Fix false positive with parenthetical expressions (#15)

Author: charithe

durationcheck.go

@@ -96,10 +96,11 @@ func isUnacceptableExpr(pass *analysis.Pass, expr ast.Expr) bool {
 		return !isAcceptableNestedExpr(pass, e)
 	case *ast.StarExpr:
 		return !isAcceptableNestedExpr(pass, e)
+	case *ast.ParenExpr:
+		return !isAcceptableNestedExpr(pass, e)
 	default:
 		return true
 	}
-
 }
 
 // isAcceptableCast returns true if the argument is an acceptable expression cast to time.Duration
@@ -153,6 +154,8 @@ func isAcceptableNestedExpr(pass *analysis.Pass, n ast.Expr) bool {
 		return isAcceptableNestedExpr(pass, e.X) && isAcceptableIdent(pass, e.Sel)
 	case *ast.StarExpr:
 		return isAcceptableNestedExpr(pass, e.X)
+	case *ast.ParenExpr:
+		return isAcceptableNestedExpr(pass, e.X)
 	default:
 		return false
 	}

testdata/src/a/a.go

@@ -1,9 +1,8 @@
 package a
 
 import (
-	"time"
-
 	"b"
+	"time"
 )
 
 const (
@@ -31,6 +30,10 @@ func validCases() {
 
 	_ = time.Second * time.Duration(10+20*5)
 
+	_ = time.Duration((foo + 20)) * time.Second
+
+	_ = time.Second * time.Duration((foo + 20))
+
 	_ = 2 * 24 * time.Hour
 
 	_ = time.Hour * 2 * 24