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fix: no-invalid-this false positive in class field initializer (#15495)
* fix: no-invalid-this false positive in class field initializer Fixes #15477 * fix jsdoc
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‎lib/rules/no-invalid-this.js

Lines changed: 50 additions & 53 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,21 @@
1111

1212
const astUtils = require("./utils/ast-utils");
1313

14+
//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
17+
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/**
19+
* Determines if the given code path is a code path with lexical `this` binding.
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* That is, if `this` within the code path refers to `this` of surrounding code path.
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* @param {CodePath} codePath Code path.
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* @param {ASTNode} node Node that started the code path.
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* @returns {boolean} `true` if it is a code path with lexical `this` binding.
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*/
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function isCodePathWithLexicalThis(codePath, node) {
26+
return codePath.origin === "function" && node.type === "ArrowFunctionExpression";
27+
}
28+
1429
//------------------------------------------------------------------------------
1530
// Rule Definition
1631
//------------------------------------------------------------------------------
@@ -72,71 +87,53 @@ module.exports = {
7287
return current;
7388
};
7489

75-
/**
76-
* Pushs new checking context into the stack.
77-
*
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* The checking context is not initialized yet.
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* Because most functions don't have `this` keyword.
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* When `this` keyword was found, the checking context is initialized.
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* @param {ASTNode} node A function node that was entered.
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* @returns {void}
83-
*/
84-
function enterFunction(node) {
85-
86-
// `this` can be invalid only under strict mode.
87-
stack.push({
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init: !context.getScope().isStrict,
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node,
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valid: true
91-
});
92-
}
90+
return {
9391

94-
/**
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* Pops the current checking context from the stack.
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* @returns {void}
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*/
98-
function exitFunction() {
99-
stack.pop();
100-
}
92+
onCodePathStart(codePath, node) {
93+
if (isCodePathWithLexicalThis(codePath, node)) {
94+
return;
95+
}
10196

102-
return {
97+
if (codePath.origin === "program") {
98+
const scope = context.getScope();
99+
const features = context.parserOptions.ecmaFeatures || {};
100+
101+
stack.push({
102+
init: true,
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node,
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valid: !(
105+
scope.isStrict ||
106+
node.sourceType === "module" ||
107+
(features.globalReturn && scope.childScopes[0].isStrict)
108+
)
109+
});
103110

104-
/*
105-
* `this` is invalid only under strict mode.
106-
* Modules is always strict mode.
107-
*/
108-
Program(node) {
109-
const scope = context.getScope(),
110-
features = context.parserOptions.ecmaFeatures || {};
111+
return;
112+
}
111113

114+
/*
115+
* `init: false` means that `valid` isn't determined yet.
116+
* Most functions don't use `this`, and the calculation for `valid`
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* is relatively costly, so we'll calculate it lazily when the first
118+
* `this` within the function is traversed. A special case are non-strict
119+
* functions, because `this` refers to the global object and therefore is
120+
* always valid, so we can set `init: true` right away.
121+
*/
112122
stack.push({
113-
init: true,
123+
init: !context.getScope().isStrict,
114124
node,
115-
valid: !(
116-
scope.isStrict ||
117-
node.sourceType === "module" ||
118-
(features.globalReturn && scope.childScopes[0].isStrict)
119-
)
125+
valid: true
120126
});
121127
},
122128

123-
"Program:exit"() {
129+
onCodePathEnd(codePath, node) {
130+
if (isCodePathWithLexicalThis(codePath, node)) {
131+
return;
132+
}
133+
124134
stack.pop();
125135
},
126136

127-
FunctionDeclaration: enterFunction,
128-
"FunctionDeclaration:exit": exitFunction,
129-
FunctionExpression: enterFunction,
130-
"FunctionExpression:exit": exitFunction,
131-
132-
// Field initializers are implicit functions.
133-
"PropertyDefinition > *.value": enterFunction,
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"PropertyDefinition > *.value:exit": exitFunction,
135-
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// Class static blocks are implicit functions.
137-
StaticBlock: enterFunction,
138-
"StaticBlock:exit": exitFunction,
139-
140137
// Reports if `this` of the current context is invalid.
141138
ThisExpression(node) {
142139
const current = stack.getCurrent();

‎tests/lib/rules/no-invalid-this.js

Lines changed: 42 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -119,6 +119,15 @@ const patterns = [
119119
valid: [NORMAL],
120120
invalid: [USE_STRICT, IMPLIED_STRICT, MODULES]
121121
},
122+
{
123+
code: "() => { this }; this;",
124+
parserOptions: {
125+
ecmaVersion: 6
126+
},
127+
errors,
128+
valid: [NORMAL],
129+
invalid: [USE_STRICT, IMPLIED_STRICT, MODULES]
130+
},
122131

123132
// IIFE.
124133
{
@@ -745,6 +754,18 @@ const patterns = [
745754
},
746755

747756
// Class fields.
757+
{
758+
code: "class C { field = this }",
759+
parserOptions: { ecmaVersion: 2022 },
760+
valid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
761+
invalid: []
762+
},
763+
{
764+
code: "class C { static field = this }",
765+
parserOptions: { ecmaVersion: 2022 },
766+
valid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
767+
invalid: []
768+
},
748769
{
749770
code: "class C { field = console.log(this); }",
750771
parserOptions: { ecmaVersion: 2022 },
@@ -776,6 +797,20 @@ const patterns = [
776797
invalid: [USE_STRICT, IMPLIED_STRICT, MODULES],
777798
errors: [{ messageId: "unexpectedThis", type: "ThisExpression" }]
778799
},
800+
{
801+
code: "class C { foo = () => this; }",
802+
parserOptions: { ecmaVersion: 2022 },
803+
valid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
804+
invalid: [],
805+
errors: [{ messageId: "unexpectedThis", type: "ThisExpression" }]
806+
},
807+
{
808+
code: "class C { foo = () => { this }; }",
809+
parserOptions: { ecmaVersion: 2022 },
810+
valid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
811+
invalid: [],
812+
errors: [{ messageId: "unexpectedThis", type: "ThisExpression" }]
813+
},
779814

780815
// Class static blocks
781816
{
@@ -817,6 +852,13 @@ const patterns = [
817852
invalid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
818853
errors: [{ messageId: "unexpectedThis", type: "ThisExpression" }]
819854
},
855+
{
856+
code: "class C { static {} [this]; }",
857+
parserOptions: { ecmaVersion: 2022 },
858+
valid: [NORMAL],
859+
invalid: [USE_STRICT, IMPLIED_STRICT, MODULES],
860+
errors: [{ messageId: "unexpectedThis", type: "ThisExpression" }]
861+
},
820862
{
821863
code: "class C { static {} [this.x]; }",
822864
parserOptions: { ecmaVersion: 2022 },

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