fix(runtime): make isSameVnode return false on initial render in a hydration case

[christian-bromann]

What is the current behavior?

Stencil believes two nodes are the same on initial render, in cases were are comparing slots with no name attached to them. This causes rendering issues and the slot node being removed.

What is the new behavior?

Instead, Stencil should not re-order its VDOM and properly hydrate the VDOM first.

Documentation

Does this introduce a breaking change?

• Yes
• No

Testing

Added some unit test to check this case.

Other information

Discovered this as part of my work on #5831

[github-actions]

@stencil/core@4.19.2 ts
tsc --noEmit --project scripts/tsconfig.json && tsx scripts/tech-debt-burndown-report.ts

--strictNullChecks error report

Typechecking with --strictNullChecks resulted in 1078 errors on this branch.

That's the same number of errors on main, so at least we're not creating new ones!

reports and statistics

Our most error-prone files

Path	Error Count
src/dev-server/index.ts	37
src/dev-server/server-process.ts	32
src/compiler/prerender/prerender-main.ts	22
src/runtime/vdom/vdom-render.ts	22
src/runtime/client-hydrate.ts	20
src/runtime/vdom/test/patch.spec.ts	19
src/runtime/vdom/test/util.spec.ts	19
src/screenshot/connector-base.ts	19
src/testing/puppeteer/puppeteer-element.ts	19
src/dev-server/request-handler.ts	15
src/compiler/prerender/prerender-optimize.ts	14
src/compiler/sys/stencil-sys.ts	14
src/runtime/connected-callback.ts	14
src/sys/node/node-sys.ts	14
src/compiler/prerender/prerender-queue.ts	13
src/compiler/sys/in-memory-fs.ts	13
src/runtime/set-value.ts	13
src/compiler/output-targets/output-www.ts	12
src/compiler/transformers/test/parse-vdom.spec.ts	12
src/compiler/transformers/transform-utils.ts	12

Our most common errors

Typescript Error Code	Count
TS2322	338
TS2345	328
TS18048	188
TS18047	99
TS2722	27
TS2532	23
TS2531	19
TS2790	11
TS2454	10
TS2352	9
TS2769	8
TS2416	7
TS2538	4
TS2493	3
TS18046	2
TS2684	1
TS2430	1

Unused exports report

There are 15 unused exports on this PR. That's the same number of errors on main, so at least we're not creating new ones!

Unused exports

File	Line	Identifier
src/runtime/bootstrap-lazy.ts	22	setNonce
src/screenshot/screenshot-fs.ts	18	readScreenshotData
src/testing/testing-utils.ts	198	withSilentWarn
src/utils/index.ts	145	CUSTOM
src/utils/index.ts	245	NODE_TYPES
src/utils/index.ts	269	normalize
src/utils/index.ts	7	escapeRegExpSpecialCharacters
src/compiler/app-core/app-data.ts	25	BUILD
src/compiler/app-core/app-data.ts	116	Env
src/compiler/app-core/app-data.ts	118	NAMESPACE
src/compiler/fs-watch/fs-watch-rebuild.ts	123	updateCacheFromRebuild
src/compiler/types/validate-primary-package-output-target.ts	82	satisfies
src/compiler/types/validate-primary-package-output-target.ts	82	Record
src/testing/puppeteer/puppeteer-declarations.ts	496	WaitForEventOptions
src/compiler/sys/fetch/write-fetch-success.ts	7	writeFetchSuccessSync

[github-actions]

PR built and packed!

Download the tarball here: https://github.com/ionic-team/stencil/actions/runs/9860736800/artifacts/1682985553

If your browser saves files to ~/Downloads you can install it like so:

unzip -d ~/Downloads ~/Downloads/stencil-core-4.19.2-dev.1720542429.a9a1305.tgz.zip && npm install ~/Downloads/stencil-core-4.19.2-dev.1720542429.a9a1305.tgz