From 1da965b65f8a0e3aa83cd9d6d38153a32f308960 Mon Sep 17 00:00:00 2001
From: SalvadorC <salvadorcavadini+github@gmail.com>
Date: Mon, 11 May 2020 02:43:56 +0200
Subject: [PATCH] =?UTF-8?q?fix=20issue=20386:=20Incorrectly=20identifies?=
=?UTF-8?q?=20channel=20draining=20as=20"empty=20code=E2=80=A6=20(#415)?=
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* fix issue 386: Incorrectly identifies channel draining as "empty code block"
* updates doc of empty-block rule
---
README.md | 2 +-
rule/empty-block.go | 64 ++++++++++++++++++-----------------------
testdata/empty-block.go | 21 ++++++++++----
3 files changed, 44 insertions(+), 43 deletions(-)
diff --git a/README.md b/README.md
index 7c6809c..e0c471f 100644
--- a/README.md
+++ b/README.md
@@ -316,7 +316,7 @@ List of all available rules. The rules ported from `golint` are left unchanged a
| [`cyclomatic`](./RULES_DESCRIPTIONS.md#cyclomatic) | int | Sets restriction for maximum Cyclomatic complexity. | no | no |
| [`max-public-structs`](./RULES_DESCRIPTIONS.md#max-public-structs) | int | The maximum number of public structs in a file. | no | no |
| [`file-header`](./RULES_DESCRIPTIONS.md#file-header) | string | Header which each file should have. | no | no |
-| [`empty-block`](./RULES_DESCRIPTIONS.md#empty-block) | n/a | Warns on empty code blocks | no | no |
+| [`empty-block`](./RULES_DESCRIPTIONS.md#empty-block) | n/a | Warns on empty code blocks | no | yes |
| [`superfluous-else`](./RULES_DESCRIPTIONS.md#superfluous-else) | n/a | Prevents redundant else statements (extends [`indent-error-flow`](./RULES_DESCRIPTIONS.md#indent-error-flow)) | no | no |
| [`confusing-naming`](./RULES_DESCRIPTIONS.md#confusing-naming) | n/a | Warns on methods with names that differ only by capitalization | no | no |
| [`get-return`](./RULES_DESCRIPTIONS.md#get-return) | n/a | Warns on getters that do not yield any result | no | no |
diff --git a/rule/empty-block.go b/rule/empty-block.go
index 7861394..4eb0ce8 100644
--- a/rule/empty-block.go
+++ b/rule/empty-block.go
@@ -2,6 +2,7 @@ package rule
import (
"go/ast"
+ "go/types"
"github.com/mgechev/revive/lint"
)
@@ -17,7 +18,12 @@ func (r *EmptyBlockRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure
failures = append(failures, failure)
}
- w := lintEmptyBlock{make([]*ast.BlockStmt, 0), onFailure}
+ err := file.Pkg.TypeCheck()
+ if err != nil {
+ panic("unable to type check " + file.Name + ":" + err.Error())
+ }
+
+ w := lintEmptyBlock{make(map[*ast.BlockStmt]bool, 0), file.Pkg, onFailure}
ast.Walk(w, file.AST)
return failures
}
@@ -28,49 +34,35 @@ func (r *EmptyBlockRule) Name() string {
}
type lintEmptyBlock struct {
- ignore []*ast.BlockStmt
+ ignore map[*ast.BlockStmt]bool
+ pkg *lint.Package
onFailure func(lint.Failure)
}
func (w lintEmptyBlock) Visit(node ast.Node) ast.Visitor {
- fd, ok := node.(*ast.FuncDecl)
- if ok {
- w.ignore = append(w.ignore, fd.Body)
+ switch n := node.(type) {
+ case *ast.FuncDecl:
+ w.ignore[n.Body] = true
return w
- }
-
- fl, ok := node.(*ast.FuncLit)
- if ok {
- w.ignore = append(w.ignore, fl.Body)
+ case *ast.FuncLit:
+ w.ignore[n.Body] = true
return w
- }
+ case *ast.RangeStmt:
+ t := w.pkg.TypeOf(n.X)
- block, ok := node.(*ast.BlockStmt)
- if !ok {
- return w
- }
-
- if mustIgnore(block, w.ignore) {
- return w
- }
-
- if len(block.List) == 0 {
- w.onFailure(lint.Failure{
- Confidence: 1,
- Node: block,
- Category: "logic",
- Failure: "this block is empty, you can remove it",
- })
+ if _, ok := t.(*types.Chan); ok {
+ w.ignore[n.Body] = true
+ }
+ case *ast.BlockStmt:
+ if !w.ignore[n] && len(n.List) == 0 {
+ w.onFailure(lint.Failure{
+ Confidence: 1,
+ Node: n,
+ Category: "logic",
+ Failure: "this block is empty, you can remove it",
+ })
+ }
}
return w
}
-
-func mustIgnore(block *ast.BlockStmt, blackList []*ast.BlockStmt) bool {
- for _, b := range blackList {
- if b == block {
- return true
- }
- }
- return false
-}
diff --git a/testdata/empty-block.go b/testdata/empty-block.go
index 9f04d5b..81b7262 100644
--- a/testdata/empty-block.go
+++ b/testdata/empty-block.go
@@ -2,18 +2,18 @@
package fixtures
-func f(x int) bool {} // Must not match
+func f(x int) {} // Must not match
-type foo struct {}
+type foo struct{}
-func (f foo) f(x *int) string {} // Must not match
-func (f *foo) g(y *int) string {} // Must not match
+func (f foo) f(x *int) {} // Must not match
+func (f *foo) g(y *int) {} // Must not match
-func g(f func() bool) string {
+func g(f func() bool) {
{ // MATCH /this block is empty, you can remove it/
}
- a := func(e error){} // Must not match
+ _ = func(e error) {} // Must not match
if ok := f(); ok { // MATCH /this block is empty, you can remove it/
// only a comment
@@ -35,4 +35,13 @@ func g(f func() bool) string {
}
+ // issue 386
+ var c = make(chan int)
+ for range c {
+ }
+
+ var s = "a string"
+ for range s { // MATCH /this block is empty, you can remove it/
+ }
+
}