fix(compiler): don't allow shadowRoot getter to avoid hydration issues

[christian-bromann]

What is the current behavior?

We have discovered an issue where a user is running into hydration issues due to the fact that they have defined a component getter like so:

  /**
   * Gets shadow root of nearest host element if one exists
   */
  private get shadowRoot() {
    return this.host.getRootNode() as ShadowRoot;
  }

What is the new behavior?

The compiler now detects this class member in a Stencil components and throws a nice error making users aware that this is not allowed.

Documentation

Does this introduce a breaking change?

• Yes
• No

This can potentially break for people that do this but don't do any client side hydration.

Testing

Added sufficient unit tests.

Other information

n/a

[github-actions]

@stencil/[email protected] ts
tsc --noEmit --project scripts/tsconfig.json && tsx scripts/tech-debt-burndown-report.ts

--strictNullChecks error report

Typechecking with --strictNullChecks resulted in 1071 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	326
TS18048	190
TS18047	99
TS2722	27
TS2532	19
TS2531	19
TS2790	11
TS2454	10
TS2352	9
TS2769	8
TS2416	7
TS2538	4
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	21	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

[tanner-reits]

Is it easier to just check the decorator name?

[christian-bromann]

Yes, but you could potentially import it with any arbitrary name which is why I did this extra step of checking if the decorator has 1 argument which contains a tag property since this is the same everywhere.

[tanner-reits]

Ah yeah, good point!