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loopdefer.go
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loopdefer.go
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// loopdefer reports defers that are called from loops.
package main
import (
"flag"
"fmt"
"go/ast"
"go/parser"
"go/token"
"os"
)
func main() {
flag.Parse()
if len(flag.Args()) == 0 {
flag.Usage()
os.Exit(1)
}
if err := run(flag.Args()); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
func run(args []string) error {
fset := token.NewFileSet()
for _, name := range args {
f, err := parser.ParseFile(fset, name, nil, 0)
if err != nil {
return err
}
v := &vis{fset: fset}
ast.Walk(v, f)
}
return nil
}
type vis struct {
fset *token.FileSet
start, end token.Pos
}
func (v *vis) Visit(node ast.Node) ast.Visitor {
if node == nil {
return nil
}
// fmt.Printf("%s:\t%T\t%+[2]v\n", v.fset.Position(node.Pos()), node)
switch x := node.(type) {
case *ast.ForStmt:
return &vis{fset: v.fset, start: x.Body.Lbrace, end: x.Body.Rbrace}
case *ast.FuncLit, *ast.FuncDecl:
return &vis{fset: v.fset}
case *ast.DeferStmt:
if v.start < x.Defer && x.Defer < v.end {
fmt.Printf("%s:\tdefer use in a loop\n", v.fset.Position(x.Defer))
}
}
return v
}
func init() {
flag.Usage = func() {
fmt.Fprintln(os.Stderr, "Usage: loopdefer file.go [otherfile.go] ...")
flag.PrintDefaults()
}
}