New: Add resolveRelativeToConfigFile setting to enable modern module …

…resolution (fixes #3458)

conf/config-schema.js

@@ -22,6 +22,7 @@ const baseConfigProperties = {
     settings: { type: "object" },
     noInlineConfig: { type: "boolean" },
     reportUnusedDisableDirectives: { type: "boolean" },
+    resolveRelativeToConfigFile: { type: "boolean" },
 
     ecmaFeatures: { type: "object" } // deprecated; logs a warning when used
 };

lib/cli-engine/config-array-factory.js

@@ -346,7 +346,12 @@ class ConfigArrayFactory {
         cwd = process.cwd(),
         resolvePluginsRelativeTo = cwd
     } = {}) {
-        internalSlotsMap.set(this, { additionalPluginPool, cwd, resolvePluginsRelativeTo: path.resolve(cwd, resolvePluginsRelativeTo) });
+        internalSlotsMap.set(this, {
+            additionalPluginPool,
+            cwd,
+            resolvePluginsRelativeTo: path.resolve(cwd, resolvePluginsRelativeTo),
+            resolveRelativeToConfigFile: false
+        });
     }
 
     /**
@@ -532,6 +537,7 @@ class ConfigArrayFactory {
             plugins: pluginList,
             processor,
             reportUnusedDisableDirectives,
+            resolveRelativeToConfigFile,
             root,
             rules,
             settings,
@@ -540,6 +546,23 @@ class ConfigArrayFactory {
         filePath,
         name
     ) {
+        if (resolveRelativeToConfigFile) {
+            const internalSlot = internalSlotsMap.get(this);
+
+            /*
+             * If we encounter a config file with resolveRelativeToConfigFile=true, then we enable that behavior
+             * permanently for all subsequent config files.  This approach is needed because ESLint normally waits
+             * to calculate config options until after everything is loaded, wheres plugins get loaded right away.
+             * This design isn't ideal, but it works in practice because "resolveRelativeToConfigFile" has a
+             * relatively simple use case:  It opts-in to the modern module resolution behavior that eventually
+             * should be the default for ESLint.
+             */
+            if (!internalSlot.resolveRelativeToConfigFile) {
+                debug("Plugins will be resolved using the resolveRelativeToConfigFile behavior");
+                internalSlot.resolveRelativeToConfigFile = true;
+            }
+        }
+
         const extendList = Array.isArray(extend) ? extend : [extend];
 
         // Flatten `extends`.
@@ -842,7 +865,13 @@ class ConfigArrayFactory {
         let error;
 
         try {
-            filePath = ModuleResolver.resolve(request, relativeTo);
+            const { resolveRelativeToConfigFile } = internalSlotsMap.get(this);
+
+            if (resolveRelativeToConfigFile) {
+                filePath = ModuleResolver.resolve(request, importerPath);
+            } else {
+                filePath = ModuleResolver.resolve(request, relativeTo);
+            }
         } catch (resolveError) {
             error = resolveError;
             /* istanbul ignore else */

lib/cli-engine/config-array/config-array.js

@@ -60,6 +60,7 @@ const { ExtractedConfig } = require("./extracted-config");
  * @property {Record<string, DependentPlugin>|undefined} plugins The plugin loaders.
  * @property {string|undefined} processor The processor name to refer plugin's processor.
  * @property {boolean|undefined} reportUnusedDisableDirectives The flag to report unused `eslint-disable` comments.
+ * @property {boolean|undefined} resolveRelativeToConfigFile When set to `true`, plugins are resolved relative to the config file that imports them.
  * @property {boolean|undefined} root The flag to express root.
  * @property {Record<string, RuleConf>|undefined} rules The rule settings
  * @property {Object|undefined} settings The shared settings.
@@ -260,6 +261,11 @@ function createConfig(instance, indices) {
             config.reportUnusedDisableDirectives = element.reportUnusedDisableDirectives;
         }
 
+        // Adopt the resolveRelativeToConfigFile which was found at first.
+        if (config.resolveRelativeToConfigFile === void 0 && element.resolveRelativeToConfigFile !== void 0) {
+            config.resolveRelativeToConfigFile = element.resolveRelativeToConfigFile;
+        }
+
         // Merge others.
         mergeWithoutOverwrite(config.env, element.env);
         mergeWithoutOverwrite(config.globals, element.globals);

lib/cli-engine/config-array/extracted-config.js

@@ -83,6 +83,12 @@ class ExtractedConfig {
          */
         this.reportUnusedDisableDirectives = void 0;
 
+        /**
+         * When set to `true`, plugins are resolved relative to the config file that imports them.
+         * @type {boolean|undefined}
+         */
+        this.resolveRelativeToConfigFile = void 0;
+
         /**
          * Rule settings.
          * @type {Record<string, [SeverityConf, ...any[]]>}

lib/shared/types.js

@@ -37,6 +37,7 @@ module.exports = {};
  * @property {string[]} [plugins] The plugin specifiers.
  * @property {string} [processor] The processor specifier.
  * @property {boolean|undefined} reportUnusedDisableDirectives The flag to report unused `eslint-disable` comments.
+ * @property {boolean|undefined} resolveRelativeToConfigFile When set to `true`, plugins are resolved relative to the config file that imports them.
  * @property {boolean} [root] The root flag.
  * @property {Record<string, RuleConf>} [rules] The rule settings.
  * @property {Object} [settings] The shared settings.
@@ -56,6 +57,7 @@ module.exports = {};
  * @property {string[]} [plugins] The plugin specifiers.
  * @property {string} [processor] The processor specifier.
  * @property {boolean|undefined} reportUnusedDisableDirectives The flag to report unused `eslint-disable` comments.
+ * @property {boolean|undefined} resolveRelativeToConfigFile When set to `true`, plugins are resolved relative to the config file that imports them.
  * @property {Record<string, RuleConf>} [rules] The rule settings.
  * @property {Object} [settings] The shared settings.
  */

tests/lib/cli-engine/config-array-factory.js

@@ -60,6 +60,7 @@ function assertConfig(actual, providedExpected) {
         parserOptions: {},
         plugins: [],
         reportUnusedDisableDirectives: void 0,
+        resolveRelativeToConfigFile: void 0,
         rules: {},
         settings: {},
         ...providedExpected

tests/lib/cli-engine/config-array/config-array.js

@@ -435,6 +435,7 @@ describe("ConfigArray", () => {
                 },
                 plugins: {},
                 processor: null,
+                resolveRelativeToConfigFile: void 0,
                 reportUnusedDisableDirectives: void 0,
                 rules: {},
                 settings: {}
@@ -466,6 +467,7 @@ describe("ConfigArray", () => {
                 },
                 plugins: {},
                 processor: null,
+                resolveRelativeToConfigFile: void 0,
                 reportUnusedDisableDirectives: void 0,
                 rules: {},
                 settings: {}
@@ -609,7 +611,8 @@ describe("ConfigArray", () => {
                 settings: {},
                 processor: null,
                 noInlineConfig: void 0,
-                reportUnusedDisableDirectives: void 0
+                reportUnusedDisableDirectives: void 0,
+                resolveRelativeToConfigFile: void 0
             });
             assert.deepStrictEqual(config[0], {
                 rules: {