internal/lsp: await the initial workspace load in ModHandle

ModHandle races with the initial workspace load if the go.mod file does
not yet exist. We should await for the initial workspace load to
complete before proceeding with update codelenses, etc.

Part of trying to figure out the flakes in golang/go#39504.
Also a few staticcheck fixes, and fix the Windows line endings in
fill_struct.go, because `git gofmt` complains.

Change-Id: Ide21a47137390792d1afb924740cff0bb6f0b764
Reviewed-on: https://go-review.googlesource.com/c/tools/+/237419
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

internal/lsp/cache/mod.go

@@ -128,12 +128,14 @@ func (mh *modHandle) Why(ctx context.Context) (*modfile.File, *protocol.ColumnMa
 	return data.origParsedFile, data.origMapper, data.why, data.err
 }
 
-func (s *snapshot) ModHandle(ctx context.Context, fh source.FileHandle) source.ModHandle {
+func (s *snapshot) ModHandle(ctx context.Context, fh source.FileHandle) (source.ModHandle, error) {
+	if err := s.awaitLoaded(ctx); err != nil {
+		return nil, err
+	}
 	uri := fh.URI()
 	if handle := s.getModHandle(uri); handle != nil {
-		return handle
+		return handle, nil
 	}
-
 	realURI, tempURI := s.view.ModFiles()
 	folder := s.View().Folder().Filename()
 	cfg := s.Config(ctx)
@@ -202,7 +204,7 @@ func (s *snapshot) ModHandle(ctx context.Context, fh source.FileHandle) source.M
 		file:   fh,
 		cfg:    cfg,
 	}
-	return s.modHandles[uri]
+	return s.modHandles[uri], nil
 }
 
 func goModWhy(ctx context.Context, cfg *packages.Config, folder string, data *modData) error {

internal/lsp/link.go

@@ -46,7 +46,11 @@ func (s *Server) documentLink(ctx context.Context, params *protocol.DocumentLink
 func modLinks(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle) ([]protocol.DocumentLink, error) {
 	view := snapshot.View()
 
-	file, m, err := snapshot.ModHandle(ctx, fh).Parse(ctx)
+	mh, err := snapshot.ModHandle(ctx, fh)
+	if err != nil {
+		return nil, err
+	}
+	file, m, err := mh.Parse(ctx)
 	if err != nil {
 		return nil, err
 	}

internal/lsp/mod/code_lens.go

@@ -33,7 +33,11 @@ func CodeLens(ctx context.Context, snapshot source.Snapshot, uri span.URI) ([]pr
 	if err != nil {
 		return nil, err
 	}
-	f, m, upgrades, err := snapshot.ModHandle(ctx, fh).Upgrades(ctx)
+	mh, err := snapshot.ModHandle(ctx, fh)
+	if err != nil {
+		return nil, err
+	}
+	f, m, upgrades, err := mh.Upgrades(ctx)
 	if err != nil {
 		return nil, err
 	}

internal/lsp/mod/format.go

@@ -12,7 +12,11 @@ func Format(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle)
 	ctx, done := event.Start(ctx, "mod.Format")
 	defer done()
 
-	file, m, err := snapshot.ModHandle(ctx, fh).Parse(ctx)
+	mh, err := snapshot.ModHandle(ctx, fh)
+	if err != nil {
+		return nil, err
+	}
+	file, m, err := mh.Parse(ctx)
 	if err != nil {
 		return nil, err
 	}

internal/lsp/mod/hover.go

@@ -23,7 +23,11 @@ func Hover(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle,
 	ctx, done := event.Start(ctx, "mod.Hover")
 	defer done()
 
-	file, m, why, err := snapshot.ModHandle(ctx, fh).Why(ctx)
+	mh, err := snapshot.ModHandle(ctx, fh)
+	if err != nil {
+		return nil, err
+	}
+	file, m, why, err := mh.Why(ctx)
 	if err != nil {
 		return nil, err
 	}

internal/lsp/source/fill_struct.go

@@ -17,7 +17,6 @@ import (
 
 // FillStruct completes all of targeted struct's fields with their default values.
 func FillStruct(ctx context.Context, snapshot Snapshot, fh FileHandle, protoRng protocol.Range) ([]protocol.CodeAction, error) {
-
 	pkg, pgh, err := getParsedFile(ctx, snapshot, fh, NarrowestPackageHandle)
 	if err != nil {
 		return nil, fmt.Errorf("getting file for struct fill code action: %v", err)

internal/lsp/source/view.go

@@ -54,7 +54,7 @@ type Snapshot interface {
 
 	// ModHandle returns a ModHandle for the passed in go.mod file handle.
 	// This function can have no data if there is no modfile detected.
-	ModHandle(ctx context.Context, fh FileHandle) ModHandle
+	ModHandle(ctx context.Context, fh FileHandle) (ModHandle, error)
 
 	// PackageHandles returns the PackageHandles for the packages that this file
 	// belongs to.