Variadic parameters don't work if some of the args are expended and some aren't

[gopherbot]

by ficoos:

Before filing a bug, please check whether it has been fixed since
the latest release: run "hg pull", "hg update default", rebuild, and
retry
what you did to
reproduce the problem.  Thanks.

What steps will reproduce the problem?
// Compiles
func RfoldInt(op func(a, b int) int, ints ...int) int {
    if len(ints) == 0 {
        return 0
    }
    if len(ints) == 1 {
        return ints[0]
    }
    return op(a, RfoldInt(ints[1:]))
}

// Doesn't
func LfoldInt(op func(a, b int) int, ints ...int) int {
    if len(ints) == 0 {
        return 0
    }
    if len(ints) == 1 {
        return ints[0]
    }
    a = ints[0]
    b = ints[1]
    return Lfold(op(a, b), ints...)
}


What is the expected output?
I would expect the LfoldInt function to compile.

What do you see instead?
Compiler prints:
too many arguments in call to LfoldInt

Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
Linux

Which revision are you using?  (hg identify)
9f2be4fbbf69 weekly/weekly.2012-01-20


Please provide any additional information below.
God speed!

[gopherbot]

Comment 1 by ficoos:

There is a type in the code I pasted.
This:
    return op(a, RfoldInt(ints[1:]))
Should be:
    return op(a, RfoldInt(ints[1:]...))

[gopherbot]

Comment 2 by ficoos:

There is a typo in the code I pasted.
This:
    return op(a, RfoldInt(ints[1:]))
Should be:
    return op(a, RfoldInt(ints[1:]...))

[gopherbot]

Comment 3 by ficoos:

Also a bug Lfold itself, gosh this is embarrassing, but this is what you get when you
make shift a piece of code in the  middle of the night. But 
This:
    return Lfold(op(a, b), ints...)
Should be:
    return Lfold(op(a, b), ints[2:]...)
But it should compile non the less

[rsc]

Comment 4:

I'm having a hard time following this.
Please use play.golang.org to get the code how you
want it for the report, so that clicking Compile shows
the error you believe is a bug, and then paste the
Share link here.
Thanks.

Status changed to WaitingForReply.

[gopherbot]

Comment 5 by ficoos:

Sorry about that.
http://play.golang.org/p/-KLRKJqXoa
Expected output is:
Rfold 15
Lfold 15

[rsc]

Comment 6:

To avoid confusion about what slice is being passed,
the ... syntax only applies when it is providing the entire
... argument; you can't splice in additional parameters
with it.
You can use an explicit append instead:
    return LfoldInt(op, append([]int{op(a, b)}, ints[2:]...)...)
However, for this specific case, I'd suggest writing foldl and foldr this way:
http://play.golang.org/p/C6d3gM44FF
Russ

Status changed to WorkingAsIntended.

[rsc]

Comment 7:

Sorry, typo: http://play.golang.org/p/A4DypCG_cV

[gopherbot]

Comment 8 by ficoos:

Thanks for the quick response