configitems: relax warning about unwanted default value stable

configitems: relax warning about unwanted default value

The original condition was a bit harsh for extension authors since third-party
extensions need to preserve compatibility with older Mercurial versions, where
no defaults would be loaded from the configtable. So let's silence the warning
if the given default value matches, which should be harmless.

--- a/mercurial/ui.py	Thu Oct 26 11:07:06 2017 -0700
+++ b/mercurial/ui.py	Tue Oct 31 22:37:30 2017 +0900
@@ -471,12 +471,16 @@
         return value
 
     def _config(self, section, name, default=_unset, untrusted=False):
-        value = default
+        value = itemdefault = default
         item = self._knownconfig.get(section, {}).get(name)
         alternates = [(section, name)]
 
         if item is not None:
             alternates.extend(item.alias)
+            if callable(item.default):
+                itemdefault = item.default()
+            else:
+                itemdefault = item.default
         else:
             msg = ("accessing unregistered config item: '%s.%s'")
             msg %= (section, name)
@@ -490,13 +494,12 @@
                 msg = "config item requires an explicit default value: '%s.%s'"
                 msg %= (section, name)
                 self.develwarn(msg, 2, 'warn-config-default')
-            elif callable(item.default):
-                    value = item.default()
             else:
-                value = item.default
+                value = itemdefault
         elif (item is not None
-              and item.default is not configitems.dynamicdefault):
-            msg = ("specifying a default value for a registered "
+              and item.default is not configitems.dynamicdefault
+              and default != itemdefault):
+            msg = ("specifying a mismatched default value for a registered "
                    "config item: '%s.%s' '%s'")
             msg %= (section, name, default)
             self.develwarn(msg, 2, 'warn-config-default')

--- a/tests/test-devel-warnings.t	Thu Oct 26 11:07:06 2017 -0700
+++ b/tests/test-devel-warnings.t	Tue Oct 31 22:37:30 2017 +0900
@@ -352,17 +352,21 @@
   > 
   > configitem('test', 'some', default='foo')
   > configitem('test', 'dynamic', default=configitems.dynamicdefault)
+  > configitem('test', 'callable', default=list)
   > # overwrite a core config
   > configitem('ui', 'quiet', default=False)
   > configitem('ui', 'interactive', default=None)
   > 
   > @command(b'buggyconfig')
   > def cmdbuggyconfig(ui, repo):
-  >     repo.ui.config('ui', 'quiet', False)
-  >     repo.ui.config('ui', 'interactive', None)
+  >     repo.ui.config('ui', 'quiet', True)
+  >     repo.ui.config('ui', 'interactive', False)
+  >     repo.ui.config('test', 'some', 'bar')
   >     repo.ui.config('test', 'some', 'foo')
   >     repo.ui.config('test', 'dynamic', 'some-required-default')
   >     repo.ui.config('test', 'dynamic')
+  >     repo.ui.config('test', 'callable', [])
+  >     repo.ui.config('test', 'callable', 'foo')
   >     repo.ui.config('test', 'unregistered')
   >     repo.ui.config('unregistered', 'unregistered')
   > EOF
@@ -370,10 +374,11 @@
   $ hg --config "extensions.buggyconfig=${TESTTMP}/buggyconfig.py" buggyconfig
   devel-warn: extension 'buggyconfig' overwrite config item 'ui.interactive' at: */mercurial/extensions.py:* (_loadextra) (glob)
   devel-warn: extension 'buggyconfig' overwrite config item 'ui.quiet' at: */mercurial/extensions.py:* (_loadextra) (glob)
-  devel-warn: specifying a default value for a registered config item: 'ui.quiet' 'False' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
-  devel-warn: specifying a default value for a registered config item: 'ui.interactive' 'None' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
-  devel-warn: specifying a default value for a registered config item: 'test.some' 'foo' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
+  devel-warn: specifying a mismatched default value for a registered config item: 'ui.quiet' 'True' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
+  devel-warn: specifying a mismatched default value for a registered config item: 'ui.interactive' 'False' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
+  devel-warn: specifying a mismatched default value for a registered config item: 'test.some' 'bar' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
   devel-warn: config item requires an explicit default value: 'test.dynamic' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
+  devel-warn: specifying a mismatched default value for a registered config item: 'test.callable' 'foo' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
   devel-warn: accessing unregistered config item: 'test.unregistered' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
   devel-warn: accessing unregistered config item: 'unregistered.unregistered' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)