[clangd] Not collect include headers for dynamic index for now.

Summary:
The new behaviors introduced by this patch:
o When include collection is enabled, we always set IncludeHeader field in Symbol
even if it's the same as FileURI in decl.
o Disable include collection in FileIndex which is currently only used to build
dynamic index. We should revisit when we actually want to use FileIndex to global
index.
o Code-completion only uses IncludeHeader to insert headers but not FileURI in
CanonicalDeclaration. This ensures that inserted headers are always canonicalized.
Note that include insertion can still be triggered for symbols that are already
included if they are merged from dynamic index and static index, but we would
only use includes that are already canonicalized (e.g. from static index).

Reason for change:
Collecting header includes in dynamic index enables inserting includes for headers
that are not indexed but opened in the editor. Comparing to inserting includes for
symbols in global/static index, this is nice-to-have but would probably require
non-trivial amount of work to get right. For example:
o Currently it's not easy to fully support CanonicalIncludes in dynamic index, given the way
we run dynamic index.
o It's also harder to reason about the correctness of include canonicalization for dynamic index
(i.e. symbols in the current file/TU) than static index where symbols are collected
offline and sanity check is possible before shipping to production.
o We have less control/flexibility over symbol info in the dynamic index
(e.g. URIs, path normalization), which could be used to help make decision when inserting includes.

As header collection (especially canonicalization) is relatively new, and enabling
it for dynamic index would immediately affect current users with only dynamic
index support, I propose we disable it for dynamic index for now to avoid
compromising other hot features like code completion and only support it for
static index where include insertion would likely to bring more value.

Reviewers: ilya-biryukov, sammccall, hokein

Subscribers: klimek, jkorous-apple, cfe-commits

Differential Revision: https://reviews.llvm.org/D43550

llvm-svn: 325764

6 files changed, 22 insertions, 36 deletions

diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index 35738fad788..d582adc9bce 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -286,13 +286,9 @@ struct CompletionCandidate {
           I.documentation = D->Documentation;
         if (I.detail.empty())
           I.detail = D->CompletionDetail;
-        // We only insert #include for items with details, since we can't tell
-        // whether the file URI of the canonical declaration would be the
-        // canonical #include without checking IncludeHeader in the detail.
         // FIXME: delay creating include insertion command to
         // "completionItem/resolve", when it is supported
-        if (!D->IncludeHeader.empty() ||
-            !IndexResult->CanonicalDeclaration.FileURI.empty()) {
+        if (!D->IncludeHeader.empty()) {
           // LSP favors additionalTextEdits over command. But we are still using
           // command here because it would be expensive to calculate #include
           // insertion edits for all candidates, and the include insertion edit
@@ -301,9 +297,7 @@ struct CompletionCandidate {
           // Command title is not added since this is not a user-facing command.
           Cmd.command = ExecuteCommandParams::CLANGD_INSERT_HEADER_INCLUDE;
           IncludeInsertion Insertion;
-          Insertion.header = D->IncludeHeader.empty()
-                                 ? IndexResult->CanonicalDeclaration.FileURI
-                                 : D->IncludeHeader;
+          Insertion.header = D->IncludeHeader;
           Insertion.textDocument.uri = URIForFile(FileName);
           Cmd.includeInsertion = std::move(Insertion);
           I.command = std::move(Cmd);
diff --git a/clang-tools-extra/clangd/index/FileIndex.cpp b/clang-tools-extra/clangd/index/FileIndex.cpp
index 3f1cdeb2a12..8a8d179557a 100644
--- a/clang-tools-extra/clangd/index/FileIndex.cpp
+++ b/clang-tools-extra/clangd/index/FileIndex.cpp
@@ -15,15 +15,6 @@ namespace clang {
 namespace clangd {
 namespace {
 
-const CanonicalIncludes *canonicalIncludesForSystemHeaders() {
-  static const auto *Includes = [] {
-    auto *I = new CanonicalIncludes();
-    addSystemHeadersMapping(I);
-    return I;
-  }();
-  return Includes;
-}
-
 /// Retrieves namespace and class level symbols in \p Decls.
 std::unique_ptr<SymbolSlab> indexAST(ASTContext &Ctx,
                                      std::shared_ptr<Preprocessor> PP,
@@ -32,12 +23,14 @@ std::unique_ptr<SymbolSlab> indexAST(ASTContext &Ctx,
   // Although we do not index symbols in main files (e.g. cpp file), information
   // in main files like definition locations of class declarations will still be
   // collected; thus, the index works for go-to-definition.
-  // FIXME(ioeric): handle IWYU pragma for dynamic index. We might want to make
-  // SymbolCollector always provides include canonicalization (e.g. IWYU, STL).
   // FIXME(ioeric): get rid of `IndexMainFiles` as this is always set to false.
   CollectorOpts.IndexMainFiles = false;
-  CollectorOpts.CollectIncludePath = true;
-  CollectorOpts.Includes = canonicalIncludesForSystemHeaders();
+  // FIXME(ioeric): we might also want to collect include headers. We would need
+  // to make sure all includes are canonicalized (with CanonicalIncludes), which
+  // is not trivial given the current way of collecting symbols: we only have
+  // AST at this point, but we also need preprocessor callbacks (e.g.
+  // CommentHandler for IWYU pragma) to canonicalize includes.
+  CollectorOpts.CollectIncludePath = false;
 
   auto Collector = std::make_shared<SymbolCollector>(std::move(CollectorOpts));
   Collector->setPreprocessor(std::move(PP));
diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
index 43ea4590f76..629db530928 100644
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -162,8 +162,8 @@ struct Symbol {
     /// directly. When this is a URI, the exact #include path needs to be
     /// calculated according to the URI scheme.
     ///
-    /// If empty, FileURI in CanonicalDeclaration should be used to calculate
-    /// the #include path.
+    /// This is a canonical include for the symbol and can be different from
+    /// FileURI in the CanonicalDeclaration.
     llvm::StringRef IncludeHeader;
   };
 
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.cpp b/clang-tools-extra/clangd/index/SymbolCollector.cpp
index 2a32565eb7a..f8fb2c29570 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ b/clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -150,8 +150,9 @@ bool shouldCollectIncludePath(index::SymbolKind Kind) {
   }
 }
 
-/// Gets a canonical include (<header>  or "header") for header of \p Loc.
-/// Returns None if the header has no canonical include.
+/// Gets a canonical include (URI of the header or <header>  or "header") for
+/// header of \p Loc.
+/// Returns None if fails to get include header for \p Loc.
 /// FIXME: we should handle .inc files whose symbols are expected be exported by
 /// their containing headers.
 llvm::Optional<std::string>
@@ -167,10 +168,8 @@ getIncludeHeader(const SourceManager &SM, SourceLocation Loc,
                  ? Mapped.str()
                  : ("\"" + Mapped + "\"").str();
   }
-  // If the header path is the same as the file path of the declaration, we skip
-  // storing the #include path; users can use the URI in declaration location to
-  // calculate the #include path.
-  return llvm::None;
+
+  return toURI(SM, SM.getFilename(Loc), Opts);
 }
 
 // Return the symbol location of the given declaration `D`.
diff --git a/clang-tools-extra/unittests/clangd/FileIndexTests.cpp b/clang-tools-extra/unittests/clangd/FileIndexTests.cpp
index 04bdf9a5c44..8ef4313d194 100644
--- a/clang-tools-extra/unittests/clangd/FileIndexTests.cpp
+++ b/clang-tools-extra/unittests/clangd/FileIndexTests.cpp
@@ -181,19 +181,19 @@ TEST(FileIndexTest, IgnoreClassMembers) {
   EXPECT_THAT(match(M, Req), UnorderedElementsAre("X"));
 }
 
-#ifndef LLVM_ON_WIN32
-TEST(FileIndexTest, CanonicalizeSystemHeader) {
+TEST(FileIndexTest, NoIncludeCollected) {
   FileIndex M;
-  std::string File = testPath("bits/basic_string");
-  M.update(File, build(File, "class string {};").getPointer());
+  M.update("f", build("f", "class string {};").getPointer());
 
   FuzzyFindRequest Req;
   Req.Query = "";
+  bool SeenSymbol = false;
   M.fuzzyFind(Req, [&](const Symbol &Sym) {
-    EXPECT_EQ(Sym.Detail->IncludeHeader, "<string>");
+    EXPECT_TRUE(Sym.Detail->IncludeHeader.empty());
+    SeenSymbol = true;
   });
+  EXPECT_TRUE(SeenSymbol);
 }
-#endif
 
 } // namespace
 } // namespace clangd
diff --git a/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp b/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
index d99aac05258..27cf6308100 100644
--- a/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
+++ b/clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
@@ -585,7 +585,7 @@ TEST_F(SymbolCollectorTest, IncludeHeaderSameAsFileURI) {
   runSymbolCollector("class Foo {};", /*Main=*/"");
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(AllOf(QName("Foo"), DeclURI(TestHeaderURI),
-                                         IncludeHeader(""))));
+                                         IncludeHeader(TestHeaderURI))));
 }
 
 #ifndef LLVM_ON_WIN32