[Fix] Non-const reference

This patch fixes returning reference of local variable.

**Self evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test: [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: Jihoon Lee <jhoon.it.lee@samsung.com>

diff --git a/nntrainer/layers/layer_context.cpp b/nntrainer/layers/layer_context.cpp
index a197bd8..92011f5 100644 (file)
--- a/nntrainer/layers/layer_context.cpp
+++ b/nntrainer/layers/layer_context.cpp
@@ -275,17 +275,10 @@ const Tensor &RunLayerContext::getInput(unsigned int idx) const {
  */
 Tensor &RunLayerContext::getInputGrad(unsigned int idx) {
   if (!inputs[idx]->hasGradient()) {
-    //
-    // TODO: This is temporal fixes. We need to find way to handle
-    //       the getInputGrad for multiple inputs ( input 1: Input Layer,
-    //       input 2: Normal Input ). In this situation, if we enable
-    //       inPlaceOptimization, it will fail.
-    //
-    // throw std::invalid_argument(
-    //   "Requesting gradient for a non-trainable tensor.");
-    //
-    return Tensor(inputs[idx]->getDim());
+    throw std::invalid_argument(
+      "Requesting gradient for a non-trainable tensor.");
   }
+
   return inputs[idx]->getGradientRef();
 }