On Wed, Jan 13, 2021 at 06:04:29PM -0500, John Snow wrote: > On 1/13/21 11:12 AM, Markus Armbruster wrote: > > John Snow <js...@redhat.com> writes: > > > > > Signed-off-by: John Snow <js...@redhat.com> > > > > > > --- > > > > > > The event_enum_members change might become irrelevant after a > > > forthcoming (?) patch by Markus, but didn't have it in-hand at time of > > > publishing. > > > > It's in my "[PATCH 00/11] Drop support for QAPIGen without a file name", > > which includes parts of your v1. The parts that are new should be > > injected into your series so they replace your "[PATCH v2 09/12] > > qapi/gen: move write method to QAPIGenC, make fname a str". Holler if > > you need help. > > > > > Signed-off-by: John Snow <js...@redhat.com> > > > --- > > > scripts/qapi/events.py | 2 +- > > > scripts/qapi/schema.py | 25 ++++++++++++++----------- > > > scripts/qapi/types.py | 9 +++++---- > > > scripts/qapi/visit.py | 6 +++--- > > > 4 files changed, 23 insertions(+), 19 deletions(-) > > > > > > diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py > > > index 9851653b9d1..9ba4f109028 100644 > > > --- a/scripts/qapi/events.py > > > +++ b/scripts/qapi/events.py > > > @@ -225,7 +225,7 @@ def visit_event(self, > > > self._event_emit_name)) > > > # Note: we generate the enum member regardless of @ifcond, to > > > # keep the enumeration usable in target-independent code. > > > - self._event_enum_members.append(QAPISchemaEnumMember(name, None)) > > > + self._event_enum_members.append(QAPISchemaEnumMember(name, info)) > > > > This "enum" is not supposed to be erroneous. If it is, it's a bug. > > > > Your patch changes how the code behaves should such a bug bite here. > > Before, we crash. Afterwards, we report the bug using @info, which I'd > > expect to produce utterly confusing error messages. > > > > It doesn't change the behavior *here*, though. It changes it whenever this > info object is used in another context. ... and who knows when or where or > why it is being used, or by whom. > > I'll have to play with this. I'm not sure there's any way to coax a bug to > happen here that I am aware of right away. Can you think of how to will one > into existence? > > > My comments on PATCH 06 apply: how the code should behave here is a > > design issue that should be kept out of this patch series. > > > > If you need to pass a value other than None to help with static typing, > > then pass a suitable poison info that will crash right where None > > crashes now.
I don't understand what would be the point of inventing something that behaves exactly like None but makes type checking less useful. With None/Optional, mypy gives us a way to be 100% sure the object isn't going to invalid. With a poison value, mypy can't tell us anymore if the code risks crashing at runtime. > > > > I think we need to, yes; or we probably really, really want to. Making the > info parameter optional really adds a lot of unidiomatic type-checking > confetti when we go to use info, and in many more contexts than just this > sorta-built-in-enum; it will creep badly. Which methods would require unidiomatic type-checking because of None/Optional? > > So, I gotta pass ...something here. but what? You want poison, but I think > it's not right to fundamentally poison all built-ins. > > Mmmmmmm. Maybe per-instance poison can be done? We actually share info > objects, but I can make poisoned copies. Using next_line() as a basis: > > def poison(self: T) -> T: > info = copy.copy(self) > info.poisoned = True > return info > > probably almost anything I do is not going to make a lot of sense unless I > can actually replicate and test the different error scenarios to prove that > we didn't make the error spaghetti unknowably worse. I see it as > functionally inevitable that I have to audit this and make sure we get good > error messages anyway, so ... maybe I just ought to do that now anyway. > > > > def gen_events(schema: QAPISchema, > > > diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py > > > index 720449feee4..0449771dfe5 100644 > > > --- a/scripts/qapi/schema.py > > > +++ b/scripts/qapi/schema.py > > > @@ -23,6 +23,7 @@ > > > from .error import QAPIError, QAPISemError > > > from .expr import check_exprs > > > from .parser import QAPISchemaParser > > > +from .source import QAPISourceInfo > > > class QAPISchemaEntity: > > > @@ -36,10 +37,10 @@ def __init__(self, name, info, doc, ifcond=None, > > > features=None): > > > self.name = name > > > self._module = None > > > # For explicitly defined entities, info points to the (explicit) > > > - # definition. For builtins (and their arrays), info is None. > > > - # For implicitly defined entities, info points to a place that > > > - # triggered the implicit definition (there may be more than one > > > - # such place). > > > + # definition. For built-in types (and their arrays), info is a > > > + # special object that evaluates to False. For implicitly defined > > > + # entities, info points to a place that triggered the implicit > > > + # definition (there may be more than one such place). > > > self.info = info > > > self.doc = doc > > > self._ifcond = ifcond or [] > > > @@ -68,7 +69,7 @@ def check_doc(self): > > > def _set_module(self, schema, info): > > > assert self._checked > > > - self._module = schema.module_by_fname(info and info.fname) > > > + self._module = schema.module_by_fname(info.fname if info else > > > None) > > > > Looks unrelated. > > > > Hmm, it sorta is. I have apparently edited this patch since I sent it, but > there was some tomfoolery over how "x and y" statements behave and this edit > was necessary at the time. > > "info and info.fname" returned None when info could actually be None, but > when it was updated to be a special source object, we could accidentally > pass that special source object as the name -- instead of None. Not good. > > I think I re-ordered some patches such that I can just pass in "info.fname" > unconditionally instead as of this patch. > > > > self._module.add_entity(self) > > > def set_module(self, schema): > > [...] > > > -- Eduardo
