[compiler] Support for context variable loop iterators #31709
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Summary: Fixing a compiler todo [ghstack-poisoned]
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Summary: Fixing a compiler todo ghstack-source-id: c4d9226b1745d003dc9945df1ac5c5a01712f909 Pull Request resolved: #31709
Summary: Fixing a compiler todo [ghstack-poisoned]
| ); | ||
| if (instr.kind === 'let') { | ||
| kind = 'let'; | ||
| let top: undefined | t.VariableDeclarator = undefined; |
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where is top used other than being assigned to?
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Body of the if and the other if conditions
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Yeah but it looks like we're reading in the if condition, modifying in the if consequent, but then not using the value again? I guess a better question is why do we need to assign to top.init in the body? I'm probably forgetting some surrounding context here.
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Oh it's an alias to the last declarator that was pushed to the list of variable declarators. Basically if we have a context iterator, the HIR is a DeclareContext followed by a StoreContext; when we lower that to JS it becomes a variable declarator without an init followed by an assingment to that variable, and here top is a reference to the uninitialized declarator, and we're setting the declarator's init to tbe the RHS of the assignment to knit everything back up.
| top?.id.name === instr.expression.left.name && | ||
| top?.init == null | ||
| ) { | ||
| top.init = instr.expression.right; |
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isn't this mutating the ast?
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Yes, I think that's ok at this stage? The node being mutated hasn't been attached to anything else yet. But can definitely just delete the declarator being mutated and re-create it instead
Summary: Fixing a compiler todo [ghstack-poisoned]
Summary: Fixing a compiler todo ghstack-source-id: c4d9226b1745d003dc9945df1ac5c5a01712f909 Pull Request resolved: #31709
Stack from ghstack (oldest at bottom):
Summary:
Fixing a compiler todo