regexp compile failures on darwin/wasm

[ribasushi]

TLDR
regexp is listed as fully implemented, yet code using it fails compilation.

Version
tinygo version 0.14.0 darwin/amd64 (using go version go1.14.7 and LLVM version 10.0.0)

Failure

~$ tinygo run tiny.go 
# command-line-arguments
/usr/local/go/src/regexp/syntax/parse.go:1535:5: interp: branch on a non-constant

traceback:
/usr/local/go/src/regexp/syntax/parse.go:774:28:
  %108 = call { %runtime._string, %runtime._interface } @"(*regexp/syntax.parser).parseClass"(%"regexp/syntax.parser"* %19, i8* %106, i64 %107, i8* undef, i8* undef), !dbg !1831
/usr/local/go/src/regexp/regexp.go:170:25:
  %4 = call { %"regexp/syntax.Regexp"*, %runtime._interface } @"regexp/syntax.Parse"(i8* %2, i64 %3, i16 %mode, i8* undef, i8* undef), !dbg !1739
/usr/local/go/src/regexp/regexp.go:133:16:
  %4 = call { %regexp.Regexp*, %runtime._interface } @regexp.compile(i8* %2, i64 %3, i16 212, i1 false, i8* undef, i8* undef), !dbg !1696
/usr/local/go/src/regexp/regexp.go:309:24:
  %4 = call { %regexp.Regexp*, %runtime._interface } @regexp.Compile(i8* %2, i64 %3, i8* undef, i8* undef), !dbg !1698
command-line-arguments/<init>:8:34:
  %0 = call %regexp.Regexp* @regexp.MustCompile(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @"command-line-arguments.init$string", i32 0, i32 0), i64 12, i8* undef, i8* undef), !dbg !1692

Expectation

~$ go run tiny.go 
(?m)^([^\n])
(?m)^\s{0,12}([^\s\n\-])
(?m)^(\s*)\-\-
\bMaxPayload\b

Testcase

package main

import (
	"fmt"
	"regexp"
)

var indenter = regexp.MustCompile(`(?m)^([^\n])`)
var nonOptIndenter = regexp.MustCompile(`(?m)^\s{0,12}([^\s\n\-])`)
var dashStripper = regexp.MustCompile(`(?m)^(\s*)\-\-`)
var maxPlaceholder = regexp.MustCompile(`\bMaxPayload\b`)

func main() {
	for _, re := range []*regexp.Regexp{
		indenter,
		nonOptIndenter,
		dashStripper,
		maxPlaceholder,
	} {
		fmt.Println(re.String())
	}
}

[deadprogram]

Note that the fact they can be imported, does not mean that all functions and types in the program can be used. For example, sometimes using some functions or types of the package will still trigger compiler errors.

via https://tinygo.org/lang-support/stdlib/

[ribasushi]

Removed the arch-label: same error with the wasm target:

~$ tinygo build -o wasm.wasm -target wasm tiny.go 
# command-line-arguments
/usr/local/go/src/regexp/syntax/parse.go:1535:5: interp: branch on a non-constant

traceback:
/usr/local/go/src/regexp/syntax/parse.go:774:28:
  %108 = call { %runtime._string, %runtime._interface } @"(*regexp/syntax.parser).parseClass"(%"regexp/syntax.parser"* %19, i8* %106, i32 %107, i8* undef, i8* undef), !dbg !1875
/usr/local/go/src/regexp/regexp.go:170:25:
  %4 = call { %"regexp/syntax.Regexp"*, %runtime._interface } @"regexp/syntax.Parse"(i8* %2, i32 %3, i16 %mode, i8* undef, i8* undef), !dbg !1783
/usr/local/go/src/regexp/regexp.go:133:16:
  %4 = call { %regexp.Regexp*, %runtime._interface } @regexp.compile(i8* %2, i32 %3, i16 212, i1 false, i8* undef, i8* undef), !dbg !1740
/usr/local/go/src/regexp/regexp.go:309:24:
  %4 = call { %regexp.Regexp*, %runtime._interface } @regexp.Compile(i8* %2, i32 %3, i8* undef, i8* undef), !dbg !1742
command-line-arguments/<init>:8:34:
  %0 = call %regexp.Regexp* @regexp.MustCompile(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @"command-line-arguments.init$string", i32 0, i32 0), i32 12, i8* undef, i8* undef), !dbg !1736

[ribasushi]

@deadprogram I really want to try to fix this: could you give me 30 seconds of pointers? Like even a previous issue/PR that is similar to this in spirit will help!

[aykevl]

You can work around this by not doing the rexexp.MustCompile in a global. This should work:

package main

import (
	"fmt"
	"regexp"
)

func main() {
	var indenter = regexp.MustCompile(`(?m)^([^\n])`)
	var nonOptIndenter = regexp.MustCompile(`(?m)^\s{0,12}([^\s\n\-])`)
	var dashStripper = regexp.MustCompile(`(?m)^(\s*)\-\-`)
	var maxPlaceholder = regexp.MustCompile(`\bMaxPayload\b`)

	for _, re := range []*regexp.Regexp{
		indenter,
		nonOptIndenter,
		dashStripper,
		maxPlaceholder,
	} {
		fmt.Println(re.String())
	}
}

[niaow]

This issue seems to have been fixed by some interp work at some point.