cmd: add a new analyzer for check missing values after append

If there is no second parameter added during append, there will be no prompt when executing go vet. Add an analyzer to detect this situation

Update #60448

Change-Id: If9848835424f310c54e3e9377aaaad4a1516871a
Reviewed-on: https://go-review.googlesource.com/c/go/+/498416
Run-TryBot: shuang cui <imcusg@gmail.com>
Run-TryBot: Tim King <taking@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Tim King <taking@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

diff --git a/src/cmd/go/internal/test/flagdefs.go b/src/cmd/go/internal/test/flagdefs.go
index 12d506862dde91a0e8434e23abf3f0f2e962092e..baa0cdf4c64d45f8e1cce4a3f8970d47b3aaf9ab 100644 (file)
--- a/src/cmd/go/internal/test/flagdefs.go
+++ b/src/cmd/go/internal/test/flagdefs.go
@@ -40,6 +40,7 @@ var passFlagToTest = map[string]bool{
 }
 
 var passAnalyzersToVet = map[string]bool{
+       "appends":          true,
        "asmdecl":          true,
        "assign":           true,
        "atomic":           true,

diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/appends.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/appends.go
new file mode 100644 (file)
index 0000000..f0b90a4
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/appends.go
@@ -0,0 +1,49 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package appends defines an Analyzer that detects
+// if there is only one variable in append.
+package appends
+
+import (
+       _ "embed"
+       "go/ast"
+       "go/types"
+
+       "golang.org/x/tools/go/analysis"
+       "golang.org/x/tools/go/analysis/passes/inspect"
+       "golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+       "golang.org/x/tools/go/ast/inspector"
+)
+
+//go:embed doc.go
+var doc string
+
+var Analyzer = &analysis.Analyzer{
+       Name:     "appends",
+       Doc:      analysisutil.MustExtractDoc(doc, "appends"),
+       URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/appends",
+       Requires: []*analysis.Analyzer{inspect.Analyzer},
+       Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+       inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+       nodeFilter := []ast.Node{
+               (*ast.CallExpr)(nil),
+       }
+       inspect.Preorder(nodeFilter, func(n ast.Node) {
+               call := n.(*ast.CallExpr)
+               if ident, ok := call.Fun.(*ast.Ident); ok && ident.Name == "append" {
+                       if _, ok := pass.TypesInfo.Uses[ident].(*types.Builtin); ok {
+                               if len(call.Args) == 1 {
+                                       pass.ReportRangef(call, "append with no values")
+                               }
+                       }
+               }
+       })
+
+       return nil, nil
+}

diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/doc.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/doc.go
new file mode 100644 (file)
index 0000000..2e6a2e0
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/appends/doc.go
@@ -0,0 +1,20 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package appends defines an Analyzer that detects
+// if there is only one variable in append.
+//
+// # Analyzer appends
+//
+// appends: check for missing values after append
+//
+// This checker reports calls to append that pass
+// no values to be appended to the slice.
+//
+//     s := []string{"a", "b", "c"}
+//     _ = append(s)
+//
+// Such calls are always no-ops and often indicate an
+// underlying mistake.
+package appends

diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index a2b1e248be8f552d5620cf1c6f5d8f8156ce116a..74f9d488f10cdc43871a958c392e9b645ff210f0 100644 (file)
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -52,6 +52,7 @@ golang.org/x/tools/cmd/bisect
 golang.org/x/tools/cover
 golang.org/x/tools/go/analysis
 golang.org/x/tools/go/analysis/internal/analysisflags
+golang.org/x/tools/go/analysis/passes/appends
 golang.org/x/tools/go/analysis/passes/asmdecl
 golang.org/x/tools/go/analysis/passes/assign
 golang.org/x/tools/go/analysis/passes/atomic

diff --git a/src/cmd/vet/main.go b/src/cmd/vet/main.go
index 2290b95033c2a428113cd228204daf9b2641316b..c5197284b56165159ffb942e35cf0ffcf0add9ce 100644 (file)
--- a/src/cmd/vet/main.go
+++ b/src/cmd/vet/main.go
@@ -9,6 +9,7 @@ import (
 
        "golang.org/x/tools/go/analysis/unitchecker"
 
+       "golang.org/x/tools/go/analysis/passes/appends"
        "golang.org/x/tools/go/analysis/passes/asmdecl"
        "golang.org/x/tools/go/analysis/passes/assign"
        "golang.org/x/tools/go/analysis/passes/atomic"
@@ -46,6 +47,7 @@ func main() {
        objabi.AddVersionFlag()
 
        unitchecker.Main(
+               appends.Analyzer,
                asmdecl.Analyzer,
                assign.Analyzer,
                atomic.Analyzer,

diff --git a/src/cmd/vet/testdata/appends/appends.go b/src/cmd/vet/testdata/appends/appends.go
new file mode 100644 (file)
index 0000000..09ef3d2
--- /dev/null
+++ b/src/cmd/vet/testdata/appends/appends.go
@@ -0,0 +1,12 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains tests for the appends checker.
+
+package appends
+
+func AppendsTest() {
+       sli := []string{"a", "b", "c"}
+       sli = append(sli) // ERROR "append with no values"
+}

diff --git a/src/cmd/vet/vet_test.go b/src/cmd/vet/vet_test.go
index 8b29907e818c9d510f87c03be748178a6e9ae94a..4bb0de00b3b2b21245d9bf4e3f3c7f36aa2f3b6d 100644 (file)
--- a/src/cmd/vet/vet_test.go
+++ b/src/cmd/vet/vet_test.go
@@ -62,6 +62,7 @@ func vetCmd(t *testing.T, arg, pkg string) *exec.Cmd {
 func TestVet(t *testing.T) {
        t.Parallel()
        for _, pkg := range []string{
+               "appends",
                "asm",
                "assign",
                "atomic",