text/template: make reflect.Value indirections more robust
Always shadow or modify the original parameter name. With code like:
func index(item reflect.Value, ... {
v := indirectInterface(item)
It was possible to incorrectly use 'item' and 'v' later in the function,
which could result in subtle bugs. This is precisely the kind of mistake
that led to #36199.
Instead, don't keep both the old and new reflect.Value variables in
scope. Always shadow or modify the original variable.
While at it, simplify the signature of 'length', to receive a
reflect.Value directly and save a few redundant lines.
Change-Id: I01416636a9d49f81246d28b91aca6413b1ba1aa5
Reviewed-on: https://go-review.googlesource.com/c/go/+/212117
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Roberto Clapis <robclap8@gmail.com> Reviewed-by: Rob Pike <r@golang.org>