fixes #46

cmd/kfulint/testdata/underef/checker_tests.go

@@ -33,7 +33,7 @@ func sampleCase2(k sampleInterface) {
 func sampleCase3() {
 	var k *[5]int
 
-	//TODO: could simplify (*k)[5] to k[5]
+	///: could simplify (*k)[2] to k[2]
 	(*k)[2] = 3
 }
 

lint/underef_checker.go

@@ -38,18 +38,32 @@ func (c *UnderefChecker) Check(f *ast.File) {
 				}
 				if expr, ok := expr.X.(*ast.StarExpr); ok {
 					if c.checkStarExpr(expr) {
-						c.warn(n)
+						c.warnSelect(n)
 						return false
 					}
 				}
+			case *ast.IndexExpr:
+				expr, ok := n.X.(*ast.ParenExpr)
+				if !ok {
+					return true
+				}
+				if expr, ok := expr.X.(*ast.StarExpr); ok {
+					if !c.checkStarExpr(expr) {
+						return true
+					}
+					if c.checkArray(expr) {
+						c.warnArray(n)
+					}
+				}
 			}
+
 			return true
 		})
 	}
 }
 
 // TODO add () to function output.
-func (c *UnderefChecker) warn(expr *ast.SelectorExpr) {
+func (c *UnderefChecker) warnSelect(expr *ast.SelectorExpr) {
 	c.ctx.addWarning(Warning{
 		Kind: "underef",
 		Node: expr,
@@ -60,6 +74,17 @@ func (c *UnderefChecker) warn(expr *ast.SelectorExpr) {
 	})
 }
 
+func (c *UnderefChecker) warnArray(expr *ast.IndexExpr) {
+	c.ctx.addWarning(Warning{
+		Kind: "underef",
+		Node: expr,
+		Text: fmt.Sprintf("could simplify %s to %s[%s]",
+			nodeString(c.ctx.FileSet, expr),
+			nodeString(c.ctx.FileSet, expr.X.(*ast.ParenExpr).X.(*ast.StarExpr).X),
+			nodeString(c.ctx.FileSet, expr.Index)),
+	})
+}
+
 // checkStarExpr checks if ast.StarExpr could be simplified
 func (c *UnderefChecker) checkStarExpr(expr *ast.StarExpr) bool {
 	// checks if expr is pointer type
@@ -75,3 +100,12 @@ func (c *UnderefChecker) checkStarExpr(expr *ast.StarExpr) bool {
 
 	return true
 }
+
+func (c *UnderefChecker) checkArray(expr *ast.StarExpr) bool {
+	typ, ok := c.ctx.TypesInfo.TypeOf(expr.X).(*types.Pointer)
+	if !ok {
+		return false
+	}
+	_, ok = typ.Elem().(*types.Array)
+	return ok
+}