[SYCL] Fix static code analysis concerns in processSYCLKernel (#2976)

Found via a static-analysis tool inside processSYCLKernel():

Pointer 'CRD' returned from call to function 'getPointeeCXXRecordDecl' may be NULL at line below:
const CXXRecordDecl *CRD = (KernelParamTy->isReferenceType()
? KernelParamTy->getPointeeCXXRecordDecl()
: KernelParamTy->getAsCXXRecordDecl());

for (auto *Method : CRD->methods()) --> will be dereferenced here

This patch fixes null pointer dereference issue inside SemaTemplateInstantiateDecl.cpp file.

Signed-off-by: Soumi Manna <[email protected]>

Author: smanna12

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -6297,6 +6297,12 @@ static void processSYCLKernel(Sema &S, FunctionDecl *FD, MangleContext &MC) {
     const CXXRecordDecl *CRD = (KernelParamTy->isReferenceType()
                                     ? KernelParamTy->getPointeeCXXRecordDecl()
                                     : KernelParamTy->getAsCXXRecordDecl());
+    if (!CRD) {
+      S.Diag(FD->getLocation(), diag::err_sycl_kernel_not_function_object);
+      FD->setInvalidDecl();
+      return;
+    }
+
     for (auto *Method : CRD->methods())
       if (Method->getOverloadedOperator() == OO_Call &&
           !Method->hasAttr<AlwaysInlineAttr>())

clang/test/SemaSYCL/kernel-not-functor.cpp

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsycl -fsycl-is-device -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsycl -fsycl-is-host -fsyntax-only -verify %s
 
 template <typename Name, typename F>
 __attribute__((sycl_kernel)) void kernel(F kernelFunc) {