text/template: :=, =, !, %, etc all assign to variables

[rsc]

http://play.golang.org/p/uxtQRPpcd9

        {{$x:=0}}{{$x}}
        {{$x=1}}{{$x}}
        {{$x!2}}{{$x}}
        {{$x%3}}{{$x}}

prints

        0
        1
        2
        3

[rsc]

Comment 1:

Changing to Go1-Must to avoid breaking Go 1 programs later.
The fix should disallow = for assignment, even though it is used (probably accidentally)
in one test.  A simple, useful future addition would be to have = for reassigning
existing variables, so it is important that = not be equivalent to := now.
This is the test that will need changing:
    {"variable declared by template", `{{template "nested" $x=.SI}},{{index $x 1}}`, "[3 4 5],4", tVal, true},

Labels changed: added go1-must.

[robpike]

Comment 2:

This issue was closed by revision 8170d81.

Status changed to Fixed.