Format struct using qualified package name

Fixes orijtech#13

Author: Cuong Manh Le

structslop.go

@@ -62,7 +62,7 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		pass.Report(analysis.Diagnostic{
 			Pos:            n.Pos(),
 			End:            n.End(),
-			Message:        fmt.Sprintf("%v has size %d, could be %d, rearrange to %v for optimal size", styp, r.oldSize, r.newSize, r.suggestedStruct),
+			Message:        fmt.Sprintf("%s has size %d, could be %d, rearrange to %s for optimal size", formatStruct(styp), r.oldSize, r.newSize, formatStruct(r.suggestedStruct)),
 			SuggestedFixes: nil,
 		})
 	})
@@ -122,3 +122,7 @@ func optimalStructArrangement(s *types.Struct) *types.Struct {
 
 	return types.NewStruct(fields, nil)
 }
+
+func formatStruct(styp *types.Struct) string {
+	return types.TypeString(styp, func(p *types.Package) string { return p.Name() })
+}

testdata/src/struct/p.go

@@ -14,6 +14,8 @@
 
 package p
 
+import "net/http/httptest"
+
 type s struct{}
 
 type s1 struct {
@@ -38,3 +40,9 @@ type s4 struct { // want `struct{.+} has size 32, could be 20, rearrange to stru
 	a3 [3]bool
 	_  [0]func()
 }
+
+type s5 struct { // want `struct{.+} has size 24, could be 20, rearrange to struct{y uint64; z \*httptest.Server; x uint32} for optimal size`
+	x uint32
+	y uint64
+	z *httptest.Server
+}