Use scope for typescript export removals. Fixes babel#10033

Rewrites:

2080042 babel#9944

a6392bd babel#10019

packages/babel-plugin-transform-typescript/src/index.js

@@ -18,22 +18,8 @@ function isInType(path) {
   }
 }
 
-function isTSExportableDeclaration(node) {
-  // all kinds of type exports that transpile to nothing
-  // exception is enums, since they transpile to JS values
-  return (
-    t.isTSInterfaceDeclaration(node) ||
-    t.isTSTypeAliasDeclaration(node) ||
-    t.isTSModuleDeclaration(node) ||
-    (t.isVariableDeclaration(node) && node.declare) ||
-    (t.isClassDeclaration(node) && node.declare) ||
-    t.isTSDeclareFunction(node)
-  );
-}
-
 interface State {
   programPath: any;
-  exportableTSNames: Set<string>;
 }
 
 const PARSED_PARAMS = new WeakSet();
@@ -57,7 +43,6 @@ export default declare(
 
         Program(path, state: State) {
           state.programPath = path;
-          state.exportableTSNames = new Set();
 
           const { file } = state;
 
@@ -70,32 +55,6 @@ export default declare(
             }
           }
 
-          // find exportable top level type declarations
-          for (const stmt of path.get("body")) {
-            if (isTSExportableDeclaration(stmt.node)) {
-              if (stmt.node.id && stmt.node.id.name) {
-                state.exportableTSNames.add(stmt.node.id.name);
-              } else if (
-                stmt.node.declarations &&
-                stmt.node.declarations.length > 0
-              ) {
-                for (const declaration of stmt.node.declarations) {
-                  if (declaration.id && declaration.id.name) {
-                    state.exportableTSNames.add(declaration.id.name);
-                  }
-                }
-              }
-            } else if (
-              t.isExportNamedDeclaration(stmt.node) &&
-              stmt.node.specifiers.length === 0 &&
-              isTSExportableDeclaration(stmt.node.declaration) &&
-              stmt.node.declaration.id &&
-              stmt.node.declaration.id.name
-            ) {
-              state.exportableTSNames.add(stmt.node.declaration.id.name);
-            }
-          }
-
           // remove type imports
           for (const stmt of path.get("body")) {
             if (t.isImportDeclaration(stmt)) {
@@ -138,31 +97,30 @@ export default declare(
           }
         },
 
-        ExportNamedDeclaration(path, { exportableTSNames }) {
+        ExportNamedDeclaration(path) {
           // remove export declaration if it's exporting only types
           if (
             path.node.specifiers.length > 0 &&
-            !path.node.specifiers.find(
-              exportSpecifier =>
-                !exportableTSNames.has(exportSpecifier.local.name),
+            !path.node.specifiers.find(exportSpecifier =>
+              path.scope.hasOwnBinding(exportSpecifier.local.name),
             )
           ) {
             path.remove();
           }
         },
 
-        ExportSpecifier(path, { exportableTSNames }) {
+        ExportSpecifier(path) {
           // remove type exports
-          if (exportableTSNames.has(path.node.local.name)) {
+          if (!path.scope.hasOwnBinding(path.node.local.name)) {
             path.remove();
           }
         },
 
-        ExportDefaultDeclaration(path, { exportableTSNames }) {
+        ExportDefaultDeclaration(path) {
           // remove whole declaration if it's exporting a TS type
           if (
             t.isIdentifier(path.node.declaration) &&
-            exportableTSNames.has(path.node.declaration.name)
+            !path.scope.hasOwnBinding(path.node.declaration.name)
           ) {
             path.remove();
           }

packages/babel-plugin-transform-typescript/test/fixtures/declarations/erased/input.mjs

@@ -1,3 +1,4 @@
+; // Otherwise-empty file
 declare const x: number;
 declare function f(): void;
 declare class C {}
@@ -7,42 +8,3 @@ declare module M {}
 declare namespace N {}
 export interface I {}
 export type T = number;
-export class C2 {}
-
-export { x, f, E, C }; // only E
-export { M, N, I as I1, T as T1 }; // everything removed
-export {
-  x as x2,
-  f as f2,
-  C as CC2,
-  E as E2,
-  M as M2,
-  N as N2,
-  I as I2,
-  T as T2,
-  C2 as C3
-}; // only E and C2
-
-interface II2 {}
-type AA = {};
-enum BB {
-  K
-}
-enum BB {
-  L = "LL"
-}
-export { II2, AA, BB };  // only BB
-export { II2 as II3, AA as AA2 };  // everything removed
-export { BB as BB1 }; // as-is
-
-interface II3 {}
-type AA2 = {};
-enum BB2 {}
-function foo() {}
-export { II3 as default, AA2 as A, BB2 as BB3, foo }; // only BB2 and foo
-
-// export an interface before declaration
-export default Bar;
-export { Bar } // everything removed
-export { Bar as Bar2, C2 as C4 } // only C4
-interface Bar {}

packages/babel-plugin-transform-typescript/test/fixtures/declarations/erased/output.mjs

@@ -1,32 +1 @@
-export class C2 {}
-export { E }; // only E
-
-// everything removed
-export { E as E2, C2 as C3 }; // only E and C2
-
-var BB;
-
-(function (BB) {
-  BB[BB["K"] = 0] = "K";
-})(BB || (BB = {}));
-
-(function (BB) {
-  BB["L"] = "LL";
-})(BB || (BB = {}));
-
-export { BB }; // only BB
-
-// everything removed
-export { BB as BB1 }; // as-is
-
-var BB2;
-
-(function (BB2) {})(BB2 || (BB2 = {}));
-
-function foo() {}
-
-export { BB2 as BB3, foo }; // only BB2 and foo
-// export an interface before declaration
-
-// everything removed
-export { C2 as C4 }; // only C4
+; // Otherwise-empty file

packages/babel-plugin-transform-typescript/test/fixtures/exports/declare-namespace/input.mjs

@@ -0,0 +1,11 @@
+export class N {
+  f1(value: N.I) {
+    value.f2();
+  }
+}
+export declare namespace N {
+  export interface I {
+    f2();
+  }
+}
+export default N;

packages/babel-plugin-transform-typescript/test/fixtures/exports/declare-namespace/output.mjs

@@ -0,0 +1,7 @@
+export class N {
+  f1(value) {
+    value.f2();
+  }
+
+}
+export default N;

packages/babel-plugin-transform-typescript/test/fixtures/exports/declared-types/input.mjs

@@ -0,0 +1,48 @@
+declare const x: number;
+declare function f(): void;
+declare class C {}
+declare enum E {}
+declare module "m" {}
+declare module M {}
+declare namespace N {}
+export interface I {}
+export type T = number;
+export class C2 {}
+
+export { x, f, E, C }; // Not-even E
+export { M, N, I as I1, T as T1 }; // everything removed
+export {
+  x as x2,
+  f as f2,
+  C as CC2,
+  E as E2,
+  M as M2,
+  N as N2,
+  I as I2,
+  T as T2,
+  C2 as C3
+}; // only C2->C3
+
+interface II2 {}
+type AA = {};
+enum BB {
+  K
+}
+enum BB {
+  L = "LL"
+}
+export { II2, AA, BB };  // only BB
+export { II2 as II3, AA as AA2 };  // everything removed
+export { BB as BB1 }; // BB->BB1
+
+interface II3 {}
+type AA2 = {};
+enum BB2 {}
+function foo() {}
+export { II3 as default, AA2 as A, BB2 as BB3, foo }; // only BB2->BB3 and foo
+
+// export an interface before declaration
+export default Bar;
+export { Bar } // everything removed
+export { Bar as Bar2, C2 as C4 } // only C2->C4
+interface Bar {}

packages/babel-plugin-transform-typescript/test/fixtures/exports/interface/input.mjs

@@ -1,2 +1,3 @@
+; // Otherwise-empty file
 export interface I {}
 export default interface A {}

packages/babel-plugin-transform-typescript/test/fixtures/exports/interface/output.mjs

@@ -0,0 +1 @@
+; // Otherwise-empty file

packages/babel-plugin-transform-typescript/test/fixtures/exports/simple/input.mjs

@@ -0,0 +1,2 @@
+export class N {}
+export default N;

packages/babel-plugin-transform-typescript/test/fixtures/exports/simple/output.mjs

@@ -0,0 +1,2 @@
+export class N {}
+export default N;