[CodeComplete] [clangd] Fix crash on ValueDecl with a null type

Reviewers: kadircet

Reviewed By: kadircet

Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D57093

llvm-svn: 352040

clang-tools-extra/clangd/ExpectedTypes.cpp

@@ -35,8 +35,10 @@ static llvm::Optional<QualType>
 typeOfCompletion(const CodeCompletionResult &R) {
   auto *VD = dyn_cast_or_null<ValueDecl>(R.Declaration);
   if (!VD)
-    return None; // We handle only variables and functions below.
+    return llvm::None; // We handle only variables and functions below.
   auto T = VD->getType();
+  if (T.isNull())
+    return llvm::None;
   if (auto FuncT = T->getAs<FunctionType>()) {
     // Functions are a special case. They are completed as 'foo()' and we want
     // to match their return type rather than the function type itself.

clang-tools-extra/unittests/clangd/CodeCompleteTests.cpp

@@ -2319,6 +2319,17 @@ TEST(CompletionTest, ObjectiveCMethodTwoArgumentsFromMiddle) {
   EXPECT_THAT(C, ElementsAre(SnippetSuffix("${1:(unsigned int)}")));
 }
 
+TEST(CompletionTest, WorksWithNullType) {
+  auto R = completions(R"cpp(
+    int main() {
+      for (auto [loopVar] : y ) { // y has to be unresolved.
+        int z = loopV^;
+      }
+    }
+  )cpp");
+  EXPECT_THAT(R.Completions, ElementsAre(Named("loopVar")));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang

clang/lib/Sema/SemaCodeComplete.cpp

@@ -680,7 +680,8 @@ QualType clang::getDeclUsageType(ASTContext &C, const NamedDecl *ND) {
     T = Property->getType();
   else if (const auto *Value = dyn_cast<ValueDecl>(ND))
     T = Value->getType();
-  else
+
+  if (T.isNull())
     return QualType();
 
   // Dig through references, function pointers, and block pointers to

clang/test/CodeCompletion/crash-null-type.cpp

@@ -0,0 +1,8 @@
+void test() {
+  for (auto [loopVar] : y) { // y has to be unresolved
+    loopVa
+  }
+}
+// RUN: not %clang_cc1 -fsyntax-only -code-completion-at=%s:3:11 %s -o - \
+// RUN:            | FileCheck %s
+// CHECK: COMPLETION: loopVar