bug: Rollup Fails to Process .cts Files After Latest StencilJS Update

[kurtinatlanta]

Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already report this problem, without success.

Stencil Version

4.28.0

Current Behavior

After updating to the latest StencilJS version, which includes an upgrade to the latest Rollup version, Rollup no longer processes .cts files correctly. This issue affects importing functions from libphonenumber-js. The same configuration worked fine in previous StencilJS versions.

This is the debug output:
Rollup: Parse Error: ../../../node_modules/libphonenumber-js/index.d.cts:42:20
RollupError: ../../../node_modules/libphonenumber-js/index.d.cts (42:20): Expected ',', got ':' (Note that
you need plugins to import files that are not JavaScript)
at getRollupError .../node_modules/@stencil/core/compiler/stencil.js:211989:39
at ParseError2.initialise .../node_modules/@stencil/core/compiler/stencil.js:227004:29
at convertNode2 .../node_modules/@stencil/core/compiler/stencil.js:215372:8
at convertProgram2 .../node_modules/@stencil/core/compiler/stencil.js:215358:10
at _Module.setSource .../node_modules/@stencil/core/compiler/stencil.js:229401:22
at async ModuleLoader.addModuleSource .../node_modules/@stencil/core/compiler/stencil.js:231346:11

Expected Behavior

The build succeeds.

System Info

Steps to Reproduce

• Update StencilJS to the latest version, which includes the Rollup upgrade.
• Use a project with a component .tsx file that imports functions from libphonenumber-js.
• Run the StencilJS build process.
• Observe that Rollup fails to process .cts files, causing the build to break.

Code Reproduction URL

https://www.google.com

Additional Information

This issue may be the same as #6193 and may have the same solution.

[jtcanfieldhpe]

+1, had similar issues for .d.mts, had to back down to 4.27.2
was missing @rollup/rollup-darwin-arm64, resolved this by adding it to my dev packages, then had:

Rollup: Parse Error: node_modules/i18next-browser-languagedetector/index.d.mts:5:7
node_modules/i18next-browser-languagedetector/index.d.mts (5:7): Expected '{', got 'type' (Note that you
need plugins to import files that are not JavaScript)

thank you! @johnjenkins

[johnjenkins]

@jtcanfieldhpe those issues have been fixed / merged already :)

• fix(build): get ts to handle .d.mts files #6197
• fix(build): add more platform specific optionalDependencies (#6195) #6196

Just teething problems dealing with a major rollup upgrade (2 > 4) ... it used to ignore a package's exports and now ... it doesn't - so we have to tweak stencil to cope with these new file types.

Will get to the CTS issue soon.

[christian-bromann]

Will get to the CTS issue soon.

@johnjenkins working on a PR

[christian-bromann]

@johnjenkins wdyt? #6199