feat: fix false negatives in no-this-before-super (#17762)

* fix: false negatives in `no-this-before-super`

* chore: move comment

* fix: traverseSegments controller.skip

* chore: format

* chore: add a little early judgment

* fix: remove skipped.has(segment)

* fix: remove unnecessary code

* fix: wrong traverse

* fix: rename variable

Author: ota-meshi

lib/linter/code-path-analysis/code-path.js

@@ -177,8 +177,8 @@ class CodePath {
         // tracks the traversal steps
         const stack = [[startSegment, 0]];
 
-        // tracks the last skipped segment during traversal
-        let skippedSegment = null;
+        // segments that have been skipped during traversal
+        const skipped = new Set();
 
         // indicates if we exited early from the traversal
         let broken = false;
@@ -193,11 +193,7 @@ class CodePath {
              * @returns {void}
              */
             skip() {
-                if (stack.length <= 1) {
-                    broken = true;
-                } else {
-                    skippedSegment = stack.at(-2)[0];
-                }
+                skipped.add(segment);
             },
 
             /**
@@ -222,6 +218,18 @@ class CodePath {
             );
         }
 
+        /**
+         * Checks if a given previous segment has been skipped.
+         * @param {CodePathSegment} prevSegment A previous segment to check.
+         * @returns {boolean} `true` if the segment has been skipped.
+         */
+        function isSkipped(prevSegment) {
+            return (
+                skipped.has(prevSegment) ||
+                segment.isLoopedPrevSegment(prevSegment)
+            );
+        }
+
         // the traversal
         while (stack.length > 0) {
 
@@ -258,17 +266,21 @@ class CodePath {
                     continue;
                 }
 
-                // Reset the skipping flag if all branches have been skipped.
-                if (skippedSegment && segment.prevSegments.includes(skippedSegment)) {
-                    skippedSegment = null;
-                }
                 visited.add(segment);
 
+
+                // Skips the segment if all previous segments have been skipped.
+                const shouldSkip = (
+                    skipped.size > 0 &&
+                    segment.prevSegments.length > 0 &&
+                    segment.prevSegments.every(isSkipped)
+                );
+
                 /*
                  * If the most recent segment hasn't been skipped, then we call
                  * the callback, passing in the segment and the controller.
                  */
-                if (!skippedSegment) {
+                if (!shouldSkip) {
                     resolvedCallback.call(this, segment, controller);
 
                     // exit if we're at the last segment
@@ -284,6 +296,10 @@ class CodePath {
                     if (broken) {
                         break;
                     }
+                } else {
+
+                    // If the most recent segment has been skipped, then mark it as skipped.
+                    skipped.add(segment);
                 }
             }
 

lib/rules/no-this-before-super.js

@@ -197,11 +197,26 @@ module.exports = {
                     return;
                 }
 
+                /**
+                 * A collection of nodes to avoid duplicate reports.
+                 * @type {Set<ASTNode>}
+                 */
+                const reported = new Set();
+
                 codePath.traverseSegments((segment, controller) => {
                     const info = segInfoMap[segment.id];
+                    const invalidNodes = info.invalidNodes
+                        .filter(
+
+                            /*
+                             * Avoid duplicate reports.
+                             * When there is a `finally`, invalidNodes may contain already reported node.
+                             */
+                            node => !reported.has(node)
+                        );
 
-                    for (let i = 0; i < info.invalidNodes.length; ++i) {
-                        const invalidNode = info.invalidNodes[i];
+                    for (const invalidNode of invalidNodes) {
+                        reported.add(invalidNode);
 
                         context.report({
                             messageId: "noBeforeSuper",
@@ -273,14 +288,12 @@ module.exports = {
                         const info = segInfoMap[segment.id];
 
                         if (info.superCalled) {
-                            info.invalidNodes = [];
                             controller.skip();
                         } else if (
                             segment.prevSegments.length > 0 &&
                             segment.prevSegments.every(isCalled)
                         ) {
                             info.superCalled = true;
-                            info.invalidNodes = [];
                         }
                     }
                 );

tests/lib/linter/code-path-analysis/code-path.js

@@ -356,6 +356,58 @@ describe("CodePathAnalyzer", () => {
             */
         });
 
+        it("should not skip the next branch when 'controller.skip()' was called.", () => {
+            const codePath = parseCodePaths("if (a) { if (b) { foo(); } bar(); } out1();")[0];
+            const order = getOrderOfTraversing(codePath, null, (segment, controller) => {
+                if (segment.id === "s1_4") {
+                    controller.skip(); // Since s1_5 is connected from s1_1, we expect it not to be skipped.
+                }
+            });
+
+            assert.deepStrictEqual(order, ["s1_1", "s1_2", "s1_3", "s1_4", "s1_5"]);
+
+            /*
+            digraph {
+                node[shape=box,style="rounded,filled",fillcolor=white];
+                initial[label="",shape=circle,style=filled,fillcolor=black,width=0.25,height=0.25];
+                final[label="",shape=doublecircle,style=filled,fillcolor=black,width=0.25,height=0.25];
+                s1_1[label="Program:enter\nIfStatement:enter\nIdentifier (a)"];
+                s1_2[label="BlockStatement:enter\nIfStatement:enter\nIdentifier (b)"];
+                s1_3[label="BlockStatement:enter\nExpressionStatement:enter\nCallExpression:enter\nIdentifier (foo)\nCallExpression:exit\nExpressionStatement:exit\nBlockStatement:exit"];
+                s1_4[label="IfStatement:exit\nExpressionStatement:enter\nCallExpression:enter\nIdentifier (bar)\nCallExpression:exit\nExpressionStatement:exit\nBlockStatement:exit"];
+                s1_5[label="IfStatement:exit\nExpressionStatement:enter\nCallExpression:enter\nIdentifier (out1)\nCallExpression:exit\nExpressionStatement:exit\nProgram:exit"];
+                initial->s1_1->s1_2->s1_3->s1_4->s1_5;
+                s1_1->s1_5;
+                s1_2->s1_4;
+                s1_5->final;
+            }
+            */
+        });
+
+        it("should skip the next branch when 'controller.skip()' was called at top segment.", () => {
+            const codePath = parseCodePaths("a; while (b) { c; }")[0];
+
+            const order = getOrderOfTraversing(codePath, null, (segment, controller) => {
+                if (segment.id === "s1_1") {
+                    controller.skip();
+                }
+            });
+
+            assert.deepStrictEqual(order, ["s1_1"]);
+
+            /*
+            digraph {
+                node[shape=box,style="rounded,filled",fillcolor=white];
+                initial[label="",shape=circle,style=filled,fillcolor=black,width=0.25,height=0.25];
+                final[label="",shape=doublecircle,style=filled,fillcolor=black,width=0.25,height=0.25];
+                s1_1[label="Program:enter\nExpressionStatement:enter\nIdentifier (a)\nExpressionStatement:exit\nWhileStatement:enter"];
+                s1_2[label="Identifier (b)"];
+                s1_3[label="BlockStatement:enter\nExpressionStatement:enter\nIdentifier (c)\nExpressionStatement:exit\nBlockStatement:exit"];
+                s1_4[label="WhileStatement:exit\nProgram:exit"];
+                initial->s1_1->s1_2->s1_3->s1_2->s1_4->final;
+            }
+            */
+        });
         /* eslint-enable internal-rules/multiline-comment-style -- Commenting out */
     });
 });

tests/lib/rules/no-this-before-super.js

@@ -60,6 +60,24 @@ ruleTester.run("no-this-before-super", rule, {
         "class A extends B { constructor() { if (a) { super(); this.a(); } else { super(); this.b(); } } }",
         "class A extends B { constructor() { if (a) super(); else super(); this.a(); } }",
         "class A extends B { constructor() { try { super(); } finally {} this.a(); } }",
+        `class A extends B {
+            constructor() {
+                while (foo) {
+                    super();
+                    this.a();
+                }
+            }
+        }`,
+        `class A extends B {
+            constructor() {
+                while (foo) {
+                    if (init) {
+                        super();
+                        this.a();
+                    }
+                }
+            }
+        }`,
 
         // https://github.com/eslint/eslint/issues/5261
         "class A extends B { constructor(a) { super(); for (const b of a) { this.a(); } } }",
@@ -186,6 +204,83 @@ ruleTester.run("no-this-before-super", rule, {
             code: "class A extends B { constructor() { foo ??= super().a; this.c(); } }",
             languageOptions: { ecmaVersion: 2021 },
             errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    if (foo) {
+                        if (bar) { }
+                        super();
+                    }
+                    this.a();
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    if (foo) {
+                    } else {
+                      super();
+                    }
+                    this.a();
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    try {
+                        call();
+                    } finally {
+                        this.a();
+                    }
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    while (foo) {
+                        super();
+                    }
+                    this.a();
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    while (foo) {
+                        this.a();
+                        super();
+                    }
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
+        },
+        {
+            code: `
+            class A extends B {
+                constructor() {
+                    while (foo) {
+                        if (init) {
+                            this.a();
+                            super();
+                        }
+                    }
+                }
+            }`,
+            errors: [{ messageId: "noBeforeSuper", data: { kind: "this" }, type: "ThisExpression" }]
         }
     ]
 });