internal/lsp/cache: copy workFile when invalidating workspace

to avoid losing workFile information when that happens. This fixes an
issue where diagnostics, hover, etc didn't show up after the initial
load when some changes were made to go.work files.

Change-Id: I42e2dcfd94a5b4726856ab0a4d8dfc9c1efc48b1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/391257
Trust: Michael Matloob <[email protected]>
Run-TryBot: Michael Matloob <[email protected]>
gopls-CI: kokoro <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: matloob

gopls/internal/regtest/workspace/workspace_test.go

@@ -802,13 +802,28 @@ func TestUseGoWorkDiagnosticMissingModule(t *testing.T) {
 go 1.18
 
 use ./foo
+-- bar/go.mod --
+module example.com/bar
 `
 	Run(t, files, func(t *testing.T, env *Env) {
 		env.OpenFile("go.work")
 		env.Await(
 			env.DiagnosticAtRegexpWithMessage("go.work", "use", "directory ./foo does not contain a module"),
 		)
-		t.Log("bar")
+		// The following tests is a regression test against an issue where we weren't
+		// copying the workFile struct field on workspace when a new one was created in
+		// (*workspace).invalidate. Set the buffer content to a working file so that
+		// invalidate recognizes the workspace to be change and copies over the workspace
+		// struct, and then set the content back to the old contents to make sure
+		// the diagnostic still shows up.
+		env.SetBufferContent("go.work", "go 1.18 \n\n use ./bar\n")
+		env.Await(
+			env.NoDiagnosticAtRegexp("go.work", "use"),
+		)
+		env.SetBufferContent("go.work", "go 1.18 \n\n use ./foo\n")
+		env.Await(
+			env.DiagnosticAtRegexpWithMessage("go.work", "use", "directory ./foo does not contain a module"),
+		)
 	})
 }
 

internal/lsp/cache/workspace.go

@@ -282,6 +282,7 @@ func (w *workspace) invalidate(ctx context.Context, changes map[span.URI]*fileCh
 		moduleSource:   w.moduleSource,
 		knownModFiles:  make(map[span.URI]struct{}),
 		activeModFiles: make(map[span.URI]struct{}),
+		workFile:       w.workFile,
 		mod:            w.mod,
 		sum:            w.sum,
 		wsDirs:         w.wsDirs,