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Use the correct CLI option to enable TDZ in Hermes #138

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Merged
merged 4 commits into from
Apr 8, 2025
Merged

Use the correct CLI option to enable TDZ in Hermes #138

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ea85e19
Use the correct CLI option to enable TDZ in Hermes
gibson042 Oct 3, 2023
58370fc
Improve and explain Hermes version detection
gibson042 Oct 3, 2023
a8db36c
Account for removal of -Xenable-tdz in Hermes version 0.13.0
gibson042 Jan 31, 2025
915eb66
Removal of Hermes -Xenable-tdz happened without a release version bump
gibson042 Jan 31, 2025
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24 changes: 23 additions & 1 deletion lib/agents/hermes.js
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,29 @@ class HermesAgent extends ConsoleAgent {
this.args.unshift('-non-strict');
}

this.args.unshift('-Xintl', '-enable-eval', '-fenable-tdz');
// Early Hermes CLI versions had `-fenable-tdz`.
// In version 0.10.0, it was replaced with `-Xenable-tdz`.
// In version 0.13.0 (release version: 0.12.0, bytecode version: 96), it was removed.
// https://github.com/facebook/hermes/commit/f811a0e75f19ab0da7dcf969a61db894fbb3cc35
// https://github.com/facebook/hermes/commit/5e2ddd5ed1c1f9af9b5b51c3ac67857a1477cb56
try {
const cp = await this.createChildProcess(['-version']);
let stdout = '';
cp.stdout.on('data', str => { stdout += str; });
await new Promise(resolve => { cp.on('close', resolve); });
// https://github.com/facebook/hermes/blob/66d3f87a8fd0436634be8a1049a1db9d3aa6e9c0/lib/CompilerDriver/CompilerDriver.cpp#L2164
const [_, releaseVersion] = /Hermes release version: (.*)/.exec(stdout);
const [__, bytecodeVersion] = /HBC bytecode version: (.*)/.exec(stdout);
if (/^0[.][0-9][.]/.test(releaseVersion)) {
this.args.unshift('-fenable-tdz');
} else if (/^0[.]1[012][.]/.test(releaseVersion) && !(+bytecodeVersion >= 96)) {
this.args.unshift('-Xenable-tdz');
}
} catch (error) {
// suppressed
}

this.args.unshift('-Xintl', '-enable-eval');

// There is currently no flag for supporting modules in Hermes
// if (options.module && this.args[0] !== '-m') {
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