Allow TypeScript type assertions in array destructuring (#10592)

* Add test * Add fix * Fix test, destructure with as assertion * Add angle-bracket assertion case * Use isBinding to make typeCastToParameter decision
babel · Nov 11, 2019 · 4cb5e0a · 4cb5e0a
1 parent b2767c7
commit 4cb5e0a
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Showing 3 changed files with 283 additions and 5 deletions.
diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
@@ -2483,7 +2483,10 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
     }
 
-    toAssignableList(exprList: N.Expression[]): $ReadOnlyArray<N.Pattern> {
+    toAssignableList(
+      exprList: N.Expression[],
+      isBinding: ?boolean,
+    ): $ReadOnlyArray<N.Pattern> {
       for (let i = 0; i < exprList.length; i++) {
         const expr = exprList[i];
         if (!expr) continue;
@@ -2493,10 +2496,14 @@ export default (superClass: Class<Parser>): Class<Parser> =>
             break;
           case "TSAsExpression":
           case "TSTypeAssertion":
-            this.raise(
-              expr.start,
-              "Unexpected type cast in parameter position.",
-            );
+            if (!isBinding) {
+              exprList[i] = this.typeCastToParameter(expr);
+            } else {
+              this.raise(
+                expr.start,
+                "Unexpected type cast in parameter position.",
+              );
+            }
             break;
         }
       }

diff --git a/packages/babel-parser/test/fixtures/typescript/cast/destructure-and-assign/input.ts b/packages/babel-parser/test/fixtures/typescript/cast/destructure-and-assign/input.ts
@@ -0,0 +1,2 @@
+[a as number] = [42];
+[<number>a] = [42];
diff --git a/packages/babel-parser/test/fixtures/typescript/cast/destructure-and-assign/output.json b/packages/babel-parser/test/fixtures/typescript/cast/destructure-and-assign/output.json
@@ -0,0 +1,269 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 41,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 2,
+      "column": 19
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 41,
+    "loc": {
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+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 2,
+        "column": 19
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 21,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
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+            "column": 21
+          }
+        },
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 0,
+          "end": 20,
+          "loc": {
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+              "line": 1,
+              "column": 0
+            },
+            "end": {
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+              "column": 20
+            }
+          },
+          "operator": "=",
+          "left": {
+            "type": "ArrayPattern",
+            "start": 0,
+            "end": 13,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 0
+              },
+              "end": {
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+                "column": 13
+              }
+            },
+            "elements": [
+              {
+                "type": "Identifier",
+                "start": 1,
+                "end": 12,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 1
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 12
+                  },
+                  "identifierName": "a"
+                },
+                "name": "a",
+                "typeAnnotation": {
+                  "type": "TSNumberKeyword",
+                  "start": 6,
+                  "end": 12,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 6
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 12
+                    }
+                  }
+                }
+              }
+            ]
+          },
+          "right": {
+            "type": "ArrayExpression",
+            "start": 16,
+            "end": 20,
+            "loc": {
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+                "column": 16
+              },
+              "end": {
+                "line": 1,
+                "column": 20
+              }
+            },
+            "elements": [
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+                "end": 19,
+                "loc": {
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+                    "line": 1,
+                    "column": 17
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 19
+                  }
+                },
+                "extra": {
+                  "rawValue": 42,
+                  "raw": "42"
+                },
+                "value": 42
+              }
+            ]
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start": 22,
+        "end": 41,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 19
+          }
+        },
+        "expression": {
+          "type": "AssignmentExpression",
+          "start": 22,
+          "end": 40,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 0
+            },
+            "end": {
+              "line": 2,
+              "column": 18
+            }
+          },
+          "operator": "=",
+          "left": {
+            "type": "ArrayPattern",
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+            "end": 33,
+            "loc": {
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+                "column": 0
+              },
+              "end": {
+                "line": 2,
+                "column": 11
+              }
+            },
+            "elements": [
+              {
+                "type": "Identifier",
+                "start": 31,
+                "end": 30,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 9
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 8
+                  },
+                  "identifierName": "a"
+                },
+                "name": "a",
+                "typeAnnotation": {
+                  "type": "TSNumberKeyword",
+                  "start": 24,
+                  "end": 30,
+                  "loc": {
+                    "start": {
+                      "line": 2,
+                      "column": 2
+                    },
+                    "end": {
+                      "line": 2,
+                      "column": 8
+                    }
+                  }
+                }
+              }
+            ]
+          },
+          "right": {
+            "type": "ArrayExpression",
+            "start": 36,
+            "end": 40,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 14
+              },
+              "end": {
+                "line": 2,
+                "column": 18
+              }
+            },
+            "elements": [
+              {
+                "type": "NumericLiteral",
+                "start": 37,
+                "end": 39,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 15
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 17
+                  }
+                },
+                "extra": {
+                  "rawValue": 42,
+                  "raw": "42"
+                },
+                "value": 42
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}