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// Copyright 2013 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 main
import (
"go/ast"
"go/token"
"go/types"
)
func init() {
register("atomic",
"check for common mistaken usages of the sync/atomic package",
checkAtomicAssignment,
assignStmt)
}
// checkAtomicAssignment walks the assignment statement checking for common
// mistaken usage of atomic package, such as: x = atomic.AddUint64(&x, 1)
func checkAtomicAssignment(f *File, node ast.Node) {
n := node.(*ast.AssignStmt)
if len(n.Lhs) != len(n.Rhs) {
return
}
if len(n.Lhs) == 1 && n.Tok == token.DEFINE {
return
}
for i, right := range n.Rhs {
call, ok := right.(*ast.CallExpr)
if !ok {
continue
}
sel, ok := call.Fun.(*ast.SelectorExpr)
if !ok {
continue
}
pkgIdent, _ := sel.X.(*ast.Ident)
pkgName, ok := f.pkg.uses[pkgIdent].(*types.PkgName)
if !ok || pkgName.Imported().Path() != "sync/atomic" {
continue
}
switch sel.Sel.Name {
case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr":
f.checkAtomicAddAssignment(n.Lhs[i], call)
}
}
}
// checkAtomicAddAssignment walks the atomic.Add* method calls checking for assigning the return value
// to the same variable being used in the operation
func (f *File) checkAtomicAddAssignment(left ast.Expr, call *ast.CallExpr) {
if len(call.Args) != 2 {
return
}
arg := call.Args[0]
broken := false
if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
broken = f.gofmt(left) == f.gofmt(uarg.X)
} else if star, ok := left.(*ast.StarExpr); ok {
broken = f.gofmt(star.X) == f.gofmt(arg)
}
if broken {
f.Bad(left.Pos(), "direct assignment to atomic value")
}
}
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