Merge pull request #5586 from loganfsmyth/config-dependency-cycles

Handle cycles of plugins compiling themselves and .babelrc.js files loading themselves

packages/babel-core/src/config/build-config-chain.js

@@ -3,6 +3,9 @@
 import { getEnv } from "./helpers/environment";
 import path from "path";
 import micromatch from "micromatch";
+import buildDebug from "debug";
+
+const debug = buildDebug("babel:config:config-chain");
 
 import { findConfigs, loadConfig } from "./loading/files";
 
@@ -67,7 +70,15 @@ class ConfigChainBuilder {
         );
       }
 
-      if (this.matchesPatterns(ignore, dirname)) return true;
+      if (this.matchesPatterns(ignore, dirname)) {
+        debug(
+          "Ignored %o because it matched one of %O from %o",
+          this.filename,
+          ignore,
+          dirname,
+        );
+        return true;
+      }
     }
 
     if (only) {
@@ -77,7 +88,15 @@ class ConfigChainBuilder {
         );
       }
 
-      if (!this.matchesPatterns(only, dirname)) return true;
+      if (!this.matchesPatterns(only, dirname)) {
+        debug(
+          "Ignored %o because it failed to match one of %O from %o",
+          this.filename,
+          only,
+          dirname,
+        );
+        return true;
+      }
     }
 
     return false;

packages/babel-core/src/config/loading/files/configuration.js

@@ -1,5 +1,6 @@
 // @flow
 
+import buildDebug from "debug";
 import path from "path";
 import fs from "fs";
 import json5 from "json5";
@@ -7,6 +8,8 @@ import resolve from "resolve";
 import { getEnv } from "../../helpers/environment";
 import { makeStrongCache } from "../../caching";
 
+const debug = buildDebug("babel:config:loading:files:configuration");
+
 type ConfigFile = {
   filepath: string,
   dirname: string,
@@ -31,6 +34,7 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
       const ignore = readIgnoreConfig(ignoreLoc);
 
       if (ignore) {
+        debug("Found ignore %o from %o.", ignore.filepath, dirname);
         confs.push(ignore);
         foundIgnore = true;
       }
@@ -57,6 +61,7 @@ export function findConfigs(dirname: string): Array<ConfigFile> {
       }, null);
 
       if (conf) {
+        debug("Found configuration %o from %o.", conf.filepath, dirname);
         confs.push(conf);
         foundConfig = true;
       }
@@ -80,6 +85,7 @@ export function loadConfig(name: string, dirname: string): ConfigFile {
     throw new Error(`Config file ${filepath} contains no configuration data`);
   }
 
+  debug("Loaded config %o from $o.", name, dirname);
   return conf;
 }
 
@@ -93,14 +99,31 @@ function readConfig(filepath) {
     : readConfigFile(filepath);
 }
 
+const LOADING_CONFIGS = new Set();
 const readConfigJS = makeStrongCache((filepath, cache) => {
   if (!fs.existsSync(filepath)) {
     cache.forever();
     return null;
   }
 
+  // The `require()` call below can make this code reentrant if a require hook like babel-register has been
+  // loaded into the system. That would cause Babel to attempt to compile the `.babelrc.js` file as it loads
+  // below. To cover this case, we auto-ignore re-entrant config processing.
+  if (LOADING_CONFIGS.has(filepath)) {
+    cache.never();
+
+    debug("Auto-ignoring usage of config %o.", filepath);
+    return {
+      filepath,
+      dirname: path.dirname(filepath),
+      options: {},
+    };
+  }
+
   let options;
   try {
+    LOADING_CONFIGS.add(filepath);
+
     // $FlowIssue
     const configModule = (require(filepath): mixed);
     options =
@@ -110,6 +133,8 @@ const readConfigJS = makeStrongCache((filepath, cache) => {
   } catch (err) {
     err.message = `${filepath}: Error while loading config - ${err.message}`;
     throw err;
+  } finally {
+    LOADING_CONFIGS.delete(filepath);
   }
 
   if (typeof options === "function") {

packages/babel-core/src/config/loading/files/plugins.js

@@ -4,9 +4,12 @@
  * This file handles all logic for converting string-based configuration references into loaded objects.
  */
 
+import buildDebug from "debug";
 import resolve from "resolve";
 import path from "path";
 
+const debug = buildDebug("babel:config:loading:files:plugins");
+
 const EXACT_RE = /^module:/;
 const BABEL_PLUGIN_PREFIX_RE = /^(?!@|module:|[^/\/]+[/\/]|babel-plugin-)/;
 const BABEL_PRESET_PREFIX_RE = /^(?!@|module:|[^/\/]+[/\/]|babel-preset-)/;
@@ -32,10 +35,10 @@ export function loadPlugin(
     throw new Error(`Plugin ${name} not found relative to ${dirname}`);
   }
 
-  return {
-    filepath,
-    value: requireModule(filepath),
-  };
+  const value = requireModule("plugin", filepath);
+  debug("Loaded plugin %o from %o.", name, dirname);
+
+  return { filepath, value };
 }
 
 export function loadPreset(
@@ -47,10 +50,11 @@ export function loadPreset(
     throw new Error(`Preset ${name} not found relative to ${dirname}`);
   }
 
-  return {
-    filepath,
-    value: requireModule(filepath),
-  };
+  const value = requireModule("preset", filepath);
+
+  debug("Loaded preset %o from %o.", name, dirname);
+
+  return { filepath, value };
 }
 
 export function loadParser(
@@ -59,7 +63,7 @@ export function loadParser(
 ): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
-  const mod = requireModule(filepath);
+  const mod = requireModule("parser", filepath);
 
   if (!mod) {
     throw new Error(
@@ -71,10 +75,13 @@ export function loadParser(
       `Parser ${name} relative to ${dirname} does not export a .parse function`,
     );
   }
+  const value = mod.parse;
+
+  debug("Loaded parser %o from %o.", name, dirname);
 
   return {
     filepath,
-    value: mod.parse,
+    value,
   };
 }
 
@@ -84,7 +91,7 @@ export function loadGenerator(
 ): { filepath: string, value: Function } {
   const filepath = resolve.sync(name, { basedir: dirname });
 
-  const mod = requireModule(filepath);
+  const mod = requireModule("generator", filepath);
 
   if (!mod) {
     throw new Error(
@@ -96,10 +103,13 @@ export function loadGenerator(
       `Generator ${name} relative to ${dirname} does not export a .print function`,
     );
   }
+  const value = mod.print;
+
+  debug("Loaded generator %o from %o.", name, dirname);
 
   return {
     filepath,
-    value: mod.print,
+    value,
   };
 }
 
@@ -185,7 +195,20 @@ function resolveStandardizedName(
   }
 }
 
-function requireModule(name: string): mixed {
+const LOADING_MODULES = new Set();
+function requireModule(type: string, name: string): mixed {
+  if (LOADING_MODULES.has(name)) {
+    throw new Error(
+      // eslint-disable-next-line max-len
+      `Reentrant ${type} detected trying to load "${name}". This module is not ignored and is trying to load itself while compiling itself, leading to a dependency cycle. We recommend adding it to your "ignore" list in your babelrc, or to a .babelignore.`,
+    );
+  }
+
+  try {
+    LOADING_MODULES.add(name);
     // $FlowIssue
     return require(name);
+  } finally {
+    LOADING_MODULES.delete(name);
+  }
 }