appends.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package appends defines an Analyzer that detects
     6  // if there is only one variable in append.
     7  package appends
     8  
     9  import (
    10  	_ "embed"
    11  	"go/ast"
    12  	"go/types"
    13  
    14  	"golang.org/x/tools/go/analysis"
    15  	"golang.org/x/tools/go/analysis/passes/inspect"
    16  	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
    17  	"golang.org/x/tools/go/ast/inspector"
    18  	"golang.org/x/tools/go/types/typeutil"
    19  )
    20  
    21  //go:embed doc.go
    22  var doc string
    23  
    24  var Analyzer = &analysis.Analyzer{
    25  	Name:     "appends",
    26  	Doc:      analysisutil.MustExtractDoc(doc, "appends"),
    27  	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/appends",
    28  	Requires: []*analysis.Analyzer{inspect.Analyzer},
    29  	Run:      run,
    30  }
    31  
    32  func run(pass *analysis.Pass) (interface{}, error) {
    33  	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
    34  
    35  	nodeFilter := []ast.Node{
    36  		(*ast.CallExpr)(nil),
    37  	}
    38  	inspect.Preorder(nodeFilter, func(n ast.Node) {
    39  		call := n.(*ast.CallExpr)
    40  		b, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Builtin)
    41  		if ok && b.Name() == "append" && len(call.Args) == 1 {
    42  			pass.ReportRangef(call, "append with no values")
    43  		}
    44  	})
    45  
    46  	return nil, nil
    47  }
    48
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