From 1cb92e538a13eae28c17c36f82a3fbbc8e96392e Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Fri, 11 Sep 2020 12:49:25 +0200
Subject: [PATCH 01/19] Added support for disabling dynamic config evaluation

---
 packages/config/package.json                  |  1 +
 packages/config/src/Config.ts                 |  8 ++
 packages/config/src/Config.types.ts           |  9 +-
 .../config/src/__tests__/getConfig-test.js    | 94 ++++++++++---------
 packages/config/src/evalConfig.ts             | 40 ++++++++
 packages/config/src/getConfig.ts              | 33 +++----
 packages/config/src/scripts/read-config.ts    | 33 ++-----
 7 files changed, 133 insertions(+), 85 deletions(-)
 create mode 100644 packages/config/src/evalConfig.ts

diff --git a/packages/config/package.json b/packages/config/package.json
index deb693d628..bdfed5bb75 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -38,6 +38,7 @@
     "@expo/json-file": "8.2.22",
     "@expo/plist": "0.0.9",
     "fs-extra": "9.0.0",
+    "getenv": "~1.0.0",
     "glob": "7.1.6",
     "invariant": "^2.2.4",
     "resolve-from": "^5.0.0",
diff --git a/packages/config/src/Config.ts b/packages/config/src/Config.ts
index 80d0736d27..54c018c207 100644
--- a/packages/config/src/Config.ts
+++ b/packages/config/src/Config.ts
@@ -1,5 +1,6 @@
 import JsonFile, { JSONObject } from '@expo/json-file';
 import fs from 'fs-extra';
+import { boolish } from 'getenv';
 import { sync as globSync } from 'glob';
 import path from 'path';
 import semver from 'semver';
@@ -22,6 +23,8 @@ import { getRootPackageJsonPath, projectHasModule } from './Modules';
 import { getExpoSDKVersion } from './Project';
 import { getDynamicConfig, getStaticConfig } from './getConfig';
 
+export const isDynamicEvalEnabled = boolish('EXPO_HOT_CONFIG', false);
+
 /**
  * If a config has an `expo` object then that will be used as the config.
  * This method reduces out other top level values if an `expo` object exists.
@@ -82,6 +85,10 @@ function getSupportedPlatforms(
  * @param options enforce criteria for a project config
  */
 export function getConfig(projectRoot: string, options: GetConfigOptions = {}): ProjectConfig {
+  if (typeof options.useDynamicEval === 'undefined' && isDynamicEvalEnabled) {
+    options.useDynamicEval = isDynamicEvalEnabled;
+  }
+
   const paths = getConfigFilePaths(projectRoot);
 
   const rawStaticConfig = paths.staticConfigPath ? getStaticConfig(paths.staticConfigPath) : null;
@@ -125,6 +132,7 @@ export function getConfig(projectRoot: string, options: GetConfigOptions = {}):
         staticConfigPath: paths.staticConfigPath,
         packageJsonPath,
         config: getContextConfig(staticConfig),
+        useDynamicEval: options.useDynamicEval,
       }
     );
     // Allow for the app.config.js to `export default null;`
diff --git a/packages/config/src/Config.types.ts b/packages/config/src/Config.types.ts
index 149733514d..0d0f4c6f0d 100644
--- a/packages/config/src/Config.types.ts
+++ b/packages/config/src/Config.types.ts
@@ -1037,9 +1037,16 @@ export type ConfigContext = {
   staticConfigPath: string | null;
   packageJsonPath: string | null;
   config: Partial<ExpoConfig>;
+  /**
+   * true when the dynamic config should be read from a spawned process. Has no effect on static (JSON) configs.
+   * This ensures that the config results are fresh without having to restart the running process that requested the config.
+   *
+   * Spawning can have huge performance penalties on low-end computers.
+   */
+  useDynamicEval?: boolean;
 };
 
-export type GetConfigOptions = {
+export type GetConfigOptions = Pick<ConfigContext, 'useDynamicEval'> & {
   skipSDKVersionRequirement?: boolean;
   strict?: boolean;
 };
diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index 18a97860aa..8db120d731 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,54 +37,64 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  // This tests error are thrown properly and ensures that a more specific
-  // config is used instead of defaulting to a valid substitution.
-  it(`throws a useful error for dynamic configs with a syntax error`, () => {
-    const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
-    expect(() => getDynamicConfig(paths.dynamicConfigPath, {})).toThrowError(
-      'Unexpected token (3:4)'
-    );
-  });
-  it(`exports a function`, () => {
-    expect(
-      getDynamicConfig(
-        join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-function.app.config.js'),
-        {}
-      ).exportedObjectType
-    ).toBe('function');
-  });
-  it(`exports an object`, () => {
-    expect(
-      getDynamicConfig(
-        join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-object.app.config.js'),
-        {}
-      ).exportedObjectType
-    ).toBe('object');
-  });
+  for (const useDynamicEval of [true, false]) {
+    describe(useDynamicEval ? 'dynamic eval' : 'standard eval', () => {
+      // This tests error are thrown properly and ensures that a more specific
+      // config is used instead of defaulting to a valid substitution.
+      it(`throws a useful error for dynamic configs with a syntax error`, () => {
+        const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
+        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useDynamicEval })).toThrowError(
+          'Unexpected token (3:4)'
+        );
+      });
+      it(`exports a function`, () => {
+        expect(
+          getDynamicConfig(
+            join(
+              __dirname,
+              'fixtures/behavior/dynamic-export-types/exports-function.app.config.js'
+            ),
+            { useDynamicEval }
+          ).exportedObjectType
+        ).toBe('function');
+      });
+      it(`exports an object`, () => {
+        expect(
+          getDynamicConfig(
+            join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-object.app.config.js'),
+            { useDynamicEval }
+          ).exportedObjectType
+        ).toBe('object');
+      });
 
-  describe('process.cwd in a child process', () => {
-    const originalCwd = process.cwd();
-    const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
+      describe('process.cwd in a child process', () => {
+        const originalCwd = process.cwd();
+        const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
 
-    beforeEach(() => {
-      process.chdir(__dirname);
-    });
+        beforeEach(() => {
+          process.chdir(__dirname);
+        });
 
-    afterEach(() => {
-      process.chdir(originalCwd);
-    });
+        afterEach(() => {
+          process.chdir(originalCwd);
+        });
 
-    it('process.cwd in read-config script is not equal to the project root', () => {
-      const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {});
-      expect(config.processCwd).toBe(__dirname);
-    });
-    it('process.cwd in read-config script is equal to the project root', () => {
-      const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-        projectRoot,
+        it('process.cwd in read-config script is not equal to the project root', () => {
+          const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
+            useDynamicEval,
+          });
+          expect(config.processCwd).toBe(__dirname);
+        });
+        it('process.cwd in read-config script is equal to the project root', () => {
+          const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
+            projectRoot,
+            useDynamicEval,
+          });
+          expect(config.processCwd).toBe(projectRoot);
+        });
       });
-      expect(config.processCwd).toBe(projectRoot);
     });
-  });
+  }
 });
 
 describe('getStaticConfig', () => {
diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
new file mode 100644
index 0000000000..a67c39af38
--- /dev/null
+++ b/packages/config/src/evalConfig.ts
@@ -0,0 +1,40 @@
+import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';
+import { ConfigError } from './Errors';
+import { serializeAndEvaluate } from './Serialize';
+
+type RawDynamicConfig = AppJSONConfig | Partial<ExpoConfig> | null;
+
+export type DynamicConfigResults = { config: RawDynamicConfig; exportedObjectType: string };
+
+/**
+ * transpile and evaluate the dynamic config object.
+ * This method is shared between the standard reading method in getConfig, and the headless script.
+ *
+ * @param options configPath path to the dynamic app.config.*, request to send to the dynamic config if it exports a function.
+ * @returns the serialized and evaluated config along with the exported object type (object or function).
+ */
+export function evalConfig(
+  configFile: string,
+  request: ConfigContext | null
+): DynamicConfigResults {
+  require('@babel/register')({
+    only: [configFile],
+    extensions: ['.ts', '.js'],
+    presets: [require.resolve('@expo/babel-preset-cli')],
+  });
+
+  let result = require(configFile);
+  if (result.default != null) {
+    result = result.default;
+  }
+  const exportedObjectType = typeof result;
+  if (typeof result === 'function') {
+    result = result(request);
+  }
+
+  if (result instanceof Promise) {
+    throw new ConfigError(`Config file ${configFile} cannot return a Promise.`, 'INVALID_CONFIG');
+  }
+
+  return { config: serializeAndEvaluate(result), exportedObjectType };
+}
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index cefa2b4208..d2cd04c080 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -3,25 +3,21 @@ import { spawnSync } from 'child_process';
 
 import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';
 import { ConfigError, errorFromJSON } from './Errors';
-import { fileExists } from './Modules';
 import { serializeAndEvaluate } from './Serialize';
-
-type RawDynamicConfig = AppJSONConfig | Partial<ExpoConfig> | null;
-
-type DynamicConfigResults = { config: RawDynamicConfig; exportedObjectType: string };
+import { DynamicConfigResults, evalConfig } from './evalConfig';
 
 function isMissingFileCode(code: string): boolean {
   return ['ENOENT', 'MODULE_NOT_FOUND', 'ENOTDIR'].includes(code);
 }
 
-function readConfigFile(
-  configFilePath: string,
-  context: ConfigContext
-): null | DynamicConfigResults {
-  if (!fileExists(configFilePath)) return null;
-
+// We cannot use async config resolution right now because Next.js doesn't support async configs.
+// If they don't add support for async Webpack configs then we may need to pull support for Next.js.
+function readConfigFile(configFile: string, context: ConfigContext): null | DynamicConfigResults {
   try {
-    return evalConfig(configFilePath, context);
+    if (context.useDynamicEval) {
+      return spawnAndEvalConfig(configFile, context);
+    }
+    return evalConfig(configFile, context);
   } catch (error) {
     // If the file doesn't exist then we should skip it and continue searching.
     if (!isMissingFileCode(error.code)) {
@@ -34,22 +30,23 @@ function readConfigFile(
 export function getDynamicConfig(configPath: string, request: ConfigContext): DynamicConfigResults {
   const config = readConfigFile(configPath, request);
   if (config) {
-    return serializeAndEvaluate(config);
+    // The config must be serialized and evaluated ahead of time so the spawned process can send it over.
+    return config;
   }
+  // TODO: It seems this is only thrown if the file cannot be found (which may never happen).
+  // If so we should throw a more helpful error.
   throw new ConfigError(`Failed to read config at: ${configPath}`, 'INVALID_CONFIG');
 }
 
-export function getStaticConfig(configPath: string): AppJSONConfig | ExpoConfig | null {
+export function getStaticConfig(configPath: string): AppJSONConfig | ExpoConfig {
   const config = JsonFile.read(configPath, { json5: true });
   if (config) {
-    return serializeAndEvaluate(config);
+    return config as any;
   }
   throw new ConfigError(`Failed to read config at: ${configPath}`, 'INVALID_CONFIG');
 }
 
-// We cannot use async config resolution right now because Next.js doesn't support async configs.
-// If they don't add support for async Webpack configs then we may need to pull support for Next.js.
-function evalConfig(configFile: string, request: ConfigContext): DynamicConfigResults {
+function spawnAndEvalConfig(configFile: string, request: ConfigContext): DynamicConfigResults {
   const spawnResults = spawnSync(
     'node',
     [
diff --git a/packages/config/src/scripts/read-config.ts b/packages/config/src/scripts/read-config.ts
index 2f89ae2029..5528a3244b 100644
--- a/packages/config/src/scripts/read-config.ts
+++ b/packages/config/src/scripts/read-config.ts
@@ -4,8 +4,8 @@
 import path from 'path';
 
 import { ConfigContext } from '../Config.types';
-import { ConfigError, errorToJSON } from '../Errors';
-import { serializeAndEvaluate } from '../Serialize';
+import { errorToJSON } from '../Errors';
+import { evalConfig } from '../evalConfig';
 
 // Makes the script crash on unhandled rejections instead of silently
 // ignoring them. In the future, promise rejections that are not handled will
@@ -21,32 +21,17 @@ let request: ConfigContext | null = null;
 if (typeof requestArg === 'string') {
   try {
     request = JSON.parse(requestArg) as ConfigContext;
-  } catch (_) {}
+  } catch {
+    // do nothing if the request fails to parse.
+    // TODO: document a case for why we should do nothing, perhaps it would make sense to have an error classification for this in the future.
+  }
 }
 
 try {
+  // TODO: do we need to resolve here?
   const configFile = path.resolve(configFileArg);
-
-  require('@babel/register')({
-    only: [configFile],
-    extensions: ['.ts', '.js'],
-    presets: [require.resolve('@expo/babel-preset-cli')],
-  });
-
-  let result = require(configFile);
-  if (result.default != null) {
-    result = result.default;
-  }
-  const exportedObjectType = typeof result;
-  if (typeof result === 'function') {
-    result = result(request);
-  }
-
-  if (result instanceof Promise) {
-    throw new ConfigError(`Config file ${configFile} cannot return a Promise.`, 'INVALID_CONFIG');
-  }
-
-  console.log(JSON.stringify({ config: serializeAndEvaluate(result), exportedObjectType }));
+  const result = evalConfig(configFile, request);
+  console.log(JSON.stringify(result));
   process.exit(0);
 } catch (error) {
   console.error(JSON.stringify(errorToJSON(error)));

From 5dfb0e3e2d51120447c11f7d4624c4b28d684898 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Fri, 11 Sep 2020 14:16:17 +0200
Subject: [PATCH 02/19] Update getConfig-test.js

---
 .../config/src/__tests__/getConfig-test.js    | 26 +++++++++++--------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index 8db120d731..5a5063f767 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -79,19 +79,23 @@ describe('getDynamicConfig', () => {
           process.chdir(originalCwd);
         });
 
-        it('process.cwd in read-config script is not equal to the project root', () => {
-          const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-            useDynamicEval,
+        if (useDynamicEval) {
+          // Test that dynamic evaluation is spawned in the expected location
+          // https://github.com/expo/expo-cli/pull/2220
+          it('process.cwd in read-config script is not equal to the project root', () => {
+            const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
+              useDynamicEval,
+            });
+            expect(config.processCwd).toBe(__dirname);
           });
-          expect(config.processCwd).toBe(__dirname);
-        });
-        it('process.cwd in read-config script is equal to the project root', () => {
-          const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-            projectRoot,
-            useDynamicEval,
+          it('process.cwd in read-config script is equal to the project root', () => {
+            const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
+              projectRoot,
+              useDynamicEval,
+            });
+            expect(config.processCwd).toBe(projectRoot);
           });
-          expect(config.processCwd).toBe(projectRoot);
-        });
+        }
       });
     });
   }

From d8c63e6332a88c3af5c2901b921a1547e26ccbcb Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Fri, 11 Sep 2020 17:01:20 +0200
Subject: [PATCH 03/19] bump versions

---
 packages/config/package.json  |  4 ++--
 packages/config/src/Config.ts |  8 +++++++-
 yarn.lock                     | 13 ++++++++++++-
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/packages/config/package.json b/packages/config/package.json
index bdfed5bb75..cdb879d78f 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -32,13 +32,13 @@
     "paths"
   ],
   "dependencies": {
-    "@babel/register": "^7.8.3",
+    "@babel/register": "~7.11.5",
     "@expo/babel-preset-cli": "0.2.17",
     "@expo/image-utils": "0.3.5",
     "@expo/json-file": "8.2.22",
     "@expo/plist": "0.0.9",
     "fs-extra": "9.0.0",
-    "getenv": "~1.0.0",
+    "getenv": "0.7.0",
     "glob": "7.1.6",
     "invariant": "^2.2.4",
     "resolve-from": "^5.0.0",
diff --git a/packages/config/src/Config.ts b/packages/config/src/Config.ts
index 54c018c207..1ff01e9294 100644
--- a/packages/config/src/Config.ts
+++ b/packages/config/src/Config.ts
@@ -158,7 +158,13 @@ function getPackageJsonAndPath(
   config: Pick<ExpoConfig, 'nodeModulesPath'> = {}
 ): [PackageJSONConfig, string] {
   const packageJsonPath = getRootPackageJsonPath(projectRoot, config);
-  return [JsonFile.read(packageJsonPath), packageJsonPath];
+
+  try {
+    return [JsonFile.read(packageJsonPath), packageJsonPath];
+  } catch (error) {
+    error.message = `Failed to parse package.json at ${packageJsonPath}\n${error.message}`;
+    throw error;
+  }
 }
 
 export function readConfigJson(
diff --git a/yarn.lock b/yarn.lock
index 63e9f8e3a9..83c0a9f4e9 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1129,7 +1129,7 @@
     "@babel/helper-plugin-utils" "^7.0.0"
     "@babel/plugin-transform-typescript" "^7.7.4"
 
-"@babel/register@^7.0.0", "@babel/register@^7.8.3":
+"@babel/register@^7.0.0":
   version "7.8.3"
   resolved "https://registry.yarnpkg.com/@babel/register/-/register-7.8.3.tgz#5d5d30cfcc918437535d724b8ac1e4a60c5db1f8"
   integrity sha512-t7UqebaWwo9nXWClIPLPloa5pN33A2leVs8Hf0e9g9YwUP8/H9NeR7DJU+4CXo23QtjChQv5a3DjEtT83ih1rg==
@@ -1140,6 +1140,17 @@
     pirates "^4.0.0"
     source-map-support "^0.5.16"
 
+"@babel/register@~7.11.5":
+  version "7.11.5"
+  resolved "https://registry.yarnpkg.com/@babel/register/-/register-7.11.5.tgz#79becf89e0ddd0fba8b92bc279bc0f5d2d7ce2ea"
+  integrity sha512-CAml0ioKX+kOAvBQDHa/+t1fgOt3qkTIz0TrRtRAT6XY0m5qYZXR85k6/sLCNPMGhYDlCFHCYuU0ybTJbvlC6w==
+  dependencies:
+    find-cache-dir "^2.0.0"
+    lodash "^4.17.19"
+    make-dir "^2.1.0"
+    pirates "^4.0.0"
+    source-map-support "^0.5.16"
+
 "@babel/runtime-corejs2@7.1.2":
   version "7.1.2"
   resolved "https://registry.yarnpkg.com/@babel/runtime-corejs2/-/runtime-corejs2-7.1.2.tgz#8695811a3fd8091f54f274b9320334e5e8c62200"

From 8b37d9a0f139ef8a47fce6ab261b7a72bcff6d0e Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sat, 12 Sep 2020 20:14:49 +0200
Subject: [PATCH 04/19] Update evalConfig.ts

---
 packages/config/src/evalConfig.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index a67c39af38..619eb102d5 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -19,6 +19,7 @@ export function evalConfig(
 ): DynamicConfigResults {
   require('@babel/register')({
     only: [configFile],
+    cache: false,
     extensions: ['.ts', '.js'],
     presets: [require.resolve('@expo/babel-preset-cli')],
   });

From c8a336015ace03f4a9f1caef4939a889e23849d7 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sat, 12 Sep 2020 20:16:24 +0200
Subject: [PATCH 05/19] dynamic eval -> hot eval

---
 packages/config/src/Config.ts                  |  6 +++---
 packages/config/src/Config.types.ts            |  4 ++--
 .../config/src/__tests__/getConfig-test.js     | 18 +++++++++---------
 packages/config/src/getConfig.ts               |  2 +-
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/packages/config/src/Config.ts b/packages/config/src/Config.ts
index 1ff01e9294..3ed513116f 100644
--- a/packages/config/src/Config.ts
+++ b/packages/config/src/Config.ts
@@ -85,8 +85,8 @@ function getSupportedPlatforms(
  * @param options enforce criteria for a project config
  */
 export function getConfig(projectRoot: string, options: GetConfigOptions = {}): ProjectConfig {
-  if (typeof options.useDynamicEval === 'undefined' && isDynamicEvalEnabled) {
-    options.useDynamicEval = isDynamicEvalEnabled;
+  if (typeof options.useHotEval === 'undefined' && isDynamicEvalEnabled) {
+    options.useHotEval = isDynamicEvalEnabled;
   }
 
   const paths = getConfigFilePaths(projectRoot);
@@ -132,7 +132,7 @@ export function getConfig(projectRoot: string, options: GetConfigOptions = {}):
         staticConfigPath: paths.staticConfigPath,
         packageJsonPath,
         config: getContextConfig(staticConfig),
-        useDynamicEval: options.useDynamicEval,
+        useHotEval: options.useHotEval,
       }
     );
     // Allow for the app.config.js to `export default null;`
diff --git a/packages/config/src/Config.types.ts b/packages/config/src/Config.types.ts
index 0d0f4c6f0d..92059e151d 100644
--- a/packages/config/src/Config.types.ts
+++ b/packages/config/src/Config.types.ts
@@ -1043,10 +1043,10 @@ export type ConfigContext = {
    *
    * Spawning can have huge performance penalties on low-end computers.
    */
-  useDynamicEval?: boolean;
+  useHotEval?: boolean;
 };
 
-export type GetConfigOptions = Pick<ConfigContext, 'useDynamicEval'> & {
+export type GetConfigOptions = Pick<ConfigContext, 'useHotEval'> & {
   skipSDKVersionRequirement?: boolean;
   strict?: boolean;
 };
diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index 5a5063f767..ed46501dc4 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,13 +37,13 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  for (const useDynamicEval of [true, false]) {
-    describe(useDynamicEval ? 'dynamic eval' : 'standard eval', () => {
+  for (const useHotEval of [true, false]) {
+    describe(useHotEval ? 'hot eval' : 'standard eval', () => {
       // This tests error are thrown properly and ensures that a more specific
       // config is used instead of defaulting to a valid substitution.
       it(`throws a useful error for dynamic configs with a syntax error`, () => {
         const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
-        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useDynamicEval })).toThrowError(
+        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
           'Unexpected token (3:4)'
         );
       });
@@ -54,7 +54,7 @@ describe('getDynamicConfig', () => {
               __dirname,
               'fixtures/behavior/dynamic-export-types/exports-function.app.config.js'
             ),
-            { useDynamicEval }
+            { useHotEval }
           ).exportedObjectType
         ).toBe('function');
       });
@@ -62,7 +62,7 @@ describe('getDynamicConfig', () => {
         expect(
           getDynamicConfig(
             join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-object.app.config.js'),
-            { useDynamicEval }
+            { useHotEval }
           ).exportedObjectType
         ).toBe('object');
       });
@@ -79,19 +79,19 @@ describe('getDynamicConfig', () => {
           process.chdir(originalCwd);
         });
 
-        if (useDynamicEval) {
-          // Test that dynamic evaluation is spawned in the expected location
+        if (useHotEval) {
+          // Test that hot evaluation is spawned in the expected location
           // https://github.com/expo/expo-cli/pull/2220
           it('process.cwd in read-config script is not equal to the project root', () => {
             const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-              useDynamicEval,
+              useHotEval,
             });
             expect(config.processCwd).toBe(__dirname);
           });
           it('process.cwd in read-config script is equal to the project root', () => {
             const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
               projectRoot,
-              useDynamicEval,
+              useHotEval,
             });
             expect(config.processCwd).toBe(projectRoot);
           });
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index d2cd04c080..0b9eb66429 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -14,7 +14,7 @@ function isMissingFileCode(code: string): boolean {
 // If they don't add support for async Webpack configs then we may need to pull support for Next.js.
 function readConfigFile(configFile: string, context: ConfigContext): null | DynamicConfigResults {
   try {
-    if (context.useDynamicEval) {
+    if (context.useHotEval) {
       return spawnAndEvalConfig(configFile, context);
     }
     return evalConfig(configFile, context);

From 59cf81810da2bc2be3d4176a122243e9aa1fd5ac Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sat, 12 Sep 2020 20:29:44 +0200
Subject: [PATCH 06/19] Update getConfig-test.js

---
 packages/config/src/__tests__/getConfig-test.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index ed46501dc4..ba62dda764 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,7 +37,7 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  for (const useHotEval of [true, false]) {
+  for (const useHotEval of [false, true]) {
     describe(useHotEval ? 'hot eval' : 'standard eval', () => {
       // This tests error are thrown properly and ensures that a more specific
       // config is used instead of defaulting to a valid substitution.

From 5ba91ffffc9282094c507bb37439a5bd618a08f2 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sat, 12 Sep 2020 20:50:34 +0200
Subject: [PATCH 07/19] create a more useful stacktrace for config errors

---
 packages/config/src/getConfig.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index 0b9eb66429..dda89def36 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -73,6 +73,12 @@ function spawnAndEvalConfig(configFile: string, request: ConfigContext): Dynamic
   } else {
     // Parse the error data and throw it as expected
     const errorData = JSON.parse(spawnResults.stderr.toString('utf8'));
-    throw errorFromJSON(errorData);
+    const error = errorFromJSON(errorData);
+
+    // @ts-ignore
+    error.isConfigError = true;
+    // @ts-ignore: Replace the babel stack with a more relevant stack.
+    error.stack = new Error().stack;
+    throw error;
   }
 }

From 1b66653b066e12de54c0e79bf919d8e197435394 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 19:16:58 +0200
Subject: [PATCH 08/19] use same babel version

---
 packages/config/package.json |  2 +-
 yarn.lock                    | 13 +------------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/packages/config/package.json b/packages/config/package.json
index cdb879d78f..fea1d0e2c3 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -32,7 +32,7 @@
     "paths"
   ],
   "dependencies": {
-    "@babel/register": "~7.11.5",
+    "@babel/register": "7.8.3",
     "@expo/babel-preset-cli": "0.2.17",
     "@expo/image-utils": "0.3.5",
     "@expo/json-file": "8.2.22",
diff --git a/yarn.lock b/yarn.lock
index 83c0a9f4e9..7fe38024ca 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1129,7 +1129,7 @@
     "@babel/helper-plugin-utils" "^7.0.0"
     "@babel/plugin-transform-typescript" "^7.7.4"
 
-"@babel/register@^7.0.0":
+"@babel/register@7.8.3", "@babel/register@^7.0.0":
   version "7.8.3"
   resolved "https://registry.yarnpkg.com/@babel/register/-/register-7.8.3.tgz#5d5d30cfcc918437535d724b8ac1e4a60c5db1f8"
   integrity sha512-t7UqebaWwo9nXWClIPLPloa5pN33A2leVs8Hf0e9g9YwUP8/H9NeR7DJU+4CXo23QtjChQv5a3DjEtT83ih1rg==
@@ -1140,17 +1140,6 @@
     pirates "^4.0.0"
     source-map-support "^0.5.16"
 
-"@babel/register@~7.11.5":
-  version "7.11.5"
-  resolved "https://registry.yarnpkg.com/@babel/register/-/register-7.11.5.tgz#79becf89e0ddd0fba8b92bc279bc0f5d2d7ce2ea"
-  integrity sha512-CAml0ioKX+kOAvBQDHa/+t1fgOt3qkTIz0TrRtRAT6XY0m5qYZXR85k6/sLCNPMGhYDlCFHCYuU0ybTJbvlC6w==
-  dependencies:
-    find-cache-dir "^2.0.0"
-    lodash "^4.17.19"
-    make-dir "^2.1.0"
-    pirates "^4.0.0"
-    source-map-support "^0.5.16"
-
 "@babel/runtime-corejs2@7.1.2":
   version "7.1.2"
   resolved "https://registry.yarnpkg.com/@babel/runtime-corejs2/-/runtime-corejs2-7.1.2.tgz#8695811a3fd8091f54f274b9320334e5e8c62200"

From de78be54bbbb5be439e5609cead2215a3e8bd07d Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 19:21:03 +0200
Subject: [PATCH 09/19] Update evalConfig.ts

---
 packages/config/src/evalConfig.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index 619eb102d5..2ac45c4485 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -7,10 +7,10 @@ type RawDynamicConfig = AppJSONConfig | Partial<ExpoConfig> | null;
 export type DynamicConfigResults = { config: RawDynamicConfig; exportedObjectType: string };
 
 /**
- * transpile and evaluate the dynamic config object.
+ * Transpile and evaluate the dynamic config object.
  * This method is shared between the standard reading method in getConfig, and the headless script.
  *
- * @param options configPath path to the dynamic app.config.*, request to send to the dynamic config if it exports a function.
+ * @param options configFile path to the dynamic app.config.*, request to send to the dynamic config if it exports a function.
  * @returns the serialized and evaluated config along with the exported object type (object or function).
  */
 export function evalConfig(

From ed0ddd74f8c2d7ae1d4f4d5e302426fe8f701bd3 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 19:26:46 +0200
Subject: [PATCH 10/19] disable hot tests

---
 packages/config/src/__tests__/getConfig-test.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index ba62dda764..6a60a1e22b 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,7 +37,7 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  for (const useHotEval of [false, true]) {
+  for (const useHotEval of [false]) {
     describe(useHotEval ? 'hot eval' : 'standard eval', () => {
       // This tests error are thrown properly and ensures that a more specific
       // config is used instead of defaulting to a valid substitution.

From 77f13fd97f038be97fd0729fbecbfe9e99a06ad6 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 19:46:23 +0200
Subject: [PATCH 11/19] fix error stack

---
 packages/config/jest.config.js                  | 2 ++
 packages/config/src/__tests__/getConfig-test.js | 2 +-
 packages/config/src/getConfig.ts                | 9 ++++-----
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/packages/config/jest.config.js b/packages/config/jest.config.js
index 28d2fb05af..6d76b22436 100644
--- a/packages/config/jest.config.js
+++ b/packages/config/jest.config.js
@@ -2,6 +2,8 @@ const path = require('path');
 
 module.exports = {
   preset: '../../jest/unit-test-config',
+  transformIgnorePatterns: ['@babel/register'],
+  verbose: true,
   rootDir: path.resolve(__dirname),
   displayName: require('./package').name,
   roots: ['__mocks__', 'src'],
diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index 6a60a1e22b..ba62dda764 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,7 +37,7 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  for (const useHotEval of [false]) {
+  for (const useHotEval of [false, true]) {
     describe(useHotEval ? 'hot eval' : 'standard eval', () => {
       // This tests error are thrown properly and ensures that a more specific
       // config is used instead of defaulting to a valid substitution.
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index dda89def36..fde5754c77 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -21,6 +21,10 @@ function readConfigFile(configFile: string, context: ConfigContext): null | Dyna
   } catch (error) {
     // If the file doesn't exist then we should skip it and continue searching.
     if (!isMissingFileCode(error.code)) {
+      // @ts-ignore
+      error.isConfigError = true;
+      // @ts-ignore: Replace the babel stack with a more relevant stack.
+      error.stack = new Error().stack;
       throw error;
     }
   }
@@ -74,11 +78,6 @@ function spawnAndEvalConfig(configFile: string, request: ConfigContext): Dynamic
     // Parse the error data and throw it as expected
     const errorData = JSON.parse(spawnResults.stderr.toString('utf8'));
     const error = errorFromJSON(errorData);
-
-    // @ts-ignore
-    error.isConfigError = true;
-    // @ts-ignore: Replace the babel stack with a more relevant stack.
-    error.stack = new Error().stack;
     throw error;
   }
 }

From c3d6df4d08faeb29406c77d224b6db1d3ff8aefe Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 19:55:13 +0200
Subject: [PATCH 12/19] ignore other babel

---
 packages/config/jest.config.js   | 2 +-
 packages/config/src/getConfig.ts | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/config/jest.config.js b/packages/config/jest.config.js
index 6d76b22436..67ae2853d6 100644
--- a/packages/config/jest.config.js
+++ b/packages/config/jest.config.js
@@ -2,7 +2,7 @@ const path = require('path');
 
 module.exports = {
   preset: '../../jest/unit-test-config',
-  transformIgnorePatterns: ['@babel/register'],
+  transformIgnorePatterns: ['node_modules/@babel/core'],
   verbose: true,
   rootDir: path.resolve(__dirname),
   displayName: require('./package').name,
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index fde5754c77..06edfa50ce 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -24,7 +24,7 @@ function readConfigFile(configFile: string, context: ConfigContext): null | Dyna
       // @ts-ignore
       error.isConfigError = true;
       // @ts-ignore: Replace the babel stack with a more relevant stack.
-      error.stack = new Error().stack;
+      // error.stack = new Error().stack;
       throw error;
     }
   }

From 4fd692a772a0790e884e101ddf67f918647d4806 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Sun, 13 Sep 2020 20:28:42 +0200
Subject: [PATCH 13/19] disable test

---
 packages/config/jest.config.js                |  2 -
 .../config/src/__tests__/getConfig-test.js    | 40 +++++++++----------
 packages/config/src/getConfig.ts              |  2 +-
 3 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/packages/config/jest.config.js b/packages/config/jest.config.js
index 67ae2853d6..28d2fb05af 100644
--- a/packages/config/jest.config.js
+++ b/packages/config/jest.config.js
@@ -2,8 +2,6 @@ const path = require('path');
 
 module.exports = {
   preset: '../../jest/unit-test-config',
-  transformIgnorePatterns: ['node_modules/@babel/core'],
-  verbose: true,
   rootDir: path.resolve(__dirname),
   displayName: require('./package').name,
   roots: ['__mocks__', 'src'],
diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index ba62dda764..458cdf9bf9 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -39,14 +39,6 @@ describe('modifyConfigAsync', () => {
 describe('getDynamicConfig', () => {
   for (const useHotEval of [false, true]) {
     describe(useHotEval ? 'hot eval' : 'standard eval', () => {
-      // This tests error are thrown properly and ensures that a more specific
-      // config is used instead of defaulting to a valid substitution.
-      it(`throws a useful error for dynamic configs with a syntax error`, () => {
-        const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
-        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
-          'Unexpected token (3:4)'
-        );
-      });
       it(`exports a function`, () => {
         expect(
           getDynamicConfig(
@@ -67,19 +59,27 @@ describe('getDynamicConfig', () => {
         ).toBe('object');
       });
 
-      describe('process.cwd in a child process', () => {
-        const originalCwd = process.cwd();
-        const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
-
-        beforeEach(() => {
-          process.chdir(__dirname);
+      if (useHotEval) {
+        // This tests error are thrown properly and ensures that a more specific
+        // config is used instead of defaulting to a valid substitution.
+        it(`throws a useful error for dynamic configs with a syntax error`, () => {
+          const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
+          expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
+            'Unexpected token (3:4)'
+          );
         });
+        describe('process.cwd in a child process', () => {
+          const originalCwd = process.cwd();
+          const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
 
-        afterEach(() => {
-          process.chdir(originalCwd);
-        });
+          beforeEach(() => {
+            process.chdir(__dirname);
+          });
+
+          afterEach(() => {
+            process.chdir(originalCwd);
+          });
 
-        if (useHotEval) {
           // Test that hot evaluation is spawned in the expected location
           // https://github.com/expo/expo-cli/pull/2220
           it('process.cwd in read-config script is not equal to the project root', () => {
@@ -95,8 +95,8 @@ describe('getDynamicConfig', () => {
             });
             expect(config.processCwd).toBe(projectRoot);
           });
-        }
-      });
+        });
+      }
     });
   }
 });
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index 06edfa50ce..fde5754c77 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -24,7 +24,7 @@ function readConfigFile(configFile: string, context: ConfigContext): null | Dyna
       // @ts-ignore
       error.isConfigError = true;
       // @ts-ignore: Replace the babel stack with a more relevant stack.
-      // error.stack = new Error().stack;
+      error.stack = new Error().stack;
       throw error;
     }
   }

From b4f9bae4ab5e0163e8bcc14f79e65598bb6fdc25 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 12:22:39 +0200
Subject: [PATCH 14/19] wip

---
 packages/config/src/__tests__/getConfig-test.js | 16 ++++++++--------
 packages/config/src/evalConfig.ts               |  1 +
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index 458cdf9bf9..ca188a5152 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -59,15 +59,15 @@ describe('getDynamicConfig', () => {
         ).toBe('object');
       });
 
+      // This tests error are thrown properly and ensures that a more specific
+      // config is used instead of defaulting to a valid substitution.
+      it(`throws a useful error for dynamic configs with a syntax error`, () => {
+        const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
+        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
+          'Unexpected token (3:4)'
+        );
+      });
       if (useHotEval) {
-        // This tests error are thrown properly and ensures that a more specific
-        // config is used instead of defaulting to a valid substitution.
-        it(`throws a useful error for dynamic configs with a syntax error`, () => {
-          const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
-          expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
-            'Unexpected token (3:4)'
-          );
-        });
         describe('process.cwd in a child process', () => {
           const originalCwd = process.cwd();
           const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index 2ac45c4485..63eac79767 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -20,6 +20,7 @@ export function evalConfig(
   require('@babel/register')({
     only: [configFile],
     cache: false,
+    cwd: request?.projectRoot ?? process.cwd(),
     extensions: ['.ts', '.js'],
     presets: [require.resolve('@expo/babel-preset-cli')],
   });

From f790e769fce7cf85bface12932f833c530ef9a36 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 14:46:56 +0200
Subject: [PATCH 15/19] [wip] use babel-core directly

---
 packages/config/package.json      |  1 +
 packages/config/src/evalConfig.ts | 14 +++++++++-----
 yarn.lock                         |  5 +++++
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/packages/config/package.json b/packages/config/package.json
index fea1d0e2c3..f484d6369f 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -41,6 +41,7 @@
     "getenv": "0.7.0",
     "glob": "7.1.6",
     "invariant": "^2.2.4",
+    "require-from-string": "^2.0.2",
     "resolve-from": "^5.0.0",
     "semver": "^7.1.3",
     "slugify": "^1.3.4",
diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index 63eac79767..0d7ac2a059 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -1,3 +1,6 @@
+import fs from 'fs-extra';
+import fromString from 'require-from-string';
+
 import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';
 import { ConfigError } from './Errors';
 import { serializeAndEvaluate } from './Serialize';
@@ -17,15 +20,16 @@ export function evalConfig(
   configFile: string,
   request: ConfigContext | null
 ): DynamicConfigResults {
-  require('@babel/register')({
+  const babel = require('@babel/core');
+  const { code } = babel.transformFileSync(require.resolve(configFile), {
     only: [configFile],
-    cache: false,
-    cwd: request?.projectRoot ?? process.cwd(),
-    extensions: ['.ts', '.js'],
+    babelrc: false,
+    ignore: [/node_modules/],
+    filename: 'unknown',
     presets: [require.resolve('@expo/babel-preset-cli')],
   });
 
-  let result = require(configFile);
+  let result = fromString(code);
   if (result.default != null) {
     result = result.default;
   }
diff --git a/yarn.lock b/yarn.lock
index 7fe38024ca..ac1fe4cf3b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -18653,6 +18653,11 @@ require-directory@^2.1.1:
   resolved "https://registry.yarnpkg.com/require-directory/-/require-directory-2.1.1.tgz#8c64ad5fd30dab1c976e2344ffe7f792a6a6df42"
   integrity sha1-jGStX9MNqxyXbiNE/+f3kqam30I=
 
+require-from-string@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/require-from-string/-/require-from-string-2.0.2.tgz#89a7fdd938261267318eafe14f9c32e598c36909"
+  integrity sha512-Xf0nWe6RseziFMu+Ap9biiUbmplq6S9/p+7w7YXP/JBHhrUDDUhwa+vANyubuqfZWTveU//DYVGsDG7RKL/vEw==
+
 require-main-filename@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/require-main-filename/-/require-main-filename-1.0.1.tgz#97f717b69d48784f5f526a6c5aa8ffdda055a4d1"

From 5cd3718052cd6784bda842314c4ebadc8821dc90 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 14:49:32 +0200
Subject: [PATCH 16/19] Update evalConfig.ts

---
 packages/config/src/evalConfig.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index 0d7ac2a059..7c1d4ead4d 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -1,4 +1,4 @@
-import fs from 'fs-extra';
+// @ts-ignore
 import fromString from 'require-from-string';
 
 import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';

From 2d5fef253dec669cd1aea378becca3d927ec5338 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 16:19:32 +0200
Subject: [PATCH 17/19] Update package.json

---
 packages/config/package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/config/package.json b/packages/config/package.json
index f484d6369f..5ae05b6176 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -32,7 +32,7 @@
     "paths"
   ],
   "dependencies": {
-    "@babel/register": "7.8.3",
+    "@babel/core": "7.9.0",
     "@expo/babel-preset-cli": "0.2.17",
     "@expo/image-utils": "0.3.5",
     "@expo/json-file": "8.2.22",

From 6a653895a84987d35e43e8188f0de2b64772c303 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 16:33:19 +0200
Subject: [PATCH 18/19] Remove useHotEval

---
 packages/config/package.json                  |   1 -
 packages/config/src/Config.ts                 |   8 --
 packages/config/src/Config.types.ts           |   9 +-
 .../config/src/__tests__/getConfig-test.js    | 102 ++++++++----------
 packages/config/src/evalConfig.ts             |   6 +-
 packages/config/src/getConfig.ts              |  39 +------
 packages/config/src/scripts/read-config.ts    |  39 -------
 7 files changed, 51 insertions(+), 153 deletions(-)
 delete mode 100644 packages/config/src/scripts/read-config.ts

diff --git a/packages/config/package.json b/packages/config/package.json
index 5ae05b6176..32b21ffbe7 100644
--- a/packages/config/package.json
+++ b/packages/config/package.json
@@ -38,7 +38,6 @@
     "@expo/json-file": "8.2.22",
     "@expo/plist": "0.0.9",
     "fs-extra": "9.0.0",
-    "getenv": "0.7.0",
     "glob": "7.1.6",
     "invariant": "^2.2.4",
     "require-from-string": "^2.0.2",
diff --git a/packages/config/src/Config.ts b/packages/config/src/Config.ts
index 3ed513116f..2fe47ee1a8 100644
--- a/packages/config/src/Config.ts
+++ b/packages/config/src/Config.ts
@@ -1,6 +1,5 @@
 import JsonFile, { JSONObject } from '@expo/json-file';
 import fs from 'fs-extra';
-import { boolish } from 'getenv';
 import { sync as globSync } from 'glob';
 import path from 'path';
 import semver from 'semver';
@@ -23,8 +22,6 @@ import { getRootPackageJsonPath, projectHasModule } from './Modules';
 import { getExpoSDKVersion } from './Project';
 import { getDynamicConfig, getStaticConfig } from './getConfig';
 
-export const isDynamicEvalEnabled = boolish('EXPO_HOT_CONFIG', false);
-
 /**
  * If a config has an `expo` object then that will be used as the config.
  * This method reduces out other top level values if an `expo` object exists.
@@ -85,10 +82,6 @@ function getSupportedPlatforms(
  * @param options enforce criteria for a project config
  */
 export function getConfig(projectRoot: string, options: GetConfigOptions = {}): ProjectConfig {
-  if (typeof options.useHotEval === 'undefined' && isDynamicEvalEnabled) {
-    options.useHotEval = isDynamicEvalEnabled;
-  }
-
   const paths = getConfigFilePaths(projectRoot);
 
   const rawStaticConfig = paths.staticConfigPath ? getStaticConfig(paths.staticConfigPath) : null;
@@ -132,7 +125,6 @@ export function getConfig(projectRoot: string, options: GetConfigOptions = {}):
         staticConfigPath: paths.staticConfigPath,
         packageJsonPath,
         config: getContextConfig(staticConfig),
-        useHotEval: options.useHotEval,
       }
     );
     // Allow for the app.config.js to `export default null;`
diff --git a/packages/config/src/Config.types.ts b/packages/config/src/Config.types.ts
index 92059e151d..149733514d 100644
--- a/packages/config/src/Config.types.ts
+++ b/packages/config/src/Config.types.ts
@@ -1037,16 +1037,9 @@ export type ConfigContext = {
   staticConfigPath: string | null;
   packageJsonPath: string | null;
   config: Partial<ExpoConfig>;
-  /**
-   * true when the dynamic config should be read from a spawned process. Has no effect on static (JSON) configs.
-   * This ensures that the config results are fresh without having to restart the running process that requested the config.
-   *
-   * Spawning can have huge performance penalties on low-end computers.
-   */
-  useHotEval?: boolean;
 };
 
-export type GetConfigOptions = Pick<ConfigContext, 'useHotEval'> & {
+export type GetConfigOptions = {
   skipSDKVersionRequirement?: boolean;
   strict?: boolean;
 };
diff --git a/packages/config/src/__tests__/getConfig-test.js b/packages/config/src/__tests__/getConfig-test.js
index ca188a5152..9350e340e0 100644
--- a/packages/config/src/__tests__/getConfig-test.js
+++ b/packages/config/src/__tests__/getConfig-test.js
@@ -37,68 +37,56 @@ describe('modifyConfigAsync', () => {
 });
 
 describe('getDynamicConfig', () => {
-  for (const useHotEval of [false, true]) {
-    describe(useHotEval ? 'hot eval' : 'standard eval', () => {
-      it(`exports a function`, () => {
-        expect(
-          getDynamicConfig(
-            join(
-              __dirname,
-              'fixtures/behavior/dynamic-export-types/exports-function.app.config.js'
-            ),
-            { useHotEval }
-          ).exportedObjectType
-        ).toBe('function');
-      });
-      it(`exports an object`, () => {
-        expect(
-          getDynamicConfig(
-            join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-object.app.config.js'),
-            { useHotEval }
-          ).exportedObjectType
-        ).toBe('object');
-      });
+  it(`exports a function`, () => {
+    expect(
+      getDynamicConfig(
+        join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-function.app.config.js'),
+        {}
+      ).exportedObjectType
+    ).toBe('function');
+  });
+  it(`exports an object`, () => {
+    expect(
+      getDynamicConfig(
+        join(__dirname, 'fixtures/behavior/dynamic-export-types/exports-object.app.config.js'),
+        {}
+      ).exportedObjectType
+    ).toBe('object');
+  });
+
+  // This tests error are thrown properly and ensures that a more specific
+  // config is used instead of defaulting to a valid substitution.
+  it(`throws a useful error for dynamic configs with a syntax error`, () => {
+    const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
+    expect(() => getDynamicConfig(paths.dynamicConfigPath, {})).toThrowError(
+      'Unexpected token (3:4)'
+    );
+  });
 
-      // This tests error are thrown properly and ensures that a more specific
-      // config is used instead of defaulting to a valid substitution.
-      it(`throws a useful error for dynamic configs with a syntax error`, () => {
-        const paths = getConfigFilePaths(join(__dirname, 'fixtures/behavior/syntax-error'));
-        expect(() => getDynamicConfig(paths.dynamicConfigPath, { useHotEval })).toThrowError(
-          'Unexpected token (3:4)'
-        );
-      });
-      if (useHotEval) {
-        describe('process.cwd in a child process', () => {
-          const originalCwd = process.cwd();
-          const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
+  describe('process.cwd in a child process', () => {
+    const originalCwd = process.cwd();
+    const projectRoot = join(__dirname, 'fixtures/behavior/dynamic-cwd');
 
-          beforeEach(() => {
-            process.chdir(__dirname);
-          });
+    beforeEach(() => {
+      process.chdir(__dirname);
+    });
 
-          afterEach(() => {
-            process.chdir(originalCwd);
-          });
+    afterEach(() => {
+      process.chdir(originalCwd);
+    });
 
-          // Test that hot evaluation is spawned in the expected location
-          // https://github.com/expo/expo-cli/pull/2220
-          it('process.cwd in read-config script is not equal to the project root', () => {
-            const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-              useHotEval,
-            });
-            expect(config.processCwd).toBe(__dirname);
-          });
-          it('process.cwd in read-config script is equal to the project root', () => {
-            const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {
-              projectRoot,
-              useHotEval,
-            });
-            expect(config.processCwd).toBe(projectRoot);
-          });
-        });
-      }
+    // Test that hot evaluation is spawned in the expected location
+    // https://github.com/expo/expo-cli/pull/2220
+    it('process.cwd in read-config script is not equal to the project root', () => {
+      const { config } = getDynamicConfig(join(projectRoot, 'app.config.ts'), {});
+      expect(config.processCwd).toBe(__dirname);
+      expect(
+        getDynamicConfig(join(projectRoot, 'app.config.ts'), {
+          projectRoot,
+        }).config.processCwd
+      ).toBe(__dirname);
     });
-  }
+  });
 });
 
 describe('getStaticConfig', () => {
diff --git a/packages/config/src/evalConfig.ts b/packages/config/src/evalConfig.ts
index 7c1d4ead4d..61e467bb65 100644
--- a/packages/config/src/evalConfig.ts
+++ b/packages/config/src/evalConfig.ts
@@ -1,9 +1,10 @@
 // @ts-ignore
-import fromString from 'require-from-string';
+import requireString from 'require-from-string';
 
 import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';
 import { ConfigError } from './Errors';
 import { serializeAndEvaluate } from './Serialize';
+// import babel from '@babel/core';
 
 type RawDynamicConfig = AppJSONConfig | Partial<ExpoConfig> | null;
 
@@ -23,13 +24,14 @@ export function evalConfig(
   const babel = require('@babel/core');
   const { code } = babel.transformFileSync(require.resolve(configFile), {
     only: [configFile],
+    cwd: request?.projectRoot || process.cwd(),
     babelrc: false,
     ignore: [/node_modules/],
     filename: 'unknown',
     presets: [require.resolve('@expo/babel-preset-cli')],
   });
 
-  let result = fromString(code);
+  let result = requireString(code);
   if (result.default != null) {
     result = result.default;
   }
diff --git a/packages/config/src/getConfig.ts b/packages/config/src/getConfig.ts
index fde5754c77..e8fc35140f 100644
--- a/packages/config/src/getConfig.ts
+++ b/packages/config/src/getConfig.ts
@@ -1,9 +1,7 @@
 import JsonFile from '@expo/json-file';
-import { spawnSync } from 'child_process';
 
 import { AppJSONConfig, ConfigContext, ExpoConfig } from './Config.types';
-import { ConfigError, errorFromJSON } from './Errors';
-import { serializeAndEvaluate } from './Serialize';
+import { ConfigError } from './Errors';
 import { DynamicConfigResults, evalConfig } from './evalConfig';
 
 function isMissingFileCode(code: string): boolean {
@@ -14,9 +12,6 @@ function isMissingFileCode(code: string): boolean {
 // If they don't add support for async Webpack configs then we may need to pull support for Next.js.
 function readConfigFile(configFile: string, context: ConfigContext): null | DynamicConfigResults {
   try {
-    if (context.useHotEval) {
-      return spawnAndEvalConfig(configFile, context);
-    }
     return evalConfig(configFile, context);
   } catch (error) {
     // If the file doesn't exist then we should skip it and continue searching.
@@ -49,35 +44,3 @@ export function getStaticConfig(configPath: string): AppJSONConfig | ExpoConfig
   }
   throw new ConfigError(`Failed to read config at: ${configPath}`, 'INVALID_CONFIG');
 }
-
-function spawnAndEvalConfig(configFile: string, request: ConfigContext): DynamicConfigResults {
-  const spawnResults = spawnSync(
-    'node',
-    [
-      require.resolve('@expo/config/build/scripts/read-config.js'),
-      '--colors',
-      configFile,
-      JSON.stringify({ ...request, config: serializeAndEvaluate(request.config) }),
-    ],
-    { cwd: request.projectRoot || process.cwd() }
-  );
-
-  if (spawnResults.status === 0) {
-    const spawnResultString = spawnResults.stdout.toString('utf8').trim();
-    const logs = spawnResultString.split('\n');
-    // Get the last console log to prevent parsing anything logged in the config.
-    const lastLog = logs.pop()!;
-    for (const log of logs) {
-      // Log out the logs from the config
-      console.log(log);
-    }
-    // Parse the final log of the script, it's the serialized config and exported object type.
-    const results = JSON.parse(lastLog);
-    return results;
-  } else {
-    // Parse the error data and throw it as expected
-    const errorData = JSON.parse(spawnResults.stderr.toString('utf8'));
-    const error = errorFromJSON(errorData);
-    throw error;
-  }
-}
diff --git a/packages/config/src/scripts/read-config.ts b/packages/config/src/scripts/read-config.ts
deleted file mode 100644
index 5528a3244b..0000000000
--- a/packages/config/src/scripts/read-config.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-#!/usr/bin/env node
-'use strict';
-
-import path from 'path';
-
-import { ConfigContext } from '../Config.types';
-import { errorToJSON } from '../Errors';
-import { evalConfig } from '../evalConfig';
-
-// Makes the script crash on unhandled rejections instead of silently
-// ignoring them. In the future, promise rejections that are not handled will
-// terminate the Node.js process with a non-zero exit code.
-process.on('unhandledRejection', err => {
-  throw err;
-});
-
-const { 3: configFileArg, 4: requestArg } = process.argv;
-
-let request: ConfigContext | null = null;
-
-if (typeof requestArg === 'string') {
-  try {
-    request = JSON.parse(requestArg) as ConfigContext;
-  } catch {
-    // do nothing if the request fails to parse.
-    // TODO: document a case for why we should do nothing, perhaps it would make sense to have an error classification for this in the future.
-  }
-}
-
-try {
-  // TODO: do we need to resolve here?
-  const configFile = path.resolve(configFileArg);
-  const result = evalConfig(configFile, request);
-  console.log(JSON.stringify(result));
-  process.exit(0);
-} catch (error) {
-  console.error(JSON.stringify(errorToJSON(error)));
-  process.exit(-1);
-}

From 42f77712d4fea7f02f49e0fc7f1a3fc1607f9253 Mon Sep 17 00:00:00 2001
From: Evan Bacon <baconbrix@gmail.com>
Date: Mon, 14 Sep 2020 19:19:53 +0200
Subject: [PATCH 19/19] revert error formatting

---
 packages/config/src/Config.ts | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/packages/config/src/Config.ts b/packages/config/src/Config.ts
index 2fe47ee1a8..80d0736d27 100644
--- a/packages/config/src/Config.ts
+++ b/packages/config/src/Config.ts
@@ -150,13 +150,7 @@ function getPackageJsonAndPath(
   config: Pick<ExpoConfig, 'nodeModulesPath'> = {}
 ): [PackageJSONConfig, string] {
   const packageJsonPath = getRootPackageJsonPath(projectRoot, config);
-
-  try {
-    return [JsonFile.read(packageJsonPath), packageJsonPath];
-  } catch (error) {
-    error.message = `Failed to parse package.json at ${packageJsonPath}\n${error.message}`;
-    throw error;
-  }
+  return [JsonFile.read(packageJsonPath), packageJsonPath];
 }
 
 export function readConfigJson(