[clangd] Fix an assertion in TypoCorrection.

[ioeric]

Summary

https://github.com/clangd/clangd/issues/7

[hokein]

clangd/IncludeFixer.cpp

195

nit: move the Unresolved below the if (!SpecifiedScope && !S).

clangd/IncludeFixer.cpp

TypoCorrection CorrectTypo(const DeclarationNameInfo &Typo, int LookupKind,
                              DeclContext *MemberContext, bool EnteringContext,
                              const ObjCObjectPointerType *OPT) override {
     assert(SemaPtr && "Sema must have been set.");
     if (SemaPtr->isSFINAEContext())
       return TypoCorrection();
     if (!SemaPtr->SourceMgr.isWrittenInMainFile(Typo.getLoc()))
       return clang::TypoCorrection();
 
-    assert(S && "Enclosing scope must be set.");
-
     UnresolvedName Unresolved;
     Unresolved.Name = Typo.getAsString();
     Unresolved.Loc = Typo.getBeginLoc();
 
     // 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;
if (SS && SS->isNotEmpty()) { // "::" or "ns::"
         else if (const auto *NS = Nested->getAsNamespace())
           SpecifiedScope = 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();
       }
     }
+    if (!SpecifiedScope && !S) // Give up if no scope available.
+      return TypoCorrection();
 
     auto *Sem = SemaPtr; // Avoid capturing `this`.
     Unresolved.GetScopes = [Sem, SpecifiedScope, S, LookupKind]() {
       std::vector<std::string> Scopes;
       if (SpecifiedScope) {
         Scopes.push_back(*SpecifiedScope);
       } else {
+        assert(S);
         // No scope qualifier is specified. Collect all accessible scopes in the
         // context.
         VisitedContextCollector Collector;
         Sem->LookupVisibleDecls(
             S, static_cast<Sema::LookupNameKind>(LookupKind), Collector,
             /*IncludeGlobalScope=*/false,
             /*LoadExternal=*/false);
 

unittests/clangd/DiagnosticsTests.cpp

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")))));
 }
 
+TEST(IncludeFixerTest, NoCrashMemebrAccess) {
+  Annotations Test(R"cpp(
+    struct X { int  xyz; };
+    void g() { X x; x.$[[xy]] }
+  )cpp");
+  auto TU = TestTU::withCode(Test.code());
+  auto Index = buildIndexWithSymbol(
+      SymbolWithHeader{"na::X", "unittest:///a.h", "\"a.h\""});
+  TU.ExternalIndex = Index.get();
+
+  EXPECT_THAT(
+      TU.build().getDiagnostics(),
+      UnorderedElementsAre(Diag(Test.range(), "no member named 'xy' in 'X'")));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang