fix(compiler): reapply changes to style import transformer

[christian-bromann]

What is the current behavior?

Currently if multiple style urls are provided, as described in the docs:

@Component({
  tag: 'my-component',
  styleUrls: ['reset.scss', 'roboto.scss', 'css-variables.scss', 'core.scss'] 
})
export class MyComponent {
  // ...
}

Only the first (reset.css) style would get applied to the component.

fixes: #5016
STENCIL-999

What is the new behavior?

Instead of just compiling the first external style, I make it loop through all external styles and join the style strings together. Here is an example:

const barCss = ":host{display:block}";
const fooCss = ":host{display:none}";

const MyComponent = class {
    // ...
};
MyComponent.style = barCss + fooCss;

export { MyComponent as my_component };

Does this introduce a breaking change?

• Yes
• No

Testing

I've added a bunch of unit and e2e tests to verify this change. You can verify the new behavior by bootstrapping a Stencil component like this:

import { Component, h } from '@stencil/core';

@Component({
  tag: 'my-component',
  styleUrls: ['bar.css', 'foo.css', 'foo.css'],
})
export class MyComponent {
  render() {
    return <div>Hello, World! I'm here</div>;
  }
}

You will see that the compiled code will only import a single css file.

Other information

After further investigations it turns out that removing the assignment to style.styleIdentifer was the problem.

[github-actions]

--strictNullChecks error report

Typechecking with --strictNullChecks resulted in 1323 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/mock-doc/serialize-node.ts	36
src/dev-server/server-process.ts	32
src/compiler/style/test/optimize-css.spec.ts	23
src/compiler/output-targets/dist-lazy/generate-lazy-module.ts	22
src/compiler/prerender/prerender-main.ts	22
src/testing/puppeteer/puppeteer-element.ts	22
src/runtime/client-hydrate.ts	20
src/screenshot/connector-base.ts	19
src/runtime/vdom/vdom-render.ts	18
src/compiler/config/test/validate-paths.spec.ts	16
src/dev-server/request-handler.ts	15
src/compiler/prerender/prerender-optimize.ts	14
src/compiler/sys/stencil-sys.ts	14
src/compiler/transpile/transpile-module.ts	14
src/runtime/vdom/vdom-annotations.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/connected-callback.ts	13

Our most common errors

Typescript Error Code	Count
TS2345	399
TS2322	374
TS18048	286
TS18047	101
TS2722	37
TS2532	30
TS2531	23
TS2454	14
TS2352	13
TS2790	10
TS2769	8
TS2538	8
TS2416	6
TS2344	5
TS2493	3
TS2488	2
TS18046	2
TS2684	1
TS2430	1

Unused exports report

There are 14 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	269	normalize
src/utils/index.ts	7	escapeRegExpSpecialCharacters
src/compiler/app-core/app-data.ts	25	BUILD
src/compiler/app-core/app-data.ts	115	Env
src/compiler/app-core/app-data.ts	117	NAMESPACE
src/compiler/fs-watch/fs-watch-rebuild.ts	123	updateCacheFromRebuild
src/compiler/types/validate-primary-package-output-target.ts	61	satisfies
src/compiler/types/validate-primary-package-output-target.ts	61	Record
src/testing/puppeteer/puppeteer-declarations.ts	485	WaitForEventOptions
src/compiler/sys/fetch/write-fetch-success.ts	7	writeFetchSuccessSync

[christian-bromann]

I revisit the part where we define the styleIdentifier and instead of creating it based on the file path I just added its position within the array to the import identifier, e.g.

import MyComponentStyle0 from './my-component.css';
import MyComponentStyle1 from './my-component.ios.css';

I think I definitely now have a good understanding how styles are compiled with Stencil 😎

[rwaskiewicz]

Looks good! Had one minor/non-blocking comment

[tanner-reits]

LGTM based on changes from the last round!

[christian-bromann]

Verified in Ionic framework and all spec tests are passing, will move ahead and merge.

[christian-bromann]

Released in v4.8.2