cp2-mod2
@@ -1315,9 +1318,9 @@
   abort: cannot follow file not in any of the specified revisions: "add0-rm2"
   [255]
 
- BROKEN: should abort
   $ hg grep --diff -fr2 data add0-rm2
-  add0-rm2:0:+:data0
+  abort: cannot follow file not in any of the specified revisions: "add0-rm2"
+  [255]
 
  BROKEN: should abort
   $ hg grep -fr2 data add0-rm2
@@ -1329,10 +1332,10 @@
   2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history from the specified revision
   $ hg grep --diff -fr2 data add0-cp2 add0-mod2
-  abort: cannot follow file not in parent revision: "add0-cp2"
-  [255]
+  add0-mod2:2:+:data2
+  add0:0:+:data0
+  add0-mod2:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr2 data add0-cp2 add0-mod2
@@ -1366,8 +1369,8 @@
   2147483647: A add0-cp4, A add0-cp4-mod4, M add0-mod4, R add0-rm4
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should include the changes in wdir
   $ hg grep --diff -fr'wdir()' data add0-mod4
+  add0-mod4:2147483647:+:data4
   add0-mod4:0:+:data0
 
   $ hg grep -fr'wdir()' data add0-mod4
@@ -1383,10 +1386,8 @@
   2147483647: A add0-cp4, A add0-cp4-mod4, M add0-mod4, R add0-rm4
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history
   $ hg grep --diff -fr'wdir()' data add0-cp4
-  abort: cannot follow file not in parent revision: "add0-cp4"
-  [255]
+  add0:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr'wdir()' data add0-cp4
@@ -1398,10 +1399,9 @@
   2147483647: A add0-cp4, A add0-cp4-mod4, M add0-mod4, R add0-rm4
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history
   $ hg grep --diff -fr'wdir()' data add0-cp4-mod4
-  abort: cannot follow file not in parent revision: "add0-cp4-mod4"
-  [255]
+  add0-cp4-mod4:2147483647:+:data4
+  add0:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr'wdir()' data add0-cp4-mod4
@@ -1415,10 +1415,12 @@
   3: A add0-cp1-cp3, A add0-cp1-mod1-cp3-mod3, R add0-cp1-mod1-rm3, M add0-mod3
   0: A add0, A add0-mod1, A add0-mod2, A add0-mod3, A add0-mod4, A add0-rm1, A add0-rm2, A add0-rm4
 
- BROKEN: should follow history
   $ hg grep --diff -fr'wdir()' data add0-cp4 add0-mod4 add0-mod3
-  abort: cannot follow file not in parent revision: "add0-cp4"
-  [255]
+  add0-mod4:2147483647:+:data4
+  add0-mod3:3:+:data3
+  add0:0:+:data0
+  add0-mod3:0:+:data0
+  add0-mod4:0:+:data0
 
  BROKEN: should follow history across renames
   $ hg grep -fr'wdir()' data add0-cp4 add0-mod4 add0-mod3