Hashing isn't stable when the file contents haven't changed

[marvinhagemeister]

Do you want to request a feature or report a bug?
Bug

What is the current behaviour?

Just noticed that on preactjs/preact-www#338 (comment) that some files have the exact same content, but a different hash with each build. This makes it hard to track size changes across builds.

If the current behaviour is a bug, please provide the steps to reproduce.

1. Run build, check size
2. Run build, check again

What is the expected behaviour?

Filenames stay the same when the content didn't change.

If this is a feature request, what is motivation or use case for changing the behaviour?

See above.

Please mention other relevant information.

Using the latest RC.

[kuldeepkeshwar]

preact-cli/packages/cli/lib/lib/webpack/webpack-client-config.js

Line 47 in 4da2229

filename: isProd ? '[name].[chunkhash:5].js' : '[name].js',

will changing chunkhash:5 to chunkhash fix it ?

[ForsakenHarmony]

I don't think so, those 5 characters should also stay the same

[kuldeepkeshwar]

Yup, I tried it. I cloned the project in a different directory & ran the build, got a different hash. it doesn't work.

[ForsakenHarmony]

Might be a webpack problem, but not sure 🤔

[ForsakenHarmony]

any reason we do path based hashing

we do?

[kuldeepkeshwar]

@marvinhagemeister @developit @ForsakenHarmony
I tested above configure with webpack@5.0.0-alpha.19. it doesn't output a different hash. Seems like updating webpack fix it.

[prateekbh]

Oooof... That's bad.
Upgrading webpack by a major version is a big deal because of plethora of plugins which might not work

[marvinhagemeister]

Agree, I'd hold off until webpack 5 is at least stable.

[kuldeepkeshwar]

Agree, I'd hold off until webpack 5 is at least stable.

plus the plugin chain 🙂

[rschristian]

Looks like this was fixed at some point in CLI or maybe back ported to Webpack v4, as we've had consistent hashes on our assets for a fair while now. This is part of our test suite, at least for non-esm assets:

preact-cli/packages/cli/tests/images/build.js

Lines 1 to 35 in 783bb01

	const common = {
	'polyfills.1ea90.js': 6426,
	'polyfills.1ea90.js.map': 21668,
	};
	exports.default = Object.assign({}, common, {
	'assets/icons/android-chrome-192x192.png': 14058,
	'assets/icons/android-chrome-512x512.png': 51484,
	'assets/icons/apple-touch-icon.png': 12746,
	'assets/icons/favicon-16x16.png': 626,
	'assets/icons/favicon-32x32.png': 1487,
	'assets/icons/mstile-150x150.png': 9050,
	'assets/preact-logo.svg': 645,
	'assets/preact-logo-inverse.svg': 649,
	'assets/favicon.ico': 15086,
	'ssr-build/ssr-bundle.2b941.css': 2601,
	'ssr-build/ssr-bundle.2b941.css.map': 3708,
	'ssr-build/ssr-bundle.js': 28830,
	'ssr-build/ssr-bundle.js.map': 52686,
	'ssr-build/asset-manifest.json': 178,
	'bundle.4c6ac.css': 1276,
	'bundle.fbf1b.js': 22529,
	'bundle.fbf1b.js.map': 111801,
	'favicon.ico': 15086,
	'index.html': 4127,
	'manifest.json': 455,
	'preact_prerender_data.json': 11,
	'push-manifest.json': 388,
	'asset-manifest.json': 1142,
	'route-home.chunk.c490f.css': 834,
	'route-home.chunk.50bd0.js': 1149,
	'route-home.chunk.50bd0.js.map': 1961,
	'route-profile.chunk.4c330.js': 3490,
	'route-profile.chunk.4c330.js.map': 15002,
	});