Regexp package : panic on repeated closure

[gopherbot]

by sebastien.geffroy:

What steps will reproduce the problem?
re := regexp.MustCompile("beginTag(?:[\n\r]|.)+?endTag")

What is the expected output? What do you see instead?
this example works great in python

regexp: compiling " begin(?:[
]|.)+?end ":  repeated closure (**, ++, etc.)
panic PC=0x2bcd98
regexp·MustCompile+0xbb /Users/seb/go/src/pkg/regexp/regexp.go:677
    regexp·MustCompile(0x749a0, 0x0, 0x14, 0x0, 0x18, ...)
tpl·*Template·parseBlock+0x30 /Users/seb/Documents/Code Source/Go/tpl/tpl.go:90
    tpl·*Template·parseBlock(0x2b57a0, 0x0, 0x2ba3f0, 0x0, 0x87, ...)
tpl·*Template·renderExtends+0xb0 /Users/seb/Documents/Code Source/Go/tpl/tpl.go:79
    tpl·*Template·renderExtends(0x2b57a0, 0x0, 0x2bcf10, 0x0)
tpl·*Template·Render+0x2a /Users/seb/Documents/Code Source/Go/tpl/tpl.go:45
    tpl·*Template·Render(0x2b57a0, 0x0, 0x2ca4d0, 0x0, 0x4, ...)
tpl·TestTpl+0x103 /Users/seb/Documents/Code Source/Go/tpl/tpl_test.go:12
    tpl·TestTpl()
testing·tRunner+0x22 /Users/seb/go/src/pkg/testing/testing.go:132
    testing·tRunner(0x2b7140, 0x0, 0x78ce0, 0x0)
goexit /Users/seb/go/src/pkg/runtime/proc.c:136
    goexit()
0x2b7140 unknown pc

goroutine 1 [4]:
gosched+0x34 /Users/seb/go/src/pkg/runtime/proc.c:522
    gosched()
chanrecv+0x38c /Users/seb/go/src/pkg/runtime/chan.c:320
    chanrecv(0x2d81e0, 0x0, 0x2bbf68, 0x0, 0x0, ...)
runtime·chanrecv1+0x50 /Users/seb/go/src/pkg/runtime/chan.c:417
    runtime·chanrecv1(0x2d81e0, 0x0)
testing·Main+0x263 /Users/seb/go/src/pkg/testing/testing.go:159
    testing·Main(0x78ce0, 0x0)
main·main+0x23 /Users/seb/Documents/Code Source/Go/tpl/_testmain.go:14
    main·main()
mainstart+0xf /Users/seb/go/src/pkg/runtime/amd64/asm.s:54
    mainstart()
goexit /Users/seb/go/src/pkg/runtime/proc.c:136
    goexit()
make: *** [test] Error 2

What is your $GOOS?  $GOARCH?
DOOS=darwin
DOARCH=amd64


Which revision are you using?  (hg identify)
a6fcf4303b0a release/release.2009-12-22

Please provide any additional information below.

[peterGo]

Comment 1:

There are many dialects of regular expressions. Go's regexp package implements a
simple regular expression library.
http://golang.org/pkg/regexp/
The error message complains about 'repeated closure (**, ++, etc.)'. Isn't your use
of '+?' a repeated closure?

[rsc]

Comment 2:

Package regexp does not support non-capturing parens (?:...)
nor does it support "non-greedy" operators like +?
Eventually there will be a replacement that does all these things
but for now, this is working as intended.

Owner changed to r...@golang.org.

Status changed to WorkingAsIntended.

[rsc]

Comment 3:

Issue #540 has been merged into this issue.