fix(@babel/traverse): Update to v7.0 stable release (#47183)

* fix(@babel/traverse): Update to v7.0 stable release

* feat(@babel/traverse): Add top‑level `visitors` export

types/babel__traverse/babel__traverse-tests.ts

@@ -1,14 +1,16 @@
-import traverse, { Visitor, NodePath, Hub } from '@babel/traverse';
+import traverse, { Hub, NodePath, Visitor, visitors } from '@babel/traverse';
 import * as t from '@babel/types';
 
 // Examples from: https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md
 const MyVisitor: Visitor = {
     Identifier: {
         enter(path) {
+            path.type; // $ExpectType "Identifier"
             const x: NodePath<t.Identifier> = path;
             console.log('Entered!');
         },
         exit(path) {
+            path.type; // $ExpectType "Identifier"
             const x: NodePath<t.Identifier> = path;
             console.log('Exited!');
         },
@@ -17,6 +19,7 @@ const MyVisitor: Visitor = {
 
 const MyVisitor2: Visitor = {
     Identifier(path) {
+        path.type; // $ExpectType "Identifier"
         console.log('Visiting: ' + path.node.name);
     },
 };
@@ -26,6 +29,10 @@ declare const ast: t.Node;
 
 traverse(ast, {
     enter(path) {
+        let actualType = path.type;
+        const expectedType: t.Node['type'] = actualType;
+        actualType = ast.type;
+
         const node = path.node;
         if (t.isIdentifier(node) && node.name === 'n') {
             node.name = 'x';
@@ -37,27 +44,31 @@ traverse(ast, {
 
 const v1: Visitor = {
     BinaryExpression(path) {
+        path.type; // $ExpectType "BinaryExpression"
+
         if (t.isIdentifier(path.node.left)) {
             // ...
         }
-        path.replaceWith(t.binaryExpression('**', path.node.left, t.numericLiteral(2))) as [
-            NodePath<t.BinaryExpression>,
-        ];
+        // $ExpectType [NodePath<BinaryExpression>]
+        path.replaceWith(t.binaryExpression('**', path.node.left, t.numericLiteral(2)));
         path.parentPath.replaceWith(
             t.expressionStatement(t.stringLiteral("Anyway the wind blows, doesn't really matter to me, to me.")),
         );
-        path.replaceInline(t.binaryExpression('**', path.node.left, t.numericLiteral(2))) as [
-            NodePath<t.BinaryExpression>,
-        ];
+        // $ExpectType [NodePath<BinaryExpression>]
+        path.replaceInline(t.binaryExpression('**', path.node.left, t.numericLiteral(2)));
+        // $ExpectType [NodePath<Node>]
         path.replaceWithSourceString('3 * 4') as [NodePath];
+        // $ExpectType [NodePath<BinaryExpression>, NodePath<ExpressionStatement>]
         path.replaceInline([
             t.binaryExpression('**', path.node.left, t.numericLiteral(2)),
             t.expressionStatement(t.stringLiteral("Anyway the wind blows, doesn't really matter to me, to me.")),
-        ]) as [NodePath<t.BinaryExpression>, NodePath<t.ExpressionStatement>];
+        ] as const);
         path.parentPath.remove();
     },
 
     Identifier(path) {
+        path.type; // $ExpectType "Identifier"
+
         if (path.isReferencedIdentifier()) {
             // ...
         }
@@ -67,14 +78,19 @@ const v1: Visitor = {
     },
 
     ReturnStatement(path) {
+        path.type; // $ExpectType "ReturnStatement"
+
+        // $ExpectType [NodePath<ExpressionStatement>, NodePath<ExpressionStatement>, NodePath<ExpressionStatement>]
         path.replaceWithMultiple([
             t.expressionStatement(t.stringLiteral('Is this the real life?')),
             t.expressionStatement(t.stringLiteral('Is this just fantasy?')),
             t.expressionStatement(t.stringLiteral('(Enjoy singing the rest of the song in your head)')),
-        ]) as [NodePath<t.ExpressionStatement>, NodePath<t.ExpressionStatement>, NodePath<t.ExpressionStatement>];
+        ] as const);
     },
 
     FunctionDeclaration(path, state) {
+        path.type; // $ExpectType "FunctionDeclaration"
+
         path.replaceWithSourceString(`function add(a, b) {
             return a + b;
         }`);
@@ -114,6 +130,8 @@ const v1: Visitor = {
         path.unshiftContainer('returnType', t.stringLiteral('hello'));
     },
     ExportDefaultDeclaration(path) {
+        path.type; // $ExpectType "ExportDefaultDeclaration"
+
         {
             const [stringPath, booleanPath] = path.replaceWithMultiple([
                 t.stringLiteral('hello'),
@@ -146,6 +164,8 @@ const v1: Visitor = {
         }
     },
     Program(path) {
+        path.type; // $ExpectType "Program"
+
         {
             const [newPath] = path.unshiftContainer('body', t.stringLiteral('hello'));
             // $ExpectType NodePath<StringLiteral>
@@ -202,6 +222,8 @@ const v1: Visitor = {
 // Binding.kind
 const BindingKindTest: Visitor = {
     Identifier(path) {
+        path.type; // $ExpectType "Identifier"
+
         const kind = path.scope.getBinding('str')!.kind;
         kind === 'module';
         kind === 'const';
@@ -218,18 +240,28 @@ interface SomeVisitorState {
 
 const VisitorStateTest: Visitor<SomeVisitorState> = {
     enter(path, state) {
+        let actualType = path.type;
+        const expectedType: t.Node['type'] = actualType;
+        actualType = ast.type;
+
         // $ExpectType SomeVisitorState
         state;
         // $ExpectType SomeVisitorState
         this;
     },
     exit(path, state) {
+        let actualType = path.type;
+        const expectedType: t.Node['type'] = actualType;
+        actualType = ast.type;
+
         // $ExpectType SomeVisitorState
         state;
         // $ExpectType SomeVisitorState
         this;
     },
     Identifier(path, state) {
+        path.type; // $ExpectType "Identifier"
+
         // $ExpectType SomeVisitorState
         state;
         // $ExpectType SomeVisitorState
@@ -237,12 +269,16 @@ const VisitorStateTest: Visitor<SomeVisitorState> = {
     },
     FunctionDeclaration: {
         enter(path, state) {
+            path.type; // $ExpectType "FunctionDeclaration"
+
             // $ExpectType SomeVisitorState
             state;
             // $ExpectType SomeVisitorState
             this;
         },
         exit(path, state) {
+            path.type; // $ExpectType "FunctionDeclaration"
+
             // $ExpectType SomeVisitorState
             state;
             // $ExpectType SomeVisitorState
@@ -258,8 +294,43 @@ const VisitorAliasTest: Visitor = {
     Expression() {},
 };
 
-const hub = new Hub('file', { options: '' });
+const hub = new Hub();
 // $ExpectType string | undefined
 hub.getCode();
 
-traverse.visitors.merge([{ Expression(path) { } }, { Expression(path) { } }]);
+declare const astExpression: t.Expression;
+
+traverse.visitors; // $ExpectType typeof visitors
+
+// $ExpectType Visitor<unknown>
+visitors.merge([
+    {
+        Expression(path) {
+            let actualType = path.type;
+            const expectedType: t.Expression['type'] = actualType;
+            actualType = astExpression.type;
+        },
+    },
+    {
+        Expression(path) {
+            let actualType = path.type;
+            const expectedType: t.Expression['type'] = actualType;
+            actualType = astExpression.type;
+        },
+    },
+]);
+
+function testNullishPath(
+    optionalPath: NodePath<t.Node | null>,
+    nullPath: NodePath<null>,
+    undefinedPath: NodePath<undefined>,
+    unknownPath: NodePath<unknown>,
+) {
+    nullPath.type; // $ExpectType undefined
+    undefinedPath.type; // $ExpectType undefined
+    unknownPath.type; // $ExpectType string | undefined
+
+    let actualType = optionalPath.type;
+    const expectedType: t.Node['type'] | undefined = actualType;
+    actualType = expectedType;
+}

types/babel__traverse/tslint.json

@@ -1,6 +1 @@
-{
-    "extends": "dtslint/dt.json",
-    "rules": {
-        "no-unnecessary-type-assertion": false
-    }
-}
+{ "extends": "dtslint/dt.json" }