extensions: add a default "*" suboptions prefix

This is similar to what we do in other section (e.g. `paths`) and allow to
change the behavior for all extensions.

Sub options on individual extensions overwrite the default settings.

Differential Revision: https://phab.mercurial-scm.org/D11823

mercurial/extensions.py

@@ -291,6 +291,8 b' def loadall(ui, whitelist=None):'
     )
     ui.log(b'extension', b'- processing %d entries\n', len(result))
     with util.timedcm('load all extensions') as stats:
+        default_sub_options = ui.configsuboptions(b"extensions", b"*")[1]
+
         for (name, path) in result:
             if path:
                 if path[0:1] == b'!':
@@ -315,8 +317,10 b' def loadall(ui, whitelist=None):'
                     error_msg = _(b'failed to import extension "%s": %s')
                     error_msg %= (name, msg)
 
+                options = default_sub_options.copy()
                 ext_options = ui.configsuboptions(b"extensions", name)[1]
-                if stringutil.parsebool(ext_options.get(b"required", b'no')):
+                options.update(ext_options)
+                if stringutil.parsebool(options.get(b"required", b'no')):
                     hint = None
                     if isinstance(inst, error.Hint) and inst.hint:
                         hint = inst.hint

mercurial/helptext/config.txt

@@ -861,6 +861,13 b' suboption in the config::'
 To debug extension loading issue, one can add `--traceback` to their mercurial
 invocation.
 
+A default setting can we set using the special `*` extension key::
+
+  [extensions]
+  *:required = yes
+  myfeature = ~/.hgext/myfeature.py
+  rebase=
+
 
 ``format``
 ----------

tests/test-check-module-imports.t

@@ -41,4 +41,5 b' will likely receive warnings about a dir'
   > -X tests/test-demandimport.py \
   > -X tests/test-imports-checker.t \
   > -X tests/test-verify-repo-operations.py \
+  > -X tests/test-extension.t \
   > | sed 's-\\-/-g' | "$PYTHON" "$import_checker" -

tests/test-extension.t

@@ -2035,3 +2035,20 b' Same check with a missing one'
   abort: failed to import extension "missing" from foo/bar/baz/I/do/not/exist/: [Errno 2] $ENOENT$: 'foo/bar/baz/I/do/not/exist'
   (loading of this extension was required, see `hg help config.extensions` for details)
   [255]
+
+Have a "default" setting for the suboption:
+
+  $ cat > $TESTTMP/mandatory-extensions/.hg/hgrc << EOF
+  > [extensions]
+  > bad = $TESTTMP/mandatory-extensions/.hg/bad.py
+  > bad:required = no
+  > good = $TESTTMP/mandatory-extensions/.hg/good.py
+  > syntax = $TESTTMP/mandatory-extensions/.hg/syntax.py
+  > *:required = yes
+  > EOF
+
+  $ hg -R mandatory-extensions id
+  *** failed to import extension "bad" from $TESTTMP/mandatory-extensions/.hg/bad.py: babar
+  abort: failed to import extension "syntax" from $TESTTMP/mandatory-extensions/.hg/syntax.py: invalid syntax (*syntax.py, line 1) (glob)
+  (loading of this extension was required, see `hg help config.extensions` for details)
+  [255]