[clangd] Only add global scope to completion query scopes for TU context.

[ioeric]

Summary

This avoids duplicated scopes in the query e.g. when anonymous namespace
is present.

[ilya-biryukov]

clangd/CodeComplete.cpp

563

Anonymous namespace inside other namespaces will also produce duplicate scopes.
Maybe simply remove the duplicates from the vector before we return it?

[ioeric]

clangd/CodeComplete.cpp

563

printNamespaceScope() will return "" for all anonymous namespaces, which should be covered as well.

[ilya-biryukov]

clangd/CodeComplete.cpp

563

I don't think that's the case.
My understanding is that printNamespaceScope("foo::<anonymous>::bar::<anonymous>") will return "foo::bar::".

[ioeric]

• Clarify documentation for printNamespaceScope

[ioeric]

• revert wrong comment

[ioeric]

I got the behavior of printNamespaceScope wrong in this patch. Will update.

[ioeric]

clangd/CodeComplete.cpp

563

Thanks for the catch! Switched to deduplicate scopes instead (D54105)

clangd/AST.h

 /// The returned location is usually the spelling location where the name of the
 /// decl occurs in the code.
 SourceLocation findNameLoc(const clang::Decl *D);
 
 /// Returns the qualified name of ND. The scope doesn't contain unwritten scopes
 /// like inline namespaces.
 std::string printQualifiedName(const NamedDecl &ND);
 
-/// Returns the first enclosing namespace scope starting from \p DC.
+/// Returns the first enclosing namespace scope starting from \p DC. This
+/// returns "" if there is no enclosing namespace or the enclosing namespace is
+/// anonymousor or inline.
 std::string printNamespaceScope(const DeclContext &DC);
 
 /// Gets the symbol ID for a declaration, if possible.
 llvm::Optional<SymbolID> getSymbolID(const Decl *D);
 
 /// Gets the symbol ID for a macro, if possible.
 /// Currently, this is an encoded USR of the macro, which incorporates macro
 /// locations (e.g. file name, offset in file).

clangd/CodeComplete.cpp

 // any scope is allowed. The first scope in the list is the preferred scope
 // (e.g. enclosing namespace).
 std::pair<std::vector<std::string>, bool>
 getQueryScopes(CodeCompletionContext &CCContext, const Sema &CCSema,
                const CodeCompleteOptions &Opts) {
   auto GetAllAccessibleScopes = [](CodeCompletionContext &CCContext) {
     SpecifiedScope Info;
     for (auto *Context : CCContext.getVisitedContexts()) {
-      if (isa<TranslationUnitDecl>(Context))
+      if (isa<TranslationUnitDecl>(Context)) {
         Info.AccessibleScopes.push_back(""); // global namespace
-      else if (isa<NamespaceDecl>(Context))
-        Info.AccessibleScopes.push_back(printNamespaceScope(*Context));
+      } else if (isa<NamespaceDecl>(Context)) {
+        auto S = printNamespaceScope(*Context);
+        if (!S.empty())
+          Info.AccessibleScopes.push_back(std::move(S));
+      }
     }
     return Info;
   };
 
   auto SS = CCContext.getCXXScopeSpecifier();
 
   // Unqualified completion (e.g. "vec^").
   if (!SS) {

unittests/clangd/CodeCompleteTests.cpp

auto Requests = captureIndexRequests(R"cpp(
       }
       } // namespace ns
   )cpp");
 
   EXPECT_THAT(Requests, ElementsAre(Field(&FuzzyFindRequest::Scopes,
                                           UnorderedElementsAre(""))));
 }
 
+TEST(CompletionTest, NoDuplicatedGlobalScope) {
+  auto Requests = captureIndexRequests(R"cpp(
+      namespace {  void f(); }
+      namespace ns {
+      ^
+      } // namespace ns
+  )cpp");
+
+  EXPECT_THAT(Requests, ElementsAre(Field(&FuzzyFindRequest::Scopes,
+                                          ElementsAre("ns::", ""))));
+}
+
 TEST(CompletionTest, NoIndexCompletionsInsideClasses) {
   auto Completions = completions(
       R"cpp(
     struct Foo {
       int SomeNameOfField;
       typedef int SomeNameOfTypedefField;
     };