internal/modindex: fix two bugs

Symbol types should be a single character, and now they are.

func F(int, float) is legal. Before it was being treated as if it were
F(), now it is treated as if it were F(_ int, _ float), which seems
better.

Change-Id: I051f60b16edccf54c4ce30f11b33a458413fa9af
Reviewed-on: https://go-review.googlesource.com/c/tools/+/620138
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: pjweinbgo

internal/modindex/symbols.go

@@ -112,9 +112,14 @@ func getFileExports(f *ast.File) []symbol {
 					continue
 				}
 				tp = strings.Replace(tp, " ", "$", -1)
-				for _, y := range x.Names {
-					result = append(result, y.Name)
+				if len(x.Names) == 0 {
+					result = append(result, "_")
 					result = append(result, tp)
+				} else {
+					for _, y := range x.Names {
+						result = append(result, y.Name)
+						result = append(result, tp)
+					}
 				}
 			}
 			sigs := strings.Join(result, " ")
@@ -124,9 +129,9 @@ func getFileExports(f *ast.File) []symbol {
 		case *ast.GenDecl:
 			switch decl.Tok {
 			case token.CONST, token.VAR:
-				tp := " V"
+				tp := "V"
 				if decl.Tok == token.CONST {
-					tp = " C"
+					tp = "C"
 				}
 				for _, sp := range decl.Specs {
 					for _, x := range sp.(*ast.ValueSpec).Names {
@@ -137,7 +142,7 @@ func getFileExports(f *ast.File) []symbol {
 				}
 			case token.TYPE:
 				for _, sp := range decl.Specs {
-					if s := newsym(pkg, sp.(*ast.TypeSpec).Name.Name, " T", ""); s != nil {
+					if s := newsym(pkg, sp.(*ast.TypeSpec).Name.Name, "T", ""); s != nil {
 						ans = append(ans, *s)
 					}
 				}