Using the regexp package gives either a stack overlow or "panic: expected exactly one index"

[arp242]

With the following:

package main

import "regexp"

var reTest = regexp.MustCompile(`^\w[\w -]+:$`)

func main() {}

I get:

panic: expected exactly one index

goroutine 6 [running]:
github.com/tinygo-org/tinygo/interp.(*runner).runAtRuntime(0xc0000c1320, 0xc001271900, 0x36, 0x53, 0xc0021352c0, 0x3, 0x3, 0x1f0c0a0, 0xc000344108, 0x11, ...)
	/data/src/tinygo/interp/interpreter.go:940 +0xd25
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc001271900, 0xc002d9c610, 0x8, 0x1f, 0xc0012591d0, 0xc0003441f8, 0x18, 0x0, 0xc002a972c0, ...)
	/data/src/tinygo/interp/interpreter.go:100 +0xa85a
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc0012716d0, 0xc002a40e10, 0x5, 0x7, 0xc000bbfec0, 0xc000e23668, 0x14, 0x0, 0xc002f9d660, ...)
	/data/src/tinygo/interp/interpreter.go:481 +0x6473
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc001271680, 0xc0029fc010, 0x6, 0x7, 0xc0008de420, 0xc00281bf90, 0x10, 0x0, 0xc002872a10, ...)
	/data/src/tinygo/interp/interpreter.go:481 +0x6473
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc001271630, 0xc002801e90, 0x4, 0x7, 0xc0008bf6e0, 0xc0027d4f60, 0xc, 0x0, 0x3ab7f900, ...)
	/data/src/tinygo/interp/interpreter.go:481 +0x6473
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc001270c30, 0xc002801910, 0x4, 0x7, 0xc0008b7200, 0xc0027d4780, 0x8, 0x0, 0x200000003, ...)
	/data/src/tinygo/interp/interpreter.go:481 +0x6473
github.com/tinygo-org/tinygo/interp.(*runner).run(0xc0000c1320, 0xc001270b90, 0x0, 0x0, 0x0, 0x0, 0x80f89a, 0x4, 0x0, 0x0, ...)
	/data/src/tinygo/interp/interpreter.go:481 +0x6473
github.com/tinygo-org/tinygo/interp.Run(0xb11710, 0xc00004cd00, 0x0, 0x0)
	/data/src/tinygo/interp/interp.go:112 +0x69f
github.com/tinygo-org/tinygo/builder.optimizeProgram(0xb11710, 0xc00025e0c0, 0xc000e627a0, 0x2)
	/data/src/tinygo/builder/build.go:649 +0x3f
github.com/tinygo-org/tinygo/builder.Build.func2(0xc001c376e0, 0x0, 0x0)
	/data/src/tinygo/builder/build.go:384 +0x7c6
github.com/tinygo-org/tinygo/builder.jobWorker(0xc000bcf680, 0xc000bcf620)
	/data/src/tinygo/builder/jobs.go:165 +0xe2
created by github.com/tinygo-org/tinygo/builder.runJobs
	/data/src/tinygo/builder/jobs.go:84 +0xc5

I attempted to reduce the complexity of the regexp to isolate the problem, but with this:

var reTest = regexp.MustCompile("0")

I get:

runtime: goroutine stack exceeds 1000000000-byte limit
runtime: sp=0xc024280380 stack=[0xc024280000, 0xc044280000]
fatal error: stack overflow

runtime stack:
runtime.throw(0x8147dd, 0xe)
	/usr/lib/go/src/runtime/panic.go:1117 +0x72
runtime.newstack()
	/usr/lib/go/src/runtime/stack.go:1069 +0x7ed
runtime.morestack()
	/usr/lib/go/src/runtime/asm_amd64.s:458 +0x8f

goroutine 53 [running]:
runtime.convT64(0x7f23f0002940, 0x0)
	/usr/lib/go/src/runtime/iface.go:360 +0x79 fp=0xc024280390 sp=0xc024280388 pc=0x429779
tinygo.org/x/go-llvm.Module.Context.func1(0x7f23f0002940, 0x42fbc2)
	/home/martin/.cache/go/pkg/mod/tinygo.org/x/go-llvm@v0.0.0-20210325115028-e7b85195e81c/ir.go:512 +0x2b fp=0xc0242803c0 sp=0xc024280390 pc=0x688e4b
tinygo.org/x/go-llvm.Module.Context(0x7f23f0002940, 0xc0242804b0)
	/home/martin/.cache/go/pkg/mod/tinygo.org/x/go-llvm@v0.0.0-20210325115028-e7b85195e81c/ir.go:512 +0x2b fp=0xc0242803e0 sp=0xc0242803c0 pc=0x67b40b
github.com/tinygo-org/tinygo/interp.rawValue.rawLLVMValue(0xc0002bb880, 0x70, 0x70, 0xc0031fb5f0, 0x70, 0xa, 0x884ec0)
	/data/src/tinygo/interp/memory.go:766 +0x5d fp=0xc0242804c0 sp=0xc0242803e0 pc=0x70d03d

[.. trim ..]

Full error over here, as it's a bit long: https://gist.github.com/arp242/eb624496c58ea151daa71009cace3d61

$ tinygo version
tinygo version 0.18.0-dev linux/amd64 (using go version go1.16.3 and LLVM version 11.0.0)

(this is commit 80caf2d)

[arp242]

I appreciate that something like the regexp package might not be supported in TinyGo btw, I just wanted to see if my little CLI program works with TinyGo now that os.Args is supported. But panics and stack overflows are not the best way to communicate that 😅

[fgsch]

Does this work not using globals? See #1306 .

[aykevl]

This panic is probably solved with #1850.

You will probably run into #1848 after that (the stack overflow). To fix that, you could move the regexp.MustCompile out of init code, for example into the main function.

But panics and stack overflows are not the best way to communicate that 😅

Well yeah, but these behaviors weren't exactly intended behavior.

[deadprogram]

So the panic should now be solved in the dev branch with #1850 merged, but we should leave open to address the stack overflow part.

[dgryski]

This particular issue seems to be solved somewhat.

~/go/src/github.com/dgryski/bug $ cat bug.go
package main

import "regexp"

var reTest = regexp.MustCompile(`^\w[\w -]+:$`)

func main() {
	println(reTest.MatchString("foobar"))
}
~/go/src/github.com/dgryski/bug $ go run bug.go
false
~/go/src/github.com/dgryski/bug $ tinygo run -target=wasi bug.go
false
~/go/src/github.com/dgryski/bug $ tinygo run bug.go
false

I agree a more generic "interp is slow" bug would be useful, but I think we have enough of those already.