message: [XLA/GPU] Fix build errors due to narrowing type conversion.
diff: @@ -3004,7 +3004,7 @@ ShapeIndex CreateShapeIndexForOutputInstruction(
  const auto& all_outputs = unnested_hlo.fused_expression_root()->operands();
  for (size_t i = 0; i < all_outputs.size(); ++i) {
  if (all_outputs[i] == &out_instr) {
  - return ShapeIndex({i});
  + return ShapeIndex({static_cast<int64>(i)});
  }
  }
  LOG(FATAL) << " Fusion root does not contain output instruction; "
  @@ -3975,7 +3975,8 @@ Status IrEmitterUnnested::EmitReductionFromOrToContiguousDimensions(
  // block_y_count is set to instr_groups.size(), so that each reduction group
  // can be run in parallel by a different BlockIdy.
  LaunchDimensions launch_dimensions(
  - {/*x=*/mapping_scheme.GetNumberOfBlocks(), /*y=*/instr_groups.size(),
  + {/*x=*/mapping_scheme.GetNumberOfBlocks(),
  + /*y=*/static_cast<int64>(instr_groups.size()),
  /*z=*/1},
  {/*x=*/mapping_scheme.GetThreadsPerBlock(), /*y=*/1, /*z=*/1});
  VLOG(3) << "Launch dimensions of " << unnested_hlo->name()
  