OS#14115684: Function-in-block semantics don't work for defer parse #4673
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In below code repro, we do not create var decl binding for `foo` inside the `nest` function in defer-parse mode. Due to this, we leave the reference to `foo` in `nest` on the pid ref stack and bind it to the formal `foo` parameter from the `test` function. This leads us to think formal `foo` is captured and try to put it into a scope slot. However, formal `foo` is not actually captured so no scope slot is allocated. When we actually generate bytecode for `test`, we hit a fail fast.
```js
function test(foo) {
function nest() {
{
function foo() {
console.log('pass');
}
}
foo();
}
nest();
}
test(()=>console.log('fail'));
```
Fix is to create the var binding for `foo` at the function declaration for `foo` even in defer-parse mode.
Fixes:
https://microsoft.visualstudio.com/web/wi.aspx?id=14115684
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@dotnet-bot test OSX static_osx_osx_debug please |
pleath
approved these changes
Feb 13, 2018
|
Thanks, Paul. |
chakrabot
pushed a commit
that referenced
this pull request
Feb 13, 2018
…'t work for defer parse Merge pull request #4673 from boingoing:DeferFunctionInBlock In below code repro, we do not create var decl binding for `foo` inside the `nest` function in defer-parse mode. Due to this, we leave the reference to `foo` in `nest` on the pid ref stack and bind it to the formal `foo` parameter from the `test` function. This leads us to think formal `foo` is captured and try to put it into a scope slot. However, formal `foo` is not actually captured so no scope slot is allocated. When we actually generate bytecode for `test`, we hit a fail fast. ```js function test(foo) { function nest() { { function foo() { console.log('pass'); } } foo(); } nest(); } test(()=>console.log('fail')); ``` Fix is to create the var binding for `foo` at the function declaration for `foo` even in defer-parse mode. Fixes: https://microsoft.visualstudio.com/web/wi.aspx?id=14115684
chakrabot
pushed a commit
that referenced
this pull request
Feb 13, 2018
…antics don't work for defer parse Merge pull request #4673 from boingoing:DeferFunctionInBlock In below code repro, we do not create var decl binding for `foo` inside the `nest` function in defer-parse mode. Due to this, we leave the reference to `foo` in `nest` on the pid ref stack and bind it to the formal `foo` parameter from the `test` function. This leads us to think formal `foo` is captured and try to put it into a scope slot. However, formal `foo` is not actually captured so no scope slot is allocated. When we actually generate bytecode for `test`, we hit a fail fast. ```js function test(foo) { function nest() { { function foo() { console.log('pass'); } } foo(); } nest(); } test(()=>console.log('fail')); ``` Fix is to create the var binding for `foo` at the function declaration for `foo` even in defer-parse mode. Fixes: https://microsoft.visualstudio.com/web/wi.aspx?id=14115684
chakrabot
pushed a commit
that referenced
this pull request
Feb 13, 2018
…-in-block semantics don't work for defer parse Merge pull request #4673 from boingoing:DeferFunctionInBlock In below code repro, we do not create var decl binding for `foo` inside the `nest` function in defer-parse mode. Due to this, we leave the reference to `foo` in `nest` on the pid ref stack and bind it to the formal `foo` parameter from the `test` function. This leads us to think formal `foo` is captured and try to put it into a scope slot. However, formal `foo` is not actually captured so no scope slot is allocated. When we actually generate bytecode for `test`, we hit a fail fast. ```js function test(foo) { function nest() { { function foo() { console.log('pass'); } } foo(); } nest(); } test(()=>console.log('fail')); ``` Fix is to create the var binding for `foo` at the function declaration for `foo` even in defer-parse mode. Fixes: https://microsoft.visualstudio.com/web/wi.aspx?id=14115684
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In below code repro, we do not create var decl binding for
fooinside thenestfunction in defer-parse mode. Due to this, we leave the reference tofooinneston the pid ref stack and bind it to the formalfooparameter from thetestfunction. This leads us to think formalfoois captured and try to put it into a scope slot. However, formalfoois not actually captured so no scope slot is allocated. When we actually generate bytecode fortest, we hit a fail fast.Fix is to create the var binding for
fooat the function declaration forfooeven in defer-parse mode.Fixes:
https://microsoft.visualstudio.com/web/wi.aspx?id=14115684