New class ICastable; new type constraint added

[mihaibudiu]

Fixed #3534

[rst0git]

LGTM

[kamleshbhalui]

@mbudiu-vmw unable to compile this test after this commit.

~/workarea/p4c/build$ ./p4test test2.p4 
test2.p4(117): [--Werror=type-error] error: Entry
            (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w4, 48w10) : execute(48w1);
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ---- Actual error:
  test2.p4(43): Cannot unify type 'Proto' with type 'bit<8>'
  enum bit<8> Proto {
              ^^^^^
  ---- Originating from:
  test2.p4(117): Table entry has type 'tuple<bool, bit<48>, bit<48>, bit<8>, bit<48>, bit<48>, bit<48>>' which is not the expected type 'tuple<bool, bit<48>, bit<48>, Proto, bit<48>, bit<48>, bit<48>>'
              (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w4, 48w10) : execute(48w1);
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
test2.p4(118): [--Werror=type-error] error: Entry
            (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w5, 48w10) : execute(48w1);
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ---- Actual error:
  test2.p4(43): Cannot unify type 'Proto' with type 'bit<8>'
  enum bit<8> Proto {
              ^^^^^
  ---- Originating from:
  test2.p4(117): Table entry has type 'tuple<bool, bit<48>, bit<48>, bit<8>, bit<48>, bit<48>, bit<48>>' which is not the expected type 'tuple<bool, bit<48>, bit<48>, Proto, bit<48>, bit<48>, bit<48>>'
              (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w4, 48w10) : execute(48w1);
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
test2.p4(119): [--Werror=type-error] error: Entry
            (true,48w3,48w3,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w6, 48w10) : execute(48w1);
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ---- Actual error:
  test2.p4(43): Cannot unify type 'Proto' with type 'bit<8>'
  enum bit<8> Proto {
              ^^^^^
  ---- Originating from:
  test2.p4(117): Table entry has type 'tuple<bool, bit<48>, bit<48>, bit<8>, bit<48>, bit<48>, bit<48>>' which is not the expected type 'tuple<bool, bit<48>, bit<48>, Proto, bit<48>, bit<48>, bit<48>>'
              (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w4, 48w10) : execute(48w1);
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

#include <core.p4>
#include <psa.p4>


typedef bit<48>  EthernetAddress;

header ethernet_t {
    EthernetAddress dstAddr;
    EthernetAddress srcAddr;
    bit<16>         etherType;
}

header ipv4_t {
    bit<4>  version;
    bit<4>  ihl;
    bit<8>  diffserv;
    bit<16> totalLen;
    bit<16> identification;
    bit<3>  flags;
    bit<13> fragOffset;
    bit<8>  ttl;
    bit<8>  protocol;
    bit<16> hdrChecksum;
    bit<32> srcAddr;
    bit<32> dstAddr;
    bit<80> newfield;
}

header tcp_t {
    bit<16> srcPort;
    bit<16> dstPort;
    bit<32> seqNo;
    bit<32> ackNo;
    bit<4>  dataOffset;
    bit<3>  res;
    bit<3>  ecn;
    bit<6>  ctrl;
    bit<16> window;
    bit<16> checksum;
    bit<16> urgentPtr;
}

enum bit<8> Proto {
proto1=0x1,
proto2=0x2
}

struct empty_metadata_t {
}


struct metadata {
     bit<16> data;
     bit<48> key1;
     bit<48> key2;
     bit<48> key3;
     bit<48> key4;
}

struct headers {
    ethernet_t       ethernet;
    ipv4_t           ipv4;
    tcp_t            tcp;
}


parser IngressParserImpl(packet_in buffer,
                         out headers hdr,
                         inout metadata user_meta,
                         in psa_ingress_parser_input_metadata_t istd,
                         in empty_metadata_t resubmit_meta,
                         in empty_metadata_t recirculate_meta)
{
    state start {
        buffer.extract(hdr.ethernet);
        transition select(hdr.ethernet.etherType) {
            0x0800 &&& 0x0F00 : parse_ipv4;
            16w0x0d00 : parse_tcp;
            default : accept;
        }
    }
    state parse_ipv4 {
        buffer.extract(hdr.ipv4);
        transition select(hdr.ipv4.protocol) {
            8w4 .. 8w7: parse_tcp;
            default: accept;
        }
    }
    state parse_tcp {
        buffer.extract(hdr.tcp);
        transition accept;
    }
}

control ingress(inout headers hdr,
                inout metadata user_meta,
                in    psa_ingress_input_metadata_t  istd,
                inout psa_ingress_output_metadata_t ostd)
{
    action execute(bit<48> x) {
        user_meta.data = 1;
    }
    table tbl {
        key = {
            hdr.ethernet.isValid(): exact;
            hdr.ethernet.dstAddr : exact;
            hdr.ethernet.srcAddr : exact;
            hdr.ipv4.protocol: exact;
            user_meta.key1 : ternary;
            user_meta.key2 : range;
            user_meta.key4: optional;

        }

        actions = { NoAction; execute; }
        const entries = {
            (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w4, 48w10) : execute(48w1);
            (true,48w1,48w2,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w5, 48w10)  : execute(48w1);
            (true,48w3,48w3,Proto.proto1, 48w2&&&48w3, 48w2 .. 48w6, 48w10) : execute(48w1);
            }
    }
    table tbl1 {
        key = {
            hdr.ethernet.isValid(): exact;
            hdr.ethernet.dstAddr : exact;
            hdr.ethernet.srcAddr : exact;
            user_meta.key3: lpm;
        }

        actions = { NoAction; execute; }
        const entries = {
            (true,48w1,48w2, 48w10) : execute(48w1);
            (true,48w1,48w2, 48w11)  : execute(48w1);
            (true,48w3,48w3, 48w12) : execute(48w1);
            }
    }
    apply {
            tbl.apply();
            tbl1.apply();
    }
}

parser EgressParserImpl(packet_in buffer,
                        out headers hdr,
                        inout metadata user_meta,
                        in psa_egress_parser_input_metadata_t istd,
                        in empty_metadata_t normal_meta,
                        in empty_metadata_t clone_i2e_meta,
                        in empty_metadata_t clone_e2e_meta)
{
    state start {
        transition accept;
    }
}

control egress(inout headers hdr,
               inout metadata user_meta,
               in    psa_egress_input_metadata_t  istd,
               inout psa_egress_output_metadata_t ostd)
{
    apply { }
}

control IngressDeparserImpl(packet_out packet,
                            out empty_metadata_t clone_i2e_meta,
                            out empty_metadata_t resubmit_meta,
                            out empty_metadata_t normal_meta,
                            inout headers hdr,
                            in metadata meta,
                            in psa_ingress_output_metadata_t istd)
{
    apply {
        packet.emit(hdr.ethernet);
        packet.emit(hdr.ipv4);
        packet.emit(hdr.tcp);
    }
}

control EgressDeparserImpl(packet_out packet,
                           out empty_metadata_t clone_e2e_meta,
                           out empty_metadata_t recirculate_meta,
                           inout headers hdr,
                           in metadata meta,
                           in psa_egress_output_metadata_t istd,
                           in psa_egress_deparser_input_metadata_t edstd)
{
    apply {
        packet.emit(hdr.ethernet);
        packet.emit(hdr.ipv4);
        packet.emit(hdr.tcp);
    }
}

IngressPipeline(IngressParserImpl(),
                ingress(),
                IngressDeparserImpl()) ip;

EgressPipeline(EgressParserImpl(),
               egress(),
               EgressDeparserImpl()) ep;

PSA_Switch(ip, PacketReplicationEngine(), ep, BufferingQueueingEngine()) main;

[mihaibudiu]

You should file this as a new issue, not as a comment to a merged PR.
I will add this as a test case and make sure it works.