Pass the uint context to the return value of uint::at (#1593)

* Construct return value from current context in uint::at

Fixes https://github.com/AztecProtocol/aztec2-internal/issues/1433

* Add uint test which asserts context inheritance

src/aztec/stdlib/primitives/bit_array/bit_array.test.cpp

@@ -94,4 +94,24 @@ TEST(stdlib_bit_array, test_byte_array_conversion)
 
     EXPECT_EQ(result, expected);
 }
-} // namespace test_stdlib_bit_array
+
+TEST(stdlib_bit_array, test_uint32_vector_constructor)
+{
+    waffle::StandardComposer composer = waffle::StandardComposer();
+
+    uint32_t a_expected = engine.get_random_uint32();
+    uint32_t b_expected = engine.get_random_uint32();
+
+    uint32 a = witness_t(&composer, a_expected);
+    uint32 b = witness_t(&composer, b_expected);
+
+    std::vector<uint32> inputs = { a, b };
+    bit_array test_bit_array = bit_array(inputs);
+
+    std::vector<uint32> result = test_bit_array.to_uint32_vector();
+
+    bit_array test_bit_array_2 = bit_array(result);
+
+    static_cast<byte_array>(test_bit_array_2).get_value();
+}
+} // namespace test_stdlib_bit_array

src/aztec/stdlib/primitives/uint/uint.cpp

@@ -338,7 +338,7 @@ template <typename Composer, typename Native> bool_t<Composer> uint<Composer, Na
          *    lo_bit + 2 high bit of (A_pivot - 4 A_{pivot - 1}) = A_pivot - 4 A_{pivot - 1} == 0
          */
         context->create_big_add_gate_with_bit_extraction(gate);
-        bool_t<Composer> result;
+        bool_t<Composer> result(context);
         result.witness_index = gate.a;
         result.witness_bool = (lo_bit == 1) ? true : false;
         return result;
@@ -364,7 +364,7 @@ template <typename Composer, typename Native> bool_t<Composer> uint<Composer, Na
      * bit extraction gate is trusted to correctly extract 6 * (high bit c - 4d).
      */
     context->create_big_add_gate_with_bit_extraction(gate);
-    bool_t<Composer> result;
+    bool_t<Composer> result(context);
     result.witness_index = gate.b;
     result.witness_bool = (hi_bit == 1) ? true : false;
     return result;
@@ -376,4 +376,4 @@ INSTANTIATE_STDLIB_TYPE_VA(uint, uint32_t);
 INSTANTIATE_STDLIB_TYPE_VA(uint, uint64_t);
 
 } // namespace stdlib
-} // namespace plonk
+} // namespace plonk

src/aztec/stdlib/primitives/uint/uint.test.cpp

@@ -1883,6 +1883,7 @@ TEST(stdlib_uint, test_at)
             bool_ct result = c.at(i);
             bool expected = (((c_val >> i) & 1UL) == 1UL) ? true : false;
             EXPECT_EQ(result.get_value(), expected);
+            EXPECT_EQ(result.get_context(), c.get_context());
         }
     };