`mergeProps` return type is broken when using generics and intersections types

[riccardoperra]

Describe the bug

I'm trying to upgrade my application to Solid 1.4.0 but I am having troubles related to the new mergeProps return type which broke some types inside my ui components library https://github.com/riccardoperra/codeimage/runs/6428736073?check_suite_focus=true

The result of the mergeProps function is ok for the most cases, but when using types that depends on generics, some properties are missing or completely broken. To me this seems related to a typescript core issue, but I think some of solid types can be improved to try to handle these errors, even if not all

Your Example Website or App

https://playground.solidjs.com/?hash=-238626028&version=1.4.1

Steps to Reproduce the Bug or Issue

Here's a playground

https://playground.solidjs.com/?hash=-238626028&version=1.4.1

It consists of:

• main.tsx: small example copied from my repo
• text-solid-1.3.4-types.tsx: an example of mergeProps with old solid types which are not throwing error
• test-solid-1.4.0-fixed-types: an example with a possible fix for solid 1.4.0

Expected behavior

Solid 1.3.4 was not throwing that error.

Screenshots or Videos

Platform

• Solid 1.4.0

Additional context

A pr with the possible fix #983

[ryansolid]

Should be fixed in 1.4.2. Thanks for the PR.