Fix null falling into object branch in untagged variant switch

[cristianoc]

Summary

• Fix null (which has typeof "object") incorrectly falling into the Object branch instead of the wildcard when pattern matching on untagged variants that have both an Object case and a null/wildcard case.
• Emit a null check before the typeof switch when both conditions are present.

Fixes #8251

Test plan

• Added test in js_json_test.res that exercises Array, Object, and wildcard matching with null input
• make test passes

🤖 Generated with Claude Code

[pkg-pr-new]

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rescript

npm i https://pkg.pr.new/rescript-lang/rescript@8253

@rescript/darwin-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-arm64@8253

@rescript/darwin-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-x64@8253

@rescript/linux-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-arm64@8253

@rescript/linux-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-x64@8253

@rescript/runtime

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@8253

@rescript/win32-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/win32-x64@8253

commit: 61b6f10

[nojaf]

Thanks!

[jagguji]

how can i use this @nojaf via the
yarn https://pkg.pr.new/rescript-lang/rescript@8253
itself ?

Also can u confirm it this handles these cases as well, sometimes the array was also falling into the object case @cristianoc
switch jsonNull { | Object() => "Object" | Array() => "Array" | _ => "default" }
switch jsonNull { | Object() => "Object" | String() => "String" | _ => "default" }
switch jsonNull { | Object() => "Object" | Number() => "Number" | _ => "default" }
switch jsonNull->JSON.Classify.classify { | Object() => "Object" | Bool() => "Boolean" | _ => "default" }
switch jsonNull { | Object() => "Object" | Array() => "Array" | String() => "String" | _ => "default" }
switch jsonArray { | Object() => "Object" | String() => "String" | _ => "default" }
switch jsonArray { | Object() => "Object" | Number() => "Number" | _ => "default" }
switch jsonArray { | Object() => "Object" | Bool(_) => "Boolean" | _ => "default" }

[nojaf]

how can i use this @nojaf via the
yarn https://pkg.pr.new/rescript-lang/rescript@8253
itself ?

I'm not sure what your expectations are this does.
But try replace you current rescript version with https://pkg.pr.new/rescript-lang/rescript@8253 in package.json.
Same for @rescript/runtime if you use it directly: https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@8253

then I would expect yarn to pick it up.

Maybe yarn dlx https://pkg.pr.new/rescript-lang/rescript@8253 but I don't really use yarn myself much. It is used in this repo but was set up by others who are more familiar with all of this.

[jagguji]

yeah i want to point to this version only @nojaf
will try the above steps

Also do u know when we can expect this fix in upcoming release ?

[jagguji]

i can't use it actually as it's using the rescript "version": "13.0.0-alpha.2", which can cause other issue, are we planning to release thsi as path in rescript 12 only
thanks @nojaf