grep: make -frREV follow history from the specified revision (BC)

This is close to what "log -frREV" will do, and is backported from
8b4b9ee6001a, "log: make -fr show complete history from the given revs"
except for the "del opts['follow']" bit.

I'm planning to rewrite cmdutil.walkchangerevs() to share the core logic
with logcmdutil, and this is the first step towards that. There are still
many broken tests, but the fundamental behavior should be fixed by this
patch.

.. bc::

   `hg grep -fr REV` now follows history from the specified `REV`, works in
   the same way as `hg log -fr REV`. The previous behavior was to limit
   the search space to `REV` while following the history.

mercurial/cmdutil.py

@@ -2254,8 +2254,12 b' def _walkrevs(repo, opts):'
     # Default --rev value depends on --follow but --follow behavior
     # depends on revisions resolved from --rev...
     follow = opts.get(b'follow') or opts.get(b'follow_first')
-    if opts.get(b'rev'):
-        revs = scmutil.revrange(repo, opts[b'rev'])
+    revspec = opts.get(b'rev')
+    if follow and revspec:
+        revs = scmutil.revrange(repo, revspec)
+        revs = repo.revs(b'reverse(::%ld)', revs)
+    elif revspec:
+        revs = scmutil.revrange(repo, revspec)
     elif follow and repo.dirstate.p1() == nullid:
         revs = smartset.baseset()
     elif follow:

tests/test-grep.t

@@ -949,12 +949,18 b' follow revision history from specified r'
   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
   $ hg grep --diff -fr2 data
   add0-cp2-mod2:2:+:data2
   add0-mod2:2:+:data2
+  add0:0:+:data0
+  add0-mod1:0:+:data0
+  add0-mod2:0:+:data0
+  add0-mod3:0:+:data0
+  add0-mod4:0:+:data0
+  add0-rm1:0:+:data0
+  add0-rm2:0:+:data0
+  add0-rm4:0:+:data0
 
- BROKEN: should follow history
   $ hg grep -fr2 data
   add0:2:data0
   add0-cp2:2:data0
@@ -967,6 +973,14 b' follow revision history from specified r'
   add0-mod4:2:data0
   add0-rm1:2:data0
   add0-rm4:2:data0
+  add0:0:data0
+  add0-mod1:0:data0
+  add0-mod2:0:data0
+  add0-mod3:0:data0
+  add0-mod4:0:data0
+  add0-rm1:0:data0
+  add0-rm2:0:data0
+  add0-rm4:0:data0
 
 follow revision history from wdir:
 
@@ -984,7 +998,6 b' follow revision history from wdir:'
   add0-rm4:2147483647:-:abort: add0-rm4@None: not found in manifest!
   [255]
 
- BROKEN: should follow history
   $ hg grep -fr'wdir()' data
   add0:2147483647:data0
   add0-cp1:2147483647:data0
@@ -1005,24 +1018,22 b' follow revision history from wdir:'
   add0-mod4:2147483647:data0
   add0-mod4:2147483647:data4
   add0-rm2:2147483647:data0
-
-follow revision history from multiple revisions:
-
-  $ hg log -fr'1+2'
-  2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
-  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 include the revision 2
-  $ hg grep --diff -fr'1+2' data
-  add0-cp1-mod1:1:+:data1
-  add0-cp1-mod1-rm3:1:+:data1
-  add0-mod1:1:+:data1
-
- BROKEN: should follow history
- BROKEN: should include the revision 2
-  $ hg grep -fr'1+2' data
+  add0:3:data0
+  add0-cp1:3:data0
+  add0-cp1-cp3:3:data0
+  add0-cp1-mod1:3:data0
+  add0-cp1-mod1:3:data1
+  add0-cp1-mod1-cp3-mod3:3:data0
+  add0-cp1-mod1-cp3-mod3:3:data1
+  add0-cp1-mod1-cp3-mod3:3:data3
+  add0-mod1:3:data0
+  add0-mod1:3:data1
+  add0-mod2:3:data0
+  add0-mod3:3:data0
+  add0-mod3:3:data3
+  add0-mod4:3:data0
+  add0-rm2:3:data0
+  add0-rm4:3:data0
   add0:1:data0
   add0-cp1:1:data0
   add0-cp1-mod1:1:data0
@@ -1036,6 +1047,56 b' follow revision history from multiple re'
   add0-mod4:1:data0
   add0-rm2:1:data0
   add0-rm4:1:data0
+  add0:0:data0
+  add0-mod1:0:data0
+  add0-mod2:0:data0
+  add0-mod3:0:data0
+  add0-mod4:0:data0
+  add0-rm1:0:data0
+  add0-rm2:0:data0
+  add0-rm4:0:data0
+
+follow revision history from multiple revisions:
+
+  $ hg log -fr'1+2'
+  2: A add0-cp2, A add0-cp2-mod2, M add0-mod2, R add0-rm2
+  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
+  add0:0:+:data0
+  add0-mod1:0:+:data0
+  add0-mod2:0:+:data0
+  add0-mod3:0:+:data0
+  add0-mod4:0:+:data0
+  add0-rm1:0:+:data0
+  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
+  add0-cp2-mod2:2:data0
+  add0-cp2-mod2:2:data2
+  add0-mod1:2:data0
+  add0-mod2:2:data0
+  add0-mod2:2:data2
+  add0-mod3:2:data0
+  add0-mod4:2:data0
+  add0-rm1:2:data0
+  add0-rm4:2:data0
+  add0:0:data0
+  add0-mod1:0:data0
+  add0-mod2:0:data0
+  add0-mod3:0:data0
+  add0-mod4:0:data0
+  add0-rm1:0:data0
+  add0-rm2:0:data0
+  add0-rm4:0:data0
 
 follow file history from wdir parent, unmodified in wdir:
 
@@ -1143,7 +1204,8 b' follow file history from wdir parent (ex'
 
  BROKEN: should abort
   $ hg grep -fr. data add0-cp1-mod1-rm3
-  [1]
+  add0-cp1-mod1-rm3:1:data0
+  add0-cp1-mod1-rm3:1:data1
 
 follow file history from wdir parent, removed in wdir:
 
@@ -1167,13 +1229,13 b' follow file history from wdir parent (ex'
   $ hg log -fr. 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. data add0-rm4
-  [1]
+  add0-rm4:0:+:data0
 
- BROKEN: should follow history
   $ hg grep -fr. data add0-rm4
   add0-rm4:3:data0
+  add0-rm4:1:data0
+  add0-rm4:0:data0
 
 follow file history from wdir parent, multiple files:
 
@@ -1207,14 +1269,14 b' follow file history from specified revis'
   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
+ BROKEN: should include the revision 2
   $ hg grep --diff -fr2 data add0-mod2
-  [1]
+  add0-mod2:0:+:data0
 
- BROKEN: should follow history
   $ hg grep -fr2 data add0-mod2
   add0-mod2:2:data0
   add0-mod2:2:data2
+  add0-mod2:0:data0
 
 follow file history from specified revision, copied but unmodified:
 
@@ -1255,11 +1317,11 b' follow file history from specified revis'
 
  BROKEN: should abort
   $ hg grep --diff -fr2 data add0-rm2
-  [1]
+  add0-rm2:0:+:data0
 
  BROKEN: should abort
   $ hg grep -fr2 data add0-rm2
-  [1]
+  add0-rm2:0:data0
 
 follow file history from specified revision, multiple files:
 
@@ -1272,11 +1334,12 b' follow file history from specified revis'
   abort: cannot follow file not in parent revision: "add0-cp2"
   [255]
 
- BROKEN: should follow history
+ BROKEN: should follow history across renames
   $ hg grep -fr2 data add0-cp2 add0-mod2
   add0-cp2:2:data0
   add0-mod2:2:data0
   add0-mod2:2:data2
+  add0-mod2:0:data0
 
 follow file history from wdir, unmodified:
 
@@ -1285,14 +1348,17 b' follow file history from wdir, unmodifie'
   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-mod3
-  [1]
+  add0-mod3:3:+:data3
+  add0-mod3:0:+:data0
 
- BROKEN: should follow history
   $ hg grep -fr'wdir()' data add0-mod3
   add0-mod3:2147483647:data0
   add0-mod3:2147483647:data3
+  add0-mod3:3:data0
+  add0-mod3:3:data3
+  add0-mod3:1:data0
+  add0-mod3:0:data0
 
 follow file history from wdir, modified:
 
@@ -1300,14 +1366,16 b' follow file history from wdir, modified:'
   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 and show the changes in wdir
+ BROKEN: should include the changes in wdir
   $ hg grep --diff -fr'wdir()' data add0-mod4
-  [1]
+  add0-mod4:0:+:data0
 
- BROKEN: should follow history
   $ hg grep -fr'wdir()' data add0-mod4
   add0-mod4:2147483647:data0
   add0-mod4:2147483647:data4
+  add0-mod4:3:data0
+  add0-mod4:1:data0
+  add0-mod4:0:data0
 
 follow file history from wdir, copied but unmodified:
 
@@ -1352,12 +1420,19 b' follow file history from wdir, multiple '
   abort: cannot follow file not in parent revision: "add0-cp4"
   [255]
 
- BROKEN: should follow history
+ BROKEN: should follow history across renames
   $ hg grep -fr'wdir()' data add0-cp4 add0-mod4 add0-mod3
   add0-cp4:2147483647:data0
   add0-mod3:2147483647:data0
   add0-mod3:2147483647:data3
   add0-mod4:2147483647:data0
   add0-mod4:2147483647:data4
+  add0-mod3:3:data0
+  add0-mod3:3:data3
+  add0-mod4:3:data0
+  add0-mod3:1:data0
+  add0-mod4:1:data0
+  add0-mod3:0:data0
+  add0-mod4:0:data0
 
   $ cd ..