verify: don't init subrepo when missing one is referenced (issue5128) (API)

Initializing a subrepo when one doesn't exist is the right thing to do when the
parent is being updated, but in few other cases.  Unfortunately, there isn't
enough context in the subrepo module to distinguish this case.  This same issue
can be caused with other subrepo aware commands, so there is a general issue
here beyond the scope of this fix.

A simpler attempt I tried was to add an '_updating' boolean to localrepo, and
set/clear it around the call to mergemod.update() in hg.updaterepo().  That
mostly worked, but doesn't handle the case where archive will clone the subrepo
if it is missing.  (I vaguely recall that there may be other commands that will
clone if needed like this, but certainly not all do.  It seems both handy, and a
bit surprising for what should be a read only operation.  It might be nice if
all commands did this consistently, but we probably need Angel's subrepo caching
first, to not make a mess of the working directory.)

I originally handled 'Exception' in order to pick up the Aborts raised in
subrepo.state(), but this turns out to be unnecessary because that is called
once and cached by ctx.sub() when iterating the subrepos.

It was suggested in the bug discussion to skip looking at the subrepo links
unless -S is specified.  I don't really like that idea because missing a subrepo
or (less likely, but worse) a corrupt .hgsubstate is a problem of the parent
repo when checking out a revision.  The -S option seems like a better fit for
functionality that would recurse into each subrepo and do a full verification.

Ultimately, the default value for 'allowcreate' should probably be flipped, but
since the default behavior was to allow creation, this is less risky for now.

mercurial/context.py

@@ -275,9 +275,9 class basectx(object):
         except error.LookupError:
             return ''
 
-    def sub(self, path):
+    def sub(self, path, allowcreate=True):
         '''return a subrepo for the stored revision of path, never wdir()'''
-        return subrepo.subrepo(self, path)
+        return subrepo.subrepo(self, path, allowcreate=allowcreate)
 
     def nullsub(self, path, pctx):
         return subrepo.nullsubrepo(self, path, pctx)

mercurial/hg.py

@@ -886,7 +886,11 def verify(repo):
             ctx = repo[rev]
             try:
                 for subpath in ctx.substate:
-                    ret = ctx.sub(subpath).verify() or ret
+                    try:
+                        ret = (ctx.sub(subpath, allowcreate=False).verify()
+                               or ret)
+                    except error.RepoError as e:
+                        repo.ui.warn(_('%s: %s\n') % (rev, e))
             except Exception:
                 repo.ui.warn(_('.hgsubstate is corrupt in revision %s\n') %
                              node.short(ctx.node()))

mercurial/subrepo.py

@@ -340,7 +340,7 def _sanitize(ui, vfs, ignore):
                           "in '%s'\n") % vfs.join(dirname))
                 vfs.unlink(vfs.reljoin(dirname, f))
 
-def subrepo(ctx, path, allowwdir=False):
+def subrepo(ctx, path, allowwdir=False, allowcreate=True):
     """return instance of the right subrepo class for subrepo in path"""
     # subrepo inherently violates our import layering rules
     # because it wants to make repo objects from deep inside the stack
@@ -356,7 +356,7 def subrepo(ctx, path, allowwdir=False):
         raise error.Abort(_('unknown subrepo type %s') % state[2])
     if allowwdir:
         state = (state[0], ctx.subrev(path), state[2])
-    return types[state[2]](ctx, path, state[:2])
+    return types[state[2]](ctx, path, state[:2], allowcreate)
 
 def nullsubrepo(ctx, path, pctx):
     """return an empty subrepo in pctx for the extant subrepo in ctx"""
@@ -375,7 +375,7 def nullsubrepo(ctx, path, pctx):
     subrev = ''
     if state[2] == 'hg':
         subrev = "0" * 40
-    return types[state[2]](pctx, path, (state[0], subrev))
+    return types[state[2]](pctx, path, (state[0], subrev), True)
 
 def newcommitphase(ui, ctx):
     commitphase = phases.newcommitphase(ui)
@@ -611,12 +611,12 class abstractsubrepo(object):
         return self.wvfs.reljoin(reporelpath(self._ctx.repo()), self._path)
 
 class hgsubrepo(abstractsubrepo):
-    def __init__(self, ctx, path, state):
+    def __init__(self, ctx, path, state, allowcreate):
         super(hgsubrepo, self).__init__(ctx, path)
         self._state = state
         r = ctx.repo()
         root = r.wjoin(path)
-        create = not r.wvfs.exists('%s/.hg' % path)
+        create = allowcreate and not r.wvfs.exists('%s/.hg' % path)
         self._repo = hg.repository(r.baseui, root, create=create)
 
         # Propagate the parent's --hidden option
@@ -1064,7 +1064,7 class hgsubrepo(abstractsubrepo):
         return reporelpath(self._repo)
 
 class svnsubrepo(abstractsubrepo):
-    def __init__(self, ctx, path, state):
+    def __init__(self, ctx, path, state, allowcreate):
         super(svnsubrepo, self).__init__(ctx, path)
         self._state = state
         self._exe = util.findexe('svn')
@@ -1284,7 +1284,7 class svnsubrepo(abstractsubrepo):
 
 
 class gitsubrepo(abstractsubrepo):
-    def __init__(self, ctx, path, state):
+    def __init__(self, ctx, path, state, allowcreate):
         super(gitsubrepo, self).__init__(ctx, path)
         self._state = state
         self._abspath = ctx.repo().wjoin(path)

tests/test-subrepo-missing.t

@@ -121,4 +121,22 verify will warn if locked-in subrepo re
   subrepo 'subrepo' is hidden in revision 674d05939c1e
   subrepo 'subrepo' not found in revision a7d05d9055a4
 
+verifying shouldn't init a new subrepo if the reference doesn't exist
+
+  $ mv subrepo b
+  $ hg verify
+  checking changesets
+  checking manifests
+  crosschecking files in changesets and manifests
+  checking files
+  2 files, 5 changesets, 5 total revisions
+  checking subrepo links
+  0: repository $TESTTMP/repo/subrepo not found (glob)
+  1: repository $TESTTMP/repo/subrepo not found (glob)
+  3: repository $TESTTMP/repo/subrepo not found (glob)
+  4: repository $TESTTMP/repo/subrepo not found (glob)
+  $ ls
+  b
+  $ mv b subrepo
+
   $ cd ..