go typecheck 源码
golang typecheck 代码
文件路径：/src/cmd/compile/internal/typecheck/typecheck.go
// Copyright 2009 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 typecheck
import (
"fmt"
"go/constant"
"go/token"
"strings"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/types"
"cmd/internal/src"
)
// Function collecting autotmps generated during typechecking,
// to be included in the package-level init function.
var InitTodoFunc = ir.NewFunc(base.Pos)
var inimport bool // set during import
var TypecheckAllowed bool
var (
NeedRuntimeType = func(*types.Type) {}
)
func AssignExpr(n ir.Node) ir.Node { return typecheck(n, ctxExpr|ctxAssign) }
func Expr(n ir.Node) ir.Node { return typecheck(n, ctxExpr) }
func Stmt(n ir.Node) ir.Node { return typecheck(n, ctxStmt) }
func Exprs(exprs []ir.Node) { typecheckslice(exprs, ctxExpr) }
func Stmts(stmts []ir.Node) { typecheckslice(stmts, ctxStmt) }
func Call(pos src.XPos, callee ir.Node, args []ir.Node, dots bool) ir.Node {
call := ir.NewCallExpr(pos, ir.OCALL, callee, args)
call.IsDDD = dots
return typecheck(call, ctxStmt|ctxExpr)
}
func Callee(n ir.Node) ir.Node {
return typecheck(n, ctxExpr|ctxCallee)
}
var importlist []*ir.Func
// AllImportedBodies reads in the bodies of all imported functions and typechecks
// them, if needed.
func AllImportedBodies() {
for _, n := range importlist {
if n.Inl != nil {
ImportedBody(n)
}
}
}
var traceIndent []byte
func tracePrint(title string, n ir.Node) func(np *ir.Node) {
indent := traceIndent
// guard against nil
var pos, op string
var tc uint8
if n != nil {
pos = base.FmtPos(n.Pos())
op = n.Op().String()
tc = n.Typecheck()
}
types.SkipSizeForTracing = true
defer func() { types.SkipSizeForTracing = false }()
fmt.Printf("%s: %s%s %p %s %v tc=%d\n", pos, indent, title, n, op, n, tc)
traceIndent = append(traceIndent, ". "...)
return func(np *ir.Node) {
traceIndent = traceIndent[:len(traceIndent)-2]
// if we have a result, use that
if np != nil {
n = *np
}
// guard against nil
// use outer pos, op so we don't get empty pos/op if n == nil (nicer output)
var tc uint8
var typ *types.Type
if n != nil {
pos = base.FmtPos(n.Pos())
op = n.Op().String()
tc = n.Typecheck()
typ = n.Type()
}
types.SkipSizeForTracing = true
defer func() { types.SkipSizeForTracing = false }()
fmt.Printf("%s: %s=> %p %s %v tc=%d type=%L\n", pos, indent, n, op, n, tc, typ)
}
}
const (
ctxStmt = 1 << iota // evaluated at statement level
ctxExpr // evaluated in value context
ctxType // evaluated in type context
ctxCallee // call-only expressions are ok
ctxMultiOK // multivalue function returns are ok
ctxAssign // assigning to expression
)
// type checks the whole tree of an expression.
// calculates expression types.
// evaluates compile time constants.
// marks variables that escape the local frame.
// rewrites n.Op to be more specific in some cases.
// Resolve resolves an ONONAME node to a definition, if any. If n is not an ONONAME node,
// Resolve returns n unchanged. If n is an ONONAME node and not in the same package,
// then n.Sym() is resolved using import data. Otherwise, Resolve returns
// n.Sym().Def. An ONONAME node can be created using ir.NewIdent(), so an imported
// symbol can be resolved via Resolve(ir.NewIdent(src.NoXPos, sym)).
func Resolve(n ir.Node) (res ir.Node) {
if n == nil || n.Op() != ir.ONONAME {
return n
}
// only trace if there's work to do
if base.EnableTrace && base.Flag.LowerT {
defer tracePrint("resolve", n)(&res)
}
if sym := n.Sym(); sym.Pkg != types.LocalPkg {
return expandDecl(n)
}
r := ir.AsNode(n.Sym().Def)
if r == nil {
return n
}
return r
}
func typecheckslice(l []ir.Node, top int) {
for i := range l {
l[i] = typecheck(l[i], top)
}
}
var _typekind = []string{
types.TINT: "int",
types.TUINT: "uint",
types.TINT8: "int8",
types.TUINT8: "uint8",
types.TINT16: "int16",
types.TUINT16: "uint16",
types.TINT32: "int32",
types.TUINT32: "uint32",
types.TINT64: "int64",
types.TUINT64: "uint64",
types.TUINTPTR: "uintptr",
types.TCOMPLEX64: "complex64",
types.TCOMPLEX128: "complex128",
types.TFLOAT32: "float32",
types.TFLOAT64: "float64",
types.TBOOL: "bool",
types.TSTRING: "string",
types.TPTR: "pointer",
types.TUNSAFEPTR: "unsafe.Pointer",
types.TSTRUCT: "struct",
types.TINTER: "interface",
types.TCHAN: "chan",
types.TMAP: "map",
types.TARRAY: "array",
types.TSLICE: "slice",
types.TFUNC: "func",
types.TNIL: "nil",
types.TIDEAL: "untyped number",
}
func typekind(t *types.Type) string {
if t.IsUntyped() {
return fmt.Sprintf("%v", t)
}
et := t.Kind()
if int(et) < len(_typekind) {
s := _typekind[et]
if s != "" {
return s
}
}
return fmt.Sprintf("etype=%d", et)
}
func cycleFor(start ir.Node) []ir.Node {
// Find the start node in typecheck_tcstack.
// We know that it must exist because each time we mark
// a node with n.SetTypecheck(2) we push it on the stack,
// and each time we mark a node with n.SetTypecheck(2) we
// pop it from the stack. We hit a cycle when we encounter
// a node marked 2 in which case is must be on the stack.
i := len(typecheck_tcstack) - 1
for i > 0 && typecheck_tcstack[i] != start {
i--
}
// collect all nodes with same Op
var cycle []ir.Node
for _, n := range typecheck_tcstack[i:] {
if n.Op() == start.Op() {
cycle = append(cycle, n)
}
}
return cycle
}
func cycleTrace(cycle []ir.Node) string {
var s string
for i, n := range cycle {
s += fmt.Sprintf("\n\t%v: %v uses %v", ir.Line(n), n, cycle[(i+1)%len(cycle)])
}
return s
}
var typecheck_tcstack []ir.Node
func Func(fn *ir.Func) {
new := Stmt(fn)
if new != fn {
base.Fatalf("typecheck changed func")
}
}
// typecheck type checks node n.
// The result of typecheck MUST be assigned back to n, e.g.
//
// n.Left = typecheck(n.Left, top)
func typecheck(n ir.Node, top int) (res ir.Node) {
// cannot type check until all the source has been parsed
if !TypecheckAllowed {
base.Fatalf("early typecheck")
}
if n == nil {
return nil
}
// only trace if there's work to do
if base.EnableTrace && base.Flag.LowerT {
defer tracePrint("typecheck", n)(&res)
}
lno := ir.SetPos(n)
// Skip over parens.
for n.Op() == ir.OPAREN {
n = n.(*ir.ParenExpr).X
}
// Resolve definition of name and value of iota lazily.
n = Resolve(n)
// Skip typecheck if already done.
// But re-typecheck ONAME/OTYPE/OLITERAL/OPACK node in case context has changed.
if n.Typecheck() == 1 || n.Typecheck() == 3 {
switch n.Op() {
case ir.ONAME, ir.OTYPE, ir.OLITERAL:
break
default:
base.Pos = lno
return n
}
}
if n.Typecheck() == 2 {
// Typechecking loop. Trying printing a meaningful message,
// otherwise a stack trace of typechecking.
switch n.Op() {
// We can already diagnose variables used as types.
case ir.ONAME:
n := n.(*ir.Name)
if top&(ctxExpr|ctxType) == ctxType {
base.Errorf("%v is not a type", n)
}
case ir.OTYPE:
// Only report a type cycle if we are expecting a type.
// Otherwise let other code report an error.
if top&ctxType == ctxType {
// A cycle containing only alias types is an error
// since it would expand indefinitely when aliases
// are substituted.
cycle := cycleFor(n)
for _, n1 := range cycle {
if n1.Name() != nil && !n1.Name().Alias() {
// Cycle is ok. But if n is an alias type and doesn't
// have a type yet, we have a recursive type declaration
// with aliases that we can't handle properly yet.
// Report an error rather than crashing later.
if n.Name() != nil && n.Name().Alias() && n.Type() == nil {
base.Pos = n.Pos()
base.Fatalf("cannot handle alias type declaration (issue #25838): %v", n)
}
base.Pos = lno
return n
}
}
base.ErrorfAt(n.Pos(), "invalid recursive type alias %v%s", n, cycleTrace(cycle))
}
case ir.OLITERAL:
if top&(ctxExpr|ctxType) == ctxType {
base.Errorf("%v is not a type", n)
break
}
base.ErrorfAt(n.Pos(), "constant definition loop%s", cycleTrace(cycleFor(n)))
}
if base.Errors() == 0 {
var trace string
for i := len(typecheck_tcstack) - 1; i >= 0; i-- {
x := typecheck_tcstack[i]
trace += fmt.Sprintf("\n\t%v %v", ir.Line(x), x)
}
base.Errorf("typechecking loop involving %v%s", n, trace)
}
base.Pos = lno
return n
}
typecheck_tcstack = append(typecheck_tcstack, n)
n.SetTypecheck(2)
n = typecheck1(n, top)
n.SetTypecheck(1)
last := len(typecheck_tcstack) - 1
typecheck_tcstack[last] = nil
typecheck_tcstack = typecheck_tcstack[:last]
_, isExpr := n.(ir.Expr)
_, isStmt := n.(ir.Stmt)
isMulti := false
switch n.Op() {
case ir.OCALLFUNC, ir.OCALLINTER, ir.OCALLMETH:
n := n.(*ir.CallExpr)
if t := n.X.Type(); t != nil && t.Kind() == types.TFUNC {
nr := t.NumResults()
isMulti = nr > 1
if nr == 0 {
isExpr = false
}
}
case ir.OAPPEND:
// Must be used (and not BinaryExpr/UnaryExpr).
isStmt = false
case ir.OCLOSE, ir.ODELETE, ir.OPANIC, ir.OPRINT, ir.OPRINTN, ir.OVARKILL, ir.OVARLIVE:
// Must not be used.
isExpr = false
isStmt = true
case ir.OCOPY, ir.ORECOVER, ir.ORECV:
// Can be used or not.
isStmt = true
}
t := n.Type()
if t != nil && !t.IsFuncArgStruct() && n.Op() != ir.OTYPE {
switch t.Kind() {
case types.TFUNC, // might have TANY; wait until it's called
types.TANY, types.TFORW, types.TIDEAL, types.TNIL, types.TBLANK:
break
default:
types.CheckSize(t)
}
}
if t != nil {
n = EvalConst(n)
t = n.Type()
}
// TODO(rsc): Lots of the complexity here is because typecheck can
// see OTYPE, ONAME, and OLITERAL nodes multiple times.
// Once we make the IR a proper tree, we should be able to simplify
// this code a bit, especially the final case.
switch {
case top&(ctxStmt|ctxExpr) == ctxExpr && !isExpr && n.Op() != ir.OTYPE && !isMulti:
base.Fatalf("%v used as value", n)
case top&ctxType == 0 && n.Op() == ir.OTYPE && t != nil:
base.Fatalf("type %v is not an expression", n.Type())
case top&(ctxStmt|ctxExpr) == ctxStmt && !isStmt && t != nil:
base.Fatalf("%v evaluated but not used", n)
case top&(ctxType|ctxExpr) == ctxType && n.Op() != ir.OTYPE && n.Op() != ir.ONONAME && (t != nil || n.Op() == ir.ONAME):
base.Fatalf("%v is not a type", n)
}
base.Pos = lno
return n
}
// indexlit implements typechecking of untyped values as
// array/slice indexes. It is almost equivalent to DefaultLit
// but also accepts untyped numeric values representable as
// value of type int (see also checkmake for comparison).
// The result of indexlit MUST be assigned back to n, e.g.
//
// n.Left = indexlit(n.Left)
func indexlit(n ir.Node) ir.Node {
if n != nil && n.Type() != nil && n.Type().Kind() == types.TIDEAL {
return DefaultLit(n, types.Types[types.TINT])
}
return n
}
// typecheck1 should ONLY be called from typecheck.
func typecheck1(n ir.Node, top int) ir.Node {
switch n.Op() {
default:
ir.Dump("typecheck", n)
base.Fatalf("typecheck %v", n.Op())
panic("unreachable")
case ir.OLITERAL:
if n.Sym() == nil && n.Type() == nil {
base.Fatalf("literal missing type: %v", n)
}
return n
case ir.ONIL:
return n
// names
case ir.ONONAME:
// Note: adderrorname looks for this string and
// adds context about the outer expression
base.FatalfAt(n.Pos(), "undefined: %v", n.Sym())
panic("unreachable")
case ir.ONAME:
n := n.(*ir.Name)
if n.BuiltinOp != 0 {
if top&ctxCallee == 0 {
base.Errorf("use of builtin %v not in function call", n.Sym())
n.SetType(nil)
return n
}
return n
}
if top&ctxAssign == 0 {
// not a write to the variable
if ir.IsBlank(n) {
base.Errorf("cannot use _ as value")
n.SetType(nil)
return n
}
n.SetUsed(true)
}
return n
case ir.OLINKSYMOFFSET:
// type already set
return n
// types (ODEREF is with exprs)
case ir.OTYPE:
return n
// type or expr
case ir.ODEREF:
n := n.(*ir.StarExpr)
return tcStar(n, top)
// x op= y
case ir.OASOP:
n := n.(*ir.AssignOpStmt)
n.X, n.Y = Expr(n.X), Expr(n.Y)
checkassign(n.X)
if n.IncDec && !okforarith[n.X.Type().Kind()] {
base.Errorf("invalid operation: %v (non-numeric type %v)", n, n.X.Type())
return n
}
switch n.AsOp {
case ir.OLSH, ir.ORSH:
n.X, n.Y, _ = tcShift(n, n.X, n.Y)
case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD, ir.OMUL, ir.OOR, ir.OSUB, ir.OXOR:
n.X, n.Y, _ = tcArith(n, n.AsOp, n.X, n.Y)
default:
base.Fatalf("invalid assign op: %v", n.AsOp)
}
return n
// logical operators
case ir.OANDAND, ir.OOROR:
n := n.(*ir.LogicalExpr)
n.X, n.Y = Expr(n.X), Expr(n.Y)
if n.X.Type() == nil || n.Y.Type() == nil {
n.SetType(nil)
return n
}
// For "x == x && len(s)", it's better to report that "len(s)" (type int)
// can't be used with "&&" than to report that "x == x" (type untyped bool)
// can't be converted to int (see issue #41500).
if !n.X.Type().IsBoolean() {
base.Errorf("invalid operation: %v (operator %v not defined on %s)", n, n.Op(), typekind(n.X.Type()))
n.SetType(nil)
return n
}
if !n.Y.Type().IsBoolean() {
base.Errorf("invalid operation: %v (operator %v not defined on %s)", n, n.Op(), typekind(n.Y.Type()))
n.SetType(nil)
return n
}
l, r, t := tcArith(n, n.Op(), n.X, n.Y)
n.X, n.Y = l, r
n.SetType(t)
return n
// shift operators
case ir.OLSH, ir.ORSH:
n := n.(*ir.BinaryExpr)
n.X, n.Y = Expr(n.X), Expr(n.Y)
l, r, t := tcShift(n, n.X, n.Y)
n.X, n.Y = l, r
n.SetType(t)
return n
// comparison operators
case ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT, ir.ONE:
n := n.(*ir.BinaryExpr)
n.X, n.Y = Expr(n.X), Expr(n.Y)
l, r, t := tcArith(n, n.Op(), n.X, n.Y)
if t != nil {
n.X, n.Y = l, r
n.SetType(types.UntypedBool)
if con := EvalConst(n); con.Op() == ir.OLITERAL {
return con
}
n.X, n.Y = defaultlit2(l, r, true)
}
return n
// binary operators
case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD, ir.OMUL, ir.OOR, ir.OSUB, ir.OXOR:
n := n.(*ir.BinaryExpr)
n.X, n.Y = Expr(n.X), Expr(n.Y)
l, r, t := tcArith(n, n.Op(), n.X, n.Y)
if t != nil && t.Kind() == types.TSTRING && n.Op() == ir.OADD {
// create or update OADDSTR node with list of strings in x + y + z + (w + v) + ...
var add *ir.AddStringExpr
if l.Op() == ir.OADDSTR {
add = l.(*ir.AddStringExpr)
add.SetPos(n.Pos())
} else {
add = ir.NewAddStringExpr(n.Pos(), []ir.Node{l})
}
if r.Op() == ir.OADDSTR {
r := r.(*ir.AddStringExpr)
add.List.Append(r.List.Take()...)
} else {
add.List.Append(r)
}
add.SetType(t)
return add
}
n.X, n.Y = l, r
n.SetType(t)
return n
case ir.OBITNOT, ir.ONEG, ir.ONOT, ir.OPLUS:
n := n.(*ir.UnaryExpr)
return tcUnaryArith(n)
// exprs
case ir.OADDR:
n := n.(*ir.AddrExpr)
return tcAddr(n)
case ir.OCOMPLIT:
return tcCompLit(n.(*ir.CompLitExpr))
case ir.OXDOT, ir.ODOT:
n := n.(*ir.SelectorExpr)
return tcDot(n, top)
case ir.ODOTTYPE:
n := n.(*ir.TypeAssertExpr)
return tcDotType(n)
case ir.OINDEX:
n := n.(*ir.IndexExpr)
return tcIndex(n)
case ir.ORECV:
n := n.(*ir.UnaryExpr)
return tcRecv(n)
case ir.OSEND:
n := n.(*ir.SendStmt)
return tcSend(n)
case ir.OSLICEHEADER:
n := n.(*ir.SliceHeaderExpr)
return tcSliceHeader(n)
case ir.OMAKESLICECOPY:
n := n.(*ir.MakeExpr)
return tcMakeSliceCopy(n)
case ir.OSLICE, ir.OSLICE3:
n := n.(*ir.SliceExpr)
return tcSlice(n)
// call and call like
case ir.OCALL:
n := n.(*ir.CallExpr)
return tcCall(n, top)
case ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
n := n.(*ir.UnaryExpr)
n.SetType(types.Types[types.TUINTPTR])
return n
case ir.OCAP, ir.OLEN:
n := n.(*ir.UnaryExpr)
return tcLenCap(n)
case ir.OREAL, ir.OIMAG:
n := n.(*ir.UnaryExpr)
return tcRealImag(n)
case ir.OCOMPLEX:
n := n.(*ir.BinaryExpr)
return tcComplex(n)
case ir.OCLOSE:
n := n.(*ir.UnaryExpr)
return tcClose(n)
case ir.ODELETE:
n := n.(*ir.CallExpr)
return tcDelete(n)
case ir.OAPPEND:
n := n.(*ir.CallExpr)
return tcAppend(n)
case ir.OCOPY:
n := n.(*ir.BinaryExpr)
return tcCopy(n)
case ir.OCONV:
n := n.(*ir.ConvExpr)
return tcConv(n)
case ir.OMAKE:
n := n.(*ir.CallExpr)
return tcMake(n)
case ir.ONEW:
n := n.(*ir.UnaryExpr)
return tcNew(n)
case ir.OPRINT, ir.OPRINTN:
n := n.(*ir.CallExpr)
return tcPrint(n)
case ir.OPANIC:
n := n.(*ir.UnaryExpr)
return tcPanic(n)
case ir.ORECOVER:
n := n.(*ir.CallExpr)
return tcRecover(n)
case ir.ORECOVERFP:
n := n.(*ir.CallExpr)
return tcRecoverFP(n)
case ir.OUNSAFEADD:
n := n.(*ir.BinaryExpr)
return tcUnsafeAdd(n)
case ir.OUNSAFESLICE:
n := n.(*ir.BinaryExpr)
return tcUnsafeSlice(n)
case ir.OCLOSURE:
n := n.(*ir.ClosureExpr)
return tcClosure(n, top)
case ir.OITAB:
n := n.(*ir.UnaryExpr)
return tcITab(n)
case ir.OIDATA:
// Whoever creates the OIDATA node must know a priori the concrete type at that moment,
// usually by just having checked the OITAB.
n := n.(*ir.UnaryExpr)
base.Fatalf("cannot typecheck interface data %v", n)
panic("unreachable")
case ir.OSPTR:
n := n.(*ir.UnaryExpr)
return tcSPtr(n)
case ir.OCFUNC:
n := n.(*ir.UnaryExpr)
n.X = Expr(n.X)
n.SetType(types.Types[types.TUINTPTR])
return n
case ir.OGETCALLERPC, ir.OGETCALLERSP:
n := n.(*ir.CallExpr)
if len(n.Args) != 0 {
base.FatalfAt(n.Pos(), "unexpected arguments: %v", n)
}
n.SetType(types.Types[types.TUINTPTR])
return n
case ir.OCONVNOP:
n := n.(*ir.ConvExpr)
n.X = Expr(n.X)
return n
// statements
case ir.OAS:
n := n.(*ir.AssignStmt)
tcAssign(n)
// Code that creates temps does not bother to set defn, so do it here.
if n.X.Op() == ir.ONAME && ir.IsAutoTmp(n.X) {
n.X.Name().Defn = n
}
return n
case ir.OAS2:
tcAssignList(n.(*ir.AssignListStmt))
return n
case ir.OBREAK,
ir.OCONTINUE,
ir.ODCL,
ir.OGOTO,
ir.OFALL,
ir.OVARKILL,
ir.OVARLIVE:
return n
case ir.OBLOCK:
n := n.(*ir.BlockStmt)
Stmts(n.List)
return n
case ir.OLABEL:
if n.Sym().IsBlank() {
// Empty identifier is valid but useless.
// Eliminate now to simplify life later.
// See issues 7538, 11589, 11593.
n = ir.NewBlockStmt(n.Pos(), nil)
}
return n
case ir.ODEFER, ir.OGO:
n := n.(*ir.GoDeferStmt)
n.Call = typecheck(n.Call, ctxStmt|ctxExpr)
tcGoDefer(n)
return n
case ir.OFOR, ir.OFORUNTIL:
n := n.(*ir.ForStmt)
return tcFor(n)
case ir.OIF:
n := n.(*ir.IfStmt)
return tcIf(n)
case ir.ORETURN:
n := n.(*ir.ReturnStmt)
return tcReturn(n)
case ir.OTAILCALL:
n := n.(*ir.TailCallStmt)
n.Call = typecheck(n.Call, ctxStmt|ctxExpr).(*ir.CallExpr)
return n
case ir.OCHECKNIL:
n := n.(*ir.UnaryExpr)
return tcCheckNil(n)
case ir.OSELECT:
tcSelect(n.(*ir.SelectStmt))
return n
case ir.OSWITCH:
tcSwitch(n.(*ir.SwitchStmt))
return n
case ir.ORANGE:
tcRange(n.(*ir.RangeStmt))
return n
case ir.OTYPESW:
n := n.(*ir.TypeSwitchGuard)
base.Fatalf("use of .(type) outside type switch")
return n
case ir.ODCLFUNC:
tcFunc(n.(*ir.Func))
return n
case ir.ODCLCONST:
n := n.(*ir.Decl)
n.X = Expr(n.X).(*ir.Name)
return n
case ir.ODCLTYPE:
n := n.(*ir.Decl)
n.X = typecheck(n.X, ctxType).(*ir.Name)
types.CheckSize(n.X.Type())
return n
}
// No return n here!
// Individual cases can type-assert n, introducing a new one.
// Each must execute its own return n.
}
func typecheckargs(n ir.InitNode) {
var list []ir.Node
switch n := n.(type) {
default:
base.Fatalf("typecheckargs %+v", n.Op())
case *ir.CallExpr:
list = n.Args
if n.IsDDD {
Exprs(list)
return
}
case *ir.ReturnStmt:
list = n.Results
}
if len(list) != 1 {
Exprs(list)
return
}
typecheckslice(list, ctxExpr|ctxMultiOK)
t := list[0].Type()
if t == nil || !t.IsFuncArgStruct() {
return
}
// Save n as n.Orig for fmt.go.
if ir.Orig(n) == n {
n.(ir.OrigNode).SetOrig(ir.SepCopy(n))
}
// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
RewriteMultiValueCall(n, list[0])
}
// RewriteNonNameCall replaces non-Name call expressions with temps,
// rewriting f()(...) to t0 := f(); t0(...).
func RewriteNonNameCall(n *ir.CallExpr) {
np := &n.X
if inst, ok := (*np).(*ir.InstExpr); ok && inst.Op() == ir.OFUNCINST {
np = &inst.X
}
if dot, ok := (*np).(*ir.SelectorExpr); ok && (dot.Op() == ir.ODOTMETH || dot.Op() == ir.ODOTINTER || dot.Op() == ir.OMETHVALUE) {
np = &dot.X // peel away method selector
}
// Check for side effects in the callee expression.
// We explicitly special case new(T) though, because it doesn't have
// observable side effects, and keeping it in place allows better escape analysis.
if !ir.Any(*np, func(n ir.Node) bool { return n.Op() != ir.ONEW && callOrChan(n) }) {
return
}
// See comment (1) in RewriteMultiValueCall.
static := ir.CurFunc == nil
if static {
ir.CurFunc = InitTodoFunc
}
tmp := Temp((*np).Type())
as := ir.NewAssignStmt(base.Pos, tmp, *np)
as.Def = true
*np = tmp
if static {
ir.CurFunc = nil
}
n.PtrInit().Append(Stmt(as))
}
// RewriteMultiValueCall rewrites multi-valued f() to use temporaries,
// so the backend wouldn't need to worry about tuple-valued expressions.
func RewriteMultiValueCall(n ir.InitNode, call ir.Node) {
// If we're outside of function context, then this call will
// be executed during the generated init function. However,
// init.go hasn't yet created it. Instead, associate the
// temporary variables with InitTodoFunc for now, and init.go
// will reassociate them later when it's appropriate. (1)
static := ir.CurFunc == nil
if static {
ir.CurFunc = InitTodoFunc
}
as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, []ir.Node{call})
results := call.Type().FieldSlice()
list := make([]ir.Node, len(results))
for i, result := range results {
tmp := Temp(result.Type)
as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, tmp))
as.Lhs.Append(tmp)
list[i] = tmp
}
if static {
ir.CurFunc = nil
}
n.PtrInit().Append(Stmt(as))
switch n := n.(type) {
default:
base.Fatalf("rewriteMultiValueCall %+v", n.Op())
case *ir.CallExpr:
n.Args = list
case *ir.ReturnStmt:
n.Results = list
case *ir.AssignListStmt:
if n.Op() != ir.OAS2FUNC {
base.Fatalf("rewriteMultiValueCall: invalid op %v", n.Op())
}
as.SetOp(ir.OAS2FUNC)
n.SetOp(ir.OAS2)
n.Rhs = make([]ir.Node, len(list))
for i, tmp := range list {
n.Rhs[i] = AssignConv(tmp, n.Lhs[i].Type(), "assignment")
}
}
}
func checksliceindex(l ir.Node, r ir.Node, tp *types.Type) bool {
t := r.Type()
if t == nil {
return false
}
if !t.IsInteger() {
base.Errorf("invalid slice index %v (type %v)", r, t)
return false
}
if r.Op() == ir.OLITERAL {
x := r.Val()
if constant.Sign(x) < 0 {
base.Errorf("invalid slice index %v (index must be non-negative)", r)
return false
} else if tp != nil && tp.NumElem() >= 0 && constant.Compare(x, token.GTR, constant.MakeInt64(tp.NumElem())) {
base.Errorf("invalid slice index %v (out of bounds for %d-element array)", r, tp.NumElem())
return false
} else if ir.IsConst(l, constant.String) && constant.Compare(x, token.GTR, constant.MakeInt64(int64(len(ir.StringVal(l))))) {
base.Errorf("invalid slice index %v (out of bounds for %d-byte string)", r, len(ir.StringVal(l)))
return false
} else if ir.ConstOverflow(x, types.Types[types.TINT]) {
base.Errorf("invalid slice index %v (index too large)", r)
return false
}
}
return true
}
func checksliceconst(lo ir.Node, hi ir.Node) bool {
if lo != nil && hi != nil && lo.Op() == ir.OLITERAL && hi.Op() == ir.OLITERAL && constant.Compare(lo.Val(), token.GTR, hi.Val()) {
base.Errorf("invalid slice index: %v > %v", lo, hi)
return false
}
return true
}
// The result of implicitstar MUST be assigned back to n, e.g.
//
// n.Left = implicitstar(n.Left)
func implicitstar(n ir.Node) ir.Node {
// insert implicit * if needed for fixed array
t := n.Type()
if t == nil || !t.IsPtr() {
return n
}
t = t.Elem()
if t == nil {
return n
}
if !t.IsArray() {
return n
}
star := ir.NewStarExpr(base.Pos, n)
star.SetImplicit(true)
return Expr(star)
}
func needOneArg(n *ir.CallExpr, f string, args ...interface{}) (ir.Node, bool) {
if len(n.Args) == 0 {
p := fmt.Sprintf(f, args...)
base.Errorf("missing argument to %s: %v", p, n)
return nil, false
}
if len(n.Args) > 1 {
p := fmt.Sprintf(f, args...)
base.Errorf("too many arguments to %s: %v", p, n)
return n.Args[0], false
}
return n.Args[0], true
}
func needTwoArgs(n *ir.CallExpr) (ir.Node, ir.Node, bool) {
if len(n.Args) != 2 {
if len(n.Args) < 2 {
base.Errorf("not enough arguments in call to %v", n)
} else {
base.Errorf("too many arguments in call to %v", n)
}
return nil, nil, false
}
return n.Args[0], n.Args[1], true
}
// Lookdot1 looks up the specified method s in the list fs of methods, returning
// the matching field or nil. If dostrcmp is 0, it matches the symbols. If
// dostrcmp is 1, it matches by name exactly. If dostrcmp is 2, it matches names
// with case folding.
func Lookdot1(errnode ir.Node, s *types.Sym, t *types.Type, fs *types.Fields, dostrcmp int) *types.Field {
var r *types.Field
for _, f := range fs.Slice() {
if dostrcmp != 0 && f.Sym.Name == s.Name {
return f
}
if dostrcmp == 2 && strings.EqualFold(f.Sym.Name, s.Name) {
return f
}
if f.Sym != s {
continue
}
if r != nil {
if errnode != nil {
base.Errorf("ambiguous selector %v", errnode)
} else if t.IsPtr() {
base.Errorf("ambiguous selector (%v).%v", t, s)
} else {
base.Errorf("ambiguous selector %v.%v", t, s)
}
break
}
r = f
}
return r
}
// typecheckMethodExpr checks selector expressions (ODOT) where the
// base expression is a type expression (OTYPE).
func typecheckMethodExpr(n *ir.SelectorExpr) (res ir.Node) {
if base.EnableTrace && base.Flag.LowerT {
defer tracePrint("typecheckMethodExpr", n)(&res)
}
t := n.X.Type()
// Compute the method set for t.
var ms *types.Fields
if t.IsInterface() {
ms = t.AllMethods()
} else {
mt := types.ReceiverBaseType(t)
if mt == nil {
base.Errorf("%v undefined (type %v has no method %v)", n, t, n.Sel)
n.SetType(nil)
return n
}
CalcMethods(mt)
ms = mt.AllMethods()
// The method expression T.m requires a wrapper when T
// is different from m's declared receiver type. We
// normally generate these wrappers while writing out
// runtime type descriptors, which is always done for
// types declared at package scope. However, we need
// to make sure to generate wrappers for anonymous
// receiver types too.
if mt.Sym() == nil {
NeedRuntimeType(t)
}
}
s := n.Sel
m := Lookdot1(n, s, t, ms, 0)
if m == nil {
if Lookdot1(n, s, t, ms, 1) != nil {
base.Errorf("%v undefined (cannot refer to unexported method %v)", n, s)
} else if _, ambig := dotpath(s, t, nil, false); ambig {
base.Errorf("%v undefined (ambiguous selector)", n) // method or field
} else {
base.Errorf("%v undefined (type %v has no method %v)", n, t, s)
}
n.SetType(nil)
return n
}
if !types.IsMethodApplicable(t, m) {
base.Errorf("invalid method expression %v (needs pointer receiver: (*%v).%S)", n, t, s)
n.SetType(nil)
return n
}
n.SetOp(ir.OMETHEXPR)
n.Selection = m
n.SetType(NewMethodType(m.Type, n.X.Type()))
return n
}
func derefall(t *types.Type) *types.Type {
for t != nil && t.IsPtr() {
t = t.Elem()
}
return t
}
// Lookdot looks up field or method n.Sel in the type t and returns the matching
// field. It transforms the op of node n to ODOTINTER or ODOTMETH, if appropriate.
// It also may add a StarExpr node to n.X as needed for access to non-pointer
// methods. If dostrcmp is 0, it matches the field/method with the exact symbol
// as n.Sel (appropriate for exported fields). If dostrcmp is 1, it matches by name
// exactly. If dostrcmp is 2, it matches names with case folding.
func Lookdot(n *ir.SelectorExpr, t *types.Type, dostrcmp int) *types.Field {
s := n.Sel
types.CalcSize(t)
var f1 *types.Field
if t.IsStruct() {
f1 = Lookdot1(n, s, t, t.Fields(), dostrcmp)
} else if t.IsInterface() {
f1 = Lookdot1(n, s, t, t.AllMethods(), dostrcmp)
}
var f2 *types.Field
if n.X.Type() == t || n.X.Type().Sym() == nil {
mt := types.ReceiverBaseType(t)
if mt != nil {
f2 = Lookdot1(n, s, mt, mt.Methods(), dostrcmp)
}
}
if f1 != nil {
if dostrcmp > 1 {
// Already in the process of diagnosing an error.
return f1
}
if f2 != nil {
base.Errorf("%v is both field and method", n.Sel)
}
if f1.Offset == types.BADWIDTH {
base.Fatalf("Lookdot badwidth t=%v, f1=%v@%p", t, f1, f1)
}
n.Selection = f1
n.SetType(f1.Type)
if t.IsInterface() {
if n.X.Type().IsPtr() {
star := ir.NewStarExpr(base.Pos, n.X)
star.SetImplicit(true)
n.X = Expr(star)
}
n.SetOp(ir.ODOTINTER)
}
return f1
}
if f2 != nil {
if dostrcmp > 1 {
// Already in the process of diagnosing an error.
return f2
}
orig := n.X
tt := n.X.Type()
types.CalcSize(tt)
rcvr := f2.Type.Recv().Type
if !types.Identical(rcvr, tt) {
if rcvr.IsPtr() && types.Identical(rcvr.Elem(), tt) {
checklvalue(n.X, "call pointer method on")
addr := NodAddr(n.X)
addr.SetImplicit(true)
n.X = typecheck(addr, ctxType|ctxExpr)
} else if tt.IsPtr() && (!rcvr.IsPtr() || rcvr.IsPtr() && rcvr.Elem().NotInHeap()) && types.Identical(tt.Elem(), rcvr) {
star := ir.NewStarExpr(base.Pos, n.X)
star.SetImplicit(true)
n.X = typecheck(star, ctxType|ctxExpr)
} else if tt.IsPtr() && tt.Elem().IsPtr() && types.Identical(derefall(tt), derefall(rcvr)) {
base.Errorf("calling method %v with receiver %L requires explicit dereference", n.Sel, n.X)
for tt.IsPtr() {
// Stop one level early for method with pointer receiver.
if rcvr.IsPtr() && !tt.Elem().IsPtr() {
break
}
star := ir.NewStarExpr(base.Pos, n.X)
star.SetImplicit(true)
n.X = typecheck(star, ctxType|ctxExpr)
tt = tt.Elem()
}
} else {
base.Fatalf("method mismatch: %v for %v", rcvr, tt)
}
}
// Check that we haven't implicitly dereferenced any defined pointer types.
for x := n.X; ; {
var inner ir.Node
implicit := false
switch x := x.(type) {
case *ir.AddrExpr:
inner, implicit = x.X, x.Implicit()
case *ir.SelectorExpr:
inner, implicit = x.X, x.Implicit()
case *ir.StarExpr:
inner, implicit = x.X, x.Implicit()
}
if !implicit {
break
}
if inner.Type().Sym() != nil && (x.Op() == ir.ODEREF || x.Op() == ir.ODOTPTR) {
// Found an implicit dereference of a defined pointer type.
// Restore n.X for better error message.
n.X = orig
return nil
}
x = inner
}
n.Selection = f2
n.SetType(f2.Type)
n.SetOp(ir.ODOTMETH)
return f2
}
return nil
}
func nokeys(l ir.Nodes) bool {
for _, n := range l {
if n.Op() == ir.OKEY || n.Op() == ir.OSTRUCTKEY {
return false
}
}
return true
}
func hasddd(t *types.Type) bool {
for _, tl := range t.Fields().Slice() {
if tl.IsDDD() {
return true
}
}
return false
}
// typecheck assignment: type list = expression list
func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl ir.Nodes, desc func() string) {
var t *types.Type
var i int
lno := base.Pos
defer func() { base.Pos = lno }()
var n ir.Node
if len(nl) == 1 {
n = nl[0]
}
n1 := tstruct.NumFields()
n2 := len(nl)
if !hasddd(tstruct) {
if isddd {
goto invalidddd
}
if n2 > n1 {
goto toomany
}
if n2 < n1 {
goto notenough
}
} else {
if !isddd {
if n2 < n1-1 {
goto notenough
}
} else {
if n2 > n1 {
goto toomany
}
if n2 < n1 {
goto notenough
}
}
}
i = 0
for _, tl := range tstruct.Fields().Slice() {
t = tl.Type
if tl.IsDDD() {
if isddd {
if i >= len(nl) {
goto notenough
}
if len(nl)-i > 1 {
goto toomany
}
n = nl[i]
ir.SetPos(n)
if n.Type() != nil {
nl[i] = assignconvfn(n, t, desc)
}
return
}
// TODO(mdempsky): Make into ... call with implicit slice.
for ; i < len(nl); i++ {
n = nl[i]
ir.SetPos(n)
if n.Type() != nil {
nl[i] = assignconvfn(n, t.Elem(), desc)
}
}
return
}
if i >= len(nl) {
goto notenough
}
n = nl[i]
ir.SetPos(n)
if n.Type() != nil {
nl[i] = assignconvfn(n, t, desc)
}
i++
}
if i < len(nl) {
goto toomany
}
invalidddd:
if isddd {
if call != nil {
base.Errorf("invalid use of ... in call to %v", call)
} else {
base.Errorf("invalid use of ... in %v", op)
}
}
return
notenough:
if n == nil || n.Type() != nil {
details := errorDetails(nl, tstruct, isddd)
if call != nil {
// call is the expression being called, not the overall call.
// Method expressions have the form T.M, and the compiler has
// rewritten those to ONAME nodes but left T in Left.
if call.Op() == ir.OMETHEXPR {
call := call.(*ir.SelectorExpr)
base.Errorf("not enough arguments in call to method expression %v%s", call, details)
} else {
base.Errorf("not enough arguments in call to %v%s", call, details)
}
} else {
base.Errorf("not enough arguments to %v%s", op, details)
}
if n != nil {
base.Fatalf("invalid call")
}
}
return
toomany:
details := errorDetails(nl, tstruct, isddd)
if call != nil {
base.Errorf("too many arguments in call to %v%s", call, details)
} else {
base.Errorf("too many arguments to %v%s", op, details)
}
}
func errorDetails(nl ir.Nodes, tstruct *types.Type, isddd bool) string {
// Suppress any return message signatures if:
//
// (1) We don't know any type at a call site (see #19012).
// (2) Any node has an unknown type.
// (3) Invalid type for variadic parameter (see #46957).
if tstruct == nil {
return "" // case 1
}
if isddd && !nl[len(nl)-1].Type().IsSlice() {
return "" // case 3
}
for _, n := range nl {
if n.Type() == nil {
return "" // case 2
}
}
return fmt.Sprintf("\n\thave %s\n\twant %v", fmtSignature(nl, isddd), tstruct)
}
// sigrepr is a type's representation to the outside world,
// in string representations of return signatures
// e.g in error messages about wrong arguments to return.
func sigrepr(t *types.Type, isddd bool) string {
switch t {
case types.UntypedString:
return "string"
case types.UntypedBool:
return "bool"
}
if t.Kind() == types.TIDEAL {
// "untyped number" is not commonly used
// outside of the compiler, so let's use "number".
// TODO(mdempsky): Revisit this.
return "number"
}
// Turn []T... argument to ...T for clearer error message.
if isddd {
if !t.IsSlice() {
base.Fatalf("bad type for ... argument: %v", t)
}
return "..." + t.Elem().String()
}
return t.String()
}
// sigerr returns the signature of the types at the call or return.
func fmtSignature(nl ir.Nodes, isddd bool) string {
if len(nl) < 1 {
return "()"
}
var typeStrings []string
for i, n := range nl {
isdddArg := isddd && i == len(nl)-1
typeStrings = append(typeStrings, sigrepr(n.Type(), isdddArg))
}
return fmt.Sprintf("(%s)", strings.Join(typeStrings, ", "))
}
// type check composite
func fielddup(name string, hash map[string]bool) {
if hash[name] {
base.Errorf("duplicate field name in struct literal: %s", name)
return
}
hash[name] = true
}
// typecheckarraylit type-checks a sequence of slice/array literal elements.
func typecheckarraylit(elemType *types.Type, bound int64, elts []ir.Node, ctx string) int64 {
// If there are key/value pairs, create a map to keep seen
// keys so we can check for duplicate indices.
var indices map[int64]bool
for _, elt := range elts {
if elt.Op() == ir.OKEY {
indices = make(map[int64]bool)
break
}
}
var key, length int64
for i, elt := range elts {
ir.SetPos(elt)
r := elts[i]
var kv *ir.KeyExpr
if elt.Op() == ir.OKEY {
elt := elt.(*ir.KeyExpr)
elt.Key = Expr(elt.Key)
key = IndexConst(elt.Key)
if key < 0 {
base.Fatalf("invalid index: %v", elt.Key)
}
kv = elt
r = elt.Value
}
r = Expr(r)
r = AssignConv(r, elemType, ctx)
if kv != nil {
kv.Value = r
} else {
elts[i] = r
}
if key >= 0 {
if indices != nil {
if indices[key] {
base.Errorf("duplicate index in %s: %d", ctx, key)
} else {
indices[key] = true
}
}
if bound >= 0 && key >= bound {
base.Errorf("array index %d out of bounds [0:%d]", key, bound)
bound = -1
}
}
key++
if key > length {
length = key
}
}
return length
}
// visible reports whether sym is exported or locally defined.
func visible(sym *types.Sym) bool {
return sym != nil && (types.IsExported(sym.Name) || sym.Pkg == types.LocalPkg)
}
// nonexported reports whether sym is an unexported field.
func nonexported(sym *types.Sym) bool {
return sym != nil && !types.IsExported(sym.Name)
}
func checklvalue(n ir.Node, verb string) {
if !ir.IsAddressable(n) {
base.Errorf("cannot %s %v", verb, n)
}
}
func checkassign(n ir.Node) {
// have already complained about n being invalid
if n.Type() == nil {
if base.Errors() == 0 {
base.Fatalf("expected an error about %v", n)
}
return
}
if ir.IsAddressable(n) {
return
}
if n.Op() == ir.OINDEXMAP {
n := n.(*ir.IndexExpr)
n.Assigned = true
return
}
defer n.SetType(nil)
switch {
case n.Op() == ir.ODOT && n.(*ir.SelectorExpr).X.Op() == ir.OINDEXMAP:
base.Errorf("cannot assign to struct field %v in map", n)
case (n.Op() == ir.OINDEX && n.(*ir.IndexExpr).X.Type().IsString()) || n.Op() == ir.OSLICESTR:
base.Errorf("cannot assign to %v (strings are immutable)", n)
case n.Op() == ir.OLITERAL && n.Sym() != nil && ir.IsConstNode(n):
base.Errorf("cannot assign to %v (declared const)", n)
default:
base.Errorf("cannot assign to %v", n)
}
}
func checkassignto(src *types.Type, dst ir.Node) {
// TODO(mdempsky): Handle all untyped types correctly.
if src == types.UntypedBool && dst.Type().IsBoolean() {
return
}
if op, why := Assignop(src, dst.Type()); op == ir.OXXX {
base.Errorf("cannot assign %v to %L in multiple assignment%s", src, dst, why)
return
}
}
// The result of stringtoruneslit MUST be assigned back to n, e.g.
//
// n.Left = stringtoruneslit(n.Left)
func stringtoruneslit(n *ir.ConvExpr) ir.Node {
if n.X.Op() != ir.OLITERAL || n.X.Val().Kind() != constant.String {
base.Fatalf("stringtoarraylit %v", n)
}
var l []ir.Node
i := 0
for _, r := range ir.StringVal(n.X) {
l = append(l, ir.NewKeyExpr(base.Pos, ir.NewInt(int64(i)), ir.NewInt(int64(r))))
i++
}
return Expr(ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, n.Type(), l))
}
func checkmake(t *types.Type, arg string, np *ir.Node) bool {
n := *np
if !n.Type().IsInteger() && n.Type().Kind() != types.TIDEAL {
base.Errorf("non-integer %s argument in make(%v) - %v", arg, t, n.Type())
return false
}
// Do range checks for constants before DefaultLit
// to avoid redundant "constant NNN overflows int" errors.
if n.Op() == ir.OLITERAL {
v := toint(n.Val())
if constant.Sign(v) < 0 {
base.Errorf("negative %s argument in make(%v)", arg, t)
return false
}
if ir.ConstOverflow(v, types.Types[types.TINT]) {
base.Errorf("%s argument too large in make(%v)", arg, t)
return false
}
}
// DefaultLit is necessary for non-constants too: n might be 1.1<<k.
// TODO(gri) The length argument requirements for (array/slice) make
// are the same as for index expressions. Factor the code better;
// for instance, indexlit might be called here and incorporate some
// of the bounds checks done for make.
n = DefaultLit(n, types.Types[types.TINT])
*np = n
return true
}
// checkunsafeslice is like checkmake but for unsafe.Slice.
func checkunsafeslice(np *ir.Node) bool {
n := *np
if !n.Type().IsInteger() && n.Type().Kind() != types.TIDEAL {
base.Errorf("non-integer len argument in unsafe.Slice - %v", n.Type())
return false
}
// Do range checks for constants before DefaultLit
// to avoid redundant "constant NNN overflows int" errors.
if n.Op() == ir.OLITERAL {
v := toint(n.Val())
if constant.Sign(v) < 0 {
base.Errorf("negative len argument in unsafe.Slice")
return false
}
if ir.ConstOverflow(v, types.Types[types.TINT]) {
base.Errorf("len argument too large in unsafe.Slice")
return false
}
}
// DefaultLit is necessary for non-constants too: n might be 1.1<<k.
n = DefaultLit(n, types.Types[types.TINT])
*np = n
return true
}
// markBreak marks control statements containing break statements with SetHasBreak(true).
func markBreak(fn *ir.Func) {
var labels map[*types.Sym]ir.Node
var implicit ir.Node
var mark func(ir.Node) bool
mark = func(n ir.Node) bool {
switch n.Op() {
default:
ir.DoChildren(n, mark)
case ir.OBREAK:
n := n.(*ir.BranchStmt)
if n.Label == nil {
setHasBreak(implicit)
} else {
setHasBreak(labels[n.Label])
}
case ir.OFOR, ir.OFORUNTIL, ir.OSWITCH, ir.OSELECT, ir.ORANGE:
old := implicit
implicit = n
var sym *types.Sym
switch n := n.(type) {
case *ir.ForStmt:
sym = n.Label
case *ir.RangeStmt:
sym = n.Label
case *ir.SelectStmt:
sym = n.Label
case *ir.SwitchStmt:
sym = n.Label
}
if sym != nil {
if labels == nil {
// Map creation delayed until we need it - most functions don't.
labels = make(map[*types.Sym]ir.Node)
}
labels[sym] = n
}
ir.DoChildren(n, mark)
if sym != nil {
delete(labels, sym)
}
implicit = old
}
return false
}
mark(fn)
}
func setHasBreak(n ir.Node) {
switch n := n.(type) {
default:
base.Fatalf("setHasBreak %+v", n.Op())
case nil:
// ignore
case *ir.ForStmt:
n.HasBreak = true
case *ir.RangeStmt:
n.HasBreak = true
case *ir.SelectStmt:
n.HasBreak = true
case *ir.SwitchStmt:
n.HasBreak = true
}
}
// isTermNodes reports whether the Nodes list ends with a terminating statement.
func isTermNodes(l ir.Nodes) bool {
s := l
c := len(s)
if c == 0 {
return false
}
return isTermNode(s[c-1])
}
// isTermNode reports whether the node n, the last one in a
// statement list, is a terminating statement.
func isTermNode(n ir.Node) bool {
switch n.Op() {
// NOTE: OLABEL is treated as a separate statement,
// not a separate prefix, so skipping to the last statement
// in the block handles the labeled statement case by
// skipping over the label. No case OLABEL here.
case ir.OBLOCK:
n := n.(*ir.BlockStmt)
return isTermNodes(n.List)
case ir.OGOTO, ir.ORETURN, ir.OTAILCALL, ir.OPANIC, ir.OFALL:
return true
case ir.OFOR, ir.OFORUNTIL:
n := n.(*ir.ForStmt)
if n.Cond != nil {
return false
}
if n.HasBreak {
return false
}
return true
case ir.OIF:
n := n.(*ir.IfStmt)
return isTermNodes(n.Body) && isTermNodes(n.Else)
case ir.OSWITCH:
n := n.(*ir.SwitchStmt)
if n.HasBreak {
return false
}
def := false
for _, cas := range n.Cases {
if !isTermNodes(cas.Body) {
return false
}
if len(cas.List) == 0 { // default
def = true
}
}
return def
case ir.OSELECT:
n := n.(*ir.SelectStmt)
if n.HasBreak {
return false
}
for _, cas := range n.Cases {
if !isTermNodes(cas.Body) {
return false
}
}
return true
}
return false
}
func Conv(n ir.Node, t *types.Type) ir.Node {
if types.Identical(n.Type(), t) {
return n
}
n = ir.NewConvExpr(base.Pos, ir.OCONV, nil, n)
n.SetType(t)
n = Expr(n)
return n
}
// ConvNop converts node n to type t using the OCONVNOP op
// and typechecks the result with ctxExpr.
func ConvNop(n ir.Node, t *types.Type) ir.Node {
if types.Identical(n.Type(), t) {
return n
}
n = ir.NewConvExpr(base.Pos, ir.OCONVNOP, nil, n)
n.SetType(t)
n = Expr(n)
return n
}
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