`p4c` should prohibit different controllable entities having the same control-plane name about p4c HOT 3 OPEN

@kfcripps This behavior has existed in p4c for quite some time. I will send links to some other p4c issues that I am aware of from years back with some discussion on the topic, but if I am recalling correctly, the reason that p4c internally takes one action and makes multiple copies of it, one for each table it is used within, has its motivation in allowing each of those copies to be optimized independently of each other, based upon the context in which the table invoking it is applied.

Here is the oldest issue I could find with the most discussion on it:

• #1949

Here are some later issues, where either other people rediscovered this, or a similar thing, or in some case I probably forgot about the old one and filed another. As one of my comments in the first issue linked below says, I would love it if we could get all the stakeholders involved into a discussion with the goal of coming up with an answer to this.

• #3228
• #2755
• #2716

There is also a PR that started with one potential change, and I believe the discussion on it led to a proposal for a different approach, one which would be a small p4c change, but I haven't thought about the details in a while to have a good evaluation of either of those proposed changes at this moment:

• #3228

from p4c.

Similarly, the following P4 program:

header h_t {
    bit<8> f;
}

control C() {
    action bar() {
    }

    table t {
        actions = { bar; }
        default_action = bar;
    }

    table t2 {
        actions = { bar; }
        default_action = bar;
    }

    apply {
        t.apply();
        t2.apply();
    }
}

control proto();
package top(proto p);

top(C()) main;

gets transformed into:

header h_t {
    bit<8> f;
}

control C() {
    @name("C.bar") action bar() {
    }
    @name("C.bar") action bar_1() {
    }
    @name("C.t") table t_0 {
        actions = {
            bar();
        }
        default_action = bar();
    }
    @name("C.t2") table t2_0 {
        actions = {
            bar_1();
        }
        default_action = bar_1();
    }
    apply {
        t_0.apply();
        t2_0.apply();
    }
}

control proto();
package top(proto p);
top(C()) main;

so we end up with two actions defined in the same scope that have the same local name (C.bar). Is this a bug per the spec?

from p4c.

@jphurl @oleg-ran-amd @rsmith-pensando

from p4c.