Extend -Z print-type-sizes to distinguish generator upvars+locals from "normal" fields.

[pnkfelix]

For example, for this code:

async fn wait() {}

async fn test(arg: [u8; 8192]) {
    wait().await;
    drop(arg);
}

async fn test_ideal(_rg: [u8; 8192]) {
    wait().await;
    // drop(arg);
}

fn main() {
    let gen_t = test([0; 8192]);
    let gen_i = test_ideal([0; 8192]);
    println!("expect {}, got: {}",
             std::mem::size_of_val(&gen_i),
             std::mem::size_of_val(&gen_t));
}

the -Z print-type-sizes output used to start with:

print-type-size type: `[async fn [email protected]:3:32: 6:2]`: 16386 bytes, alignment: 1 bytes
print-type-size     discriminant: 1 bytes
print-type-size     variant `Suspend0`: 16385 bytes
print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size         field `.arg`: 8192 bytes
print-type-size         field `.__awaitee`: 1 bytes
...
print-type-size type: `std::mem::ManuallyDrop<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
print-type-size     field `.value`: 8192 bytes
...

but with this change, it now instead prints:

print-type-size type: `[async fn [email protected]:3:32: 6:2]`: 16386 bytes, alignment: 1 bytes
print-type-size     discriminant: 1 bytes
print-type-size     variant `Suspend0`: 16385 bytes
print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size         local `.arg`: 8192 bytes
print-type-size         local `.__awaitee`: 1 bytes
...
print-type-size type: `std::mem::ManuallyDrop<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
print-type-size     field `.value`: 8192 bytes

(spawned off of investigation of #62958 )

[rustbot]

r? @michaelwoerister

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[compiler-errors]

r=me once CI is happy

[pnkfelix]

@bors r=compiler-errors rollup=true

[bors]

📌 Commit 362c4fa has been approved by compiler-errors

It is now in the queue for this repository.

[compiler-errors]

@bors rollup=always