[PATCH] Offer typo suggestions for 'using'.

[Kaelyn Uhrain]

That looks much better!

One last note: in UsingValidatorCCC, instead of defining droppedSpecifier
as "Candidate.WillReplaceSpecifier() && LookupName ==
Candidate.getAsString(LangOpts)", it would be faster and safer to define it
as "Candidate.WillReplaceSpecifier() &&
!Candidate.getCorrectionSpecifier()". The former is
checking specifically for changing "a::foo" to "foo" (dropping the
qualifier from the current name), while the latter would also match
changing "a::foo" to "bar" The latter is safer since a completely
unqualified name is invalid for a "using" declaration, and faster since it
doesn't have to build a string representation of the possibly-qualified
name and then do a string comparison, but simply checks that the candidate
has a NestedNameSpecifier* if it is going to replace the current specifier.
And UsingValidation won't need LookupName or LangOpts. :)


On Tue, Jul 9, 2013 at 3:23 PM, Luke Zarko <zarko at google.com> wrote:

> That cleaned things up a bit. Now for the cases where the code used to
> remove the using decl it instead suggests a fully-qualified
> replacement to preserve syntax correctness while still allowing the
> compilation to continue:
>
> namespace using_suggestion_ty_dropped_specifier {
> class AAA {}; // expected-note
> {{'::using_suggestion_ty_dropped_specifier::AAA' declared here}}
> namespace N { }
> using N::AAA; // expected-error {{no member named 'AAA' in namespace
> 'using_suggestion_ty_dropped_specifier::N'; did you mean
> '::using_suggestion_ty_dropped_specifier::AAA'?}}
> }
>
>
> On Tue, Jul 9, 2013 at 1:09 PM, Kaelyn Uhrain <rikka at google.com> wrote:
> > The new patch looks pretty good except for one thing: the handling of a
> typo
> > correction that removed the name qualifier.
> >
> > Right now in the case where the best correction is an unqualified name,
> the
> > error message suggests replacing the qualified name with the unqualified
> one
> > in the "using" statement but will sometimes include a FixIt to remove the
> > entire "using" statement. Since a "using" statement with an unqualified
> name
> > is not valid syntax, you need to either change the error message to
> suggest
> > dropping the "using" statement in this situation, or you need to change
> > UsingValidatorCCC::ValidateCandidate to exclude any correction candidates
> > that would drop the qualifier. Since removing entire statements is a big
> > stretch beyond typo correction (which just suggests alternate,
> potentially
> > qualified, identifiers), I vote strongly for the latter option of
> rejecting
> > candidates that would result in having an unqualified name in the "using"
> > statement--which is to say, reject candidates where droppedSpecifier
> would
> > be true, and in the diagnostic message just use a literal 0 since
> > droppedSpecifier would never be true.
> >
> > As a minor nit, your change to Sema::BuildUsingDeclaration can be further
> > simplified by dropping the "if" from "if (NamedDecl *ND =
> > Corrected.getCorrectionDecl())" since UsingValidatorCCC rejects any
> > candidate that does not have a NamedDecl. Once that "if" is gone you can
> > drop the second "if (R.empty())" and just mark the UsingDecl as invalid,
> > etc, if typo correction fails.
> >
> > On Tue, Jul 9, 2013 at 10:46 AM, Luke Zarko <zarko at google.com> wrote:
> >>
> >> Thanks for the feedback!
> >>
> >> 1- I've removed the guard.
> >> 2- Done. I've also added a FixIt to remove using decls that typo
> >> correction claims have unnecessary specifiers.
> >> 3- Done; I believe I understand what droppedSpecifier means, but
> >> there's a few tests I added in test/SemaCXX/using-decl-1.cpp that seem
> >> to show that it's maybe not making all the corrections it might be
> >> able to (is droppedSpecifier all-or-nothing?)
> >>
> >> On Mon, Jul 8, 2013 at 11:14 AM, Kaelyn Uhrain <rikka at google.com>
> wrote:
> >> > Luke,
> >> >
> >> > I just looked through the patch and have a few questions/comments
> about
> >> > it:
> >> >
> >> > 1) Why do you only perform typo correction when the scope is not
> NULL? I
> >> > did
> >> > not see any issues within tools/clang/test/ with the guard removed.
> >> > Plus, as
> >> > I mentioned on IRC, there is only one path in typo correction that
> >> > dereferences the scope without checking it is not NULL, that path
> seems
> >> > to
> >> > be a hard-to-reach path and/or irrelevant in the context you are
> running
> >> > it
> >> > (iirc, it was only reached from a very ObjC-specific code path), and
> is
> >> > most
> >> > likely a bug in the code.
> >> >
> >> > 2) Is there a reason you aren't providing a fixit hint for the typo
> >> > correction? If so, why can't one be provided? (And in the case that a
> >> > fixit
> >> > cannot be provided, you need to drop the declaration of CorrectedStr
> >> > since
> >> > it isn't being used.) If a fixit hint can be provided, please do and
> add
> >> > a
> >> > test for the fixit hint to an appropriate file under test/FixIt/;
> >> > basically
> >> > you just need to put one of your tests that offers a correction under
> >> > there
> >> > to make sure that the fixit hint provides the right substitution in
> the
> >> > right place and doesn't introduce additional compilation errors.
> >> >
> >> > 3) You'll need to update your patch against clang HEAD and make sure
> >> > your
> >> > tests still run, since last week I submitted some typo correction
> >> > changes
> >> > and diag::err_no_member_suggest takes an additional argument to
> support
> >> > dropping namespace qualifiers (look for declarations of "bool
> >> > droppedSpecifier", e.g. in TryNamespaceTypoCorrection in
> SemaDeclCXX.cpp
> >> > or
> >> > in Sema::BuildCXXNestedNameSpecifier in SemaCXXScopeSpec.cpp, for
> >> > examples
> >> > of how to determine if the correction is dropping the name specifier
> but
> >> > not
> >> > changing the base identifier).
> >> >
> >> > Cheers,
> >> > Kaelyn
> >> >
> >> >
> >> > On Mon, Jul 8, 2013 at 10:28 AM, Luke Zarko <zarko at google.com> wrote:
> >> >>
> >> >> Ping--is there still something that needs to be done to this?
> >> >>
> >> >>
> >> >> On Wed, Jun 26, 2013 at 3:04 PM, Luke Zarko <zarko at google.com>
> wrote:
> >> >> > Thanks for looking it over!
> >> >> >
> >> >> > I've attached an updated patch with the indent fix (clang-format
> >> >> > wanted the extra two spaces for some reason) and tests for
> >> >> > IsTypeName/isa<TypeDecl> combinations. I moved the tests to
> >> >> > using-decl-1.cpp; they seemed more appropriate there.
> >> >> >
> >> >> > It's unclear how to get into the IsInstantiation case, since the
> >> >> > callers of BuildUsingDeclaration always seem to pass in 0 for Scope
> >> >> > when they pass true for instantiation
> >> >> > (TemplateDeclInstantiator::VisitUnresolvedUsingTypenameDecl,
> >> >> > TemplateDeclInstantiator::VisitUnresolvedUsingValueDecl). Using
> >> >> > getScopeForContext(CurContext) to try and get at a Scope when I
> need
> >> >> > it for CorrectTypo returned null. UsingValidatorCCC's checks should
> >> >> > be
> >> >> > logically equivalent to the checks subsequent in the source file.
> >> >> >
> >> >> > On Wed, Jun 26, 2013 at 12:41 PM, Richard Smith
> >> >> > <richard at metafoo.co.uk>
> >> >> > wrote:
> >> >> >> On Wed, Jun 26, 2013 at 12:35 PM, Luke Zarko <zarko at google.com>
> >> >> >> wrote:
> >> >> >>> I found a case where Clang doesn't yet help with typo correction:
> >> >> >>>
> >> >> >>> tests/base_using.cc:
> >> >> >>>
> >> >> >>> namespace Q { class AAA {}; }
> >> >> >>> using Q::AAB;
> >> >> >>>
> >> >> >>> Before:
> >> >> >>>
> >> >> >>> tests/base_using.cc:2:10: error: no member named 'AAB' in
> namespace
> >> >> >>> 'Q'
> >> >> >>> using Q::AAB;
> >> >> >>>       ~~~^
> >> >> >>>
> >> >> >>> After:
> >> >> >>>
> >> >> >>> tests/base_using.cc:2:10: error: no member named 'AAB' in
> namespace
> >> >> >>> 'Q'; did you mean 'AAA'?
> >> >> >>> using Q::AAB;
> >> >> >>>       ~~~^
> >> >> >>> tests/base_using.cc:1:21: note: 'AAA' declared here
> >> >> >>> namespace Q { class AAA {}; }
> >> >> >>>                     ^
> >> >> >>
> >> >> >> Code change looks good, but could do with more test coverage for
> the
> >> >> >> type name / non-type-name / in instantiation cases.
> >> >> >>
> >> >> >> +        Diag(R.getNameLoc(), diag::err_no_member_suggest)
> >> >> >> +            << NameInfo.getName() << LookupContext <<
> >> >> >> CorrectedQuotedStr
> >> >> >> +            << SS.getRange();
> >> >> >>
> >> >> >> We typically indent << only two spaces, not four (clang-format
> >> >> >> bug?).
> >> >> _______________________________________________
> >> >> cfe-commits mailing list
> >> >> cfe-commits at cs.uiuc.edu
> >> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >> >
> >> >
> >>
> >> _______________________________________________
> >> cfe-commits mailing list
> >> cfe-commits at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >>
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20130709/06013d67/attachment.html>