From d2239a1fdec452e24ede04e990d16d42516fa538 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ari=20Perkki=C3=B6?= <ari.perkkio@gmail.com>
Date: Thu, 19 Nov 2020 00:18:44 +0200
Subject: [PATCH] Fix: no-useless-constructor crash on bodyless constructor
 (fixes #13830) (#13842)

---
 lib/rules/no-useless-constructor.js           |   8 +
 .../typescript-parsers/declare-class.js       | 418 ++++++++++++++++++
 tests/lib/rules/no-useless-constructor.js     |   6 +-
 3 files changed, 431 insertions(+), 1 deletion(-)
 create mode 100644 tests/fixtures/parsers/typescript-parsers/declare-class.js

diff --git a/lib/rules/no-useless-constructor.js b/lib/rules/no-useless-constructor.js
index 4c34aeda715..baabe7ec80f 100644
--- a/lib/rules/no-useless-constructor.js
+++ b/lib/rules/no-useless-constructor.js
@@ -162,6 +162,14 @@ module.exports = {
                 return;
             }
 
+            /*
+             * Prevent crashing on parsers which do not require class constructor
+             * to have a body, e.g. typescript and flow
+             */
+            if (!node.value.body) {
+                return;
+            }
+
             const body = node.value.body.body;
             const ctorParams = node.value.params;
             const superClass = node.parent.parent.superClass;
diff --git a/tests/fixtures/parsers/typescript-parsers/declare-class.js b/tests/fixtures/parsers/typescript-parsers/declare-class.js
new file mode 100644
index 00000000000..4cd91b4182d
--- /dev/null
+++ b/tests/fixtures/parsers/typescript-parsers/declare-class.js
@@ -0,0 +1,418 @@
+"use strict";
+
+/*
+ * Parsed on astexplorer.net using @typescript-eslint/parser@4.1.0
+ *
+ * Source:
+ * declare class A { constructor(options: any); }
+ */
+
+exports.parse = () => ({
+  "type": "Program",
+  "body": [
+    {
+      "type": "ClassDeclaration",
+      "id": {
+        "type": "Identifier",
+        "name": "A",
+        "range": [
+          14,
+          15
+        ],
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 14
+          },
+          "end": {
+            "line": 1,
+            "column": 15
+          }
+        }
+      },
+      "body": {
+        "type": "ClassBody",
+        "body": [
+          {
+            "type": "MethodDefinition",
+            "key": {
+              "type": "Identifier",
+              "name": "constructor",
+              "range": [
+                18,
+                29
+              ],
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 18
+                },
+                "end": {
+                  "line": 1,
+                  "column": 29
+                }
+              }
+            },
+            "value": {
+              "type": "TSEmptyBodyFunctionExpression",
+              "id": null,
+              "params": [
+                {
+                  "type": "Identifier",
+                  "name": "options",
+                  "range": [
+                    30,
+                    42
+                  ],
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 30
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 42
+                    }
+                  },
+                  "typeAnnotation": {
+                    "type": "TSTypeAnnotation",
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 37
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 42
+                      }
+                    },
+                    "range": [
+                      37,
+                      42
+                    ],
+                    "typeAnnotation": {
+                      "type": "TSAnyKeyword",
+                      "range": [
+                        39,
+                        42
+                      ],
+                      "loc": {
+                        "start": {
+                          "line": 1,
+                          "column": 39
+                        },
+                        "end": {
+                          "line": 1,
+                          "column": 42
+                        }
+                      }
+                    }
+                  }
+                }
+              ],
+              "generator": false,
+              "expression": false,
+              "async": false,
+              "body": null,
+              "range": [
+                29,
+                44
+              ],
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 29
+                },
+                "end": {
+                  "line": 1,
+                  "column": 44
+                }
+              }
+            },
+            "computed": false,
+            "static": false,
+            "kind": "constructor",
+            "range": [
+              18,
+              44
+            ],
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 18
+              },
+              "end": {
+                "line": 1,
+                "column": 44
+              }
+            }
+          }
+        ],
+        "range": [
+          16,
+          46
+        ],
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 16
+          },
+          "end": {
+            "line": 1,
+            "column": 46
+          }
+        }
+      },
+      "superClass": null,
+      "range": [
+        0,
+        46
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 46
+        }
+      },
+      "declare": true
+    }
+  ],
+  "sourceType": "module",
+  "range": [
+    0,
+    46
+  ],
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 46
+    }
+  },
+  "tokens": [
+    {
+      "type": "Identifier",
+      "value": "declare",
+      "range": [
+        0,
+        7
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 7
+        }
+      }
+    },
+    {
+      "type": "Keyword",
+      "value": "class",
+      "range": [
+        8,
+        13
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 8
+        },
+        "end": {
+          "line": 1,
+          "column": 13
+        }
+      }
+    },
+    {
+      "type": "Identifier",
+      "value": "A",
+      "range": [
+        14,
+        15
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 14
+        },
+        "end": {
+          "line": 1,
+          "column": 15
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": "{",
+      "range": [
+        16,
+        17
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 16
+        },
+        "end": {
+          "line": 1,
+          "column": 17
+        }
+      }
+    },
+    {
+      "type": "Identifier",
+      "value": "constructor",
+      "range": [
+        18,
+        29
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 18
+        },
+        "end": {
+          "line": 1,
+          "column": 29
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": "(",
+      "range": [
+        29,
+        30
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 29
+        },
+        "end": {
+          "line": 1,
+          "column": 30
+        }
+      }
+    },
+    {
+      "type": "Identifier",
+      "value": "options",
+      "range": [
+        30,
+        37
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 30
+        },
+        "end": {
+          "line": 1,
+          "column": 37
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": ":",
+      "range": [
+        37,
+        38
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 37
+        },
+        "end": {
+          "line": 1,
+          "column": 38
+        }
+      }
+    },
+    {
+      "type": "Identifier",
+      "value": "any",
+      "range": [
+        39,
+        42
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 39
+        },
+        "end": {
+          "line": 1,
+          "column": 42
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": ")",
+      "range": [
+        42,
+        43
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 42
+        },
+        "end": {
+          "line": 1,
+          "column": 43
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": ";",
+      "range": [
+        43,
+        44
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 43
+        },
+        "end": {
+          "line": 1,
+          "column": 44
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": "}",
+      "range": [
+        45,
+        46
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 45
+        },
+        "end": {
+          "line": 1,
+          "column": 46
+        }
+      }
+    }
+  ],
+  "comments": []
+});
\ No newline at end of file
diff --git a/tests/lib/rules/no-useless-constructor.js b/tests/lib/rules/no-useless-constructor.js
index 039a40efb5a..e42a6b267e8 100644
--- a/tests/lib/rules/no-useless-constructor.js
+++ b/tests/lib/rules/no-useless-constructor.js
@@ -36,7 +36,11 @@ ruleTester.run("no-useless-constructor", rule, {
         "class A extends B { constructor(foo, bar){ super(foo); } }",
         "class A extends B { constructor(test) { super(); } }",
         "class A extends B { constructor() { foo; } }",
-        "class A extends B { constructor(foo, bar) { super(bar); } }"
+        "class A extends B { constructor(foo, bar) { super(bar); } }",
+        {
+            code: "declare class A { constructor(options: any); }",
+            parser: require.resolve("../../fixtures/parsers/typescript-parsers/declare-class")
+        }
     ],
     invalid: [
         {