atomic.go

     1  // Copyright 2013 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 atomic
     6  
     7  import (
     8  	_ "embed"
     9  	"go/ast"
    10  	"go/token"
    11  
    12  	"golang.org/x/tools/go/analysis"
    13  	"golang.org/x/tools/go/analysis/passes/inspect"
    14  	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
    15  	"golang.org/x/tools/go/ast/inspector"
    16  	"golang.org/x/tools/go/types/typeutil"
    17  	"golang.org/x/tools/internal/analysisinternal"
    18  )
    19  
    20  //go:embed doc.go
    21  var doc string
    22  
    23  var Analyzer = &analysis.Analyzer{
    24  	Name:             "atomic",
    25  	Doc:              analysisutil.MustExtractDoc(doc, "atomic"),
    26  	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomic",
    27  	Requires:         []*analysis.Analyzer{inspect.Analyzer},
    28  	RunDespiteErrors: true,
    29  	Run:              run,
    30  }
    31  
    32  func run(pass *analysis.Pass) (any, error) {
    33  	if !analysisinternal.Imports(pass.Pkg, "sync/atomic") {
    34  		return nil, nil // doesn't directly import sync/atomic
    35  	}
    36  
    37  	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
    38  
    39  	nodeFilter := []ast.Node{
    40  		(*ast.AssignStmt)(nil),
    41  	}
    42  	inspect.Preorder(nodeFilter, func(node ast.Node) {
    43  		n := node.(*ast.AssignStmt)
    44  		if len(n.Lhs) != len(n.Rhs) {
    45  			return
    46  		}
    47  		if len(n.Lhs) == 1 && n.Tok == token.DEFINE {
    48  			return
    49  		}
    50  
    51  		for i, right := range n.Rhs {
    52  			call, ok := right.(*ast.CallExpr)
    53  			if !ok {
    54  				continue
    55  			}
    56  			obj := typeutil.Callee(pass.TypesInfo, call)
    57  			if analysisinternal.IsFunctionNamed(obj, "sync/atomic", "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr") {
    58  				checkAtomicAddAssignment(pass, n.Lhs[i], call)
    59  			}
    60  		}
    61  	})
    62  	return nil, nil
    63  }
    64  
    65  // checkAtomicAddAssignment walks the atomic.Add* method calls checking
    66  // for assigning the return value to the same variable being used in the
    67  // operation
    68  func checkAtomicAddAssignment(pass *analysis.Pass, left ast.Expr, call *ast.CallExpr) {
    69  	if len(call.Args) != 2 {
    70  		return
    71  	}
    72  	arg := call.Args[0]
    73  	broken := false
    74  
    75  	gofmt := func(e ast.Expr) string { return analysisinternal.Format(pass.Fset, e) }
    76  
    77  	if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
    78  		broken = gofmt(left) == gofmt(uarg.X)
    79  	} else if star, ok := left.(*ast.StarExpr); ok {
    80  		broken = gofmt(star.X) == gofmt(arg)
    81  	}
    82  
    83  	if broken {
    84  		pass.ReportRangef(left, "direct assignment to atomic value")
    85  	}
    86  }
    87
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