Expose the envName as a programmatic and CLI option.

packages/babel-core/src/config/option-manager.js

@@ -103,7 +103,7 @@ class OptionManager {
   init(inputOpts: {}) {
     const args = validate("arguments", inputOpts);
 
-    const envName = getEnv();
+    const { envName = getEnv() } = args;
 
     const configChain = buildConfigChain(args, envName);
     if (!configChain) return null;
@@ -133,6 +133,7 @@ class OptionManager {
       .filter(plugins => plugins.length > 0)
       .map(plugins => ({ plugins }));
     opts.passPerPreset = opts.presets.length > 0;
+    opts.envName = envName;
 
     return {
       options: opts,

packages/babel-core/src/config/options.js

@@ -28,6 +28,10 @@ const ROOT_VALIDATORS: ValidatorSet = {
   >),
   code: (assertBoolean: Validator<$PropertyType<ValidatedOptions, "code">>),
   ast: (assertBoolean: Validator<$PropertyType<ValidatedOptions, "ast">>),
+
+  envName: (assertString: Validator<
+    $PropertyType<ValidatedOptions, "envName">,
+  >),
 };
 
 const NONPRESET_VALIDATORS: ValidatorSet = {
@@ -130,6 +134,7 @@ export type ValidatedOptions = {
   code?: boolean,
   ast?: boolean,
   inputSourceMap?: RootInputSourceMapOption,
+  envName?: string,
 
   extends?: string,
   env?: EnvSet<ValidatedOptions>,