Update: Code path analysis for class fields (fixes #14343)

docs/developer-guide/code-path-analysis/README.md

@@ -27,6 +27,7 @@ This has references of both the initial segment and the final segments of a code
 `CodePath` has the following properties:
 
 * `id` (`string`) - A unique string. Respective rules can use `id` to save additional information for each code path.
+* `origin` (`string`) - The reason that the code path was started. May be `"program"`, `"function"`, or `"class-field-initializer"`.
 * `initialSegment` (`CodePathSegment`) - The initial segment of this code path.
 * `finalSegments` (`CodePathSegment[]`) - The final segments which includes both returned and thrown.
 * `returnedSegments` (`CodePathSegment[]`) - The final segments which includes only returned.

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

@@ -29,6 +29,18 @@ function isCaseNode(node) {
     return Boolean(node.test);
 }
 
+/**
+ * Checks if a given node appears as the value of a PropertyDefinition node.
+ * @param {ASTNode} node THe node to check.
+ * @returns {boolean} `true` if the node is a PropertyDefinition value,
+ *      false if not.
+ */
+function isPropertyDefinitionValue(node) {
+    const parent = node.parent;
+
+    return parent && parent.type === "PropertyDefinition" && parent.value === node;
+}
+
 /**
  * Checks whether the given logical operator is taken into account for the code
  * path analysis.
@@ -138,6 +150,7 @@ function isIdentifierReference(node) {
             return parent.id !== node;
 
         case "Property":
+        case "PropertyDefinition":
         case "MethodDefinition":
             return (
                 parent.key !== node ||
@@ -388,29 +401,64 @@ function processCodePathToEnter(analyzer, node) {
     let state = codePath && CodePath.getState(codePath);
     const parent = node.parent;
 
+    /**
+     * Creates a new code path and trigger the onCodePathStart event
+     * based on the currently selected node.
+     * @param {string} origin The reason the code path was started.
+     * @returns {void}
+     */
+    function startCodePath(origin) {
+        if (codePath) {
+
+            // Emits onCodePathSegmentStart events if updated.
+            forwardCurrentToHead(analyzer, node);
+            debug.dumpState(node, state, false);
+        }
+
+        // Create the code path of this scope.
+        codePath = analyzer.codePath = new CodePath({
+            id: analyzer.idGenerator.next(),
+            origin,
+            upper: codePath,
+            onLooped: analyzer.onLooped
+        });
+        state = CodePath.getState(codePath);
+
+        // Emits onCodePathStart events.
+        debug.dump(`onCodePathStart ${codePath.id}`);
+        analyzer.emitter.emit("onCodePathStart", codePath, node);
+    }
+
+    /*
+     * Special case: The right side of class field initializer is considered
+     * to be its own function, so we need to start a new code path in this
+     * case.
+     */
+    if (isPropertyDefinitionValue(node)) {
+        startCodePath("class-field-initializer");
+
+        /*
+         * Intentional fall through because `node` needs to also be
+         * processed by the code below. For example, if we have:
+         *
+         * class Foo {
+         *     a = () => {}
+         * }
+         *
+         * In this case, we also need start a second code path.
+         */
+
+    }
+
     switch (node.type) {
         case "Program":
+            startCodePath("program");
+            break;
+
         case "FunctionDeclaration":
         case "FunctionExpression":
         case "ArrowFunctionExpression":
-            if (codePath) {
-
-                // Emits onCodePathSegmentStart events if updated.
-                forwardCurrentToHead(analyzer, node);
-                debug.dumpState(node, state, false);
-            }
-
-            // Create the code path of this scope.
-            codePath = analyzer.codePath = new CodePath(
-                analyzer.idGenerator.next(),
-                codePath,
-                analyzer.onLooped
-            );
-            state = CodePath.getState(codePath);
-
-            // Emits onCodePathStart events.
-            debug.dump(`onCodePathStart ${codePath.id}`);
-            analyzer.emitter.emit("onCodePathStart", codePath, node);
+            startCodePath("function");
             break;
 
         case "ChainExpression":
@@ -503,6 +551,7 @@ function processCodePathToEnter(analyzer, node) {
  * @returns {void}
  */
 function processCodePathToExit(analyzer, node) {
+
     const codePath = analyzer.codePath;
     const state = CodePath.getState(codePath);
     let dontForward = false;
@@ -627,28 +676,38 @@ function processCodePathToExit(analyzer, node) {
  * @returns {void}
  */
 function postprocess(analyzer, node) {
+
+    /**
+     * Ends the code path for the current node.
+     * @returns {void}
+     */
+    function endCodePath() {
+        let codePath = analyzer.codePath;
+
+        // Mark the current path as the final node.
+        CodePath.getState(codePath).makeFinal();
+
+        // Emits onCodePathSegmentEnd event of the current segments.
+        leaveFromCurrentSegment(analyzer, node);
+
+        // Emits onCodePathEnd event of this code path.
+        debug.dump(`onCodePathEnd ${codePath.id}`);
+        analyzer.emitter.emit("onCodePathEnd", codePath, node);
+        debug.dumpDot(codePath);
+
+        codePath = analyzer.codePath = analyzer.codePath.upper;
+        if (codePath) {
+            debug.dumpState(node, CodePath.getState(codePath), true);
+        }
+
+    }
+
     switch (node.type) {
         case "Program":
         case "FunctionDeclaration":
         case "FunctionExpression":
         case "ArrowFunctionExpression": {
-            let codePath = analyzer.codePath;
-
-            // Mark the current path as the final node.
-            CodePath.getState(codePath).makeFinal();
-
-            // Emits onCodePathSegmentEnd event of the current segments.
-            leaveFromCurrentSegment(analyzer, node);
-
-            // Emits onCodePathEnd event of this code path.
-            debug.dump(`onCodePathEnd ${codePath.id}`);
-            analyzer.emitter.emit("onCodePathEnd", codePath, node);
-            debug.dumpDot(codePath);
-
-            codePath = analyzer.codePath = analyzer.codePath.upper;
-            if (codePath) {
-                debug.dumpState(node, CodePath.getState(codePath), true);
-            }
+            endCodePath();
             break;
         }
 
@@ -662,6 +721,27 @@ function postprocess(analyzer, node) {
         default:
             break;
     }
+
+    /*
+     * Special case: The right side of class field initializer is considered
+     * to be its own function, so we need to end a code path in this
+     * case.
+     *
+     * We need to check after the other checks in order to close the
+     * code paths in the correct order for code like this:
+     *
+     *
+     * class Foo {
+     *     a = () => {}
+     * }
+     *
+     * In this case, The ArrowFunctionExpression code path is closed first
+     * and then we need to close the code path for the PropertyDefinition
+     * value.
+     */
+    if (isPropertyDefinitionValue(node)) {
+        endCodePath();
+    }
 }
 
 //------------------------------------------------------------------------------

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

@@ -22,11 +22,14 @@ const IdGenerator = require("./id-generator");
 class CodePath {
 
     /**
-     * @param {string} id An identifier.
-     * @param {CodePath|null} upper The code path of the upper function scope.
-     * @param {Function} onLooped A callback function to notify looping.
+     * Creates a new instance.
+     * @param {Object} options Options for the function (see below).
+     * @param {string} options.id An identifier.
+     * @param {string} options.origin The type of code path origin.
+     * @param {CodePath|null} options.upper The code path of the upper function scope.
+     * @param {Function} options.onLooped A callback function to notify looping.
      */
-    constructor(id, upper, onLooped) {
+    constructor({ id, origin, upper, onLooped }) {
 
         /**
          * The identifier of this code path.
@@ -35,6 +38,13 @@ class CodePath {
          */
         this.id = id;
 
+        /**
+         * The reason that this code path was started. May be "program",
+         * "function", or "class-field-initializer".
+         * @type {string}
+         */
+        this.origin = origin;
+
         /**
          * The code path of the upper function scope.
          * @type {CodePath|null}

tests/fixtures/code-path-analysis/class-fields-init--arrow-function.js

@@ -0,0 +1,37 @@
+/*expected
+initial->s3_1->final;
+*/
+/*expected
+initial->s2_1->final;
+*/
+/*expected
+initial->s1_1->final;
+*/
+
+class Foo { a = () => b }
+
+/*DOT
+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];
+s3_1[label="ArrowFunctionExpression:enter\nIdentifier (b)\nArrowFunctionExpression:exit"];
+initial->s3_1->final;
+}
+
+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];
+    s2_1[label="ArrowFunctionExpression"];
+    initial->s2_1->final;
+}
+
+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\nClassDeclaration:enter\nIdentifier (Foo)\nClassBody:enter\nPropertyDefinition:enter\nIdentifier (a)\nArrowFunctionExpression\nPropertyDefinition:exit\nClassBody:exit\nClassDeclaration:exit\nProgram:exit"];
+    initial->s1_1->final;
+}
+*/

tests/fixtures/code-path-analysis/class-fields-init--call-expression.js

@@ -0,0 +1,26 @@
+/*expected
+initial->s2_1->final;
+*/
+/*expected
+initial->s1_1->final;
+*/
+
+class Foo { a = b() }
+
+/*DOT
+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];
+    s2_1[label="CallExpression:enter\nIdentifier (b)\nCallExpression:exit"];
+    initial->s2_1->final;
+}
+
+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\nClassDeclaration:enter\nIdentifier (Foo)\nClassBody:enter\nPropertyDefinition:enter\nIdentifier (a)\nCallExpression\nPropertyDefinition:exit\nClassBody:exit\nClassDeclaration:exit\nProgram:exit"];
+    initial->s1_1->final;
+}
+*/

tests/fixtures/code-path-analysis/class-fields-init--conditional.js

@@ -0,0 +1,32 @@
+/*expected
+initial->s2_1->s2_2->s2_4;
+s2_1->s2_3->s2_4->final;
+*/
+/*expected
+initial->s1_1->final;
+*/
+
+
+class Foo { a = b ? c : d }
+
+/*DOT
+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];
+    s2_1[label="ConditionalExpression:enter\nIdentifier (b)"];
+    s2_2[label="Identifier (c)"];
+    s2_4[label="ConditionalExpression:exit"];
+    s2_3[label="Identifier (d)"];
+    initial->s2_1->s2_2->s2_4;
+    s2_1->s2_3->s2_4->final;
+}
+
+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\nClassDeclaration:enter\nIdentifier (Foo)\nClassBody:enter\nPropertyDefinition:enter\nIdentifier (a)\nConditionalExpression\nPropertyDefinition:exit\nClassBody:exit\nClassDeclaration:exit\nProgram:exit"];
+    initial->s1_1->final;
+}
+*/

tests/fixtures/code-path-analysis/class-fields-init--simple.js

@@ -0,0 +1,28 @@
+/*expected
+initial->s2_1->final;
+*/
+/*expected
+initial->s1_1->final;
+*/
+
+class Foo {
+    a = b;
+}
+
+/*DOT
+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];
+    s2_1[label="Identifier (b)"];
+    initial->s2_1->final;
+}
+
+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\nClassDeclaration:enter\nIdentifier (Foo)\nClassBody:enter\nPropertyDefinition:enter\nIdentifier (a)\nIdentifier (b)\nPropertyDefinition:exit\nClassBody:exit\nClassDeclaration:exit\nProgram:exit"];
+    initial->s1_1->final;
+}
+*/