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kotlin-fork/compiler/fir/analysis-tests/testData/resolve/smartcasts/stability/overridenOpenVal.dot
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pyos a9be27e330 FIR CFG: add union nodes
Quick quiz:

 Q: In a CFG, what does `a -> b -> c -> d` mean?
 A: `a`, then `b`, then `c`, then `d`.

 Q: In a CFG, what does `a -> b -> d; a -> c -> d` mean?
 A: `a`, then `b` or `c`, then `d`.

 Q: So how do you encode "a, then (b, then c) or (c, then b), then d`?
 A: You can't.

Problem is, you need to, because that's what `a; run2({ b }, { c }); d`
does when `run2` has a contract that it calls both its lambda arguments
in-place: `shuffle(listOf(block1, block2)).forEach { it() }` is a
perfectly valid implementation for it, as little sense as that makes.

So that's what union nodes solve. When a node implements
`UnionNodeMarker`, its inputs are interpreted as "all visited in some
order" instead of the normal "one of the inputs is visited".

Currently this is used for data flow. It *should* also be used for
control flow, but it isn't. But it should be. But that's not so easy.

BTW, `try` exit is NOT a union node; although lambdas in one branch can
be completed according to types' of lambdas in another, data does not
flow between the branches anyway (since we don't know how much of the
`try` executed before jumping into `catch`, and `catch`es are mutually
exclusive) so a `try` expression is more like `when` than a function
call with called-in-place-exactly-once arguments. The fact that
`exitTryExpression` used `processUnionOfArguments` in a weird way
should've hinted at that, but now we know for certain.
2022-12-08 10:19:29 +00:00

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digraph overridenOpenVal_kt {
graph [nodesep=3]
node [shape=box penwidth=2]
edge [penwidth=2]
subgraph cluster_0 {
color=red
0 [label="Enter function <init>" style="filled" fillcolor=red];
1 [label="Delegated constructor call: super<R|kotlin/Any|>()" style="filled" fillcolor=yellow];
2 [label="Exit function <init>" style="filled" fillcolor=red];
}
0 -> {1};
1 -> {2};
subgraph cluster_1 {
color=red
3 [label="Enter property" style="filled" fillcolor=red];
4 [label="Access variable R|<local>/x|"];
5 [label="Exit property" style="filled" fillcolor=red];
}
3 -> {4};
4 -> {5};
5 -> {8} [color=green];
subgraph cluster_2 {
color=red
6 [label="Enter class A" style="filled" fillcolor=red];
7 [label="Part of class initialization"];
8 [label="Exit class A" style="filled" fillcolor=red];
}
6 -> {7} [color=green];
7 -> {8} [style=dotted];
7 -> {3} [color=green];
7 -> {3} [style=dashed];
subgraph cluster_3 {
color=red
9 [label="Enter function <init>" style="filled" fillcolor=red];
10 [label="Access variable R|<local>/x|"];
11 [label="Delegated constructor call: super<R|A|>(...)" style="filled" fillcolor=yellow];
12 [label="Exit function <init>" style="filled" fillcolor=red];
}
9 -> {10};
10 -> {11};
11 -> {12};
subgraph cluster_4 {
color=red
13 [label="Enter function test_1" style="filled" fillcolor=red];
subgraph cluster_5 {
color=blue
14 [label="Enter block"];
subgraph cluster_6 {
color=blue
15 [label="Enter when"];
subgraph cluster_7 {
color=blue
16 [label="Enter when branch condition "];
17 [label="Access variable R|/A.x|"];
18 [label="Type operator: (this@R|/B|.R|/A.x| is R|kotlin/String|)"];
19 [label="Exit when branch condition"];
}
20 [label="Synthetic else branch"];
21 [label="Enter when branch result"];
subgraph cluster_8 {
color=blue
22 [label="Enter block"];
23 [label="Access variable R|/A.x|"];
24 [label="Smart cast: this@R|/B|.R|/A.x|"];
25 [label="Access variable R|kotlin/String.length|"];
26 [label="Exit block"];
}
27 [label="Exit when branch result"];
28 [label="Exit when"];
}
29 [label="Exit block"];
}
30 [label="Exit function test_1" style="filled" fillcolor=red];
}
13 -> {14};
14 -> {15};
15 -> {16};
16 -> {17};
17 -> {18};
18 -> {19};
19 -> {21 20};
20 -> {28};
21 -> {22};
22 -> {23};
23 -> {24};
24 -> {25};
25 -> {26};
26 -> {27};
27 -> {28};
28 -> {29};
29 -> {30};
subgraph cluster_9 {
color=red
31 [label="Enter class B" style="filled" fillcolor=red];
32 [label="Exit class B" style="filled" fillcolor=red];
}
31 -> {32} [color=green];
subgraph cluster_10 {
color=red
33 [label="Enter function test_2" style="filled" fillcolor=red];
subgraph cluster_11 {
color=blue
34 [label="Enter block"];
subgraph cluster_12 {
color=blue
35 [label="Enter when"];
subgraph cluster_13 {
color=blue
36 [label="Enter when branch condition "];
37 [label="Access variable R|<local>/b|"];
38 [label="Access variable R|/A.x|"];
39 [label="Type operator: (R|<local>/b|.R|/A.x| is R|kotlin/String|)"];
40 [label="Exit when branch condition"];
}
41 [label="Synthetic else branch"];
42 [label="Enter when branch result"];
subgraph cluster_14 {
color=blue
43 [label="Enter block"];
44 [label="Access variable R|<local>/b|"];
45 [label="Access variable R|/A.x|"];
46 [label="Smart cast: R|<local>/b|.R|/A.x|"];
47 [label="Access variable R|kotlin/String.length|"];
48 [label="Exit block"];
}
49 [label="Exit when branch result"];
50 [label="Exit when"];
}
51 [label="Exit block"];
}
52 [label="Exit function test_2" style="filled" fillcolor=red];
}
33 -> {34};
34 -> {35};
35 -> {36};
36 -> {37};
37 -> {38};
38 -> {39};
39 -> {40};
40 -> {42 41};
41 -> {50};
42 -> {43};
43 -> {44};
44 -> {45};
45 -> {46};
46 -> {47};
47 -> {48};
48 -> {49};
49 -> {50};
50 -> {51};
51 -> {52};
}