[include-fixer] Correct nested class search for identifiers with scoped information

Summary:
include-fixer will firstly try to use scoped namespace context information to
search identifier. However, in some cases, it's unsafe to do nested class
search, because it might treat the identifier as a nested class of scoped
namespace.

Given the following code, and the symbol database only has two classes: "foo" and
"b::Bar".

    namespace foo { Bar t; }

Before getting fixing, include-fixer will never search "Bar" symbol.
Because it firstly tries to search "foo::Bar", there is no "Bar" in foo namespace,
then it finds "foo" in database finally. So it treats "Bar" is a nested class
of "foo".

Reviewers: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D23023

llvm-svn: 277442

clang-tools-extra/include-fixer/IncludeFixer.cpp

@@ -275,8 +275,11 @@ private:
     // 1. lookup a::b::foo.
     // 2. lookup b::foo.
     std::string QueryString = ScopedQualifiers.str() + Query.str();
-    MatchedSymbols = SymbolIndexMgr.search(QueryString);
-    if (MatchedSymbols.empty() && !ScopedQualifiers.empty())
+    // It's unsafe to do nested search for the identifier with scoped namespace
+    // context, it might treat the identifier as a nested class of the scoped
+    // namespace.
+    MatchedSymbols = SymbolIndexMgr.search(QueryString, /*IsNestedSearch=*/false);
+    if (MatchedSymbols.empty())
       MatchedSymbols = SymbolIndexMgr.search(Query);
     DEBUG(llvm::dbgs() << "Having found " << MatchedSymbols.size()
                        << " symbols\n");

clang-tools-extra/include-fixer/IncludeFixerContext.cpp

@@ -44,7 +44,8 @@ std::string createQualifiedNameForReplacement(
   std::string StrippedQualifiers;
   while (!SymbolQualifiers.empty() &&
          !llvm::StringRef(QualifiedName).endswith(SymbolQualifiers.back())) {
-    StrippedQualifiers = "::" + SymbolQualifiers.back().str();
+    StrippedQualifiers =
+        "::" + SymbolQualifiers.back().str() + StrippedQualifiers;
     SymbolQualifiers.pop_back();
   }
   // Append the missing stripped qualifiers.

clang-tools-extra/include-fixer/SymbolIndexManager.cpp

@@ -42,7 +42,8 @@ static void rankByPopularity(std::vector<SymbolInfo> &Symbols) {
 }
 
 std::vector<find_all_symbols::SymbolInfo>
-SymbolIndexManager::search(llvm::StringRef Identifier) const {
+SymbolIndexManager::search(llvm::StringRef Identifier,
+                           bool IsNestedSearch) const {
   // The identifier may be fully qualified, so split it and get all the context
   // names.
   llvm::SmallVector<llvm::StringRef, 8> Names;
@@ -60,7 +61,7 @@ SymbolIndexManager::search(llvm::StringRef Identifier) const {
   // either) and can report that result.
   bool TookPrefix = false;
   std::vector<clang::find_all_symbols::SymbolInfo> MatchedSymbols;
-  while (MatchedSymbols.empty() && !Names.empty()) {
+  do {
     std::vector<clang::find_all_symbols::SymbolInfo> Symbols;
     for (const auto &DB : SymbolIndices) {
       auto Res = DB->search(Names.back().str());
@@ -116,7 +117,7 @@ SymbolIndexManager::search(llvm::StringRef Identifier) const {
     }
     Names.pop_back();
     TookPrefix = true;
-  }
+  } while (MatchedSymbols.empty() && !Names.empty() && IsNestedSearch);
 
   rankByPopularity(MatchedSymbols);
   return MatchedSymbols;

clang-tools-extra/include-fixer/SymbolIndexManager.h

@@ -28,12 +28,15 @@ public:
   /// Search for header files to be included for an identifier.
   /// \param Identifier The identifier being searched for. May or may not be
   ///                   fully qualified.
-  /// \returns A list of inclusion candidates, in a format ready for being
-  ///          pasted after an #include token.
-  // FIXME: Move mapping from SymbolInfo to headers out of
-  // SymbolIndexManager::search and return SymbolInfos instead of header paths.
+  /// \param IsNestedSearch Whether searching nested classes. If true, the
+  ///        method tries to strip identifier name parts from the end until it
+  ///        finds the corresponding candidates in database (e.g for identifier
+  ///        "b::foo", the method will try to find "b" if it fails to find
+  ///        "b::foo").
+  ///
+  /// \returns A list of symbol candidates.
   std::vector<find_all_symbols::SymbolInfo>
-  search(llvm::StringRef Identifier) const;
+  search(llvm::StringRef Identifier, bool IsNestedSearch = true) const;
 
 private:
   std::vector<std::unique_ptr<SymbolIndex>> SymbolIndices;

clang-tools-extra/unittests/include-fixer/IncludeFixerTest.cpp

@@ -77,6 +77,12 @@ static std::string runIncludeFixer(
       SymbolInfo("Vector", SymbolInfo::SymbolKind::Class, "\"Vector.h\"", 2,
                  {{SymbolInfo::ContextType::Namespace, "a"}},
                  /*num_occurrences=*/1),
+      SymbolInfo("StrCat", SymbolInfo::SymbolKind::Class, "\"strcat.h\"",
+                 1, {{SymbolInfo::ContextType::Namespace, "str"}}),
+      SymbolInfo("str", SymbolInfo::SymbolKind::Class, "\"str.h\"",
+                 1, {}),
+      SymbolInfo("foo2", SymbolInfo::SymbolKind::Class, "\"foo2.h\"",
+                 1, {}),
   };
   auto SymbolIndexMgr = llvm::make_unique<include_fixer::SymbolIndexManager>();
   SymbolIndexMgr->addSymbolIndex(
@@ -189,6 +195,16 @@ TEST(IncludeFixer, ScopedNamespaceSymbols) {
   // full match.
   EXPECT_EQ("#include \"bar.h\"\nnamespace A {\na::b::bar b;\n}",
             runIncludeFixer("namespace A {\nb::bar b;\n}"));
+
+  // Finds candidates for "str::StrCat".
+  EXPECT_EQ("#include \"strcat.h\"\nnamespace foo2 {\nstr::StrCat b;\n}",
+            runIncludeFixer("namespace foo2 {\nstr::StrCat b;\n}"));
+  // str::StrCat2 doesn't exist.
+  // In these two cases, StrCat2 is a nested class of class str.
+  EXPECT_EQ("#include \"str.h\"\nnamespace foo2 {\nstr::StrCat2 b;\n}",
+            runIncludeFixer("namespace foo2 {\nstr::StrCat2 b;\n}"));
+  EXPECT_EQ("#include \"str.h\"\nnamespace ns {\nstr::StrCat2 b;\n}",
+            runIncludeFixer("namespace ns {\nstr::StrCat2 b;\n}"));
 }
 
 TEST(IncludeFixer, EnumConstantSymbols) {
@@ -253,7 +269,7 @@ TEST(IncludeFixer, FixNamespaceQualifiers) {
   // Test nested classes.
   EXPECT_EQ("#include \"bar.h\"\nnamespace d {\na::b::bar::t b;\n}\n",
             runIncludeFixer("namespace d {\nbar::t b;\n}\n"));
-  EXPECT_EQ("#include \"bar2.h\"\nnamespace c {\na::c::bar::t b;\n}\n",
+  EXPECT_EQ("#include \"bar.h\"\nnamespace c {\na::b::bar::t b;\n}\n",
             runIncludeFixer("namespace c {\nbar::t b;\n}\n"));
   EXPECT_EQ("#include \"bar.h\"\nnamespace a {\nb::bar::t b;\n}\n",
             runIncludeFixer("namespace a {\nbar::t b;\n}\n"));