fix #5154 (nested for loop syntax & break behavior)

[nolta]

Output of:

julia> for i=1:3, j=1:3
           println("$i $j")
           i == 1 && j == 2 && break
       end

before:

1 1
1 2
2 1
2 2
2 3
3 1
3 2
3 3

and after:

1 1
1 2

[JeffBezanson]

Wow, thanks, I forgot about this one. I think it would be good to put this in 0.3.

[quinnj]

+1

[JeffBezanson]

I think this should parse as a single for expression, with a (tuple ...) of the ranges. The parsed form should visually match the source code. All the inner- forms will then be confined to lowering, where they will not bother people.

[JeffBezanson]

Ok I think this is now ready to go.

[tkelman]

According to bisect, merging this (dd85daa) caused the following test failure on Win64:

Tony@TK-samsung ~/julia/test
$ ../usr/bin/julia runtests.jl spawn
     * spawn
       [stdio passthrough ok]
exception on 1: ERROR: new not defined
 in IPv4 at socket.jl:15
 in connect at socket.jl:600
while loading spawn.jl, in expression starting on line 134
ERROR: new not defined
 in IPv4 at socket.jl:15
 in connect at socket.jl:600
while loading spawn.jl, in expression starting on line 134
while loading D:\cygwin64\home\Tony\julia\test\runtests.jl, in expression starting on line 46

Looks a little like #5153?

[tkelman]

And it went away again. The hell?

[JeffBezanson]

That is a very slippery error, probably GC-related, that is very sensitive to the exact allocation workload.