configitems: adds a developer warning when accessing undeclared configuration

Now that all known options are declared, we setup a warning to make sure it will
stay this way.

We disable the warning in two tests checking other behavior with random options.

mercurial/configitems.py

@@ -249,6 +249,9 b" coreconfigitem('devel', 'warn-config-def"
 coreconfigitem('devel', 'user.obsmarker',
     default=None,
 )
+coreconfigitem('devel', 'warn-config-unknown',
+    default=None,
+)
 coreconfigitem('diff', 'nodates',
     default=False,
 )

mercurial/ui.py

@@ -477,6 +477,10 b' class ui(object):'
 
         if item is not None:
             alternates.extend(item.alias)
+        else:
+            msg = ("accessing unregistered config item: '%s.%s'")
+            msg %= (section, name)
+            self.develwarn(msg, 2, 'warn-config-unknown')
 
         if default is _unset:
             if item is None:

tests/test-devel-warnings.t

@@ -363,6 +363,8 b' Test warning on config option access and'
   >     repo.ui.config('test', 'some', 'foo')
   >     repo.ui.config('test', 'dynamic', 'some-required-default')
   >     repo.ui.config('test', 'dynamic')
+  >     repo.ui.config('test', 'unregistered')
+  >     repo.ui.config('unregistered', 'unregistered')
   > EOF
 
   $ hg --config "extensions.buggyconfig=${TESTTMP}/buggyconfig.py" buggyconfig
@@ -372,5 +374,7 b' Test warning on config option access and'
   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: config item requires an explicit default value: 'test.dynamic' 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)
 
   $ cd ..

tests/test-trusted.py

@@ -67,6 +67,13 b" def testui(user='foo', group='bar', tuse"
                                      trusted))
 
     u = uimod.ui.load()
+    # disable the configuration registration warning
+    #
+    # the purpose of this test is to check the old behavior, not to validate the
+    # behavior from registered item. so we silent warning related to unregisted
+    # config.
+    u.setconfig('devel', 'warn-config-unknown', False, 'test')
+    u.setconfig('devel', 'all-warnings', False, 'test')
     u.setconfig('ui', 'debug', str(bool(debug)))
     u.setconfig('ui', 'report_untrusted', str(bool(report)))
     u.readconfig('.hg/hgrc')
@@ -157,6 +164,13 b" print(u.config('foobar', 'baz'))"
 print()
 print("# read trusted, untrusted, new ui, trusted")
 u = uimod.ui.load()
+# disable the configuration registration warning
+#
+# the purpose of this test is to check the old behavior, not to validate the
+# behavior from registered item. so we silent warning related to unregisted
+# config.
+u.setconfig('devel', 'warn-config-unknown', False, 'test')
+u.setconfig('devel', 'all-warnings', False, 'test')
 u.setconfig('ui', 'debug', 'on')
 u.readconfig(filename)
 u2 = u.copy()

tests/test-ui-config.py

@@ -6,6 +6,15 b' from mercurial import ('
 )
 
 testui = uimod.ui.load()
+
+# disable the configuration registration warning
+#
+# the purpose of this test is to check the old behavior, not to validate the
+# behavior from registered item. so we silent warning related to unregisted
+# config.
+testui.setconfig('devel', 'warn-config-unknown', False, 'test')
+testui.setconfig('devel', 'all-warnings', False, 'test')
+
 parsed = dispatch._parseconfig(testui, [
     'values.string=string value',
     'values.bool1=true',