Flow opaque type aliases (#5990)

lib/types.js

@@ -592,6 +592,13 @@ declare class BabelNodeDeclareTypeAlias extends BabelNode {
   right: any;
 }
 
+declare class BabelNodeDeclareOpaqueType extends BabelNode {
+  type: "DeclareOpaqueType";
+  id: any;
+  typeParameters: any;
+  supertype: any;
+}
+
 declare class BabelNodeDeclareVariable extends BabelNode {
   type: "DeclareVariable";
   id: any;
@@ -710,6 +717,14 @@ declare class BabelNodeTypeAlias extends BabelNode {
   right: any;
 }
 
+declare class BabelNodeOpaqueType extends BabelNode {
+  type: "OpaqueType";
+  id: any;
+  typeParameters: any;
+  supertype: any;
+  impltype: any;
+}
+
 declare class BabelNodeTypeCastExpression extends BabelNode {
   type: "TypeCastExpression";
   expression: any;
@@ -1217,7 +1232,7 @@ type BabelNodeBinary = BabelNodeBinaryExpression | BabelNodeLogicalExpression;
 type BabelNodeScopable = BabelNodeBlockStatement | BabelNodeCatchClause | BabelNodeDoWhileStatement | BabelNodeForInStatement | BabelNodeForStatement | BabelNodeFunctionDeclaration | BabelNodeFunctionExpression | BabelNodeProgram | BabelNodeObjectMethod | BabelNodeSwitchStatement | BabelNodeWhileStatement | BabelNodeArrowFunctionExpression | BabelNodeClassDeclaration | BabelNodeClassExpression | BabelNodeForOfStatement | BabelNodeClassMethod;
 type BabelNodeBlockParent = BabelNodeBlockStatement | BabelNodeDoWhileStatement | BabelNodeForInStatement | BabelNodeForStatement | BabelNodeFunctionDeclaration | BabelNodeFunctionExpression | BabelNodeProgram | BabelNodeObjectMethod | BabelNodeSwitchStatement | BabelNodeWhileStatement | BabelNodeArrowFunctionExpression | BabelNodeForOfStatement | BabelNodeClassMethod;
 type BabelNodeBlock = BabelNodeBlockStatement | BabelNodeProgram;
-type BabelNodeStatement = BabelNodeBlockStatement | BabelNodeBreakStatement | BabelNodeContinueStatement | BabelNodeDebuggerStatement | BabelNodeDoWhileStatement | BabelNodeEmptyStatement | BabelNodeExpressionStatement | BabelNodeForInStatement | BabelNodeForStatement | BabelNodeFunctionDeclaration | BabelNodeIfStatement | BabelNodeLabeledStatement | BabelNodeReturnStatement | BabelNodeSwitchStatement | BabelNodeThrowStatement | BabelNodeTryStatement | BabelNodeVariableDeclaration | BabelNodeWhileStatement | BabelNodeWithStatement | BabelNodeClassDeclaration | BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration | BabelNodeForOfStatement | BabelNodeImportDeclaration | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias | BabelNodeTSDeclareFunction | BabelNodeTSInterfaceDeclaration | BabelNodeTSTypeAliasDeclaration | BabelNodeTSEnumDeclaration | BabelNodeTSModuleDeclaration | BabelNodeTSImportEqualsDeclaration | BabelNodeTSExportAssignment | BabelNodeTSNamespaceExportDeclaration;
+type BabelNodeStatement = BabelNodeBlockStatement | BabelNodeBreakStatement | BabelNodeContinueStatement | BabelNodeDebuggerStatement | BabelNodeDoWhileStatement | BabelNodeEmptyStatement | BabelNodeExpressionStatement | BabelNodeForInStatement | BabelNodeForStatement | BabelNodeFunctionDeclaration | BabelNodeIfStatement | BabelNodeLabeledStatement | BabelNodeReturnStatement | BabelNodeSwitchStatement | BabelNodeThrowStatement | BabelNodeTryStatement | BabelNodeVariableDeclaration | BabelNodeWhileStatement | BabelNodeWithStatement | BabelNodeClassDeclaration | BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration | BabelNodeForOfStatement | BabelNodeImportDeclaration | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareOpaqueType | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias | BabelNodeOpaqueType | BabelNodeTSDeclareFunction | BabelNodeTSInterfaceDeclaration | BabelNodeTSTypeAliasDeclaration | BabelNodeTSEnumDeclaration | BabelNodeTSModuleDeclaration | BabelNodeTSImportEqualsDeclaration | BabelNodeTSExportAssignment | BabelNodeTSNamespaceExportDeclaration;
 type BabelNodeTerminatorless = BabelNodeBreakStatement | BabelNodeContinueStatement | BabelNodeReturnStatement | BabelNodeThrowStatement | BabelNodeYieldExpression | BabelNodeAwaitExpression;
 type BabelNodeCompletionStatement = BabelNodeBreakStatement | BabelNodeContinueStatement | BabelNodeReturnStatement | BabelNodeThrowStatement;
 type BabelNodeConditional = BabelNodeConditionalExpression | BabelNodeIfStatement;
@@ -1229,7 +1244,7 @@ type BabelNodeForXStatement = BabelNodeForInStatement | BabelNodeForOfStatement;
 type BabelNodeFunction = BabelNodeFunctionDeclaration | BabelNodeFunctionExpression | BabelNodeObjectMethod | BabelNodeArrowFunctionExpression | BabelNodeClassMethod;
 type BabelNodeFunctionParent = BabelNodeFunctionDeclaration | BabelNodeFunctionExpression | BabelNodeProgram | BabelNodeObjectMethod | BabelNodeArrowFunctionExpression | BabelNodeClassMethod;
 type BabelNodePureish = BabelNodeFunctionDeclaration | BabelNodeFunctionExpression | BabelNodeStringLiteral | BabelNodeNumericLiteral | BabelNodeNullLiteral | BabelNodeBooleanLiteral | BabelNodeArrowFunctionExpression | BabelNodeClassDeclaration | BabelNodeClassExpression;
-type BabelNodeDeclaration = BabelNodeFunctionDeclaration | BabelNodeVariableDeclaration | BabelNodeClassDeclaration | BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration | BabelNodeImportDeclaration | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias | BabelNodeTSDeclareFunction | BabelNodeTSInterfaceDeclaration | BabelNodeTSTypeAliasDeclaration | BabelNodeTSEnumDeclaration | BabelNodeTSModuleDeclaration;
+type BabelNodeDeclaration = BabelNodeFunctionDeclaration | BabelNodeVariableDeclaration | BabelNodeClassDeclaration | BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration | BabelNodeImportDeclaration | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareOpaqueType | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias | BabelNodeOpaqueType | BabelNodeTSDeclareFunction | BabelNodeTSInterfaceDeclaration | BabelNodeTSTypeAliasDeclaration | BabelNodeTSEnumDeclaration | BabelNodeTSModuleDeclaration;
 type BabelNodePatternLike = BabelNodeIdentifier | BabelNodeRestElement | BabelNodeAssignmentPattern | BabelNodeArrayPattern | BabelNodeObjectPattern;
 type BabelNodeLVal = BabelNodeIdentifier | BabelNodeMemberExpression | BabelNodeRestElement | BabelNodeAssignmentPattern | BabelNodeArrayPattern | BabelNodeObjectPattern | BabelNodeTSParameterProperty;
 type BabelNodeTSEntityName = BabelNodeIdentifier | BabelNodeTSQualifiedName;
@@ -1245,9 +1260,9 @@ type BabelNodeClass = BabelNodeClassDeclaration | BabelNodeClassExpression;
 type BabelNodeModuleDeclaration = BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration | BabelNodeImportDeclaration;
 type BabelNodeExportDeclaration = BabelNodeExportAllDeclaration | BabelNodeExportDefaultDeclaration | BabelNodeExportNamedDeclaration;
 type BabelNodeModuleSpecifier = BabelNodeExportSpecifier | BabelNodeImportDefaultSpecifier | BabelNodeImportNamespaceSpecifier | BabelNodeImportSpecifier | BabelNodeExportDefaultSpecifier | BabelNodeExportNamespaceSpecifier;
-type BabelNodeFlow = BabelNodeAnyTypeAnnotation | BabelNodeArrayTypeAnnotation | BabelNodeBooleanTypeAnnotation | BabelNodeBooleanLiteralTypeAnnotation | BabelNodeNullLiteralTypeAnnotation | BabelNodeClassImplements | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeDeclaredPredicate | BabelNodeExistsTypeAnnotation | BabelNodeFunctionTypeAnnotation | BabelNodeFunctionTypeParam | BabelNodeGenericTypeAnnotation | BabelNodeInferredPredicate | BabelNodeInterfaceExtends | BabelNodeInterfaceDeclaration | BabelNodeIntersectionTypeAnnotation | BabelNodeMixedTypeAnnotation | BabelNodeEmptyTypeAnnotation | BabelNodeNullableTypeAnnotation | BabelNodeNumberLiteralTypeAnnotation | BabelNodeNumberTypeAnnotation | BabelNodeStringLiteralTypeAnnotation | BabelNodeStringTypeAnnotation | BabelNodeThisTypeAnnotation | BabelNodeTupleTypeAnnotation | BabelNodeTypeofTypeAnnotation | BabelNodeTypeAlias | BabelNodeTypeCastExpression | BabelNodeObjectTypeAnnotation | BabelNodeObjectTypeCallProperty | BabelNodeObjectTypeIndexer | BabelNodeObjectTypeProperty | BabelNodeObjectTypeSpreadProperty | BabelNodeQualifiedTypeIdentifier | BabelNodeUnionTypeAnnotation | BabelNodeVoidTypeAnnotation | BabelNodeTypeAnnotation | BabelNodeTypeParameterInstantiation | BabelNodeTypeParameterDeclaration | BabelNodeTypeParameter;
+type BabelNodeFlow = BabelNodeAnyTypeAnnotation | BabelNodeArrayTypeAnnotation | BabelNodeBooleanTypeAnnotation | BabelNodeBooleanLiteralTypeAnnotation | BabelNodeNullLiteralTypeAnnotation | BabelNodeClassImplements | BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareOpaqueType | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeDeclaredPredicate | BabelNodeExistsTypeAnnotation | BabelNodeFunctionTypeAnnotation | BabelNodeFunctionTypeParam | BabelNodeGenericTypeAnnotation | BabelNodeInferredPredicate | BabelNodeInterfaceExtends | BabelNodeInterfaceDeclaration | BabelNodeIntersectionTypeAnnotation | BabelNodeMixedTypeAnnotation | BabelNodeEmptyTypeAnnotation | BabelNodeNullableTypeAnnotation | BabelNodeNumberLiteralTypeAnnotation | BabelNodeNumberTypeAnnotation | BabelNodeStringLiteralTypeAnnotation | BabelNodeStringTypeAnnotation | BabelNodeThisTypeAnnotation | BabelNodeTupleTypeAnnotation | BabelNodeTypeofTypeAnnotation | BabelNodeTypeAlias | BabelNodeOpaqueType | BabelNodeTypeCastExpression | BabelNodeObjectTypeAnnotation | BabelNodeObjectTypeCallProperty | BabelNodeObjectTypeIndexer | BabelNodeObjectTypeProperty | BabelNodeObjectTypeSpreadProperty | BabelNodeQualifiedTypeIdentifier | BabelNodeUnionTypeAnnotation | BabelNodeVoidTypeAnnotation | BabelNodeTypeAnnotation | BabelNodeTypeParameterInstantiation | BabelNodeTypeParameterDeclaration | BabelNodeTypeParameter;
 type BabelNodeFlowBaseAnnotation = BabelNodeAnyTypeAnnotation | BabelNodeBooleanTypeAnnotation | BabelNodeNullLiteralTypeAnnotation | BabelNodeMixedTypeAnnotation | BabelNodeEmptyTypeAnnotation | BabelNodeNumberTypeAnnotation | BabelNodeStringTypeAnnotation | BabelNodeThisTypeAnnotation | BabelNodeVoidTypeAnnotation;
-type BabelNodeFlowDeclaration = BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias;
+type BabelNodeFlowDeclaration = BabelNodeDeclareClass | BabelNodeDeclareFunction | BabelNodeDeclareInterface | BabelNodeDeclareModule | BabelNodeDeclareModuleExports | BabelNodeDeclareTypeAlias | BabelNodeDeclareOpaqueType | BabelNodeDeclareVariable | BabelNodeDeclareExportDeclaration | BabelNodeDeclareExportAllDeclaration | BabelNodeInterfaceDeclaration | BabelNodeTypeAlias | BabelNodeOpaqueType;
 type BabelNodeFlowPredicate = BabelNodeDeclaredPredicate | BabelNodeInferredPredicate;
 type BabelNodeJSX = BabelNodeJSXAttribute | BabelNodeJSXClosingElement | BabelNodeJSXElement | BabelNodeJSXEmptyExpression | BabelNodeJSXExpressionContainer | BabelNodeJSXSpreadChild | BabelNodeJSXIdentifier | BabelNodeJSXMemberExpression | BabelNodeJSXNamespacedName | BabelNodeJSXOpeningElement | BabelNodeJSXSpreadAttribute | BabelNodeJSXText;
 type BabelNodeTSTypeElement = BabelNodeTSCallSignatureDeclaration | BabelNodeTSConstructSignatureDeclaration | BabelNodeTSPropertySignature | BabelNodeTSMethodSignature | BabelNodeTSIndexSignature;
@@ -1338,6 +1353,7 @@ declare module "babel-types" {
   declare function declareModule(id: any, body: any): BabelNodeDeclareModule;
   declare function declareModuleExports(typeAnnotation: any): BabelNodeDeclareModuleExports;
   declare function declareTypeAlias(id: any, typeParameters: any, right: any): BabelNodeDeclareTypeAlias;
+  declare function declareOpaqueType(id: any, typeParameters: any, supertype: any): BabelNodeDeclareOpaqueType;
   declare function declareVariable(id: any): BabelNodeDeclareVariable;
   declare function declareExportDeclaration(declaration: any, specifiers: any, source: any): BabelNodeDeclareExportDeclaration;
   declare function declareExportAllDeclaration(source: any): BabelNodeDeclareExportAllDeclaration;
@@ -1361,6 +1377,7 @@ declare module "babel-types" {
   declare function tupleTypeAnnotation(types: any): BabelNodeTupleTypeAnnotation;
   declare function typeofTypeAnnotation(argument: any): BabelNodeTypeofTypeAnnotation;
   declare function typeAlias(id: any, typeParameters: any, right: any): BabelNodeTypeAlias;
+  declare function opaqueType(id: any, typeParameters: any, supertype: any, impltype: any): BabelNodeOpaqueType;
   declare function typeCastExpression(expression: any, typeAnnotation: any): BabelNodeTypeCastExpression;
   declare function objectTypeAnnotation(properties: any, indexers: any, callProperties: any): BabelNodeObjectTypeAnnotation;
   declare function objectTypeCallProperty(value: any): BabelNodeObjectTypeCallProperty;
@@ -1530,6 +1547,7 @@ declare module "babel-types" {
   declare function isDeclareModule(node: Object, opts?: Object): boolean;
   declare function isDeclareModuleExports(node: Object, opts?: Object): boolean;
   declare function isDeclareTypeAlias(node: Object, opts?: Object): boolean;
+  declare function isDeclareOpaqueType(node: Object, opts?: Object): boolean;
   declare function isDeclareVariable(node: Object, opts?: Object): boolean;
   declare function isDeclareExportDeclaration(node: Object, opts?: Object): boolean;
   declare function isDeclareExportAllDeclaration(node: Object, opts?: Object): boolean;
@@ -1553,6 +1571,7 @@ declare module "babel-types" {
   declare function isTupleTypeAnnotation(node: Object, opts?: Object): boolean;
   declare function isTypeofTypeAnnotation(node: Object, opts?: Object): boolean;
   declare function isTypeAlias(node: Object, opts?: Object): boolean;
+  declare function isOpaqueType(node: Object, opts?: Object): boolean;
   declare function isTypeCastExpression(node: Object, opts?: Object): boolean;
   declare function isObjectTypeAnnotation(node: Object, opts?: Object): boolean;
   declare function isObjectTypeCallProperty(node: Object, opts?: Object): boolean;

packages/babel-generator/src/generators/flow.js

@@ -95,6 +95,14 @@ export function DeclareTypeAlias(node: Object) {
   this.TypeAlias(node);
 }
 
+export function DeclareOpaqueType(node: Object, parent: Object) {
+  if (!t.isDeclareExportDeclaration(parent)) {
+    this.word("declare");
+    this.space();
+  }
+  this.OpaqueType(node);
+}
+
 export function DeclareVariable(node: Object, parent: Object) {
   if (!t.isDeclareExportDeclaration(parent)) {
     this.word("declare");
@@ -303,6 +311,27 @@ export function TypeAlias(node: Object) {
   this.semicolon();
 }
 
+export function OpaqueType(node: Object) {
+  this.word("opaque");
+  this.space();
+  this.word("type");
+  this.space();
+  this.print(node.id, node);
+  this.print(node.typeParameters, node);
+  if (node.supertype) {
+    this.token(":");
+    this.space();
+    this.print(node.supertype, node);
+  }
+  if (node.impltype) {
+    this.space();
+    this.token("=");
+    this.space();
+    this.print(node.impltype, node);
+  }
+  this.semicolon();
+}
+
 export function ObjectTypeAnnotation(node: Object) {
   if (node.exact) {
     this.token("{|");

packages/babel-generator/test/fixtures/flow/declare-exports/actual.js

@@ -24,3 +24,9 @@ declare module B {
 }
 
 declare module "foo" { declare export type * from "bar"; }
+declare export opaque type Foo;
+declare export opaque type Bar<T>;
+declare export opaque type Baz: Foo;
+declare export opaque type Foo<T>: Bar<T>;
+declare export opaque type Foo<T>: Bar;
+declare export opaque type Foo: Bar<T>;

packages/babel-generator/test/fixtures/flow/declare-exports/expected.js

@@ -32,4 +32,10 @@ declare module B {
 }
 declare module "foo" {
   declare export type * from "bar";
-}
+}
+declare export opaque type Foo;
+declare export opaque type Bar<T>;
+declare export opaque type Baz: Foo;
+declare export opaque type Foo<T>: Bar<T>;
+declare export opaque type Foo<T>: Bar;
+declare export opaque type Foo: Bar<T>;

packages/babel-generator/test/fixtures/flow/declare-statements/actual.js

@@ -19,3 +19,7 @@ declare type B = {
 declare interface I { foo: string }
 declare interface I<T> { foo: T }
 declare module.exports: { foo: string }
+declare opaque type Foo<T>: Bar<T>;
+declare opaque type ID;
+declare opaque type num: number;
+declare opaque type NumArray;

packages/babel-generator/test/fixtures/flow/declare-statements/expected.js

@@ -37,4 +37,8 @@ declare interface I<T> {
 }
 declare module.exports: {
   foo: string
-}
+}
+declare opaque type Foo<T>: Bar<T>;
+declare opaque type ID;
+declare opaque type num: number;
+declare opaque type NumArray;

packages/babel-generator/test/fixtures/flow/opaque-type-alias/actual.js

@@ -0,0 +1,14 @@
+opaque type ID = string;
+opaque type Foo<T> = Bar<T>;
+opaque type Maybe<T> = _Maybe<T, *>;
+export opaque type Foo = number;
+
+opaque type union =
+ | {type: "A"}
+ | {type: "B"}
+;
+
+opaque type overloads =
+  & ((x: string) => number)
+  & ((x: number) => string)
+;

packages/babel-generator/test/fixtures/flow/opaque-type-alias/expected.js

@@ -0,0 +1,10 @@
+opaque type ID = string;
+opaque type Foo<T> = Bar<T>;
+opaque type Maybe<T> = _Maybe<T, *>;
+export opaque type Foo = number;
+opaque type union = {
+  type: "A"
+} | {
+  type: "B"
+};
+opaque type overloads = (x: string) => number & (x: number) => string;

packages/babel-plugin-transform-flow-comments/test/fixtures/flow-comments/opaque-type-alias/actual.js

@@ -0,0 +1,15 @@
+function a() {}
+opaque type A = number;
+opaque type B = {
+  name: string;
+};
+
+opaque type union =
+ | {type: "A"}
+ | {type: "B"}
+;
+
+opaque type overloads =
+  & ((x: string) => number)
+  & ((x: number) => string)
+;

packages/babel-plugin-transform-flow-comments/test/fixtures/flow-comments/opaque-type-alias/expected.js

@@ -0,0 +1,16 @@
+function a() {}
+/*:: opaque type A = number;*/
+
+/*:: opaque type B = {
+  name: string;
+};*/
+
+/*:: opaque type union =
+ | {type: "A"}
+ | {type: "B"}
+;*/
+
+/*:: opaque type overloads =
+  & ((x: string) => number)
+  & ((x: number) => string)
+;*/

packages/babel-plugin-transform-flow-strip-types/test/fixtures/strip-types/strip-opaque-type-alias/actual.js

@@ -0,0 +1,16 @@
+opaque type ID = string;
+opaque type Foo<T> = Bar<T>
+export opaque type Foo = number;
+
+opaque type union =
+ | {type: "A"}
+ | {type: "B"}
+;
+
+opaque type overloads =
+  & ((x: string) => number)
+  & ((x: number) => string)
+;
+
+declare opaque type Foo: Bar;
+declare export opaque type Foo: Bar;

packages/babel-types/README.md

@@ -507,6 +507,21 @@ Aliases: `Flow`, `FlowDeclaration`, `Statement`, `Declaration`
 
 ---
 
+### declareOpaqueType
+```javascript
+t.declareOpaqueType(id, typeParameters, supertype)
+```
+
+See also `t.isDeclareOpaqueType(node, opts)` and `t.assertDeclareOpaqueType(node, opts)`.
+
+Aliases: `Flow`, `FlowDeclaration`, `Statement`, `Declaration`
+
+ - `id` (required)
+ - `typeParameters` (required)
+ - `supertype` (required)
+
+---
+
 ### declareTypeAlias
 ```javascript
 t.declareTypeAlias(id, typeParameters, right)
@@ -1505,6 +1520,22 @@ Aliases: `Flow`, `UserWhitespacable`
 
 ---
 
+### opaqueType
+```javascript
+t.opaqueType(id, typeParameters, supertype, impltype)
+```
+
+See also `t.isOpaqueType(node, opts)` and `t.assertOpaqueType(node, opts)`.
+
+Aliases: `Flow`, `FlowDeclaration`, `Statement`, `Declaration`
+
+ - `id` (required)
+ - `typeParameters` (required)
+ - `supertype` (required)
+ - `impltype` (required)
+
+---
+
 ### parenthesizedExpression
 ```javascript
 t.parenthesizedExpression(expression)

packages/babel-types/src/definitions/flow.js

@@ -88,6 +88,14 @@ defineType("DeclareTypeAlias", {
   },
 });
 
+defineType("DeclareOpaqueType", {
+  visitor: ["id", "typeParameters", "supertype"],
+  aliases: ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  fields: {
+    // todo
+  },
+});
+
 defineType("DeclareVariable", {
   visitor: ["id"],
   aliases: ["Flow", "FlowDeclaration", "Statement", "Declaration"],
@@ -252,6 +260,14 @@ defineType("TypeAlias", {
   },
 });
 
+defineType("OpaqueType", {
+  visitor: ["id", "typeParameters", "supertype", "impltype"],
+  aliases: ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  fields: {
+    // todo
+  },
+});
+
 defineType("TypeCastExpression", {
   visitor: ["expression", "typeAnnotation"],
   aliases: ["Flow", "ExpressionWrapper", "Expression"],

packages/babel-types/src/retrievers.js

@@ -70,6 +70,7 @@ getBindingIdentifiers.keys = {
   DeclareVariable: ["id"],
   InterfaceDeclaration: ["id"],
   TypeAlias: ["id"],
+  OpaqueType: ["id"],
 
   CatchClause: ["param"],
   LabeledStatement: ["label"],