lookupString returns 0 for incomplete UTF-8 sequences, so to
prevent infinite loops we must specifically check for that case.
However, CL 73730 which fixed this issue in 2017 was lost in the
shuffle that allowed multiple Unicode versions in x/text (CL 83235),
and the fix was never applied to idna9.0.0.go.

This CL fixes that oversight.

Updates golang/go#22184

Change-Id: I3a6ab08b157f4017560020ff259d1afbe49a9e71
Reviewed-on: https://go-review.googlesource.com/c/text/+/361494
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

It got added by 'go mod tidy' in CL 471399
because the '; ' separator was missing.

For golang/go#48523.
For golang/go#58737.

Change-Id: I63642a4f49beb9679f9c5bbb4e2aa8ed0cc73c9e
Reviewed-on: https://go-review.googlesource.com/c/text/+/501835
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>

This prepares for an upcoming Unicode upgrade.

Beyond Unicode 13 the size of mappings will grow beyond
what can be represented in the allocated 13 bits. Instread
of doubling the size of info, we introduce a table of indices
into the mappings data. This also allows us to remove the
length byte, reducing the overhead of introducing this new
table.

This change allows for about a 5x growth of the number
of mappings, which should suffice for the foreseeable
future.

Change-Id: Id475dc2473145a1f36bd83b983fa4aa170df6206
Reviewed-on: https://go-review.googlesource.com/c/text/+/501515
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>