Implicit cast is allowed on types introduced by the type keyword when it shoudn't

[jaehyun1ee]

Spec section 7.6. Introducing new types mentions that type introduced by the type keyword is not a synonym with its underlying type.

However, tests psa-dpdk-binary-operations-1.p4, psa-dpdk-binary-operations.p4, psa-dpdk-header-union-typedef.p4, pins_fabric.p4. pins_middleblock.p4, and pins_wbb.p4 expect that new types can be implicitly cast to their underlying types.

For example,

// psa-dpdk-binary-operations-1.p4

typedef bit<32>  PortIdUint_t;
type PortIdUint_t         PortId_t;
struct psa_ingress_input_metadata_t {
  PortId_t                 ingress_port;
  // ...
}

control MyIC(
    inout ethernet_t a,
    inout metadata b,
    in psa_ingress_input_metadata_t c,
    inout psa_ingress_output_metadata_t d) {
    bit<8> Op1 = 0x2;
    bit<16> Op2 = 0x23;
    action forward() {
        b.meta = 32w0x1 << c.ingress_port; // c.ingress_port is of type PortId_t, should use (bit<32>) c.ingress_port instead.
    }
    // ...
}