tree 4c129ec0ae5dbbd0fbd06938537b3eb70ebf0fab
parent 5492d01d98d3be4e014a66fc31953c04cc38c8c8
author Robert Findley <rfindley@google.com> 1631639223 -0400
committer Robert Findley <rfindley@google.com> 1631664816 +0000

go/internal/gcimporter: update iimport.go to support type parameters

This CL pulls in the latest changes from go/internal/gcimporter, while
avoiding breaking the build on older go versions. To help maintain
compatibility with older Go versions while minimizing the diff with the
standard library importer, the internal/typeparams package was
significantly expanded.

I decided to use type aliases in the internal/typeparams package on Go
version >= go1.18, and placeholder types on Go version < go1.18. This
reduces the amount of copying needed in the APIs, though it might not be
the best decision if we ever decide to export this package.
Documentation was also updated to be more concise and specific to the Go
version being used.

In order to actually fix the x/tools Trybot for packages using generics
in the standard library, we need to switch from the 'typeparams' build
constraint to the 'go1.18' build constraint. This means if we make any
additional API changes in go/types we'll have to submit them with a
broken x/tools Trybot and then immediately fix the x/tools build.

Change-Id: Ifa0b1c37b89dc549ee295fa3a959f03deda86e56
Reviewed-on: https://go-review.googlesource.com/c/tools/+/349949
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>