[clangd] Fix hover crash on broken code

Differential Revision: https://reviews.llvm.org/D101743

Author: kadircet

clang-tools-extra/clangd/Hover.cpp

@@ -505,7 +505,7 @@ llvm::Optional<StringRef> setterVariableName(const CXXMethodDecl *CMD) {
   if (auto *CE = llvm::dyn_cast<CallExpr>(RHS->IgnoreCasts())) {
     if (CE->getNumArgs() != 1)
       return llvm::None;
-    auto *ND = llvm::dyn_cast<NamedDecl>(CE->getCalleeDecl());
+    auto *ND = llvm::dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl());
     if (!ND || !ND->getIdentifier() || ND->getName() != "move" ||
         !ND->isInStdNamespace())
       return llvm::None;

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

@@ -2438,6 +2438,20 @@ TEST(Hover, DocsFromAST) {
   }
 }
 
+TEST(Hover, NoCrash) {
+  Annotations T(R"cpp(
+    /* error-ok */
+    template<typename T> T foo(T);
+
+    // Setter variable heuristic might fail if the callexpr is broken.
+    struct X { int Y; void [[^setY]](float) { Y = foo(undefined); } };)cpp");
+
+  TestTU TU = TestTU::withCode(T.code());
+  auto AST = TU.build();
+  for (const auto &P : T.points())
+    getHover(AST, P, format::getLLVMStyle(), nullptr);
+}
+
 TEST(Hover, DocsFromMostSpecial) {
   Annotations T(R"cpp(
   // doc1