internal/lsp: fix references for transitive dependencies

We need to search all transitive dependencies of a package, not just its
immediate imports.

Fixes golang/go#38100

Change-Id: I15b4dbe226ba851691ca0c95460c3648ede32f04
Reviewed-on: https://go-review.googlesource.com/c/tools/+/227030
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Rohan Challa <rohan@golang.org>

internal/lsp/source/implementation.go

@@ -247,11 +247,18 @@ func qualifiedObjsAtProtocolPos(ctx context.Context, s Snapshot, fh FileHandle,
 			}
 			objs = append(objs, obj)
 		}
+		// Get all of the transitive dependencies of the search package.
 		pkgs := make(map[*types.Package]Package)
-		pkgs[searchpkg.GetTypes()] = searchpkg
-		for _, imp := range searchpkg.Imports() {
-			pkgs[imp.GetTypes()] = imp
+		var addPkg func(pkg Package)
+		addPkg = func(pkg Package) {
+			pkgs[pkg.GetTypes()] = pkg
+			for _, imp := range pkg.Imports() {
+				if _, ok := pkgs[imp.GetTypes()]; !ok {
+					addPkg(imp)
+				}
+			}
 		}
+		addPkg(searchpkg)
 		for _, obj := range objs {
 			if obj.Parent() == types.Universe {
 				return nil, fmt.Errorf("%w %q", errBuiltin, obj.Name())

internal/lsp/testdata/lsp/primarymod/references/another/another.go

@@ -0,0 +1,13 @@
+// Package another has another type.
+package another
+
+import (
+	other "golang.org/x/tools/internal/lsp/references/other"
+)
+
+func _() {
+	xes := other.GetXes()
+	for _, x := range xes {
+		_ = x.Y //@mark(anotherXY, "Y"),refs("Y", typeXY, anotherXY, GetXesY)
+	}
+}

internal/lsp/testdata/lsp/primarymod/references/other/other.go

@@ -4,6 +4,14 @@ import (
 	references "golang.org/x/tools/internal/lsp/references"
 )
 
+func GetXes() []references.X {
+	return []references.X{
+		{
+			Y: 1, //@mark(GetXesY, "Y"),refs("Y", typeXY, GetXesY, anotherXY)
+		},
+	}
+}
+
 func _() {
 	references.Q = "hello" //@mark(assignExpQ, "Q")
 	bob := func(_ string) {}

internal/lsp/testdata/lsp/primarymod/references/refs.go

@@ -3,6 +3,10 @@ package refs
 
 type i int //@mark(typeI, "i"),refs("i", typeI, argI, returnI, embeddedI)
 
+type X struct {
+	Y int //@mark(typeXY, "Y")
+}
+
 func _(_ i) []bool { //@mark(argI, "i")
 	return nil
 }

internal/lsp/testdata/lsp/summary.txt.golden

@@ -15,7 +15,7 @@ SuggestedFixCount = 6
 DefinitionsCount = 45
 TypeDefinitionsCount = 2
 HighlightsCount = 52
-ReferencesCount = 9
+ReferencesCount = 11
 RenamesCount = 24
 PrepareRenamesCount = 7
 SymbolsCount = 3