Bug Report

Current Behavior
The following code should throw a syntax error if the parser plugin bigInt is enabled.

Input Code

• REPL or Repo link if applicable: https://babeljs.io/repl#?babili=false&browsers=&build=&builtIns=false&spec=false&loose=false&code_lz=AwDgnAdkA&debug=false&forceAllTransforms=false&shippedProposals=false&circleciRepo=&evaluate=false&fileSize=false&timeTravel=false&sourceType=script&lineWrap=true&presets=env&prettier=false&targets=&version=7.6.0&externalPlugins=%40babel%2Fplugin-syntax-bigint%407.4.4

089n

Expected behavior/code
It should throw Invalid BigIntLiteral error.

Background

We use tokenizer to process the source code into a stream of tokens and 08n will be processed in readNumber

The NonOctal Decimal Integer Literal is defined as

NonOctalDecimalInteger:
0 DecimalDigits

DecimalDigits:
DecimalDigit DecimalDigits_opt

DecimalDigit:
0 1 2 3 4 5 6 7 8 9

The above grammar requires a NonOctal Decimal Integer Literal to be a sequence of decimal digits starting with zero and the length is at least 2.

Possible Solution

1. Detect NonOctal Decimal Integer Literal in readNumber. Throw an error here when it is detected.

2. Add a test on https://github.com/babel/babel/tree/master/packages/babel-parser/test/fixtures/experimental/bigint

3. Run make test-test262-update-whitelist to update the whitelist, the following lines are expected to be removed.
   

   babel/scripts/tests/test262/test262_whitelist.txt

   Lines 113 to 116 in 9c1ad0a

   	language/literals/bigint/non-octal-like-invalid-0008n.js(default)
   	language/literals/bigint/non-octal-like-invalid-012348n.js(default)
   	language/literals/bigint/non-octal-like-invalid-08n.js(default)
   	language/literals/bigint/non-octal-like-invalid-09n.js(default)

If you don't know how to clone Babel, follow these steps: (you need to have make and yarn available on your machine).

1. Write a comment there to let other possible contributors know that you are working on this bug.
2. Fork the repo
3. Run git clone https://github.com/<YOUR_USERNAME>/babel.git && cd babel
4. Run yarn && make bootstrap
5. Wait ⏳
6. Run make watch (or make build whenever you change a file)
7. Add a test (only input.js; output.js will be automatically generated)
8. Update the code!
9. yarn jest parser to run the tests
   • If some test outputs don't match but the new results are correct, you can delete the bad output.js files and run the tests again
10. If it is working, run make test to run all the tests
11. Run git push and open a PR!