[PATCH] D140915: [clangd] Fix getQueryScopes for using-directive with inline namespace

[Tom Praschan via Phabricator via cfe-commits]

tom-anders marked an inline comment as done.
tom-anders added inline comments.


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Comment at: clang-tools-extra/clangd/CodeComplete.cpp:1714
+    }
+    llvm::copy_if(SpecifiedScopes.scopesForIndexQuery(),
+                  std::back_inserter(QueryScopes),
----------------
Should I add a `reserve` here for QueryScopes and AccessibleScopes? Would make this a bit more complicated for a small performance boost.


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Comment at: clang-tools-extra/clangd/CodeComplete.cpp:712
+    std::vector<std::string> EnclosingAtFrontForCompletion;
     std::string EnclosingScope = printNamespaceScope(*CCSema.CurContext);
+    EnclosingAtFrontForIndex.push_back(EnclosingScope);
----------------
kadircet wrote:
> note that this is actually going to skip inline namespaces (and you're using that in the returned set)
Hm I should probably fix this and add another regression test for this..?


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Comment at: clang-tools-extra/clangd/CodeComplete.cpp:1660
     // First scope is the (modified) enclosing scope.
     QueryScopes = Scopes.scopesForIndexQuery();
     ScopeProximity.emplace(QueryScopes);
----------------
kadircet wrote:
> we should be setting `AccessibleScopes` too
Ah thanks, that's what caused the one failing test. I just copied over QueryScopes here for now, looks like this doesn't need any special handling for inline namespaces, does it?


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Comment at: clang-tools-extra/clangd/CodeComplete.cpp:674
+    else if (const auto *ND = dyn_cast<NamespaceDecl>(Context)) {
+      if (ND->isInlineNamespace())
+        Scopes.AccessibleScopes.push_back(printQualifiedName(*ND) + "::");
----------------
kadircet wrote:
> tom-anders wrote:
> > kadircet wrote:
> > > tom-anders wrote:
> > > > kadircet wrote:
> > > > > tom-anders wrote:
> > > > > > kadircet wrote:
> > > > > > > since we know that the `Context` is a `NamespaceDecl` it should be safe to use `printQualifiedName` always. any reason for the extra branching here (apart from minimizing the change to behaviour)? if not I think we can get rid of the special casing.
> > > > > > Unfortunately, this fails CompletionTest.EnclosingScopeComesFirst and CompletionTest.NoDuplicatedQueryScopes, I think because of anonymous namespaces (where printNameSpaceScope would return an empty string, but (printQualifiedName(*ND) + "::" does not). 
> > > > > i see. taking a closer look at this `getQueryScopes` is used for two things:
> > > > > - The scopes to query with fuzzyfind requests, hence this should use the same "serialization" as symbolcollector (which only strips anon namespaces today, but initially it were to strip both anon & inline namespaces. it got changed inside clang without clangd tests catching it).
> > > > > - The shortening of the fully qualified name in `CodeCompletionBuilder`. Not having inline namespaces spelled in the available namespaces implies getting wrong qualifiers (such as the bug you're fixing).
> > > > > 
> > > > > so considering the requirements here:
> > > > > - when querying index, we actually want to hide inline namespaces (as `ns::hidden::Foo` should be a viable alternative even if only `ns::` is accessible). so we should actually fix `printQualifiedName` to set `SuppressInlineNamespace` in printing policy to restore the old behaviour (and keep using `printNamespaceScope` here).
> > > > > - inside `CodeCompletionBuilder`, we shouldn't use the same scopes we use during index queries. we should use the visible namespaces while preserving inline namespace information and only ignoring the anonymous namespaces.
> > > > > 
> > > > > hence can we have 2 separate scopes in `CodeCompleteFlow` instead?
> > > > > One called `QueryScopes`, which has the behavior we have today (fixing printQualifiedName is a separate issues).
> > > > > Other called `AccessibleScopes`, which has accessible namespaces spelled **with** inline namespaces, so that we can get proper qualification during code-complete.
> > > > > 
> > > > > does that make sense?
> > > > tbh I'm a bit confused - I understand your requirements, but am not sure I understand your proposed solution. Can you expand a bit further? Looking at the code, there are already both `QueryScopes` and `AccessibleScopes` variables/fields in various classes, I'm not really sure at which places you want to make changes.
> > > sorry for the long and confusing answer :D
> > > 
> > > I was talking about `CodeCompleteFlow` class specifically, inside `CodeComplete.cpp`. Currently it only has `QueryScopes`, derived from the visible contexts reported by Sema. Unfortunately it loses some granularity to fetch more symbols from index hence it should not be used when picking the required qualifier.
> > > My suggestion is to add a new field in `CodeCompleteFlow` called `AccessibleScope`, which is derived at the same stage as `QueryScopes`, while preserving inline namespaces, and used when creating `CodeCompletionBuilder` in `CodeCompleteFlow::toCodeCompletion` (instead of `QueryScopes`).
> > Ok, think I got it - To make this a bit less confusing, I first renamed SpecifiedScope::AccessibleScopes to SpecifiedScope::QueryScopes (that's the number under which it is (and was) stored in CodeCompleteFlow anyway) and then added a back a new field AccessibleScopes, that keeps the inline namespaces. This is then stored in CodeCompleteFlow:AccessibleScopes and passed to the CodeCompletionBuilder instead of QueryScopes.
> > 
> > This now still passes all existing tests and I verified in my editor that it also fixes the original issue. 
> > 
> > I couldn't figure out how to write a regression test for this now though :(
> > I couldn't figure out how to write a regression test for this now though :(
> 
> We've got a bunch of tests in `unittests/CodeCompleteTests.cpp`, something like:
> ```
> TEST(CompletionTest, QualificationWithInlineNamespace) {
>   auto Results = completions(R"cpp(
>     namespace a { inline namespace b {} }
>     using namespace a::b;
>     void f() { Foo^ }
>   )cpp",
>                              {cls("a::Foo")});
>   EXPECT_THAT(Results.Completions,
>               UnorderedElementsAre(AllOf(qualifier("a::"), named("Foo"))));
> }
> ```
> 
> should fail without your patch, and pass afterwards.
That works, thanks!


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  https://reviews.llvm.org/D140915/new/

https://reviews.llvm.org/D140915