internal/lsp/cache: don't trim types.Info with staticcheck enabled

As predicted in CL 308730, there are some analyzers that need this: all
of staticcheck. (I probably should've seen that coming.) For now, don't
do the trimming when staticcheck is on. Since staticcheck ~doubles
memory footprint, those users probably don't care much.

Change-Id: I7cfd96b3654e3617d28d62015928a45a85407d13
Reviewed-on: https://go-review.googlesource.com/c/tools/+/311376
Trust: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/lsp/cache/check.go

@@ -454,7 +454,11 @@ func typeCheck(ctx context.Context, snapshot *snapshot, m *metadata, mode source
 		return nil, ctx.Err()
 	}
 
-	trimTypesInfo(files, pkg.typesInfo)
+	// staticcheck requires full type information. Reduce memory usage for
+	// everyone else.
+	if !snapshot.view.Options().Staticcheck {
+		trimTypesInfo(files, pkg.typesInfo)
+	}
 
 	// We don't care about a package's errors unless we have parsed it in full.
 	if mode != source.ParseFull {