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

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet added inline comments.


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:646
   // "" for global namespace, "ns::" for normal namespace.
+  std::vector<std::string> QueryScopes;
+  // Like QueryScopes, but also contains inline namespaces.
----------------
could you actually change the comments above to showcase an inline namespace and keep this as `AccessibleScopes`.

Then introduce `QueryScopes` with a comment saying that `This is an overestimate of AccessibleScopes, e.g. it ignores inline namespaces, to fetch more relevant symbols from index`.


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:653
 
+  // Construct scopes to use for code completion. The results are deduplicated.
+  std::vector<std::string> scopesForCodeCompletion() {
----------------
`Scopes that are accessible from current context. Used for dropping unnecessary namespecifiers.


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:654
+  // Construct scopes to use for code completion. The results are deduplicated.
+  std::vector<std::string> scopesForCodeCompletion() {
+    std::set<std::string> Results;
----------------
s/scopesForCodeCompletion/scopesForQualificaiton


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:676
 // (e.g. enclosing namespace).
-std::pair<std::vector<std::string>, bool>
+std::tuple<std::vector<std::string>, std::vector<std::string>, bool>
 getQueryScopes(CodeCompletionContext &CCContext, const Sema &CCSema,
----------------
can we have a dedicated struct for return type here? especially the "enclosing namespace first" logic seem to be getting out of control. so what about updating `SpecificedScope` to have two new fields `std::optional<std::string> EnclosingNamespace;` and a `bool AllowAllScopes;`? that way we can just call getQueryScopes/getAccessibleScopes on needed places and make sure they're putting the EnclosingNamespace (if it exists) in front.


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:712
+    std::vector<std::string> EnclosingAtFrontForCompletion;
     std::string EnclosingScope = printNamespaceScope(*CCSema.CurContext);
+    EnclosingAtFrontForIndex.push_back(EnclosingScope);
----------------
note that this is actually going to skip inline namespaces (and you're using that in the returned set)


================
Comment at: clang-tools-extra/clangd/CodeComplete.cpp:1660
     // First scope is the (modified) enclosing scope.
     QueryScopes = Scopes.scopesForIndexQuery();
     ScopeProximity.emplace(QueryScopes);
----------------
we should be setting `AccessibleScopes` too


================
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) + "::");
----------------
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.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140915/new/

https://reviews.llvm.org/D140915