Fix arrow function body parsing #117
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We add three failing tests:
1. {()=>{};``}
2. {x=>x;``}
3. {f:x=>x,y:2}
We also add a fourth test mirroring the third but with a function block
body instead of an expression. The hope is that we get no regressions
when we change the representation of arrow functions.
The issue with the current parsing rules and representation is that arrow function bodies are not statements, they're either function blocks or expressions. Looking at the specification (https://www.ecma-international.org/ecma-262/#prod-ExpressionBody) we see that the expressions are `AssignmentExpression` in particular. Making this change appears to fix the additional tests, but it breaks minification.
The minifier was treating arrow functions with block bodies incorrectly
if they contained a single expression statement with no return
statement. It was transforming them into arrow functions with expression
bodies.
This means for instance that in
```js
let x = (() => { 42 })();
```
`x` would equal `undefined` before minification, but would equal `42`
after minification. The fix is to change the tests to match the correct
behavior.
|
Thanks for the fix, @gabejohnson, I'm encountering the same error. @erikd are there any issues with this being merged? |
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Fixes #116
The issue with the current parsing rules and representation is that arrow function bodies are not statements, they're either function blocks or expressions. Looking at the specification we see that the expressions are
AssignmentExpressionin particular.Making this change fixes the issues mentioned in #116, but breaks minification tests. This turns out not to be a problem, as minification for the cases covered by the failing tests resulted in behavior inconsistent with the non-minified version: