tree 687a94d45e161abb4913705e743dfcafe8a9a724
parent dd44d981dbad7191278fb629ed83bf2fd94cf1e5
author Robert Griesemer <gri@golang.org> 1674776344 -0800
committer Gopher Robot <gobot@golang.org> 1675287029 +0000

go/types, types2: replace unifier type parameter list with a map

Further simplify the unifier by using a mapping from type parameter
to type (argument) handle, where a handle is just an indirection to
the actual type associated with the type parameter.

If multiple type parameters are "joined", i.e., share the same type
(argument), then they use the same handle. Thus, if one of the type
parameters gets a type, all type parameters sharing the same handle
get the same type.

The handles mapping replaces the indices list (mapping from type
parameter index to types index). Because each handle holds any
associated type directly, we also don't need a types list anymore.

We still keep the incoming type parameter list to maintain the same
order for printing and reporting inferred types. We may be able to
eliminate this list as well in future CLs.

Change-Id: I389527dbb325b828c91050e59902ae546c3d0347
Reviewed-on: https://go-review.googlesource.com/c/go/+/463228
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>