[CodeComplete] Fix a crash in preferred type and signature help

Summary: Null type pointers could be dereferenced in some cases.

Reviewers: kadircet, sammccall

Reviewed By: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71329

2 files changed, 14 insertions, 3 deletions

diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 7dfe71fb9eb..fecd70b17e5 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -1862,9 +1862,11 @@ Parser::ParseCXXTypeConstructExpression(const DeclSpec &DS) {
     CommaLocsTy CommaLocs;
 
     auto RunSignatureHelp = [&]() {
-      QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
-          getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
-          DS.getEndLoc(), Exprs, T.getOpenLocation());
+      QualType PreferredType;
+      if (TypeRep)
+        PreferredType = Actions.ProduceConstructorSignatureHelp(
+            getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
+            DS.getEndLoc(), Exprs, T.getOpenLocation());
       CalledSignatureHelp = true;
       return PreferredType;
     };
@@ -3038,6 +3040,7 @@ Parser::ParseCXXNewExpression(bool UseGlobal, SourceLocation Start) {
       auto RunSignatureHelp = [&]() {
         ParsedType TypeRep =
             Actions.ActOnTypeName(getCurScope(), DeclaratorInfo).get();
+        assert(TypeRep && "invalid types should be handled before");
         QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
             getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
             DeclaratorInfo.getEndLoc(), ConstructorArgs, ConstructorLParen);
diff --git a/clang/unittests/Sema/CodeCompleteTest.cpp b/clang/unittests/Sema/CodeCompleteTest.cpp
index ab1792ba637..a9441a679ca 100644
--- a/clang/unittests/Sema/CodeCompleteTest.cpp
+++ b/clang/unittests/Sema/CodeCompleteTest.cpp
@@ -481,4 +481,12 @@ TEST(PreferredTypeTest, FunctionArguments) {
   )cpp";
   EXPECT_THAT(collectPreferredTypes(Code), Each("vector<int>"));
 }
+
+TEST(PreferredTypeTest, NoCrashOnInvalidTypes) {
+  StringRef Code = R"cpp(
+    auto x = decltype(&1)(^);
+    auto y = new decltype(&1)(^);
+  )cpp";
+  EXPECT_THAT(collectPreferredTypes(Code), Each("NULL TYPE"));
+}
 } // namespace