feat: Implement onUnreachableCodePathStart/End

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

@@ -192,15 +192,18 @@ function forwardCurrentToHead(analyzer, node) {
         headSegment = headSegments[i];
 
         if (currentSegment !== headSegment && currentSegment) {
-            debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
 
-            if (currentSegment.reachable) {
-                analyzer.emitter.emit(
-                    "onCodePathSegmentEnd",
-                    currentSegment,
-                    node
-                );
-            }
+            const eventName = currentSegment.reachable
+                ? "onCodePathSegmentEnd"
+                : "onUnreachableCodePathSegmentEnd";
+
+            debug.dump(`${eventName} ${currentSegment.id}`);
+
+            analyzer.emitter.emit(
+                eventName,
+                currentSegment,
+                node
+            );
         }
     }
 
@@ -213,16 +216,19 @@ function forwardCurrentToHead(analyzer, node) {
         headSegment = headSegments[i];
 
         if (currentSegment !== headSegment && headSegment) {
-            debug.dump(`onCodePathSegmentStart ${headSegment.id}`);
+
+            const eventName = headSegment.reachable
+                ? "onCodePathSegmentStart"
+                : "onUnreachableCodePathSegmentStart";
+
+            debug.dump(`${eventName} ${headSegment.id}`);
 
             CodePathSegment.markUsed(headSegment);
-            if (headSegment.reachable) {
-                analyzer.emitter.emit(
-                    "onCodePathSegmentStart",
-                    headSegment,
-                    node
-                );
-            }
+            analyzer.emitter.emit(
+                eventName,
+                headSegment,
+                node
+            );
         }
     }
 
@@ -241,15 +247,17 @@ function leaveFromCurrentSegment(analyzer, node) {
 
     for (let i = 0; i < currentSegments.length; ++i) {
         const currentSegment = currentSegments[i];
+        const eventName = currentSegment.reachable
+            ? "onCodePathSegmentEnd"
+            : "onUnreachableCodePathSegmentEnd";
 
-        debug.dump(`onCodePathSegmentEnd ${currentSegment.id}`);
-        if (currentSegment.reachable) {
-            analyzer.emitter.emit(
-                "onCodePathSegmentEnd",
-                currentSegment,
-                node
-            );
-        }
+        debug.dump(`${eventName} ${currentSegment.id}`);
+
+        analyzer.emitter.emit(
+            eventName,
+            currentSegment,
+            node
+        );
     }
 
     state.currentSegments = [];

lib/linter/linter.js

@@ -898,6 +898,7 @@ const DEPRECATED_SOURCECODE_PASSTHROUGHS = {
     getTokensBetween: "getTokensBetween"
 };
 
+
 const BASE_TRAVERSAL_CONTEXT = Object.freeze(
     Object.keys(DEPRECATED_SOURCECODE_PASSTHROUGHS).reduce(
         (contextInfo, methodName) =>

lib/rules/array-callback-return.js

@@ -18,15 +18,6 @@ const astUtils = require("./utils/ast-utils");
 const TARGET_NODE_TYPE = /^(?:Arrow)?FunctionExpression$/u;
 const TARGET_METHODS = /^(?:every|filter|find(?:Last)?(?:Index)?|flatMap|forEach|map|reduce(?:Right)?|some|sort|toSorted)$/u;
 
-/**
- * Checks a given code path segment is reachable.
- * @param {CodePathSegment} segment A segment to check.
- * @returns {boolean} `true` if the segment is reachable.
- */
-function isReachable(segment) {
-    return segment.reachable;
-}
-
 /**
  * Checks a given node is a member access which has the specified name's
  * property.
@@ -38,6 +29,22 @@ function isTargetMethod(node) {
     return astUtils.isSpecificMemberAccess(node, null, TARGET_METHODS);
 }
 
+/**
+ * Checks all segments in a set and returns true if any are reachable.
+ * @param {Set<CodePathSegment>} segments The segments to check.
+ * @returns {boolean} True if any segment is reachable; false otherwise.
+ */
+function isAnySegmentReachable(segments) {
+
+    for (const segment of segments) {
+        if (segment.reachable) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 /**
  * Returns a human-legible description of an array method
  * @param {string} arrayMethodName A method name to fully qualify
@@ -205,7 +212,7 @@ module.exports = {
                     messageId = "expectedNoReturnValue";
                 }
             } else {
-                if (node.body.type === "BlockStatement" && funcInfo.codePath.currentSegments.some(isReachable)) {
+                if (node.body.type === "BlockStatement" && isAnySegmentReachable(funcInfo.currentSegments)) {
                     messageId = funcInfo.hasReturn ? "expectedAtEnd" : "expectedInside";
                 }
             }
@@ -242,7 +249,8 @@ module.exports = {
                         methodName &&
                         !node.async &&
                         !node.generator,
-                    node
+                    node,
+                    currentSegments: new Set()
                 };
             },
 
@@ -251,6 +259,23 @@ module.exports = {
                 funcInfo = funcInfo.upper;
             },
 
+            onUnreachableCodePathSegmentStart(segment) {
+                funcInfo.currentSegments.add(segment);
+            },
+
+            onUnreachableCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+            onCodePathSegmentStart(segment) {
+                funcInfo.currentSegments.add(segment);
+            },
+
+            onCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+
             // Checks the return statement is valid.
             ReturnStatement(node) {
 

lib/rules/consistent-return.js

@@ -16,12 +16,23 @@ const { upperCaseFirst } = require("../shared/string-utils");
 //------------------------------------------------------------------------------
 
 /**
- * Checks whether or not a given code path segment is unreachable.
- * @param {CodePathSegment} segment A CodePathSegment to check.
- * @returns {boolean} `true` if the segment is unreachable.
+ * Checks all segments in a set and returns true if all are unreachable.
+ * @param {Set<CodePathSegment>} segments The segments to check.
+ * @returns {boolean} True if all segments are unreachable; false otherwise.
  */
-function isUnreachable(segment) {
-    return !segment.reachable;
+function areAllSegmentsUnreachable(segments) {
+
+    if (segments.size === 0) {
+        return false;
+    }
+
+    for (const segment of segments) {
+        if (segment.reachable) {
+            return false;
+        }
+    }
+
+    return true;
 }
 
 /**
@@ -88,7 +99,7 @@ module.exports = {
              * When unreachable, all paths are returned or thrown.
              */
             if (!funcInfo.hasReturnValue ||
-                funcInfo.codePath.currentSegments.every(isUnreachable) ||
+                areAllSegmentsUnreachable(funcInfo.currentSegments) ||
                 astUtils.isES5Constructor(node) ||
                 isClassConstructor(node)
             ) {
@@ -141,13 +152,31 @@ module.exports = {
                     hasReturn: false,
                     hasReturnValue: false,
                     messageId: "",
-                    node
+                    node,
+                    currentSegments: new Set()
                 };
             },
             onCodePathEnd() {
                 funcInfo = funcInfo.upper;
             },
 
+            onUnreachableCodePathSegmentStart(segment) {
+                funcInfo.currentSegments.add(segment);
+            },
+
+            onUnreachableCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+            onCodePathSegmentStart(segment) {
+                funcInfo.currentSegments.add(segment);
+            },
+
+            onCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+
             // Reports a given return statement if it's inconsistent.
             ReturnStatement(node) {
                 const argument = node.argument;

lib/rules/constructor-super.js

@@ -10,12 +10,19 @@
 //------------------------------------------------------------------------------
 
 /**
- * Checks whether a given code path segment is reachable or not.
- * @param {CodePathSegment} segment A code path segment to check.
- * @returns {boolean} `true` if the segment is reachable.
+ * Checks all segments in a set and returns true if any are reachable.
+ * @param {Set<CodePathSegment>} segments The segments to check.
+ * @returns {boolean} True if any segment is reachable; false otherwise.
  */
-function isReachable(segment) {
-    return segment.reachable;
+function isAnySegmentReachable(segments) {
+
+    for (const segment of segments) {
+        if (segment.reachable) {
+            return true;
+        }
+    }
+
+    return false;
 }
 
 /**
@@ -210,15 +217,17 @@ module.exports = {
                         isConstructor: true,
                         hasExtends: Boolean(superClass),
                         superIsConstructor: isPossibleConstructor(superClass),
-                        codePath
+                        codePath,
+                        currentSegments: new Set()
                     };
                 } else {
                     funcInfo = {
                         upper: funcInfo,
                         isConstructor: false,
                         hasExtends: false,
                         superIsConstructor: false,
-                        codePath
+                        codePath,
+                        currentSegments: new Set()
                     };
                 }
             },
@@ -261,6 +270,9 @@ module.exports = {
              * @returns {void}
              */
             onCodePathSegmentStart(segment) {
+
+                funcInfo.currentSegments.add(segment);
+
                 if (!(funcInfo && funcInfo.isConstructor && funcInfo.hasExtends)) {
                     return;
                 }
@@ -281,6 +293,19 @@ module.exports = {
                 }
             },
 
+            onUnreachableCodePathSegmentStart(segment) {
+                funcInfo.currentSegments.add(segment);
+            },
+
+            onUnreachableCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+            onCodePathSegmentEnd(segment) {
+                funcInfo.currentSegments.delete(segment);
+            },
+
+
             /**
              * Update information of the code path segment when a code path was
              * looped.
@@ -344,12 +369,11 @@ module.exports = {
 
                 // Reports if needed.
                 if (funcInfo.hasExtends) {
-                    const segments = funcInfo.codePath.currentSegments;
+                    const segments = funcInfo.currentSegments;
                     let duplicate = false;
                     let info = null;
 
-                    for (let i = 0; i < segments.length; ++i) {
-                        const segment = segments[i];
+                    for (const segment of segments) {
 
                         if (segment.reachable) {
                             info = segInfoMap[segment.id];
@@ -374,7 +398,7 @@ module.exports = {
                             info.validNodes.push(node);
                         }
                     }
-                } else if (funcInfo.codePath.currentSegments.some(isReachable)) {
+                } else if (isAnySegmentReachable(funcInfo.currentSegments)) {
                     context.report({
                         messageId: "unexpected",
                         node
@@ -398,10 +422,9 @@ module.exports = {
                 }
 
                 // Returning argument is a substitute of 'super()'.
-                const segments = funcInfo.codePath.currentSegments;
+                const segments = funcInfo.currentSegments;
 
-                for (let i = 0; i < segments.length; ++i) {
-                    const segment = segments[i];
+                for (const segment of segments) {
 
                     if (segment.reachable) {
                         const info = segInfoMap[segment.id];