fix: panic in store.SprintStoreOps

[tbruyelle]

2 ways to reproduce :

• Using a filetest:

 go run ./gnovm/cmd/gno test -verbose ./examples/gno.land/p/demo/tests/ -run file/z0
?       ./examples/gno.land/p/demo/tests/subtests 	[no test files]
=== RUN   file/z0_filetest.gno
panic: expected JSON object but got "20"

goroutine 1 [running]:
github.com/gnolang/gno/tm2/pkg/amino.(*Codec).MustMarshalJSON(...)
	/home/tom/src/gno/tm2/pkg/amino/amino.go:818
github.com/gnolang/gno/tm2/pkg/amino.MustMarshalJSON({0xda1d40?, 0xc0001305a0?})
	/home/tom/src/gno/tm2/pkg/amino/amino.go:140 +0x53
github.com/gnolang/gno/gnovm/pkg/gnolang.StoreOp.String({0x0, {0x1026bf0, 0xc0001305a0}, {0x0, 0x0}})
	/home/tom/src/gno/gnovm/pkg/gnolang/store.go:654 +0xb2
github.com/gnolang/gno/gnovm/pkg/gnolang.(*defaultStore).SprintStoreOps(0xc0000166c0)
	/home/tom/src/gno/gnovm/pkg/gnolang/store.go:687 +0xff
github.com/gnolang/gno/gnovm/tests.RunFileTest({0xc000357158, 0x11}, {0xc0003691a0, 0x2e}, {0xc0001499e8, 0x1, 0x1013280?})
	/home/tom/src/gno/gnovm/tests/file.go:325 +0x44e
main.gnoTestPkg({0xc000116500, 0x20}, {0x0?, 0x0, 0x1?}, {0xc00035b720, 0x1, 0xc000129af8?}, 0xc00034c8c0, 0xc0002948c0)
	/home/tom/src/gno/gnovm/cmd/gno/test.go:337 +0x876
main.execTest(0xc00034c8c0, {0xc00035b590, 0x1, 0x1}, 0xc000036220?)
	/home/tom/src/gno/gnovm/cmd/gno/test.go:208 +0xb67
main.newTestCmd.func1({0x0?, 0x0?}, {0xc00035b590?, 0xc00035f118?, 0x0?})
	/home/tom/src/gno/gnovm/cmd/gno/test.go:51 +0x32
github.com/gnolang/gno/tm2/pkg/commands.(*Command).Run(0x5?, {0x1018768?, 0xc00003a130?})
	/home/tom/src/gno/tm2/pkg/commands/command.go:233 +0x1ac
github.com/gnolang/gno/tm2/pkg/commands.(*Command).Run(0xc00035ee70?, {0x1018768?, 0xc00003a130?})
	/home/tom/src/gno/tm2/pkg/commands/command.go:237 +0x154
github.com/gnolang/gno/tm2/pkg/commands.(*Command).ParseAndRun(0x4059dc?, {0x1018768, 0xc00003a130}, {0xc0000361f0?, 0x401240?, 0x0?})
	/home/tom/src/gno/tm2/pkg/commands/command.go:118 +0x4f
main.main()
	/home/tom/src/gno/gnovm/cmd/gno/main.go:14 +0x75
exit status 2

• using a go unit test:

$  go test ./gnovm/pkg/gnolang/ -v -run Amino
=== RUN   TestAminoMustMarshalJSONPanics
"20"
--- FAIL: TestAminoMustMarshalJSONPanics (0.00s)
panic: expected JSON object but got "20" [recovered]
	panic: expected JSON object but got "20"

goroutine 6 [running]:
testing.tRunner.func1.2({0xc15460, 0xc0002d2fc0})
	/usr/lib/go/src/testing/testing.go:1526 +0x24e
testing.tRunner.func1()
	/usr/lib/go/src/testing/testing.go:1529 +0x39f
panic({0xc15460, 0xc0002d2fc0})
	/usr/lib/go/src/runtime/panic.go:884 +0x213
github.com/gnolang/gno/tm2/pkg/amino.(*Codec).MustMarshalJSON(...)
	/home/tom/src/gno/tm2/pkg/amino/amino.go:818
github.com/gnolang/gno/tm2/pkg/amino.MustMarshalJSON({0xc59ec0?, 0xc0001c42d0?})
	/home/tom/src/gno/tm2/pkg/amino/amino.go:140 +0x53
github.com/gnolang/gno/gnovm/pkg/gnolang.TestAminoMustMarshalJSONPanics(0x0?)
	/home/tom/src/gno/gnovm/pkg/gnolang/values_test.go:20 +0x134
testing.tRunner(0xc000300000, 0xcd8f40)
	/usr/lib/go/src/testing/testing.go:1576 +0x10b
created by testing.(*T).Run
	/usr/lib/go/src/testing/testing.go:1629 +0x3ea
FAIL	github.com/gnolang/gno/gnovm/pkg/gnolang	0.008s
FAIL

Additional notes:

• when // Realm: instruction is present, it triggers a comparison between the store and the content of the instruction.
• when the store content is serialized before the comparison, this panic happens in the amino code
• this doesn't affect all // Realm: instruction, for instance examples/gno.land/p/demo/avl/z_0_filetest.gno is still working well

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[moul]

Output with standard JSON: https://gist.github.com/moul/cc7fda42d648ceae144d9bff55a20d7e

[moul]

I think this is because // Realm: contains a non-json thing. You don't have the error if you just have // Realm: without any content.

I think it's related to one of your other PRs, with the goal to make --update-golden-tests also for // Realm:, nope?

Maybe the best move is:

• improve error handling, with a more explicit message if we are in comparison mode (not in update mode).
• make -update-golden-tests overwrite the content whatever it is so that we quickly only have valid JSON, and no need for handcrafted JSON here.

[tbruyelle]

I think this is because // Realm: contains a non-json thing. You don't have the error if you just have // Realm: without any content.

That's also what I thought initially, but store.SprintStoreOps() doesn't rely on the content // Realm: only on the content of the store. Proof of this, if you change the // Realm: instruction of the one that works ( examples/gno.land/p/demo/avl/z_0_filetest.gno), to

// Realm:
// xxx

then there is no panic.

I think the panic is due to :

• an unexpected content of the store
  OR
• a bug in the amino encoder

I think it's related to one of your other PRs, with the goal to make --update-golden-tests also for // Realm:, nope?

The PR you're referring to doesn't exist yet, there's just a preliminary PR that brings test to make it doable (#1023).

[tbruyelle]

Output with standard JSON: gist.github.com/moul/cc7fda42d648ceae144d9bff55a20d7e

How did you achieve that? using only json.Encode from the stdlib ?

[tbruyelle]

I found the culprit :

file gnovm/stdlibgs/std/crypto.gno :

package std

type Address string // NOTE: bech32

func (a Address) String() string {
	return string(a)
}

const RawAddressSize = 20   // <--------------------- interpreted as a bigint

type RawAddress [RawAddressSize]byte

Proof of this, if I change the value to 21, the panic becomes

panic: expected JSON object but got "21"

So I think it's related to how gno bigint are interpreted in amino. If I change again this const to

const RawAddressSize = int(20)

Everything works properly.

Does anyone know if something has changed in the way that const are interpreted ? Why is it a bigint here ?

[moul]

bigint is in the codebase from day 1: 6ff6762#diff-14db1b285d73487af27af13336ae8cf7797355a680b7049b5dd36771d72794ef and we need to support such types and will even work on improving the support (several related discussions).

I believe using bigint as the default type for numeric constants is a bug.

The implementation of bigint seems incomplete, possibly due to lacking marshalling helpers in values.go, causing the mentioned panic.

@jaekwon wdyt?

[tbruyelle]

@moul found a fix \o/
see commit 4b6891a for content and explanation (this commit message should be used for the merge commit if we're OK on the review).

EDIT: commit hash

[moul]

Output with standard JSON: gist.github.com/moul/cc7fda42d648ceae144d9bff55a20d7e

How did you achieve that? using only json.Encode from the stdlib ?

Yeah, I often use my library for debugging: https://pkg.go.dev/moul.io/godev#PrettyJSONPB :)