[SYCLomatic] Fix internal error when the template argument decls are empty (#2844)

Signed-off-by: Chen, Sheng S <sheng.s.chen@intel.com>

Author: ShengchenJ

clang/lib/DPCT/RuleInfra/ExprAnalysis.cpp

@@ -870,7 +870,8 @@ void ExprAnalysis::analyzeExpr(const UnaryExprOrTypeTraitExpr *UETT) {
 }
 
 inline void ExprAnalysis::analyzeExpr(const UnresolvedLookupExpr *ULE) {
-  RefString = ULE->decls().begin().getDecl()->getQualifiedNameAsString();
+  if (ULE != nullptr && !ULE->decls().empty())
+    RefString = ULE->decls().begin().getDecl()->getQualifiedNameAsString();
 }
 
 void ExprAnalysis::analyzeExpr(const ExplicitCastExpr *Cast) {

clang/test/dpct/internal_error/auto_deduce_fail_in_kernel.cu

@@ -9,3 +9,23 @@ __device__ void test_auto() {
 
   auto tid = get_tid();
 }
+
+ namespace test {
+
+ enum norm_type_ {
+   NORM1,
+   NORM2,
+   ABS_MAX,
+   ABS_MIN
+ };
+
+ template <typename T, bool fixed, int nColor, int... N>
+ double norm(const GaugeField &u, int d, norm_type_ type, IntList<nColor, N...>) {
+   double norm_ = 0.0;
+     if constexpr (sizeof...(N) > 0) {
+       norm<T, fixed>(u, d, type, IntList<N...>());
+     }
+   return norm_;
+ }
+
+ } // namespace test