[PATCH 2 of 2 v3] extensions: catch uisetup and extsetup failures and don't let them break hg

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1496758188 14400
#      Tue Jun 06 10:09:48 2017 -0400
# Node ID ee3c6ce7b496edaaeb7eaeab8c98269be69beb85
# Parent  198f2c598d30802ef4fd65afdc770de2dd45981a
extensions: catch uisetup and extsetup failures and don't let them break hg

Otherwise users of the patience diff extension will be unable to run
anything at all in hg 4.3 until they figure out what's broken.

diff --git a/mercurial/extensions.py b/mercurial/extensions.py
--- a/mercurial/extensions.py
+++ b/mercurial/extensions.py
@@ -167,17 +167,31 @@ def load(ui, name, path):
 def _runuisetup(name, ui):
     uisetup = getattr(_extensions[name], 'uisetup', None)
     if uisetup:
-        uisetup(ui)
+        try:
+            uisetup(ui)
+        except Exception as inst:
+            ui.traceback()
+            msg = _forbytes(inst)
+            ui.warn(_("*** failed to set up extension %s: %s\n") % (name, msg))
+            return False
+    return True
 
 def _runextsetup(name, ui):
     extsetup = getattr(_extensions[name], 'extsetup', None)
     if extsetup:
         try:
-            extsetup(ui)
-        except TypeError:
-            if inspect.getargspec(extsetup).args:
-                raise
-            extsetup() # old extsetup with no ui argument
+            try:
+                extsetup(ui)
+            except TypeError:
+                if inspect.getargspec(extsetup).args:
+                    raise
+                extsetup() # old extsetup with no ui argument
+        except Exception as inst:
+            ui.traceback()
+            msg = _forbytes(inst)
+            ui.warn(_("*** failed to set up extension %s: %s\n") % (name, msg))
+            return False
+    return True
 
 def loadall(ui, whitelist=None):
     result = ui.configitems("extensions")
@@ -203,11 +217,19 @@ def loadall(ui, whitelist=None):
                 ui.warn(_("*** (%s)\n") % inst.hint)
             ui.traceback()
 
+    broken = set()
     for name in _order[newindex:]:
-        _runuisetup(name, ui)
+        if not _runuisetup(name, ui):
+            broken.add(name)
 
     for name in _order[newindex:]:
-        _runextsetup(name, ui)
+        if name in broken:
+            continue
+        if not _runextsetup(name, ui):
+            broken.add(name)
+
+    for name in broken:
+        _extensions[name] = None
 
     # Call aftercallbacks that were never met.
     for shortname in _aftercallbacks:
@@ -215,7 +237,7 @@ def loadall(ui, whitelist=None):
             continue
 
         for fn in _aftercallbacks[shortname]:
-            fn(loaded=False)
+            fn(loaded=_extensions[shortname] is not None)
 
     # loadall() is called multiple times and lingering _aftercallbacks
     # entries could result in double execution. See issue4646.
diff --git a/tests/test-extension.t b/tests/test-extension.t
--- a/tests/test-extension.t
+++ b/tests/test-extension.t
@@ -1625,9 +1625,35 @@ Make sure a broken uisetup doesn't globa
   > baduisetup = $PWD/baduisetup.py
   > EOF
 
-Broken: an extension that triggers the import of bdiff during uisetup
-can't be easily debugged:
+Even though the extension fails during uisetup, hg is still basically usable:
   $ hg version
-  abort: No module named bdiff!
-  (did you forget to compile extensions?)
-  [255]
+  *** failed to set up extension baduisetup: No module named bdiff
+  Mercurial Distributed SCM (version *) (glob)
+  (see https://mercurial-scm.org for more information)
+  
+  Copyright (C) 2005-2017 Matt Mackall and others
+  This is free software; see the source for copying conditions. There is NO
+  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+  $ hg version --traceback
+  Traceback (most recent call last):
+    File "*/mercurial/extensions.py", line *, in _runuisetup (glob)
+      uisetup(ui)
+    File "$TESTTMP/baduisetup.py", line 10, in uisetup
+      extensions.wrapfunction(bdiff, 'blocks', blockswrapper)
+    File "*/mercurial/extensions.py", line *, in wrapfunction (glob)
+      origfn = getattr(container, funcname)
+    File "*/hgdemandimport/demandimportpy2.py", line *, in __getattr__ (glob)
+      self._load()
+    File "*/hgdemandimport/demandimportpy2.py", line *, in _load (glob)
+      mod = _hgextimport(_import, head, globals, locals, None, level)
+    File "*/hgdemandimport/demandimportpy2.py", line *, in _hgextimport (glob)
+      return importfunc(name, globals, *args, **kwargs)
+  ImportError: No module named bdiff
+  *** failed to set up extension baduisetup: No module named bdiff
+  Mercurial Distributed SCM (version *) (glob)
+  (see https://mercurial-scm.org for more information)
+  
+  Copyright (C) 2005-2017 Matt Mackall and others
+  This is free software; see the source for copying conditions. There is NO
+  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
diff --git a/tests/test-flagprocessor.t b/tests/test-flagprocessor.t
--- a/tests/test-flagprocessor.t
+++ b/tests/test-flagprocessor.t
@@ -161,7 +161,8 @@
   > EOF
   $ echo 'this should fail' > file
   $ hg commit -Aqm 'add file'
-  abort: cannot register multiple processors on flag '0x8'.
+  *** failed to set up extension duplicate: cannot register multiple processors on flag '0x8'.
+  abort: missing processor for flag '0x1'!
   [255]
 
   $ cd ..