[SYCL][NFC] Fix bug with dereference null return value (#7275)

Reported by static analyzer tool. 

Dereference null return value:

In <unnamed>::SyclKernelBodyCreator::enterArray(clang::FieldDecl *,
clang::QualType, clang::QualType): Return value of function which
returns null is dereferenced without checking


bool enterArray(FieldDecl *FD, QualType ArrayType,
                  QualType ElementType) final {

   // returned_null: getAsConstantArrayType returns nullptr
// identity_transfer: Member function call
this->SemaRef->getASTContext()->getAsConstantArrayType(ArrayType)->getSize()
// returns an offset off
this->SemaRef->getASTContext()->getAsConstantArrayType(ArrayType)
(this).

// Dereference null return value (NULL_RETURNS) dereference:
Dereferencing a pointer that might be nullptr

this->SemaRef->getASTContext()->getAsConstantArrayType(ArrayType)->getSize()
when calling getZExtValue

    uint64_t ArraySize = SemaRef.getASTContext()
                             .getAsConstantArrayType(ArrayType)
                             ->getSize()
                             .getZExtValue();
    addCollectionInitListExpr(ArrayType, ArraySize);
    ArrayInfos.emplace_back(getFieldEntity(FD, ArrayType), 0);

This patch updates the codes to resolve the bug.

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

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

Author: smanna12

clang/lib/Sema/SemaSYCL.cpp

@@ -3497,10 +3497,10 @@ class SyclKernelBodyCreator : public SyclKernelFieldHandler {
 
   bool enterArray(FieldDecl *FD, QualType ArrayType,
                   QualType ElementType) final {
-    uint64_t ArraySize = SemaRef.getASTContext()
-                             .getAsConstantArrayType(ArrayType)
-                             ->getSize()
-                             .getZExtValue();
+    const ConstantArrayType *CAT =
+        SemaRef.getASTContext().getAsConstantArrayType(ArrayType);
+    assert(CAT && "Should only be called on constant-size array.");
+    uint64_t ArraySize = CAT->getSize().getZExtValue();
     addCollectionInitListExpr(ArrayType, ArraySize);
     ArrayInfos.emplace_back(getFieldEntity(FD, ArrayType), 0);