D9346: errors: create "similarity hint" for UnknownIdentifier eagerly in constructor

[martinvonz (Martin von Zweigbergk)]

martinvonz created this revision.
Herald added a reviewer: hg-reviewers.
Herald added a subscriber: mercurial-patches.

REVISION SUMMARY
  No code wanted to do anything but to produce a hint from it anyway, so
  we might as well just store the hint in the exception (which already
  extended `Hint`). That way we can easily convert it to a
  `ConfigException` when it's parsing of configuration that fails.
  
  I was wondering if the purpose of lazily creating the string was so we
  don't create it in cases where it won't get printed anyway. However, I
  couldn't find any places where that could happen. If we do find such
  places, we could instead revert to making it lazy but add a function
  on `UnknownIdentifier` for creating the hint string.
  
  I dropped the comment saying "make sure to check fileset first, as
  revset can invoke fileset", which was added in 4e240d6ab898 <https://phab.mercurial-scm.org/rHG4e240d6ab8981932dc75ecb3129d08c9c59a8649> (dispatch:
  offer near-edit-distance suggestions for {file,rev}set functions,
  2015-01-26). I couldn't figure out what it meant. The author of that
  patch also did not remember the reason for it. Perhaps changes that
  have happened since then made it so it no longer matters.

REPOSITORY
  rHG Mercurial

BRANCH
  default

REVISION DETAIL
  https://phab.mercurial-scm.org/D9346

AFFECTED FILES
  mercurial/error.py
  mercurial/scmutil.py

CHANGE DETAILS

diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -150,13 +150,7 @@
         )
     else:
         write(_(b"hg: parse error: %s\n") % inst.message)
-    if isinstance(inst, error.UnknownIdentifier):
-        # make sure to check fileset first, as revset can invoke fileset
-        similar = error.getsimilar(inst.symbols, inst.function)
-        hint = error.similarity_hint(similar)
-        if hint:
-            write(b"(%s)\n" % hint)
-    elif inst.hint:
+    if inst.hint:
         write(_(b"(%s)\n") % inst.hint)
 
 
diff --git a/mercurial/error.py b/mercurial/error.py
--- a/mercurial/error.py
+++ b/mercurial/error.py
@@ -297,9 +297,12 @@
     def __init__(self, function, symbols):
         from .i18n import _
 
-        ParseError.__init__(self, _(b"unknown identifier: %s") % function)
-        self.function = function
-        self.symbols = symbols
+        similar = getsimilar(symbols, function)
+        hint = similarity_hint(similar)
+
+        ParseError.__init__(
+            self, _(b"unknown identifier: %s") % function, hint=hint
+        )
 
 
 class RepoError(Hint, Exception):



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