for range <int> compiles but crashes at runtime (should be a typecheck error given Go 1.17 baseline) #4680
Description
Summary
The following program compiles in Gno but panics at runtime:
package main
func main() {
for range 1000 {
}
}Since Gno targets Go 1.17 semantics, range over an integer should be rejected at type-check time. “Range over int” only became valid Go syntax in Go 1.22; before that, it must be a compile-time error like:
cannot range over 1000 (type untyped int) (or equivalent). ([tip.golang.org][1]
Steps to Reproduce
-
Create
main.gno:package main func main() { for range 1000 { } }
-
Build/run with Gno.
-
Observe a runtime panic.
Expected Behavior
- The program should fail to compile with a typecheck error, because ranging over integers isn’t supported in Go 1.17.
Actual Behavior
-
The program builds and then panics at runtime.
-
Runtime output / panic trace:
testing.tRunner.func1.2({0x100f1aaa0, 0x1400035c318})
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/testing/testing.go:1734 +0x1ac
testing.tRunner.func1()
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/testing/testing.go:1737 +0x334
panic({0x100f1aaa0?, 0x1400035c318?})
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/runtime/panic.go:792 +0x124
github.com/gnolang/gno/gnovm/pkg/gnolang.(*bodyStmt).LastStmt(...)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/nodes.go:1013
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).Stacktrace(0x1400020a588)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:421 +0x4f0
github.com/gnolang/gno/gnovm/pkg/test.(*TestOptions).runTest.func1()
/Users/ghost/Documents/projects/gno/gnovm/pkg/test/filetest.go:312 +0x2a8
panic({0x100e12ee0?, 0x1400004abc0?})
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/runtime/panic.go:792 +0x124
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).Run.func1()
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:1258 +0x174
panic({0x100e12ee0?, 0x1400004abc0?})
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/runtime/panic.go:792 +0x124
github.com/gnolang/gno/gnovm/pkg/gnolang.(*TypedValue).GetLength(0x100f9f5d8?)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/values.go:2049 +0x38c
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).doOpExec(0x1400020a588, 0x40?)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/op_exec.go:154 +0xf74
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).Run(0x1400020a588, {0x100b11785?, 0x140004be248?})
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:1576 +0x9ec
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).RunStatement(0x1400020a588, {0x100b11785, 0x8}, {0x100fa6e80, 0x140000574a0})
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:922 +0x280
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).runFunc(0x1400020a588, {0x100b11785, 0x8}, {0x100b0d31b, 0x4}, 0x2?)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:767 +0x3ac
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).RunMain(...)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/machine.go:771
github.com/gnolang/gno/gnovm/pkg/test.(*TestOptions).runTest(0x140000cc180, 0x1400020a588, {0x100b0d31b, 0x4}, {0x140001d7160?, 0x100f91540?}, {0x140001f7e00, 0x92, 0x140004a40f0?}, {0x0, ...}, ...)
/Users/ghost/Documents/projects/gno/gnovm/pkg/test/filetest.go:359 +0xeb0
github.com/gnolang/gno/gnovm/pkg/test.(*TestOptions).runFiletest(0x140000cc180, {0x140001d7160, 0xa}, {0x140001f7e00, 0x92, 0x200}, {0x100fae100, 0x140004a4b40}, 0x1)
/Users/ghost/Documents/projects/gno/gnovm/pkg/test/filetest.go:82 +0x67c
github.com/gnolang/gno/gnovm/pkg/test.(*TestOptions).RunFiletest(0x14000591f18?, {0x140001d7160?, 0x140004a4000?}, {0x140001f7e00?, 0x0?, 0x10041a763?}, {0x100fae100?, 0x140004a4b40?})
/Users/ghost/Documents/projects/gno/gnovm/pkg/test/filetest.go:32 +0x88
github.com/gnolang/gno/gnovm/pkg/gnolang_test.TestFiles.func2.4(0x140002b5dc0)
/Users/ghost/Documents/projects/gno/gnovm/pkg/gnolang/files_test.go:109 +0xc0
testing.tRunner(0x140002b5dc0, 0x140003debd0)
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/testing/testing.go:1792 +0xe4
created by testing.(*T).Run in goroutine 11
/Users/ghost/go/pkg/mod/golang.org/[email protected]/src/testing/testing.go:1851 +0x374
FAIL github.com/gnolang/gno/gnovm/pkg/gnolang
Analysis
- Go added “range over integers” (
for i := range N { ... }) in Go 1.22 only. Under Go 1.17 semantics,rangeis limited to arrays, slices, strings, maps, and channels, sorange 1000should be rejected during type checking. Allowing it to pass the checker and then failing at runtime suggests the parser/type checker accepts the construct but the backend can’t execute it. ([tip.golang.org][1], [go.dev][2])
Possible Fixes
- Enforce a typecheck error when the range expression is of (untyped) integer type under the Go 1.17 rules; or
- If We intends to adopt Go 1.22 behavior, implement full range-over-int semantics (0..N-1) consistently across the compiler/runtime.