[ts 4.7] Support optional variance annotations

packages/babel-generator/src/generators/typescript.ts

@@ -25,6 +25,16 @@ export function TSTypeParameterInstantiation(
 export { TSTypeParameterInstantiation as TSTypeParameterDeclaration };
 
 export function TSTypeParameter(this: Printer, node: t.TSTypeParameter) {
+  if (node.in) {
+    this.word("in");
+    this.space();
+  }
+
+  if (node.out) {
+    this.word("out");
+    this.space();
+  }
+
   this.word(
     !process.env.BABEL_8_BREAKING
       ? (node.name as unknown as string)

packages/babel-parser/src/plugins/typescript/index.js

@@ -47,7 +47,8 @@ type TsModifier =
   | "declare"
   | "static"
   | "override"
-  | N.Accessibility;
+  | N.Accessibility
+  | N.VarianceAnnotations;
 
 function nonNull<T>(x: ?T): T {
   if (x == null) {
@@ -153,6 +154,10 @@ const TSErrors = ParseErrorEnum`typescript`(_ => ({
   InvalidModifierOnTypeMember: _<{| modifier: TsModifier |}>(
     ({ modifier }) => `'${modifier}' modifier cannot appear on a type member.`,
   ),
+  InvalidModifierOnTypeParameter: _<{| modifier: TsModifier |}>(
+    ({ modifier }) =>
+      `'${modifier}' modifier cannot appear on a type parameter.`,
+  ),
   InvalidModifiersOrder: _<{| orderedModifiers: [TsModifier, TsModifier] |}>(
     ({ orderedModifiers }) =>
       `'${orderedModifiers[0]}' modifier must precede '${orderedModifiers[1]}' modifier.`,
@@ -286,6 +291,10 @@ function tsIsAccessModifier(modifier: string): boolean %checks {
   );
 }
 
+function tsIsVarianceAnnotations(modifier: string): boolean %checks {
+  return modifier === "in" || modifier === "out";
+}
+
 export default (superClass: Class<Parser>): Class<Parser> =>
   class extends superClass {
     getScopeHandler(): Class<TypeScriptScopeHandler> {
@@ -324,7 +333,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       allowedModifiers: T[],
       stopOnStartOfClassStaticBlock?: boolean,
     ): ?T {
-      if (!tokenIsIdentifier(this.state.type)) {
+      if (!tokenIsIdentifier(this.state.type) && this.state.type !== tt._in) {
         return undefined;
       }
 
@@ -350,6 +359,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       allowedModifiers,
       disallowedModifiers,
       stopOnStartOfClassStaticBlock,
+      errorTemplate = TSErrors.InvalidModifierOnTypeMember,
     }: {
       modified: {
         [key: TsModifier]: ?true,
@@ -358,6 +368,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       allowedModifiers: TsModifier[],
       disallowedModifiers?: TsModifier[],
       stopOnStartOfClassStaticBlock?: boolean,
+      // FIXME: make sure errorTemplate can receive `modifier`
+      errorTemplate?: any,
     }): void {
       const enforceOrder = (loc, modifier, before, after) => {
         if (modifier === before && modified[after]) {
@@ -401,6 +413,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
             modified.accessibility = modifier;
           }
+        } else if (tsIsVarianceAnnotations(modifier)) {
+          if (modified[modifier]) {
+            this.raise(TSErrors.DuplicateModifier, { at: startLoc, modifier });
+          }
+          modified[modifier] = true;
+
+          enforceOrder(startLoc, modifier, "in", "out");
         } else {
           if (Object.hasOwnProperty.call(modified, modifier)) {
             this.raise(TSErrors.DuplicateModifier, { at: startLoc, modifier });
@@ -417,7 +436,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         }
 
         if (disallowedModifiers?.includes(modifier)) {
-          this.raise(TSErrors.InvalidModifierOnTypeMember, {
+          this.raise(errorTemplate, {
             at: startLoc,
             modifier,
           });
@@ -635,6 +654,22 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
     tsParseTypeParameter(): N.TsTypeParameter {
       const node: N.TsTypeParameter = this.startNode();
+
+      this.tsParseModifiers({
+        modified: node,
+        allowedModifiers: ["in", "out"],
+        disallowedModifiers: [
+          "public",
+          "private",
+          "protected",
+          "readonly",
+          "declare",
+          "abstract",
+          "override",
+        ],
+        errorTemplate: TSErrors.InvalidModifierOnTypeParameter,
+      });
+
       node.name = this.tsParseTypeParameterName();
       node.constraint = this.tsEatThenParseType(tt._extends);
       node.default = this.tsEatThenParseType(tt.eq);

packages/babel-parser/src/types.js

@@ -707,6 +707,8 @@ export type ModuleExpression = NodeBase & {
 // TypeScript access modifiers
 export type Accessibility = "public" | "protected" | "private";
 
+export type VarianceAnnotations = "in" | "out";
+
 export type PatternBase = HasDecorators & {
   // TODO: All not in spec
   // Flow/TypeScript only:
@@ -1040,6 +1042,8 @@ export type TsTypeParameter = NodeBase & {
   type: "TSTypeParameter",
   // TODO(Babel-8): remove string type support
   name: string | Identifier,
+  in?: boolean,
+  out?: boolean,
   constraint?: TsType,
   default?: TsType,
 };

packages/babel-parser/test/fixtures/typescript/types/variance-annotations-babel-7/input.ts

@@ -0,0 +1,11 @@
+type Covariant<out T> = {
+    x: T;
+}
+
+type Contravariant<in T> = {
+    f: (x: T) => void;
+}
+
+type Invariant<in out T> = {
+    f: (x: T) => T;
+}

packages/babel-parser/test/fixtures/typescript/types/variance-annotations-babel-7/options.json

@@ -0,0 +1,3 @@
+{
+  "BABEL_8_BREAKING": false
+}

packages/babel-parser/test/fixtures/typescript/types/variance-annotations-babel-7/output.json

@@ -0,0 +1,215 @@
+{
+  "type": "File",
+  "start":0,"end":144,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":11,"column":1,"index":144}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":144,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":11,"column":1,"index":144}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":0,"end":37,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":3,"column":1,"index":37}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":14,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":14,"index":14},"identifierName":"Covariant"},
+          "name": "Covariant"
+        },
+        "typeParameters": {
+          "type": "TSTypeParameterDeclaration",
+          "start":14,"end":21,"loc":{"start":{"line":1,"column":14,"index":14},"end":{"line":1,"column":21,"index":21}},
+          "params": [
+            {
+              "type": "TSTypeParameter",
+              "start":15,"end":20,"loc":{"start":{"line":1,"column":15,"index":15},"end":{"line":1,"column":20,"index":20}},
+              "out": true,
+              "name": "T"
+            }
+          ]
+        },
+        "typeAnnotation": {
+          "type": "TSTypeLiteral",
+          "start":24,"end":37,"loc":{"start":{"line":1,"column":24,"index":24},"end":{"line":3,"column":1,"index":37}},
+          "members": [
+            {
+              "type": "TSPropertySignature",
+              "start":30,"end":35,"loc":{"start":{"line":2,"column":4,"index":30},"end":{"line":2,"column":9,"index":35}},
+              "key": {
+                "type": "Identifier",
+                "start":30,"end":31,"loc":{"start":{"line":2,"column":4,"index":30},"end":{"line":2,"column":5,"index":31},"identifierName":"x"},
+                "name": "x"
+              },
+              "computed": false,
+              "typeAnnotation": {
+                "type": "TSTypeAnnotation",
+                "start":31,"end":34,"loc":{"start":{"line":2,"column":5,"index":31},"end":{"line":2,"column":8,"index":34}},
+                "typeAnnotation": {
+                  "type": "TSTypeReference",
+                  "start":33,"end":34,"loc":{"start":{"line":2,"column":7,"index":33},"end":{"line":2,"column":8,"index":34}},
+                  "typeName": {
+                    "type": "Identifier",
+                    "start":33,"end":34,"loc":{"start":{"line":2,"column":7,"index":33},"end":{"line":2,"column":8,"index":34},"identifierName":"T"},
+                    "name": "T"
+                  }
+                }
+              }
+            }
+          ]
+        }
+      },
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":39,"end":92,"loc":{"start":{"line":5,"column":0,"index":39},"end":{"line":7,"column":1,"index":92}},
+        "id": {
+          "type": "Identifier",
+          "start":44,"end":57,"loc":{"start":{"line":5,"column":5,"index":44},"end":{"line":5,"column":18,"index":57},"identifierName":"Contravariant"},
+          "name": "Contravariant"
+        },
+        "typeParameters": {
+          "type": "TSTypeParameterDeclaration",
+          "start":57,"end":63,"loc":{"start":{"line":5,"column":18,"index":57},"end":{"line":5,"column":24,"index":63}},
+          "params": [
+            {
+              "type": "TSTypeParameter",
+              "start":58,"end":62,"loc":{"start":{"line":5,"column":19,"index":58},"end":{"line":5,"column":23,"index":62}},
+              "in": true,
+              "name": "T"
+            }
+          ]
+        },
+        "typeAnnotation": {
+          "type": "TSTypeLiteral",
+          "start":66,"end":92,"loc":{"start":{"line":5,"column":27,"index":66},"end":{"line":7,"column":1,"index":92}},
+          "members": [
+            {
+              "type": "TSPropertySignature",
+              "start":72,"end":90,"loc":{"start":{"line":6,"column":4,"index":72},"end":{"line":6,"column":22,"index":90}},
+              "key": {
+                "type": "Identifier",
+                "start":72,"end":73,"loc":{"start":{"line":6,"column":4,"index":72},"end":{"line":6,"column":5,"index":73},"identifierName":"f"},
+                "name": "f"
+              },
+              "computed": false,
+              "typeAnnotation": {
+                "type": "TSTypeAnnotation",
+                "start":73,"end":89,"loc":{"start":{"line":6,"column":5,"index":73},"end":{"line":6,"column":21,"index":89}},
+                "typeAnnotation": {
+                  "type": "TSFunctionType",
+                  "start":75,"end":89,"loc":{"start":{"line":6,"column":7,"index":75},"end":{"line":6,"column":21,"index":89}},
+                  "parameters": [
+                    {
+                      "type": "Identifier",
+                      "start":76,"end":80,"loc":{"start":{"line":6,"column":8,"index":76},"end":{"line":6,"column":12,"index":80},"identifierName":"x"},
+                      "name": "x",
+                      "typeAnnotation": {
+                        "type": "TSTypeAnnotation",
+                        "start":77,"end":80,"loc":{"start":{"line":6,"column":9,"index":77},"end":{"line":6,"column":12,"index":80}},
+                        "typeAnnotation": {
+                          "type": "TSTypeReference",
+                          "start":79,"end":80,"loc":{"start":{"line":6,"column":11,"index":79},"end":{"line":6,"column":12,"index":80}},
+                          "typeName": {
+                            "type": "Identifier",
+                            "start":79,"end":80,"loc":{"start":{"line":6,"column":11,"index":79},"end":{"line":6,"column":12,"index":80},"identifierName":"T"},
+                            "name": "T"
+                          }
+                        }
+                      }
+                    }
+                  ],
+                  "typeAnnotation": {
+                    "type": "TSTypeAnnotation",
+                    "start":82,"end":89,"loc":{"start":{"line":6,"column":14,"index":82},"end":{"line":6,"column":21,"index":89}},
+                    "typeAnnotation": {
+                      "type": "TSVoidKeyword",
+                      "start":85,"end":89,"loc":{"start":{"line":6,"column":17,"index":85},"end":{"line":6,"column":21,"index":89}}
+                    }
+                  }
+                }
+              }
+            }
+          ]
+        }
+      },
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":94,"end":144,"loc":{"start":{"line":9,"column":0,"index":94},"end":{"line":11,"column":1,"index":144}},
+        "id": {
+          "type": "Identifier",
+          "start":99,"end":108,"loc":{"start":{"line":9,"column":5,"index":99},"end":{"line":9,"column":14,"index":108},"identifierName":"Invariant"},
+          "name": "Invariant"
+        },
+        "typeParameters": {
+          "type": "TSTypeParameterDeclaration",
+          "start":108,"end":118,"loc":{"start":{"line":9,"column":14,"index":108},"end":{"line":9,"column":24,"index":118}},
+          "params": [
+            {
+              "type": "TSTypeParameter",
+              "start":109,"end":117,"loc":{"start":{"line":9,"column":15,"index":109},"end":{"line":9,"column":23,"index":117}},
+              "in": true,
+              "out": true,
+              "name": "T"
+            }
+          ]
+        },
+        "typeAnnotation": {
+          "type": "TSTypeLiteral",
+          "start":121,"end":144,"loc":{"start":{"line":9,"column":27,"index":121},"end":{"line":11,"column":1,"index":144}},
+          "members": [
+            {
+              "type": "TSPropertySignature",
+              "start":127,"end":142,"loc":{"start":{"line":10,"column":4,"index":127},"end":{"line":10,"column":19,"index":142}},
+              "key": {
+                "type": "Identifier",
+                "start":127,"end":128,"loc":{"start":{"line":10,"column":4,"index":127},"end":{"line":10,"column":5,"index":128},"identifierName":"f"},
+                "name": "f"
+              },
+              "computed": false,
+              "typeAnnotation": {
+                "type": "TSTypeAnnotation",
+                "start":128,"end":141,"loc":{"start":{"line":10,"column":5,"index":128},"end":{"line":10,"column":18,"index":141}},
+                "typeAnnotation": {
+                  "type": "TSFunctionType",
+                  "start":130,"end":141,"loc":{"start":{"line":10,"column":7,"index":130},"end":{"line":10,"column":18,"index":141}},
+                  "parameters": [
+                    {
+                      "type": "Identifier",
+                      "start":131,"end":135,"loc":{"start":{"line":10,"column":8,"index":131},"end":{"line":10,"column":12,"index":135},"identifierName":"x"},
+                      "name": "x",
+                      "typeAnnotation": {
+                        "type": "TSTypeAnnotation",
+                        "start":132,"end":135,"loc":{"start":{"line":10,"column":9,"index":132},"end":{"line":10,"column":12,"index":135}},
+                        "typeAnnotation": {
+                          "type": "TSTypeReference",
+                          "start":134,"end":135,"loc":{"start":{"line":10,"column":11,"index":134},"end":{"line":10,"column":12,"index":135}},
+                          "typeName": {
+                            "type": "Identifier",
+                            "start":134,"end":135,"loc":{"start":{"line":10,"column":11,"index":134},"end":{"line":10,"column":12,"index":135},"identifierName":"T"},
+                            "name": "T"
+                          }
+                        }
+                      }
+                    }
+                  ],
+                  "typeAnnotation": {
+                    "type": "TSTypeAnnotation",
+                    "start":137,"end":141,"loc":{"start":{"line":10,"column":14,"index":137},"end":{"line":10,"column":18,"index":141}},
+                    "typeAnnotation": {
+                      "type": "TSTypeReference",
+                      "start":140,"end":141,"loc":{"start":{"line":10,"column":17,"index":140},"end":{"line":10,"column":18,"index":141}},
+                      "typeName": {
+                        "type": "Identifier",
+                        "start":140,"end":141,"loc":{"start":{"line":10,"column":17,"index":140},"end":{"line":10,"column":18,"index":141},"identifierName":"T"},
+                        "name": "T"
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/types/variance-annotations-error/input.ts

@@ -0,0 +1,4 @@
+type T20<public T> = T;  // Error
+type T21<in out in T> = T;  // Error
+type T22<in out out T> = T;  // Error
+type T23<out in T> = T;  // Error

packages/babel-parser/test/fixtures/typescript/types/variance-annotations-error/options.json

@@ -0,0 +1,3 @@
+{
+  "BABEL_8_BREAKING": true
+}