[clangd] Suggest adding missing includes for typos (like include-fixer).

[ioeric]

Summary

This adds include-fixer feature into clangd based on D56903. Clangd now captures
diagnostics caused by typos and attach include insertion fixes to potentially
fix the typo.

[ioeric]

• revert unintended change

[ioeric]

• Rebase on D56903.

[ioeric]

• Rebase on D56903

[ioeric]

• Rebase on origin/master

[ioeric]

Ping

[sammccall]

clangd/IncludeFixer.cpp

75

"default" looks a bit scary - could still end up with false positives.
Can we cover a few of the most common cases (even if we know they're not exhaustive) to start with?

201

a comment that we never return a valid correction to try to recover, our suggested fixes always require a rebuild.

207

why do we do this here rather than compute the scopes/name already in CorrectTypo()?

Passing around more of these AST objects and doing the computations later seems a bit more fragile.

225

limit?

231

why put these into a slab and then build fixes later, rather than build the fixes immediately?

239

Doesn't seem worth special casing this, below code will work fine.

244

the fixes can overlap: distinct symbols may be defined in the same header.
Common case: function overloads.

At some level we "just want to deduplicate" these.
It's slightly complicated because of the tricky way we calculate the edits.
Maybe the best thing is to pass in all the symbols to fixesForSymbol() instead of just one.

One thing to keep in mind is a future where we want to pull in results across namespaces: the fixes for "include 'a.h' for x::Foo" and "include 'a.h' for y::Foo" need to be distinct because of the different added qualifiers.
So it'd be good to end up with an explicit e.g. map<header_to_include, Fix> to deduplicate, then we can just change the key to pair<header_to_include, qualifier_to_insert>

clangd/IncludeFixer.h

35–37

Having to inject the whole compiler into the include fixer doesn't seem right. Apart from the huge scope, we're also going to register parts of the include fixer with the compiler.

A few observations:

• all we actually need here is Sema and the SM (available through Sema)
• it's only the typo recorder that needs access to Sema
• the typo recorder gets fed the Sema instance (ExternalSemaSource::InitializeSema)
• the fact that fixTypo() needs to access the typo recorder doesn't seem necessary

So I'd suggest changing this function to return a *new* ExternalSemaSource that stashes the last typo in this IncludeFixer object directly.

e.g.

llvm::IntrusiveRefCntPtr<ExternalSemaSource> typoRecorder() {
  return new TypoRecorder(LastTypo);
}
private:
  Optional<TypoRecord> LastTypo;
  class TypoRecorder : public ExternalSemaSource {
    Sema *S;
    Optional<TypoRecord> &Out;
    InitializeSema(Sema& S) { this->S = &S; }
    CorrectTypo(...) {
      assert(S);
      ...
      Out = ...;
    }
  }

46

This would be a reasonable place to document what the feature is and how it works :-)

e.g.

/// Returns an ExternalSemaSource that records failed name lookups in Sema.
/// This allows IncludeFixer to suggest inserting headers that define those names.

57

So an annoying naming thing: I find the use of "typo" to describe this feature really confusing. There's no actual typo, and conflating Sema's typo-correction fixes (which allow the parse to recover) and our generated fixes (which requires changing the source and rebuilding) breaks my brain a bit.

I'd suggest calling this "unresolved name" throughout, except when specifically referring to the mechanism by which we observe unresolved names.
e.g. TypoRecorder -> UnresolvedNameRecorder etc.

66

I think TypoRecorder can be merely declared here, and defined in the CC file?

[ioeric]

• address review comments.

[ioeric]

clangd/IncludeFixer.cpp

207

Because not all typos will result in diagnostics. Computing scopes could be expensive, so we would only want to do that when necessary. For example, sema can perform typo corrections for both x and y in x::y, while only one diagnostic (for either x or y) would be generated.

231

good point.

clangd/IncludeFixer.h

35–37

Great idea. Thanks!

I've done most of the suggested refactoring.

the fact that fixTypo() needs to access the typo recorder doesn't seem necessary.

Do you mean access to *Sema*? The IncludeFixer still needs sema because we don't want to run Lookup for each typo sema encounters. We only want to do that for typos that make it to diagnostics. See my response to the other comment about this for details.

[sammccall]

clangd/IncludeFixer.cpp

80

you never seem to clear LastUnresolvedName - I guess you at least want to clear it after using it.
It would be more robust to clear after every diagnostic - would this work?

162

note that if you have symbols in different scopes from the same header, you're only generating one fix and it will only mention one of the symbols.

It's fine to decide this case doesn't matter, but it's worth adding a comment.
(Alternatively, using a set of pair<inserted-header, qualified-name> to track dupes would avoid this)

169

SemaPtr?

182

The FIXME makes sense, but it's not clear to me what the code below it does or how it relates to the comment.

maybe separate with a blank line and then "Extract the typed scope" or so?

207

If the goal is to make the scope computation lazy, CorrectTypo can store them as a std::function<std::vector<string>()> - that way we can still group the related code and dependencies together.

This function can capture the Sema instance by pointer - this deserves a comment that sema must be alive to access the scopes.

211

nit: recover

216

unused

clangd/IncludeFixer.h

35–37

Yes, I meant Sema here. I think we can avoid IncludeFixer holding a reference to Sema directly.

57

I don't think this is done: there are still 20+ references to "typo" in this patch.
I think they should all be changed, apart from the implementation of CorrectTypo() and a comment explaining the use of this mechanism.
Happy to discuss if you don't think this is a good idea, though!

60

nit: the comment on Loc and LookupKind don't say anything, remove them?

60

nit: why take a parameter here, when it's always *LastUnresolvedName?

61

please use real names for these fields (EnclosingScope, SpecifiedScope?)

Maybe it would help documenting here to have a more complete example e.g.

namespace ns { int Y = foo::x }

Name is x
Loc is points at x (or f?)
EnclosingScope is ns::
SpecifiedScope is either ns::foo:: or foo:: (depending how 'foo' was resolved)

[ioeric]

• address review comments

[sammccall]

Great stuff! Sorry for the delay here.

clangd/IncludeFixer.h

61

nit: this isn't really a callback, I think.
Just "Lazily get the possible scopes of the unresolved name"?

66

"i.e. typo" is confusing here, as these aren't actually typos

[ioeric]

• Merge remote-tracking branch 'origin/master' into typo
• address review comments

change-namespace/ChangeNamespace.cpp

 //===-- ChangeNamespace.cpp - Change namespace implementation -------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+
 #include "ChangeNamespace.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/Format/Format.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 
 using namespace clang::ast_matchers;

clangd/ClangdUnit.cpp

if (Index && !BuildDir.getError()) {
     auto Style = getFormatStyleForFile(MainInput.getFile(), Content, VFS.get());
     auto Inserter = llvm::make_unique<IncludeInserter>(
         MainInput.getFile(), Content, Style, BuildDir.get(),
         Clang->getPreprocessor().getHeaderSearchInfo());
     if (Preamble) {
       for (const auto &Inc : Preamble->Includes.MainFileIncludes)
         Inserter->addExisting(Inc);
     }
-    FixIncludes.emplace(MainInput.getFile(), std::move(Inserter), *Index);
+    FixIncludes.emplace(*Clang, MainInput.getFile(), std::move(Inserter),
+                        *Index);
     ASTDiags.setIncludeFixer(*FixIncludes);
+    Clang->setExternalSemaSource(FixIncludes->typoRecorder());
   }
 
   // Copy over the includes from the preamble, then combine with the
   // non-preamble includes below.
   auto Includes = Preamble ? Preamble->Includes : IncludeStructure{};
   // Replay the preamble includes so that clang-tidy checks can see them.
   if (Preamble)
     ReplayPreamble::attach(Includes, *Clang);

clangd/IncludeFixer.h

 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INCLUDE_FIXER_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INCLUDE_FIXER_H
 
 #include "Diagnostics.h"
 #include "Headers.h"
 #include "index/Index.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Sema/ExternalSemaSource.h"
+#include "clang/Sema/Sema.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
 
 namespace clang {
 namespace clangd {
 
 /// Attempts to recover from error diagnostics by suggesting include insertion
 /// fixes. For example, member access into incomplete type can be fixes by
 /// include headers with the definition.
 class IncludeFixer {
 public:
-  IncludeFixer(llvm::StringRef File, std::unique_ptr<IncludeInserter> Inserter,
+  IncludeFixer(CompilerInstance &Compiler, llvm::StringRef File,
+               std::unique_ptr<IncludeInserter> Inserter,
                const SymbolIndex &Index)
-      : File(File), Inserter(std::move(Inserter)), Index(Index) {}
+      : File(File), Inserter(std::move(Inserter)), Index(Index),
+        Compiler(Compiler), RecordTypo(new TypoRecorder(Compiler)) {}
 
   /// Returns include insertions that can potentially recover the diagnostic.
   std::vector<Fix> fix(DiagnosticsEngine::Level DiagLevel,
                        const clang::Diagnostic &Info) const;
 
+  /// Returns an ExternalSemaSource that records typos seen in Sema. It must be
+  /// used in the same Sema run as the IncludeFixer.
+  llvm::IntrusiveRefCntPtr<ExternalSemaSource> typoRecorder() {
+    return RecordTypo;
+  }
+
 private:
-  /// Attempts to recover diagnostic caused by an incomplete type \p T.
   std::vector<Fix> fixInCompleteType(const Type &T) const;
 
-  /// Generates header insertion fixes for \p Sym.
   std::vector<Fix> fixesForSymbol(const Symbol &Sym) const;
 
+  struct TypoRecord {
+    std::string Typo;   // The typo identifier e.g. "X" in ns::X.
+    SourceLocation Loc; // Location of the typo.
+    Scope *S;           // Scope in which the typo is found.
+    llvm::Optional<std::string> SS; // The scope qualifier before the typo.
+    Sema::LookupNameKind LookupKind; // LookupKind of the typo.
+  };
+
+  /// Records the last typo seen by Sema.
+  class TypoRecorder : public ExternalSemaSource {
+  public:
+    TypoRecorder(CompilerInstance &Compiler) : Compiler(Compiler) {}
+
+    // Captures the latest typo.
+    TypoCorrection CorrectTypo(const DeclarationNameInfo &Typo, int LookupKind,
+                               Scope *S, CXXScopeSpec *SS,
+                               CorrectionCandidateCallback &CCC,
+                               DeclContext *MemberContext, bool EnteringContext,
+                               const ObjCObjectPointerType *OPT) override;
+
+    llvm::Optional<TypoRecord> lastTypo() const { return LastTypo; }
+
+  private:
+    CompilerInstance &Compiler;
+
+    llvm::Optional<TypoRecord> LastTypo;
+  };
+
+  /// Attempts to fix the typo associated with the current diagnostic. We assume
+  /// a diagnostic is caused by a typo when they have the same source location
+  /// and the typo is the last typo we've seen during the Sema run.
+  std::vector<Fix> fixTypo(const TypoRecord &Typo) const;
+
   std::string File;
   std::unique_ptr<IncludeInserter> Inserter;
   const SymbolIndex &Index;
+  CompilerInstance &Compiler;
+  // This collects the last typo so that we can associate it with the
+  // diagnostic.
+  llvm::IntrusiveRefCntPtr<TypoRecorder> RecordTypo;
 };
 
 } // namespace clangd
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INCLUDE_FIXER_H

clangd/IncludeFixer.cpp

 //===--- IncludeFixer.cpp ----------------------------------------*- C++-*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "IncludeFixer.h"
 #include "AST.h"
 #include "Diagnostics.h"
 #include "Logger.h"
 #include "SourceCode.h"
 #include "index/Index.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclBase.h"
+#include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticSema.h"
+#include "clang/Sema/DeclSpec.h"
+#include "clang/Sema/Lookup.h"
+#include "clang/Sema/Scope.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Sema/TypoCorrection.h"
 #include "llvm/ADT/None.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
+#include <vector>
 
 namespace clang {
 namespace clangd {
 
 namespace {
 
 bool isIncompleteTypeDiag(unsigned int DiagID) {
   return DiagID == diag::err_incomplete_type ||
          DiagID == diag::err_incomplete_member_access ||
          DiagID == diag::err_incomplete_base_class;
 }
 
+// Collects contexts visited during a Sema name lookup.
+class VisitedContextCollector : public VisibleDeclConsumer {
+public:
+  void EnteredContext(DeclContext *Ctx) override { Visited.push_back(Ctx); }
+
+  void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
+                 bool InBaseClass) override {}
+
+  std::vector<DeclContext *> takeVisitedContexts() {
+    return std::move(Visited);
+  }
+
+private:
+  std::vector<DeclContext *> Visited;
+};
+
 } // namespace
 
 std::vector<Fix> IncludeFixer::fix(DiagnosticsEngine::Level DiagLevel,
                                    const clang::Diagnostic &Info) const {
   if (isIncompleteTypeDiag(Info.getID())) {
     // Incomplete type diagnostics should have a QualType argument for the
     // incomplete type.
     for (unsigned i = 0; i < Info.getNumArgs(); ++i) {
       if (Info.getArgKind(i) == DiagnosticsEngine::ak_qualtype) {
         auto QT = QualType::getFromOpaquePtr((void *)Info.getRawArg(i));
         if (const Type *T = QT.getTypePtrOrNull())
           if (T->isIncompleteType())
             return fixInCompleteType(*T);
       }
     }
+  } else if (auto LastTypo = RecordTypo->lastTypo()) {
+    // Try to fix typos caused by missing declaraion.
+    // E.g.
+    //   clang::SourceManager SM;
+    //          ~~~~~~~~~~~~~
+    //          Typo
+    //   or
+    //   namespace clang {  SourceManager SM; }
+    //                      ~~~~~~~~~~~~~
+    //                      Typo
+    // We only attempt to recover a diagnostic if it has the same location as
+    // the last seen typo.
+    if (DiagLevel >= DiagnosticsEngine::Error &&
+        LastTypo->Loc == Info.getLocation())
+      return fixTypo(*LastTypo);
   }
   return {};
 }
 
 std::vector<Fix> IncludeFixer::fixInCompleteType(const Type &T) const {
   // Only handle incomplete TagDecl type.
   const TagDecl *TD = T.getAsTagDecl();
   if (!TD)
for (const auto &Inc : getRankedIncludes(Sym)) {
     } else {
       vlog("Failed to calculate include insertion for {0} into {1}: {2}", File,
            Inc, llvm::toString(ToInclude.takeError()));
     }
   }
   return Fixes;
 }
 
+TypoCorrection IncludeFixer::TypoRecorder::CorrectTypo(
+    const DeclarationNameInfo &Typo, int LookupKind, Scope *S, CXXScopeSpec *SS,
+    CorrectionCandidateCallback &CCC, DeclContext *MemberContext,
+    bool EnteringContext, const ObjCObjectPointerType *OPT) {
+  if (Compiler.getSema().isSFINAEContext())
+    return TypoCorrection();
+  if (!Compiler.getSourceManager().isWrittenInMainFile(Typo.getLoc()))
+    return clang::TypoCorrection();
+
+  TypoRecord Record;
+  Record.Typo = Typo.getAsString();
+  Record.Loc = Typo.getBeginLoc();
+  assert(S);
+  Record.S = S;
+  Record.LookupKind = static_cast<Sema::LookupNameKind>(LookupKind);
+
+  // FIXME: support invalid scope before a type name. In the following example,
+  // namespace "clang::tidy::" hasn't been declared/imported.
+  //    namespace clang {
+  //    void f() {
+  //      tidy::Check c;
+  //      ~~~~
+  //      // or
+  //      clang::tidy::Check c;
+  //             ~~~~
+  //    }
+  //    }
+  // For both cases, the typo and the diagnostic are both on "tidy", and no
+  // diagnostic is generated for "Check". However, what we want to fix is
+  // "clang::tidy::Check".
+  if (SS && SS->isNotEmpty()) { // "::" or "ns::"
+    if (auto *Nested = SS->getScopeRep()) {
+      if (Nested->getKind() == NestedNameSpecifier::Global)
+        Record.SS = "";
+      else if (const auto *NS = Nested->getAsNamespace())
+        Record.SS = printNamespaceScope(*NS);
+      else
+        // We don't fix symbols in scopes that are not top-level e.g. class
+        // members, as we don't collect includes for them.
+        return TypoCorrection();
+    }
+  }
+
+  LastTypo = std::move(Record);
+
+  return TypoCorrection();
+}
+
+std::vector<Fix> IncludeFixer::fixTypo(const TypoRecord &Typo) const {
+  std::vector<std::string> Scopes;
+  if (Typo.SS) {
+    Scopes.push_back(*Typo.SS);
+  } else {
+    // No scope qualifier is specified. Collect all accessible scopes in the
+    // context.
+    VisitedContextCollector Collector;
+    Compiler.getSema().LookupVisibleDecls(Typo.S, Typo.LookupKind, Collector,
+                                          /*IncludeGlobalScope=*/false,
+                                          /*LoadExternal=*/false);
+
+    Scopes.push_back("");
+    for (const auto *Ctx : Collector.takeVisitedContexts())
+      if (isa<NamespaceDecl>(Ctx))
+        Scopes.push_back(printNamespaceScope(*Ctx));
+  }
+  vlog("Trying to fix typo \"{0}\" in scopes: [{1}]", Typo.Typo,
+       llvm::join(Scopes.begin(), Scopes.end(), ", "));
+
+  FuzzyFindRequest Req;
+  Req.AnyScope = false;
+  Req.Query = Typo.Typo;
+  Req.Scopes = Scopes;
+  Req.RestrictForCodeCompletion = true;
+
+  SymbolSlab::Builder Matches;
+  Index.fuzzyFind(Req, [&](const Symbol &Sym) {
+    if (Sym.Name != Req.Query)
+      return;
+    if (!Sym.IncludeHeaders.empty())
+      Matches.insert(Sym);
+  });
+  auto Syms = std::move(Matches).build();
+  if (Syms.empty())
+    return {};
+  std::vector<Fix> Results;
+  for (const auto &Sym : Syms) {
+    auto Fixes = fixesForSymbol(Sym);
+    Results.insert(Results.end(), Fixes.begin(), Fixes.end());
+  }
+  return Results;
+}
+
 } // namespace clangd
 } // namespace clang

unittests/clangd/IncludeFixerTests.cpp

 //===-- ClangdUnitTests.cpp - ClangdUnit tests ------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "Annotations.h"
 #include "ClangdUnit.h"
 #include "IncludeFixer.h"
 #include "TestIndex.h"
 #include "TestTU.h"
 #include "index/MemIndex.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 namespace clang {
 namespace clangd {
 namespace {
 
 using testing::UnorderedElementsAre;
 
 testing::Matcher<const Diag &> WithFix(testing::Matcher<Fix> FixMatcher) {
-  return Field(&Diag::Fixes, ElementsAre(FixMatcher));
+  return Field(&Diag::Fixes, UnorderedElementsAre(FixMatcher));
+}
+
+testing::Matcher<const Diag &> WithFix(testing::Matcher<Fix> FixMatcher1,
+                                       testing::Matcher<Fix> FixMatcher2) {
+  return Field(&Diag::Fixes, UnorderedElementsAre(FixMatcher1, FixMatcher2));
 }
 
 MATCHER_P2(Diag, Range, Message,
            "Diag at " + llvm::to_string(Range) + " = [" + Message + "]") {
   return arg.Range == Range && arg.Message == Message;
 }
 
 MATCHER_P3(Fix, Range, Replacement, Message,
            "Fix " + llvm::to_string(Range) + " => " +
                testing::PrintToString(Replacement) + " = [" + Message + "]") {
   return arg.Message == Message && arg.Edits.size() == 1 &&
          arg.Edits[0].range == Range && arg.Edits[0].newText == Replacement;
 }
 
+struct SymbolWithHeader {
+  std::string QName;
+  std::string DeclaringFile;
+  std::string IncludeHeader;
+};
+
+std::unique_ptr<SymbolIndex> buildIndexWithSymbol(llvm::ArrayRef<SymbolWithHeader> Syms) {
+  SymbolSlab::Builder Slab;
+  for (const auto &S : Syms) {
+    Symbol Sym = symbol(S.QName);
+    Sym.Flags |= Symbol::IndexedForCodeCompletion;
+    Sym.CanonicalDeclaration.FileURI = S.DeclaringFile.c_str();
+    Sym.IncludeHeaders.emplace_back(S.IncludeHeader, 1);
+    Slab.insert(Sym);
+  }
+  return MemIndex::build(std::move(Slab).build(), RefSlab());
+}
+
 TEST(IncludeFixerTest, IncompleteType) {
   Annotations Test(R"cpp(
 $insert[[]]namespace ns {
   class X;
 }
 class Y : $base[[public ns::X]] {};
 int main() {
   ns::X *x;
   x$access[[->]]f();
 }
   )cpp");
   auto TU = TestTU::withCode(Test.code());
-  Symbol Sym = symbol("ns::X");
-  Sym.Flags |= Symbol::IndexedForCodeCompletion;
-  Sym.CanonicalDeclaration.FileURI = "unittest:///x.h";
-  Sym.IncludeHeaders.emplace_back("\"x.h\"", 1);
-
-  SymbolSlab::Builder Slab;
-  Slab.insert(Sym);
-  auto Index = MemIndex::build(std::move(Slab).build(), RefSlab());
+  auto Index = buildIndexWithSymbol(
+      {SymbolWithHeader{"ns::X", "unittest:///x.h", "\"x.h\""}});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
       UnorderedElementsAre(
           AllOf(Diag(Test.range("base"), "base class has incomplete type"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(Diag(Test.range("access"),
                      "member access into incomplete type 'ns::X'"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X")))));
 }
 
+TEST(IncludeFixerTest, Typo) {
+  Annotations Test(R"cpp(
+$insert[[]]namespace ns {
+void foo() {
+  $unqualified[[X]] x;
+}
+}
+void bar() {
+  ns::$qualified[[X]] x; // ns:: is valid.
+  ::$global[[Global]] glob;
+}
+  )cpp");
+  auto TU = TestTU::withCode(Test.code());
+  auto Index = buildIndexWithSymbol(
+      {SymbolWithHeader{"ns::X", "unittest:///x.h", "\"x.h\""},
+       SymbolWithHeader{"Global", "unittest:///global.h", "\"global.h\""}});
+  TU.ExternalIndex = Index.get();
+
+  EXPECT_THAT(
+      TU.build().getDiagnostics(),
+      UnorderedElementsAre(
+          AllOf(Diag(Test.range("unqualified"), "unknown type name 'X'"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                            "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("qualified"),
+                     "no type named 'X' in namespace 'ns'"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                            "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("global"),
+                     "no type named 'Global' in the global namespace"),
+                WithFix(Fix(Test.range("insert"), "#include \"global.h\"\n",
+                            "Add include \"global.h\" for symbol Global")))));
+}
+
+TEST(IncludeFixerTest, MultipleMatchedSymbols) {
+  Annotations Test(R"cpp(
+$insert[[]]namespace na {
+namespace nb {
+void foo() {
+  $unqualified[[X]] x;
+}
+}
+}
+  )cpp");
+  auto TU = TestTU::withCode(Test.code());
+  auto Index = buildIndexWithSymbol(
+      {SymbolWithHeader{"na::X", "unittest:///a.h", "\"a.h\""},
+       SymbolWithHeader{"na::nb::X", "unittest:///b.h", "\"b.h\""}});
+  TU.ExternalIndex = Index.get();
+
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(AllOf(
+                  Diag(Test.range("unqualified"), "unknown type name 'X'"),
+                  WithFix(Fix(Test.range("insert"), "#include \"a.h\"\n",
+                              "Add include \"a.h\" for symbol na::X"),
+                          Fix(Test.range("insert"), "#include \"b.h\"\n",
+                              "Add include \"b.h\" for symbol na::nb::X")))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang