Fix internal build error (#600)

* Update util_qsim.h

* Update util_qsim_test.cc

* Update circuit_parser_qsim_test.cc

* Update tfq_inner_product_grad.cc

* Fix format

* Fix interal errors

Author: jaeyoo

tensorflow_quantum/core/ops/math_ops/tfq_inner_product_grad.cc

@@ -477,8 +477,6 @@ REGISTER_OP("TfqInnerProductGrad")
 
       tensorflow::shape_inference::DimensionHandle output_rows =
           c->Dim(programs_shape, 0);
-      tensorflow::shape_inference::DimensionHandle output_cols =
-          c->Dim(symbol_names_shape, 0);
 
       // Use kUnknownDim instead to prevent shape inference from breaking
       //   @tf.custom_gradient code in fidelity_op.py. The grad function has

tensorflow_quantum/core/ops/noise/tfq_noisy_sampled_expectation.cc

@@ -196,7 +196,7 @@ class TfqNoisySampledExpectationOp : public tensorflow::OpKernel {
       int nq = num_qubits[i];
 
       // (#679) Just ignore empty program
-      if (ncircuits[i].channels.size() == 0) {
+      if (ncircuits[i].channels.empty()) {
         for (int j = 0; j < pauli_sums[i].size(); j++) {
           (*output_tensor)(i, j) = -2.0;
         }
@@ -315,7 +315,7 @@ class TfqNoisySampledExpectationOp : public tensorflow::OpKernel {
         int rep_offset = rep_offsets[start][i];
 
         // (#679) Just ignore empty program
-        if (ncircuits[i].channels.size() == 0) {
+        if (ncircuits[i].channels.empty()) {
           for (int j = 0; j < pauli_sums[i].size(); j++) {
             (*output_tensor)(i, j) = -2.0;
           }

tensorflow_quantum/core/src/circuit_parser_qsim_test.cc

@@ -1535,7 +1535,7 @@ TEST(QsimCircuitParserTest, NoisyEmpty) {
   Program program_proto;
   Circuit* circuit_proto = program_proto.mutable_circuit();
   circuit_proto->set_scheduling_strategy(circuit_proto->MOMENT_BY_MOMENT);
-  Moment* moments_proto = circuit_proto->add_moments();
+  (void)circuit_proto->add_moments();
 
   NoisyQsimCircuit test_circuit;
   ASSERT_EQ(

tensorflow_quantum/core/src/util_qsim.h

@@ -235,7 +235,7 @@ tensorflow::Status ComputeSampledExpectationQsim(
       unsigned int location;
       // GridQubit id should be parsed down to integer at this upstream
       //  so it is safe to just use atoi.
-      bool unused = absl::SimpleAtoi(pair.qubit_id(), &location);
+      (void)absl::SimpleAtoi(pair.qubit_id(), &location);
       // Parity functions use little-endian indexing
       parity_bits.push_back(state.num_qubits() - location - 1);
     }

tensorflow_quantum/core/src/util_qsim_test.cc

@@ -493,7 +493,8 @@ TEST(UtilQsimTest, AccumulateOperatorsBasic) {
   p_term_scratch2->set_coefficient_real(-5.0);
 
   // 0.5 * (0.123ZX -3X + 4I) + 0.25 * (-5I) applied onto psi.
-  AccumulateOperators({p_sum, p_sum2}, {0.5, 0.25}, sim, ss, sv, scratch, dest);
+  (void)AccumulateOperators({p_sum, p_sum2}, {0.5, 0.25}, sim, ss, sv, scratch,
+                            dest);
 
   // Check that dest got accumulated onto.
   EXPECT_NEAR(ss.GetAmpl(dest, 0).real(), 0.577925, 1e-5);
@@ -535,7 +536,7 @@ TEST(UtilQsimTest, AccumulateOperatorsEmpty) {
   auto scratch = ss.Create(2);
   auto dest = ss.Create(2);
 
-  AccumulateOperators({}, {}, sim, ss, sv, scratch, dest);
+  (void)AccumulateOperators({}, {}, sim, ss, sv, scratch, dest);
 
   // Check sv is still in zero state.
   EXPECT_NEAR(ss.GetAmpl(sv, 0).real(), 1.0, 1e-5);
@@ -599,7 +600,7 @@ TEST(UtilQsimTest, AccumulateFusedCircuitsBasic) {
   // Initialize coeffs.
   std::vector<float> coeffs = {1.23, 4.56};
 
-  AccumulateFusedCircuits(coeffs, fused_circuits, sim, ss, scratch, dest);
+  (void)AccumulateFusedCircuits(coeffs, fused_circuits, sim, ss, scratch, dest);
 
   // Scratch has coeffs[r][c] * fused circuits[r][c] where r, c = last indices.
   // Check that dest got accumulated onto.
@@ -628,7 +629,7 @@ TEST(UtilQsimTest, AccumulateFusedCircuitsEmpty) {
   auto scratch = ss.Create(2);
   auto dest = ss.Create(2);
 
-  AccumulateFusedCircuits({}, {}, sim, ss, scratch, dest);
+  (void)AccumulateFusedCircuits({}, {}, sim, ss, scratch, dest);
 
   // scratch has garbage value.
   // Check that dest contains all zeros.

tensorflow_quantum/python/layers/high_level/controlled_pqc.py

@@ -215,7 +215,7 @@ def __init__(self,
                              "tfq.layers.ControlledPQC. Please use "
                              "tfq.layers.NoisyControlledPQC instead.")
 
-        not_default = backend is not 'noiseless'
+        not_default = backend != 'noiseless'
         not_default &= backend is not None  # legacy backend=None support.
         if not isinstance(
                 backend,

tensorflow_quantum/python/layers/high_level/pqc.py

@@ -230,7 +230,7 @@ def __init__(
                              "tfq.layers.PQC. Please use tfq.layers.NoisyPQC "
                              "instead.")
 
-        not_default = backend is not 'noiseless'
+        not_default = backend != 'noiseless'
         not_default &= backend is not None  # legacy backend=None support.
         if not isinstance(
                 backend,