482 lines
12 KiB
Go
482 lines
12 KiB
Go
// Package code answers structural and type questions about Go code.
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package code
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import (
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"flag"
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"fmt"
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"go/ast"
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"go/constant"
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"go/token"
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"go/types"
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"strings"
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"golang.org/x/tools/go/analysis"
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"golang.org/x/tools/go/analysis/passes/inspect"
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"golang.org/x/tools/go/ast/astutil"
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"golang.org/x/tools/go/ast/inspector"
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"honnef.co/go/tools/facts"
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"honnef.co/go/tools/go/types/typeutil"
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"honnef.co/go/tools/ir"
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"honnef.co/go/tools/lint"
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)
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type Positioner interface {
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Pos() token.Pos
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}
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func CallName(call *ir.CallCommon) string {
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if call.IsInvoke() {
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return ""
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}
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switch v := call.Value.(type) {
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case *ir.Function:
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fn, ok := v.Object().(*types.Func)
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if !ok {
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return ""
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}
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return lint.FuncName(fn)
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case *ir.Builtin:
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return v.Name()
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}
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return ""
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}
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func IsCallTo(call *ir.CallCommon, name string) bool { return CallName(call) == name }
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func IsCallToAny(call *ir.CallCommon, names ...string) bool {
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q := CallName(call)
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for _, name := range names {
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if q == name {
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return true
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}
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}
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return false
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}
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func IsType(T types.Type, name string) bool { return types.TypeString(T, nil) == name }
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func FilterDebug(instr []ir.Instruction) []ir.Instruction {
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var out []ir.Instruction
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for _, ins := range instr {
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if _, ok := ins.(*ir.DebugRef); !ok {
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out = append(out, ins)
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}
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}
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return out
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}
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func IsExample(fn *ir.Function) bool {
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if !strings.HasPrefix(fn.Name(), "Example") {
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return false
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}
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f := fn.Prog.Fset.File(fn.Pos())
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if f == nil {
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return false
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}
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return strings.HasSuffix(f.Name(), "_test.go")
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}
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func IsPointerLike(T types.Type) bool {
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switch T := T.Underlying().(type) {
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case *types.Interface, *types.Chan, *types.Map, *types.Signature, *types.Pointer:
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return true
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case *types.Basic:
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return T.Kind() == types.UnsafePointer
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}
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return false
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}
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func IsIdent(expr ast.Expr, ident string) bool {
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id, ok := expr.(*ast.Ident)
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return ok && id.Name == ident
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}
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// isBlank returns whether id is the blank identifier "_".
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// If id == nil, the answer is false.
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func IsBlank(id ast.Expr) bool {
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ident, _ := id.(*ast.Ident)
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return ident != nil && ident.Name == "_"
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}
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func IsIntLiteral(expr ast.Expr, literal string) bool {
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lit, ok := expr.(*ast.BasicLit)
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return ok && lit.Kind == token.INT && lit.Value == literal
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}
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// Deprecated: use IsIntLiteral instead
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func IsZero(expr ast.Expr) bool {
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return IsIntLiteral(expr, "0")
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}
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func IsOfType(pass *analysis.Pass, expr ast.Expr, name string) bool {
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return IsType(pass.TypesInfo.TypeOf(expr), name)
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}
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func IsInTest(pass *analysis.Pass, node Positioner) bool {
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// FIXME(dh): this doesn't work for global variables with
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// initializers
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f := pass.Fset.File(node.Pos())
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return f != nil && strings.HasSuffix(f.Name(), "_test.go")
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}
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// IsMain reports whether the package being processed is a package
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// main.
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func IsMain(pass *analysis.Pass) bool {
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return pass.Pkg.Name() == "main"
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}
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// IsMainLike reports whether the package being processed is a
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// main-like package. A main-like package is a package that is
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// package main, or that is intended to be used by a tool framework
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// such as cobra to implement a command.
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//
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// Note that this function errs on the side of false positives; it may
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// return true for packages that aren't main-like. IsMainLike is
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// intended for analyses that wish to suppress diagnostics for
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// main-like packages to avoid false positives.
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func IsMainLike(pass *analysis.Pass) bool {
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if pass.Pkg.Name() == "main" {
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return true
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}
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for _, imp := range pass.Pkg.Imports() {
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if imp.Path() == "github.com/spf13/cobra" {
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return true
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}
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}
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return false
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}
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func SelectorName(pass *analysis.Pass, expr *ast.SelectorExpr) string {
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info := pass.TypesInfo
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sel := info.Selections[expr]
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if sel == nil {
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if x, ok := expr.X.(*ast.Ident); ok {
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pkg, ok := info.ObjectOf(x).(*types.PkgName)
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if !ok {
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// This shouldn't happen
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return fmt.Sprintf("%s.%s", x.Name, expr.Sel.Name)
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}
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return fmt.Sprintf("%s.%s", pkg.Imported().Path(), expr.Sel.Name)
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}
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panic(fmt.Sprintf("unsupported selector: %v", expr))
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}
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return fmt.Sprintf("(%s).%s", sel.Recv(), sel.Obj().Name())
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}
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func IsNil(pass *analysis.Pass, expr ast.Expr) bool {
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return pass.TypesInfo.Types[expr].IsNil()
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}
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func BoolConst(pass *analysis.Pass, expr ast.Expr) bool {
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val := pass.TypesInfo.ObjectOf(expr.(*ast.Ident)).(*types.Const).Val()
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return constant.BoolVal(val)
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}
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func IsBoolConst(pass *analysis.Pass, expr ast.Expr) bool {
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// We explicitly don't support typed bools because more often than
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// not, custom bool types are used as binary enums and the
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// explicit comparison is desired.
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ident, ok := expr.(*ast.Ident)
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if !ok {
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return false
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}
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obj := pass.TypesInfo.ObjectOf(ident)
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c, ok := obj.(*types.Const)
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if !ok {
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return false
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}
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basic, ok := c.Type().(*types.Basic)
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if !ok {
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return false
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}
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if basic.Kind() != types.UntypedBool && basic.Kind() != types.Bool {
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return false
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}
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return true
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}
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func ExprToInt(pass *analysis.Pass, expr ast.Expr) (int64, bool) {
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tv := pass.TypesInfo.Types[expr]
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if tv.Value == nil {
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return 0, false
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}
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if tv.Value.Kind() != constant.Int {
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return 0, false
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}
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return constant.Int64Val(tv.Value)
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}
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func ExprToString(pass *analysis.Pass, expr ast.Expr) (string, bool) {
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val := pass.TypesInfo.Types[expr].Value
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if val == nil {
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return "", false
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}
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if val.Kind() != constant.String {
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return "", false
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}
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return constant.StringVal(val), true
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}
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// Dereference returns a pointer's element type; otherwise it returns
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// T.
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func Dereference(T types.Type) types.Type {
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if p, ok := T.Underlying().(*types.Pointer); ok {
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return p.Elem()
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}
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return T
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}
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// DereferenceR returns a pointer's element type; otherwise it returns
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// T. If the element type is itself a pointer, DereferenceR will be
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// applied recursively.
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func DereferenceR(T types.Type) types.Type {
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if p, ok := T.Underlying().(*types.Pointer); ok {
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return DereferenceR(p.Elem())
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}
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return T
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}
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func CallNameAST(pass *analysis.Pass, call *ast.CallExpr) string {
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switch fun := astutil.Unparen(call.Fun).(type) {
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case *ast.SelectorExpr:
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fn, ok := pass.TypesInfo.ObjectOf(fun.Sel).(*types.Func)
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if !ok {
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return ""
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}
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return lint.FuncName(fn)
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case *ast.Ident:
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obj := pass.TypesInfo.ObjectOf(fun)
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switch obj := obj.(type) {
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case *types.Func:
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return lint.FuncName(obj)
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case *types.Builtin:
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return obj.Name()
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default:
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return ""
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}
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default:
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return ""
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}
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}
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func IsCallToAST(pass *analysis.Pass, node ast.Node, name string) bool {
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call, ok := node.(*ast.CallExpr)
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if !ok {
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return false
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}
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return CallNameAST(pass, call) == name
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}
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func IsCallToAnyAST(pass *analysis.Pass, node ast.Node, names ...string) bool {
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call, ok := node.(*ast.CallExpr)
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if !ok {
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return false
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}
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q := CallNameAST(pass, call)
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for _, name := range names {
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if q == name {
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return true
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}
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}
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return false
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}
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func Preamble(f *ast.File) string {
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cutoff := f.Package
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if f.Doc != nil {
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cutoff = f.Doc.Pos()
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}
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var out []string
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for _, cmt := range f.Comments {
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if cmt.Pos() >= cutoff {
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break
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}
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out = append(out, cmt.Text())
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}
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return strings.Join(out, "\n")
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}
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func GroupSpecs(fset *token.FileSet, specs []ast.Spec) [][]ast.Spec {
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if len(specs) == 0 {
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return nil
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}
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groups := make([][]ast.Spec, 1)
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groups[0] = append(groups[0], specs[0])
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for _, spec := range specs[1:] {
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g := groups[len(groups)-1]
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if fset.PositionFor(spec.Pos(), false).Line-1 !=
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fset.PositionFor(g[len(g)-1].End(), false).Line {
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groups = append(groups, nil)
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}
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groups[len(groups)-1] = append(groups[len(groups)-1], spec)
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}
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return groups
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}
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func IsObject(obj types.Object, name string) bool {
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var path string
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if pkg := obj.Pkg(); pkg != nil {
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path = pkg.Path() + "."
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}
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return path+obj.Name() == name
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}
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type Field struct {
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Var *types.Var
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Tag string
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Path []int
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}
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// FlattenFields recursively flattens T and embedded structs,
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// returning a list of fields. If multiple fields with the same name
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// exist, all will be returned.
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func FlattenFields(T *types.Struct) []Field {
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return flattenFields(T, nil, nil)
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}
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func flattenFields(T *types.Struct, path []int, seen map[types.Type]bool) []Field {
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if seen == nil {
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seen = map[types.Type]bool{}
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}
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if seen[T] {
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return nil
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}
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seen[T] = true
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var out []Field
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for i := 0; i < T.NumFields(); i++ {
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field := T.Field(i)
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tag := T.Tag(i)
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np := append(path[:len(path):len(path)], i)
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if field.Anonymous() {
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if s, ok := Dereference(field.Type()).Underlying().(*types.Struct); ok {
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out = append(out, flattenFields(s, np, seen)...)
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}
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} else {
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out = append(out, Field{field, tag, np})
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}
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}
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return out
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}
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func File(pass *analysis.Pass, node Positioner) *ast.File {
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m := pass.ResultOf[facts.TokenFile].(map[*token.File]*ast.File)
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return m[pass.Fset.File(node.Pos())]
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}
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// IsGenerated reports whether pos is in a generated file, It ignores
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// //line directives.
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func IsGenerated(pass *analysis.Pass, pos token.Pos) bool {
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_, ok := Generator(pass, pos)
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return ok
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}
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// Generator returns the generator that generated the file containing
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// pos. It ignores //line directives.
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func Generator(pass *analysis.Pass, pos token.Pos) (facts.Generator, bool) {
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file := pass.Fset.PositionFor(pos, false).Filename
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m := pass.ResultOf[facts.Generated].(map[string]facts.Generator)
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g, ok := m[file]
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return g, ok
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}
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// MayHaveSideEffects reports whether expr may have side effects. If
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// the purity argument is nil, this function implements a purely
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// syntactic check, meaning that any function call may have side
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// effects, regardless of the called function's body. Otherwise,
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// purity will be consulted to determine the purity of function calls.
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func MayHaveSideEffects(pass *analysis.Pass, expr ast.Expr, purity facts.PurityResult) bool {
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switch expr := expr.(type) {
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case *ast.BadExpr:
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return true
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case *ast.Ellipsis:
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return MayHaveSideEffects(pass, expr.Elt, purity)
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case *ast.FuncLit:
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// the literal itself cannot have side ffects, only calling it
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// might, which is handled by CallExpr.
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return false
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case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
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// types cannot have side effects
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return false
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case *ast.BasicLit:
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return false
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case *ast.BinaryExpr:
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return MayHaveSideEffects(pass, expr.X, purity) || MayHaveSideEffects(pass, expr.Y, purity)
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case *ast.CallExpr:
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if purity == nil {
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return true
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}
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switch obj := typeutil.Callee(pass.TypesInfo, expr).(type) {
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case *types.Func:
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if _, ok := purity[obj]; !ok {
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return true
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}
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case *types.Builtin:
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switch obj.Name() {
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case "len", "cap":
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default:
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return true
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}
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default:
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return true
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}
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for _, arg := range expr.Args {
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if MayHaveSideEffects(pass, arg, purity) {
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return true
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}
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}
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return false
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case *ast.CompositeLit:
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if MayHaveSideEffects(pass, expr.Type, purity) {
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return true
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}
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for _, elt := range expr.Elts {
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if MayHaveSideEffects(pass, elt, purity) {
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return true
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}
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}
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return false
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case *ast.Ident:
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return false
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case *ast.IndexExpr:
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return MayHaveSideEffects(pass, expr.X, purity) || MayHaveSideEffects(pass, expr.Index, purity)
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case *ast.KeyValueExpr:
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return MayHaveSideEffects(pass, expr.Key, purity) || MayHaveSideEffects(pass, expr.Value, purity)
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case *ast.SelectorExpr:
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return MayHaveSideEffects(pass, expr.X, purity)
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case *ast.SliceExpr:
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return MayHaveSideEffects(pass, expr.X, purity) ||
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MayHaveSideEffects(pass, expr.Low, purity) ||
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MayHaveSideEffects(pass, expr.High, purity) ||
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MayHaveSideEffects(pass, expr.Max, purity)
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case *ast.StarExpr:
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return MayHaveSideEffects(pass, expr.X, purity)
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case *ast.TypeAssertExpr:
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return MayHaveSideEffects(pass, expr.X, purity)
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case *ast.UnaryExpr:
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if MayHaveSideEffects(pass, expr.X, purity) {
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return true
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}
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return expr.Op == token.ARROW
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case *ast.ParenExpr:
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return MayHaveSideEffects(pass, expr.X, purity)
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case nil:
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return false
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default:
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panic(fmt.Sprintf("internal error: unhandled type %T", expr))
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}
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}
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func IsGoVersion(pass *analysis.Pass, minor int) bool {
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version := pass.Analyzer.Flags.Lookup("go").Value.(flag.Getter).Get().(int)
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return version >= minor
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}
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func Preorder(pass *analysis.Pass, fn func(ast.Node), types ...ast.Node) {
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pass.ResultOf[inspect.Analyzer].(*inspector.Inspector).Preorder(types, fn)
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}
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