Macro crashes with SIGSEGV when non-ASCII character in string template literal with interpolation

[maxmilton]

What version of Bun is running?

0.6.14

What platform is your computer?

Linux 6.4.3-arch1-1 x86_64 unknown

What steps can reproduce the bug?

1. Create file index.ts:

import { fn } from './macro' assert { type: 'macro' };

fn(`© ${''}`); // <-- note the copyright symbol character

2. Create file macro.ts:

export function fn(str) {
  return str;
}

3. Run bun build ./index.ts or bun ./index.ts.

What is the expected behavior?

Template literals are processed correctly as Unicode when passed as macro arguments.
Bun process runs without a segmentation fault.

What do you see instead?

~/P/bun-macro-sigsegv master• ❱ bun build ./index.ts
fish: Job 1, 'bun build ./index.ts' terminated by signal SIGSEGV (Address boundary error)

Additional information

When there is no interpolation in the template literal the macro works as expected, even when it contains non-ASCII characters.

Where there are only ASCII characters, interpolation in the template literal the macro works as expected.

Happens on both stable v0.6.14 (b5665739) and current canary v0.6.15 (c39c11e1).

[Jarred-Sumner]

Interesting, this code is supposed to panic instead of segfault.

https://github.com/oven-sh/bun/blob/main/src/js_ast.zig#L10026-L10028

[maxmilton]

I've only seen that condition trigger when trying to use a macro as a tagged template literal function, like so:

import { fn } from './macro' assert { type: 'macro' };

fn`...`;

[maxmilton]

Using the macro in a test sheds some light on why it's seg faulting. There is an extra character being prepended to Unicode characters outside the ASCII range.

Try:

1. Create file index.test.ts:

import { test, expect } from 'bun:test';
import { fn } from './macro' assert { type: 'macro' };

test('fails', () => {
  expect(fn('©')).toBe('©');
});

2. Run bun test.

---

Result:

~/P/_/bun-macro-sigsegv ❱ bun test
bun test v0.6.14 (b5665739)

index.test.ts:
1 | import { test, expect } from 'bun:test';
2 | import { fn } from './macro' assert { type: 'macro' };
3 | 
4 | test('fails', () => {
5 |   expect(fn('©')).toBe('©');
      ^
error: expect(received).toBe(expected)

Expected: "©"
Received: "©"

      at /home/xxxx/xxxx/bun-macro-sigsegv/index.test.ts:5:2
✗ fails [0.12ms]

 0 pass
 1 fail
 1 expect() calls
Ran 1 tests across 1 files. 1 total [6.00ms]

---

So it's likely something to do with string handling in macro arguments and probably not template literals specifically since the test uses a regular string.

[maxmilton]

Continued in: #3830