Update: treat all literals like boolean literal in no-constant-condition #13245
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| Original file line number | Diff line number | Diff line change |
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@@ -9,9 +9,6 @@ | |
| // Helpers | ||
| //------------------------------------------------------------------------------ | ||
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| //------------------------------------------------------------------------------ | ||
| // Rule Definition | ||
| //------------------------------------------------------------------------------ | ||
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@@ -56,6 +53,39 @@ module.exports = { | |
| // Helpers | ||
| //-------------------------------------------------------------------------- | ||
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| /** | ||
| * checks if a node is truthy | ||
| * @param {ASTNode} node any literal node | ||
| * @returns {boolean} true when node is truthy | ||
| */ | ||
| function isLiteralTruthy(node) { | ||
| if (node.value === null) { | ||
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| /* | ||
| * it might be null literal or a bigint/regex literal but not supported on current environment. | ||
| * https://github.com/estree/estree/blob/14df8a024956ea289bd55b9c2226a1d5b8a473ee/es5.md#regexpliteral | ||
| * https://github.com/estree/estree/blob/14df8a024956ea289bd55b9c2226a1d5b8a473ee/es2020.md#bigintliteral | ||
| */ | ||
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| if (node.raw === "null") { | ||
| return false; | ||
| } | ||
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| // regex is always truthy | ||
| if (typeof node.regex === "object") { | ||
| return true; | ||
| } | ||
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| // https://tc39.es/ecma262/#sec-literals-numeric-literals | ||
| if (typeof node.bigint === "string") { | ||
| return !(/^0+$/u.test(node.bigint) || /^0[box]0+$/ui.test(node.bigint)); | ||
| } | ||
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| throw new Error(`unsupported literal: ${node.raw}`); | ||
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There was a problem hiding this comment. We aim to not intentionally crash on unknown syntax. Can we return Since it will be a 3-state, maybe we could also rename this function to |
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| } | ||
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| return !!node.value; | ||
| } | ||
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| /** | ||
| * Checks if a branch node of LogicalExpression short circuits the whole condition | ||
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@@ -66,15 +96,23 @@ module.exports = { | |
| function isLogicalIdentity(node, operator) { | ||
| switch (node.type) { | ||
| case "Literal": | ||
| return (operator === "||" && isLiteralTruthy(node)) || | ||
| (operator === "&&" && !isLiteralTruthy(node)); | ||
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| case "UnaryExpression": | ||
| return (operator === "&&" && node.operator === "void"); | ||
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| case "LogicalExpression": | ||
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| /* | ||
| * handles `a && false || b` | ||
| * `false` is an identity element of `&&` but not `||` | ||
| */ | ||
| return operator === node.operator && | ||
| ( | ||
| isLogicalIdentity(node.left, node.operator) || | ||
| isLogicalIdentity(node.right, node.operator) | ||
| ); | ||
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| // no default | ||
| } | ||
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@@ -129,21 +167,9 @@ module.exports = { | |
| const isLeftConstant = isConstant(node.left, inBooleanPosition); | ||
| const isRightConstant = isConstant(node.right, inBooleanPosition); | ||
| const isLeftShortCircuit = (isLeftConstant && isLogicalIdentity(node.left, node.operator)); | ||
| const isRightShortCircuit = (inBooleanPosition && isRightConstant && isLogicalIdentity(node.right, node.operator)); | ||
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There was a problem hiding this comment. This is indeed a bug that should be fixed whether or not #13238 gets accepted. Could we maybe also this: (
!node.parent ||
node.parent.type !== "BinaryExpression" ||
!(EQUALITY_OPERATORS.includes(node.parent.operator) || RELATIONAL_OPERATORS.includes(node.parent.operator))
)replace with just I think it might fix similar bugs, such as: /*eslint no-constant-condition: "error"*/
if ((foo || 'bar' || 'bar') === 'bar'); // error, false positiveThough, it seems that the whole condition starting with /*eslint no-constant-condition: "error"*/
if (a && false || b); // error, false positiveThere was a problem hiding this comment. The cause is an inappropriate propagation of short circuit. |
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| return (isLeftConstant && isRightConstant) || | ||
| isLeftShortCircuit || | ||
| isRightShortCircuit; | ||
| } | ||
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This is well-done, but I'd prefer to remove this branch. All Node versions we support now will have the bigint value in
node.value, and we're already using that fact in some rules, likeyoda.In a worst-case scenario (e.g., an old browser, though we don't officially support use of ESLint in browsers) bigint literals will be just ignored, which doesn't look that bad.
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👌 That would simplify implementation a lot.
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Thanks for the very quick response!
Sorry if my post was confusing, I meant to remove only the bigint part.
This was ok:
Regex syntax may have more changes in the future, so we will always use
node.regexin rules.There was a problem hiding this comment.
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🤦♂️ fixed.