Incorrect yield and try-finally behaviour

[tomas-c]

Describe the bug

I'm using Next.js with SWC and redux-saga and noticed that updating Next.js from 12.2.1 to 12.3.1 broke redux-saga for me.

Turns out wrapping a yield statement in a try-finally block doesn't behave as it should with SWC.

Input code

(() => {
  function* generator() {
    try {
      while (true) {
        yield "foo";
      }
    } finally {
      yield "bar";
    }
  }

  function test() {
    const gen = generator();
    console.log(gen.next().value);
    console.log(gen.next().value);
    console.log(gen.next().value);
    console.log(gen.next().value);
  }

  test();
})();

Config

Copied from playground defaults:

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": false
    },
    "target": "es5",
    "loose": false,
    "minify": {
      "compress": false,
      "mangle": false
    }
  },
  "module": {
    "type": "es6"
  },
  "minify": false,
  "isModule": true
}

Playground link

https://play.swc.rs/?version=1.3.2&code=H4sIAAAAAAAAA72PwQ2DMAxF70zxxSn0wAIR3SWlhkayYimYtqjK7gQaUSboxbb8v%2B1nYxp0V3wqYJhDr17CBSMFik4lZnFTAI1LqYDXwzPBaJypOZrA4onvqAeR2pZm2nPC4INj%2Fm0o1puLxboZU3VigNKkx%2FVewqQbFbozmz1EYWpZRpPFNtA7T7ZPx5nvr5b9gy%2B4rVKT4wq0x%2FTnXgEAAA%3D%3D&config=H4sIAAAAAAAAA0WNSwrDMAxE76J1ts0id%2BghjKsEF%2F%2FQKBBjfPfawSU7aebpqdIXlrZK2QhYxoQS1Vy0kZbMsOKy0kKKHu3Gg1tfjBysHWG8eudTAs92oeCi28sw2RSyMPBUJh7%2BT7YuCulzjqDez27hSu1xzDuH9wRVTm4%2FOkwQUrUAAAA%3D

Expected behavior

Running the input code from the playground outputs

foo
foo
foo
foo

Actual behavior

Running the output code from the playground outputs

foo
bar
foo
bar

Version

1.3.2

Additional context

No response

[kdy1]

Expected output:

"use strict";

function generator() {
    return __generator(this, function (_a) {
        switch (_a.label) {
            case 0:
                _a.trys.push([0, , 4, 6]);
                _a.label = 1;
            case 1:
                if (!true) return [3 /*break*/, 3];
                return [4 /*yield*/, "foo"];
            case 2:
                _a.sent();
                return [3 /*break*/, 1];
            case 3: return [3 /*break*/, 6];
            case 4: return [4 /*yield*/, "bar"];
            case 5:
                _a.sent();
                return [7 /*endfinally*/];
            case 6: return [2 /*return*/];
        }
    });
}

Output of swc:

function generator() {
    return __generator(this, function(_state) {
        switch(_state.label){
            case 0:
                _state.trys.push([
                    0,
                    ,
                    3,
                    5
                ]);
                if (!true) return [
                    3,
                    2
                ];
                return [
                    4,
                    "foo"
                ];
            case 1:
                _state.sent();
                return [
                    3,
                    0
                ];
            case 2:
                return [
                    3,
                    5
                ];
            case 3:
                return [
                    4,
                    "bar"
                ];
            case 4:
                _state.sent();
                return [
                    7
                ];
            case 5:
                return [
                    2
                ];
        }
    });
}

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.