Ensure useState and useReducer initializer functions are double invoked in StrictMode

[eps1lon]

Summary

Fixes #25583 (comment)

In StrictMode we used to double invoke state initializer functions in StrictMode (I started bisecting from 17 where this was already the case). Our docs imply this:

Functions that you pass to useState, set functions, useMemo, or useReducer
-- https://react.dev/reference/react/StrictMode#fixing-bugs-found-by-double-rendering-in-development

However, in #25583 we stopped doing that but likely because we never had a test.

Now we double invoke again using the same pattern we use for double invoking updater functions.

How did you test this change?

• added test for state initializer invocations

[rickhanlonii]

Lol this comment is funny now

react/packages/react-reconciler/src/ReactFiberHooks.js

Lines 566 to 567 in 178f435

	// There are plenty of tests to ensure this behavior is correct.
	const shouldDoubleRenderDEV =

[react-sizebot]

Comparing: f5a3158...3b83783

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	+0.14%	176.57 kB	176.82 kB	+0.17%	55.00 kB	55.10 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.14%	178.69 kB	178.94 kB	+0.10%	55.64 kB	55.69 kB
facebook-www/ReactDOM-prod.classic.js	+0.14%	591.32 kB	592.15 kB	+0.15%	104.34 kB	104.49 kB
facebook-www/ReactDOM-prod.modern.js	+0.14%	575.08 kB	575.91 kB	+0.15%	101.43 kB	101.58 kB
test_utils/ReactAllWarnings.js	Deleted	67.56 kB	0.00 kB	Deleted	16.59 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
facebook-react-native/react-test-renderer/cjs/ReactTestRenderer-dev.js	+0.38%	936.25 kB	939.83 kB	+0.38%	187.73 kB	188.45 kB
react-native/implementations/ReactFabric-dev.js	+0.37%	977.95 kB	981.53 kB	+0.36%	197.71 kB	198.43 kB
react-native/implementations/ReactNativeRenderer-dev.js	+0.36%	994.24 kB	997.81 kB	+0.36%	201.99 kB	202.71 kB
oss-stable-semver/react-art/cjs/react-art.production.min.js	+0.25%	99.72 kB	99.96 kB	+0.25%	30.64 kB	30.72 kB
oss-stable/react-art/cjs/react-art.production.min.js	+0.25%	99.77 kB	100.02 kB	+0.26%	30.67 kB	30.75 kB
oss-experimental/react-art/cjs/react-art.production.min.js	+0.24%	101.72 kB	101.97 kB	+0.14%	31.27 kB	31.31 kB
facebook-www/ReactART-prod.modern.js	+0.24%	350.58 kB	351.41 kB	+0.25%	59.38 kB	59.53 kB
facebook-www/ReactART-prod.classic.js	+0.23%	361.55 kB	362.37 kB	+0.25%	61.34 kB	61.49 kB
oss-stable-semver/react-reconciler/cjs/react-reconciler.production.min.js	+0.21%	115.23 kB	115.47 kB	+0.23%	35.67 kB	35.75 kB
oss-stable/react-reconciler/cjs/react-reconciler.production.min.js	+0.21%	115.25 kB	115.50 kB	+0.23%	35.69 kB	35.77 kB
oss-experimental/react-reconciler/cjs/react-reconciler.production.min.js	+0.21%	117.16 kB	117.41 kB	+0.36%	36.31 kB	36.44 kB
oss-stable-semver/react-art/cjs/react-art.production.js	+0.20%	597.32 kB	598.54 kB	+0.21%	133.58 kB	133.86 kB
oss-stable/react-art/cjs/react-art.production.js	+0.20%	597.35 kB	598.56 kB	+0.21%	133.60 kB	133.89 kB
oss-experimental/react-art/cjs/react-art.production.js	+0.20%	604.76 kB	605.97 kB	+0.21%	135.34 kB	135.62 kB
test_utils/ReactAllWarnings.js	Deleted	67.56 kB	0.00 kB	Deleted	16.59 kB	0.00 kB

Generated by 🚫 dangerJS against 3b83783

[rickhanlonii]

@eps1lon should we also add the dimming like in #28249?