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fix: replace undefined with void 0 to avoid edge case #15511

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Merged
merged 5 commits into from
Mar 14, 2025
Merged

fix: replace undefined with void 0 to avoid edge case #15511

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ec2bb95
replace 'undefined' with 'void 0'
Ocean-OS Mar 14, 2025
85f84ca
lint
Ocean-OS Mar 14, 2025
c06b252
YALF
Ocean-OS Mar 14, 2025
e0f1daf
reuse expression
Rich-Harris Mar 14, 2025
05ed17b
oops
Rich-Harris Mar 14, 2025
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5 changes: 5 additions & 0 deletions .changeset/curvy-countries-flow.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'svelte': patch
---

fix: replace `undefined` with `void 0` to avoid edge case
3 changes: 1 addition & 2 deletions packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js
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Expand Up @@ -116,8 +116,7 @@ export function VariableDeclaration(node, context) {
}

const args = /** @type {CallExpression} */ (init).arguments;
const value =
args.length === 0 ? b.id('undefined') : /** @type {Expression} */ (context.visit(args[0]));
const value = args.length > 0 ? /** @type {Expression} */ (context.visit(args[0])) : b.void0;

if (rune === '$state' || rune === '$state.raw') {
/**
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4 changes: 2 additions & 2 deletions packages/svelte/src/compiler/phases/3-transform/server/visitors/CallExpression.js
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Expand Up @@ -13,11 +13,11 @@ export function CallExpression(node, context) {
const rune = get_rune(node, context.state.scope);

if (rune === '$host') {
return b.id('undefined');
return b.void0;
}

if (rune === '$effect.tracking') {
return b.literal(false);
return b.false;
}

if (rune === '$effect.root') {
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5 changes: 2 additions & 3 deletions packages/svelte/src/compiler/phases/3-transform/server/visitors/VariableDeclaration.js
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Expand Up @@ -45,7 +45,7 @@ export function VariableDeclaration(node, context) {
) {
const right = node.right.arguments.length
? /** @type {Expression} */ (context.visit(node.right.arguments[0]))
: b.id('undefined');
: b.void0;
return b.assignment_pattern(node.left, right);
}
}
Expand Down Expand Up @@ -75,8 +75,7 @@ export function VariableDeclaration(node, context) {
}

const args = /** @type {CallExpression} */ (init).arguments;
const value =
args.length === 0 ? b.id('undefined') : /** @type {Expression} */ (context.visit(args[0]));
const value = args.length > 0 ? /** @type {Expression} */ (context.visit(args[0])) : b.void0;

if (rune === '$derived.by') {
declarations.push(
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2 changes: 2 additions & 0 deletions packages/svelte/src/compiler/utils/builders.js
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Expand Up @@ -154,6 +154,8 @@ export function unary(operator, argument) {
return { type: 'UnaryExpression', argument, operator, prefix: true };
}

export const void0 = unary('void', b.literal(0));

/**
* @param {ESTree.Expression} test
* @param {ESTree.Expression} consequent
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