fix(gnovm): reject make(chan T) at preprocess time

[davd-gzl]

fix #5233

make(chan T) previously passed deployment but panicked with 'not yet implemented' at runtime, leaving a implicit panic on-chain. Reject it during preprocessing instead, producing a clean deployment error.

[Gno2D2]

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[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
gnovm/pkg/gnolang/preprocess.go	0.00%	3 Missing ⚠️
gnovm/pkg/gnolang/uverse.go	0.00%	1 Missing ⚠️

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[MikaelVallenet]

Implem looks OK, however it's just a runtime panic like a user could throw an explicit one, it's not security issue.
Still IMO it makes sense to block at deployment since there is no expected usecase from this.

[Villaquiranm]

LGTM

[omarsy]

If we're going to reject channels at preprocess time, I think the scope should be broader than just make(chan T). Any reference to a channel type could be caught early, for example:

package main

func ch1() chan int {
	return nil
}

func main() {
	var ch chan int
	_ = ch1()
	println(ch)
}

This deploys fine today even though channels aren't supported. IMO if we want a preprocess-time error, it should trigger when the chan type itself is encountered, not only on make. That way var ch chan int, func() chan int, type C chan int, etc. would all be rejected consistently, rather than only catching the one specific case of constructing a channel via make.

[thehowl]

I suggest we change this PR so that at preprocess time, whenever we process a type expression and it is a chan, we just panic, so we also reject files of this kind:

package main

func main() {
	type T chan int
	var ch chan int
	_ = ch
	_ = T(nil)
	println("ok")
}

[davd-gzl]

I've applied the recommended fix: f15edb2 @thehowl @omarsy
Thank you, it's indeed much simpler / better

[ltzmaxwell]

Currently, the preprocess stage disallows the chan type, but there are still some occurrences at runtime, which looks inconsistent. It's acceptable as is, but need a proper comment somewhere maybe in preprocess.go to document the current situation and future plan.

[Copilot]

Pull request overview

This PR addresses gnovm issue #5233 by rejecting channel types (e.g. make(chan T) and chan T in declarations/signatures) during preprocessing, preventing “not yet implemented” runtime panics from being deployed on-chain.

Changes:

• Add preprocess-time rejection for ChanTypeExpr, aligning runtime behavior with a clean deployment/preprocess error.
• Update runtime make() handling to emit a consistent “channel type is not yet supported” message as a backstop.
• Adjust/add filetests and integration fixtures to avoid/cover channel-type usage.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
gnovm/pkg/gnolang/preprocess.go	Rejects ChanTypeExpr during preprocessing; adds/adjusts related handling paths.
gnovm/pkg/gnolang/uverse.go	Updates make() chan-type runtime backstop panic message.
gnovm/pkg/gnolang/transcribe.go	Adds ChanTypeExpr handling, but currently panics inside traversal (see comments).
gnovm/tests/files/chan_make0.gno	New filetest covering make(chan int) rejection.
gnovm/tests/files/chan_type{0,1,2,3}.gno	New filetests covering chan usage in var/type/sig/struct-field contexts.
gnovm/tests/files/recurse0.gno	Removes channel fields from a recursion/type-printing test and updates golden output.
gnovm/tests/files/extern/net/http/http.gno	Removes CloseNotifier interface due to <-chan return type.
gnovm/tests/files/assign_unnamed_type/unnamedtype7_filetest.gno	Reworks test away from channels to a pointer-based unnamed-type case.
gnovm/pkg/benchops/gno/opcodes/opcode.gno	Updates benchmark/opcode expectations and example struct away from chan types.
gno.land/pkg/integration/testdata/addpkg_{public,private}.txtar	Removes saved channel fields from integration test fixtures.