[include-fixer] Make search handle fully qualified names correctly.

[bkramer]

Summary

If a search string starts with "::" we don't want to return any results
for suffixes of that string.

[hokein]

LGTM with one nit.

include-fixer/SymbolIndexManager.cpp

73

Might be IsMatched &= (SymbolContext == Symbol.getContexts().end()); for reading clearly?

include-fixer/SymbolIndexManager.cpp

 
 std::vector<std::string>
 SymbolIndexManager::search(llvm::StringRef Identifier) const {
   // The identifier may be fully qualified, so split it and get all the context
   // names.
   llvm::SmallVector<llvm::StringRef, 8> Names;
   Identifier.split(Names, "::");
 
+  bool IsFullyQualified = false;
+  if (Identifier.startswith("::")) {
+    Names.erase(Names.begin()); // Drop first (empty) element.
+    IsFullyQualified = true;
+  }
+
   // As long as we don't find a result keep stripping name parts from the end.
   // This is to support nested classes which aren't recorded in the database.
   // Eventually we will either hit a class (namespaces aren't in the database
   // either) and can report that result.
   std::vector<std::string> Results;
   while (Results.empty() && !Names.empty()) {
     std::vector<clang::find_all_symbols::SymbolInfo> Symbols;
     for (const auto &DB : SymbolIndices) {
for (const auto &Symbol : Symbols) {
             // Skip non-scoped enum context.
             ++SymbolContext;
           } else {
             IsMatched = false;
             break;
           }
         }
 
+        // If the name was qualified we only want to add results if we evaluated
+        // all contexts.
+        if (IsFullyQualified)
+          IsMatched &= SymbolContext == Symbol.getContexts().end();
+
         // FIXME: Support full match. At this point, we only find symbols in
         // database which end with the same contexts with the identifier.
         if (IsMatched && IdentiferContext == Names.rend()) {
           // FIXME: file path should never be in the form of <...> or "...", but
           // the unit test with fixed database use <...> file path, which might
           // need to be changed.
           // FIXME: if the file path is a system header name, we want to use
           // angle brackets.

unittests/include-fixer/IncludeFixerTest.cpp

EXPECT_EQ(
       "#include \"foo.h\"\n#include <string>\nstd::string::size_type foo;\n",
       runIncludeFixer("#include \"foo.h\"\nstd::string::size_type foo;\n"));
 
   // string without "std::" can also be fixed since fixed db results go through
   // SymbolIndexManager, and SymbolIndexManager matches unqualified identifiers
   // too.
   EXPECT_EQ("#include <string>\n\nstring foo;\n",
             runIncludeFixer("string foo;\n"));
+
+  // Fully qualified name.
+  EXPECT_EQ("#include <string>\n\n::std::string foo;\n",
+            runIncludeFixer("::std::string foo;\n"));
+  // Should not match std::string.
+  EXPECT_EQ("::string foo;\n", runIncludeFixer("::string foo;\n"));
 }
 
 TEST(IncludeFixer, IncompleteType) {
   EXPECT_EQ(
       "#include \"foo.h\"\n#include <string>\n"
       "namespace std {\nclass string;\n}\nstring foo;\n",
       runIncludeFixer("#include \"foo.h\"\n"
                       "namespace std {\nclass string;\n}\nstring foo;\n"));