feature: babel-core: add cloneInputAst (#10241)

Co-authored-by: coderaiser <coderaiser@cloudcmd.io>

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

@@ -81,6 +81,7 @@ export default function* loadPrivatePartialConfig(
     root: rootDir = ".",
     rootMode = "root",
     caller,
+    cloneInputAst = true,
   } = args;
   const absoluteCwd = path.resolve(cwd);
   const absoluteRootDir = yield* resolveRootMode(
@@ -110,6 +111,7 @@ export default function* loadPrivatePartialConfig(
   // Tack the passes onto the object itself so that, if this object is
   // passed back to Babel a second time, it will be in the right structure
   // to not change behavior.
+  options.cloneInputAst = cloneInputAst;
   options.babelrc = false;
   options.configFile = false;
   options.passPerPreset = false;

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

@@ -51,6 +51,10 @@ const ROOT_VALIDATORS: ValidatorSet = {
   code: (assertBoolean: Validator<$PropertyType<ValidatedOptions, "code">>),
   ast: (assertBoolean: Validator<$PropertyType<ValidatedOptions, "ast">>),
 
+  cloneInputAst: (assertBoolean: Validator<
+    $PropertyType<ValidatedOptions, "cloneInputAst">,
+  >),
+
   envName: (assertString: Validator<
     $PropertyType<ValidatedOptions, "envName">,
   >),
@@ -184,6 +188,7 @@ export type ValidatedOptions = {
   rootMode?: RootMode,
   code?: boolean,
   ast?: boolean,
+  cloneInputAst?: boolean,
   inputSourceMap?: RootInputSourceMapOption,
   envName?: string,
   caller?: CallerMetadata,

packages/babel-core/src/transformation/normalize-file.js

@@ -34,7 +34,11 @@ export default function* normalizeFile(
     } else if (ast.type !== "File") {
       throw new Error("AST root must be a Program or File node");
     }
-    ast = cloneDeep(ast);
+
+    const { cloneInputAst } = options;
+    if (cloneInputAst) {
+      ast = cloneDeep(ast);
+    }
   } else {
     ast = yield* parser(pluginPasses, options, code);
   }