tree dbe7517ec374f01c47ba8b9831b08d7426143bea
parent 30f191f36d2b3d1701093fb6ab0258d139649d92
author Robert Findley <rfindley@google.com> 1675185696 -0500
committer Robert Findley <rfindley@google.com> 1675365704 +0000

gopls/internal/lsp/source: use syntax alone in FormatVarType

FormatVarType re-formats a variable type using syntax, in order to get
accurate presentation of aliases and ellipses. However, as a result it
required typed syntax trees for the type declaration, which may exist in
a distinct package from the current package.

In the near future we may not have typed syntax trees for these
packages. We could type-check on demand, but (1) that could be costly
and (2) it may break qualification using the go/types qualifier.

Instead, perform this operation using a qualifier based on syntax
and metadata, so that we only need a fully parsed file rather than a
fully type-checked package. The resulting expressions may be inaccurate
due to built-ins, "." imported packages, or missing metadata, but that
seems acceptable for the current use-cases of this function, which are
in completion and signature help.

While doing this, add a FormatNodeWithFile helper that allows formatting
a node from a *token.File, rather than *token.FileSet. This can help us
avoid relying on a global fileset. To facilitate this, move the GetLines
helper from internal/gcimporter into a shared tokeninternal package.

For golang/go#57987

Change-Id: I3b8a5256bc2261be8b5175ee360b9336228928ac
Reviewed-on: https://go-review.googlesource.com/c/tools/+/464301
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>