Fix incorrect JSON being silently parsed. (#113)

Author: ota-meshi

src/parser/extend-parser.ts

@@ -4,7 +4,11 @@ import type { Parser, Options } from "acorn"
 import type { Comment } from "../types"
 import type { Node } from "estree"
 import { getAcorn } from "./modules/acorn"
-import { ParseError, throwUnexpectedCommentError } from "./errors"
+import {
+    ParseError,
+    throwUnexpectedCommentError,
+    throwUnexpectedTokenError,
+} from "./errors"
 import { TokenConvertor } from "./convert"
 import type { JSONSyntaxContext } from "./syntax-context"
 
@@ -36,10 +40,20 @@ export function getParser(): typeof Parser {
                 nodes: Node[]
             },
             code: string,
+            pos: number,
         ) {
             super(
                 ((): Options => {
                     const tokenConvertor = new TokenConvertor(options.ctx, code)
+
+                    const onToken: Options["onToken"] =
+                        options.onToken ||
+                        ((token) => {
+                            const t = tokenConvertor.convertToken(token)
+                            if (t) {
+                                this[PRIVATE].tokenStore.add(t)
+                            }
+                        })
                     return {
                         // do not use spread, because we don't want to pass any unknown options to acorn
                         ecmaVersion: options.ecmaVersion,
@@ -49,12 +63,7 @@ export function getParser(): typeof Parser {
                         allowReserved: true,
 
                         // Collect tokens
-                        onToken: (token) => {
-                            const t = tokenConvertor.convertToken(token)
-                            if (t) {
-                                this[PRIVATE].tokenStore.add(t)
-                            }
-                        },
+                        onToken,
 
                         // Collect comments
                         onComment: (
@@ -82,6 +91,7 @@ export function getParser(): typeof Parser {
                     }
                 })(),
                 code,
+                pos,
             )
             this[PRIVATE] = {
                 code,
@@ -171,3 +181,26 @@ export function getParser(): typeof Parser {
 
     return parserCache
 }
+
+/** Get extend parser */
+export function getAnyTokenErrorParser(): typeof Parser {
+    const parser = class ExtendParser extends getParser() {
+        public constructor(options: Options, code: string, pos: number) {
+            super(
+                {
+                    ...options,
+                    onToken: (token) => {
+                        return throwUnexpectedTokenError(
+                            code.slice(...token.range!),
+                            token,
+                        )
+                    },
+                },
+                code,
+                pos,
+            )
+        }
+    }
+
+    return parser
+}

src/parser/parser.ts

@@ -7,7 +7,7 @@ import { convertProgramNode } from "./convert"
 import { TokenStore } from "./token-store"
 import type { JSONProgram } from "./ast"
 import { lte } from "semver"
-import { getParser } from "./extend-parser"
+import { getAnyTokenErrorParser, getParser } from "./extend-parser"
 import type { JSONSyntaxContext } from "./syntax-context"
 
 const DEFAULT_ECMA_VERSION = "latest"
@@ -58,6 +58,27 @@ export function parseForESLint(
         ;(node as any).type = `JSON${node.type}`
     }
     const ast = convertProgramNode(baseAst as never, tokenStore, ctx, code)
+    let lastIndex = Math.max(
+        baseAst.range![1],
+        comments[comments.length - 1]?.range![1] ?? 0,
+    )
+    let lastChar = code[lastIndex]
+    while (
+        lastChar === "\n" ||
+        lastChar === "\r" ||
+        lastChar === " " ||
+        lastChar === "\t"
+    ) {
+        lastIndex++
+        lastChar = code[lastIndex]
+    }
+    if (lastIndex < code.length) {
+        getAnyTokenErrorParser().parseExpressionAt(
+            code,
+            lastIndex,
+            parserOptions,
+        )
+    }
     ast.tokens = tokens
     ast.comments = comments
     return {

tests/fixtures/parser/ast/comments-03-input.json5

@@ -0,0 +1,5 @@
+{
+  /* comment */
+}
+// comment
+  /* comment */

tests/fixtures/parser/ast/comments-03-output.json

@@ -0,0 +1,148 @@
+{
+  "type": "Program",
+  "body": [
+    {
+      "type": "JSONExpressionStatement",
+      "expression": {
+        "type": "JSONObjectExpression",
+        "properties": [],
+        "range": [
+          0,
+          19
+        ],
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 1
+          }
+        }
+      },
+      "range": [
+        0,
+        19
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 3,
+          "column": 1
+        }
+      }
+    }
+  ],
+  "comments": [
+    {
+      "type": "Block",
+      "value": " comment ",
+      "range": [
+        4,
+        17
+      ],
+      "loc": {
+        "start": {
+          "line": 2,
+          "column": 2
+        },
+        "end": {
+          "line": 2,
+          "column": 15
+        }
+      }
+    },
+    {
+      "type": "Line",
+      "value": " comment",
+      "range": [
+        20,
+        30
+      ],
+      "loc": {
+        "start": {
+          "line": 4,
+          "column": 0
+        },
+        "end": {
+          "line": 4,
+          "column": 10
+        }
+      }
+    },
+    {
+      "type": "Block",
+      "value": " comment ",
+      "range": [
+        33,
+        46
+      ],
+      "loc": {
+        "start": {
+          "line": 5,
+          "column": 2
+        },
+        "end": {
+          "line": 5,
+          "column": 15
+        }
+      }
+    }
+  ],
+  "tokens": [
+    {
+      "type": "Punctuator",
+      "value": "{",
+      "range": [
+        0,
+        1
+      ],
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 1
+        }
+      }
+    },
+    {
+      "type": "Punctuator",
+      "value": "}",
+      "range": [
+        18,
+        19
+      ],
+      "loc": {
+        "start": {
+          "line": 3,
+          "column": 0
+        },
+        "end": {
+          "line": 3,
+          "column": 1
+        }
+      }
+    }
+  ],
+  "range": [
+    0,
+    47
+  ],
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 6,
+      "column": 0
+    }
+  }
+}

tests/src/parser/errors.ts

@@ -24,6 +24,22 @@ function getParseError(code: string): ParseError {
 
 describe("Check that parsing error is correct.", () => {
     for (const { code, message, lineNumber, column, index, char } of [
+        {
+            code: `"foo": 42`,
+            message: "Unexpected token ':'.",
+            lineNumber: 1,
+            column: 6,
+            index: 5,
+            char: ":",
+        },
+        {
+            code: `"foo":`,
+            message: "Unexpected token ':'.",
+            lineNumber: 1,
+            column: 6,
+            index: 5,
+            char: ":",
+        },
         {
             code: `
 {