// 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 gc
import (
"cmd/compile/internal/types"
"cmd/internal/objabi"
"fmt"
"strings"
)
// To enable tracing support (-t flag), set enableTrace to true.
const enableTrace = false
var trace bool
var traceIndent []byte
func tracePrint(title string, n *Node) func(np **Node) {
indent := traceIndent
// guard against nil
var pos, op string
var tc uint8
if n != nil {
pos = linestr(n.Pos)
op = n.Op.String()
tc = n.Typecheck()
}
fmt.Printf("%s: %s%s %p %s %v tc=%d\n", pos, indent, title, n, op, n, tc)
traceIndent = append(traceIndent, ". "...)
return func(np **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 = linestr(n.Pos)
op = n.Op.String()
tc = n.Typecheck()
typ = n.Type
}
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
Etype // evaluated in type context
ctxCallee // call-only expressions are ok
ctxMultiOK // multivalue function returns are ok
ctxAssign // assigning to expression
ctxCompLit // type in composite literal
)
// 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.
var typecheckdefstack []*Node
// resolve ONONAME to definition, if any.
func resolve(n *Node) (res *Node) {
if n == nil || n.Op != ONONAME {
return n
}
// only trace if there's work to do
if enableTrace && trace {
defer tracePrint("resolve", n)(&res)
}
if n.Sym.Pkg != localpkg {
if inimport {
Fatalf("recursive inimport")
}
inimport = true
expandDecl(n)
inimport = false
return n
}
r := asNode(n.Sym.Def)
if r == nil {
return n
}
if r.Op == OIOTA {
if i := len(typecheckdefstack); i > 0 {
if x := typecheckdefstack[i-1]; x.Op == OLITERAL {
return nodintconst(x.Iota())
}
}
return n
}
return r
}
func typecheckslice(l []*Node, top int) {
for i := range l {
l[i] = typecheck(l[i], top)
}
}
var _typekind = []string{
TINT: "int",
TUINT: "uint",
TINT8: "int8",
TUINT8: "uint8",
TINT16: "int16",
TUINT16: "uint16",
TINT32: "int32",
TUINT32: "uint32",
TINT64: "int64",
TUINT64: "uint64",
TUINTPTR: "uintptr",
TCOMPLEX64: "complex64",
TCOMPLEX128: "complex128",
TFLOAT32: "float32",
TFLOAT64: "float64",
TBOOL: "bool",
TSTRING: "string",
TPTR: "pointer",
TUNSAFEPTR: "unsafe.Pointer",
TSTRUCT: "struct",
TINTER: "interface",
TCHAN: "chan",
TMAP: "map",
TARRAY: "array",
TSLICE: "slice",
TFUNC: "func",
TNIL: "nil",
TIDEAL: "untyped number",
}
func typekind(t *types.Type) string {
if t.IsSlice() {
return "slice"
}
et := t.Etype
if int(et) < len(_typekind) {
s := _typekind[et]
if s != "" {
return s
}
}
return fmt.Sprintf("etype=%d", et)
}
func cycleFor(start *Node) []*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 []*Node
for _, n := range typecheck_tcstack[i:] {
if n.Op == start.Op {
cycle = append(cycle, n)
}
}
return cycle
}
func cycleTrace(cycle []*Node) string {
var s string
for i, n := range cycle {
s += fmt.Sprintf("\n\t%v: %v uses %v", n.Line(), n, cycle[(i+1)%len(cycle)])
}
return s
}
var typecheck_tcstack []*Node
// 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 *Node, top int) (res *Node) {
// cannot type check until all the source has been parsed
if !typecheckok {
Fatalf("early typecheck")
}
if n == nil {
return nil
}
// only trace if there's work to do
if enableTrace && trace {
defer tracePrint("typecheck", n)(&res)
}
lno := setlineno(n)
// Skip over parens.
for n.Op == OPAREN {
n = n.Left
}
// 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 {
switch n.Op {
case ONAME, OTYPE, OLITERAL, OPACK:
break
default:
lineno = 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 ONAME:
if top&(ctxExpr|Etype) == Etype {
yyerror("%v is not a type", n)
}
case OTYPE:
// Only report a type cycle if we are expecting a type.
// Otherwise let other code report an error.
if top&Etype == Etype {
// 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.Param.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.Param.Alias && n.Type == nil {
lineno = n.Pos
Fatalf("cannot handle alias type declaration (issue #25838): %v", n)
}
lineno = lno
return n
}
}
yyerrorl(n.Pos, "invalid recursive type alias %v%s", n, cycleTrace(cycle))
}
case OLITERAL:
if top&(ctxExpr|Etype) == Etype {
yyerror("%v is not a type", n)
break
}
yyerrorl(n.Pos, "constant definition loop%s", cycleTrace(cycleFor(n)))
}
if nsavederrors+nerrors == 0 {
var trace string
for i := len(typecheck_tcstack) - 1; i >= 0; i-- {
x := typecheck_tcstack[i]
trace += fmt.Sprintf("\n\t%v %v", x.Line(), x)
}
yyerror("typechecking loop involving %v%s", n, trace)
}
lineno = lno
return n
}
n.SetTypecheck(2)
typecheck_tcstack = append(typecheck_tcstack, n)
n = typecheck1(n, top)
n.SetTypecheck(1)
last := len(typecheck_tcstack) - 1
typecheck_tcstack[last] = nil
typecheck_tcstack = typecheck_tcstack[:last]
lineno = 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 *Node) *Node {
if n != nil && n.Type != nil && n.Type.Etype == TIDEAL {
return defaultlit(n, types.Types[TINT])
}
return n
}
// The result of typecheck1 MUST be assigned back to n, e.g.
// n.Left = typecheck1(n.Left, top)
func typecheck1(n *Node, top int) (res *Node) {
if enableTrace && trace {
defer tracePrint("typecheck1", n)(&res)
}
switch n.Op {
case OLITERAL, ONAME, ONONAME, OTYPE:
if n.Sym == nil {
break
}
if n.Op == ONAME && n.SubOp() != 0 && top&ctxCallee == 0 {
yyerror("use of builtin %v not in function call", n.Sym)
n.Type = nil
return n
}
typecheckdef(n)
if n.Op == ONONAME {
n.Type = nil
return n
}
}
ok := 0
switch n.Op {
// until typecheck is complete, do nothing.
default:
Dump("typecheck", n)
Fatalf("typecheck %v", n.Op)
// names
case OLITERAL:
ok |= ctxExpr
if n.Type == nil && n.Val().Ctype() == CTSTR {
n.Type = types.Idealstring
}
case ONONAME:
ok |= ctxExpr
case ONAME:
if n.Name.Decldepth == 0 {
n.Name.Decldepth = decldepth
}
if n.SubOp() != 0 {
ok |= ctxCallee
break
}
if top&ctxAssign == 0 {
// not a write to the variable
if n.isBlank() {
yyerror("cannot use _ as value")
n.Type = nil
return n
}
n.Name.SetUsed(true)
}
ok |= ctxExpr
case OPACK:
yyerror("use of package %v without selector", n.Sym)
n.Type = nil
return n
case ODDD:
break
// types (ODEREF is with exprs)
case OTYPE:
ok |= Etype
if n.Type == nil {
return n
}
case OTARRAY:
ok |= Etype
r := typecheck(n.Right, Etype)
if r.Type == nil {
n.Type = nil
return n
}
var t *types.Type
if n.Left == nil {
t = types.NewSlice(r.Type)
} else if n.Left.Op == ODDD {
if top&ctxCompLit == 0 {
if !n.Diag() {
n.SetDiag(true)
yyerror("use of [...] array outside of array literal")
}
n.Type = nil
return n
}
t = types.NewDDDArray(r.Type)
} else {
n.Left = indexlit(typecheck(n.Left, ctxExpr))
l := n.Left
if consttype(l) != CTINT {
switch {
case l.Type == nil:
// Error already reported elsewhere.
case l.Type.IsInteger() && l.Op != OLITERAL:
yyerror("non-constant array bound %v", l)
default:
yyerror("invalid array bound %v", l)
}
n.Type = nil
return n
}
v := l.Val()
if doesoverflow(v, types.Types[TINT]) {
yyerror("array bound is too large")
n.Type = nil
return n
}
bound := v.U.(*Mpint).Int64()
if bound < 0 {
yyerror("array bound must be non-negative")
n.Type = nil
return n
}
t = types.NewArray(r.Type, bound)
}
n.Op = OTYPE
n.Type = t
n.Left = nil
n.Right = nil
if !t.IsDDDArray() {
checkwidth(t)
}
case OTMAP:
ok |= Etype
n.Left = typecheck(n.Left, Etype)
n.Right = typecheck(n.Right, Etype)
l := n.Left
r := n.Right
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
if l.Type.NotInHeap() {
yyerror("go:notinheap map key not allowed")
}
if r.Type.NotInHeap() {
yyerror("go:notinheap map value not allowed")
}
n.Op = OTYPE
n.Type = types.NewMap(l.Type, r.Type)
mapqueue = append(mapqueue, n) // check map keys when all types are settled
n.Left = nil
n.Right = nil
case OTCHAN:
ok |= Etype
n.Left = typecheck(n.Left, Etype)
l := n.Left
if l.Type == nil {
n.Type = nil
return n
}
if l.Type.NotInHeap() {
yyerror("chan of go:notinheap type not allowed")
}
t := types.NewChan(l.Type, n.TChanDir())
n.Op = OTYPE
n.Type = t
n.Left = nil
n.ResetAux()
case OTSTRUCT:
ok |= Etype
n.Op = OTYPE
n.Type = tostruct(n.List.Slice())
if n.Type == nil || n.Type.Broke() {
n.Type = nil
return n
}
n.List.Set(nil)
case OTINTER:
ok |= Etype
n.Op = OTYPE
n.Type = tointerface(n.List.Slice())
if n.Type == nil {
return n
}
case OTFUNC:
ok |= Etype
n.Op = OTYPE
n.Type = functype(n.Left, n.List.Slice(), n.Rlist.Slice())
if n.Type == nil {
return n
}
n.Left = nil
n.List.Set(nil)
n.Rlist.Set(nil)
// type or expr
case ODEREF:
n.Left = typecheck(n.Left, ctxExpr|Etype|top&ctxCompLit)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
if l.Op == OTYPE {
ok |= Etype
n.Op = OTYPE
n.Type = types.NewPtr(l.Type)
// Ensure l.Type gets dowidth'd for the backend. Issue 20174.
// Don't checkwidth [...] arrays, though, since they
// will be replaced by concrete-sized arrays. Issue 20333.
if !l.Type.IsDDDArray() {
checkwidth(l.Type)
}
n.Left = nil
break
}
if !t.IsPtr() {
if top&(ctxExpr|ctxStmt) != 0 {
yyerror("invalid indirect of %L", n.Left)
n.Type = nil
return n
}
break
}
ok |= ctxExpr
n.Type = t.Elem()
// arithmetic exprs
case OASOP,
OADD,
OAND,
OANDAND,
OANDNOT,
ODIV,
OEQ,
OGE,
OGT,
OLE,
OLT,
OLSH,
ORSH,
OMOD,
OMUL,
ONE,
OOR,
OOROR,
OSUB,
OXOR:
var l *Node
var op Op
var r *Node
if n.Op == OASOP {
ok |= ctxStmt
n.Left = typecheck(n.Left, ctxExpr)
n.Right = typecheck(n.Right, ctxExpr)
l = n.Left
r = n.Right
checkassign(n, n.Left)
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
if n.Implicit() && !okforarith[l.Type.Etype] {
yyerror("invalid operation: %v (non-numeric type %v)", n, l.Type)
n.Type = nil
return n
}
// TODO(marvin): Fix Node.EType type union.
op = n.SubOp()
} else {
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
n.Right = typecheck(n.Right, ctxExpr)
l = n.Left
r = n.Right
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
op = n.Op
}
if op == OLSH || op == ORSH {
r = defaultlit(r, types.Types[TUINT])
n.Right = r
t := r.Type
if !t.IsInteger() {
yyerror("invalid operation: %v (shift count type %v, must be integer)", n, r.Type)
n.Type = nil
return n
}
if t.IsSigned() && !langSupported(1, 13) {
yyerrorv("go1.13", "invalid operation: %v (signed shift count type %v)", n, r.Type)
n.Type = nil
return n
}
t = l.Type
if t != nil && t.Etype != TIDEAL && !t.IsInteger() {
yyerror("invalid operation: %v (shift of type %v)", n, t)
n.Type = nil
return n
}
// no defaultlit for left
// the outer context gives the type
n.Type = l.Type
break
}
// ideal mixed with non-ideal
l, r = defaultlit2(l, r, false)
n.Left = l
n.Right = r
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
t := l.Type
if t.Etype == TIDEAL {
t = r.Type
}
et := t.Etype
if et == TIDEAL {
et = TINT
}
aop := OXXX
if iscmp[n.Op] && t.Etype != TIDEAL && !types.Identical(l.Type, r.Type) {
// comparison is okay as long as one side is
// assignable to the other. convert so they have
// the same type.
//
// the only conversion that isn't a no-op is concrete == interface.
// in that case, check comparability of the concrete type.
// The conversion allocates, so only do it if the concrete type is huge.
converted := false
if r.Type.Etype != TBLANK {
aop = assignop(l.Type, r.Type, nil)
if aop != 0 {
if r.Type.IsInterface() && !l.Type.IsInterface() && !IsComparable(l.Type) {
yyerror("invalid operation: %v (operator %v not defined on %s)", n, op, typekind(l.Type))
n.Type = nil
return n
}
dowidth(l.Type)
if r.Type.IsInterface() == l.Type.IsInterface() || l.Type.Width >= 1<<16 {
l = nod(aop, l, nil)
l.Type = r.Type
l.SetTypecheck(1)
n.Left = l
}
t = r.Type
converted = true
}
}
if !converted && l.Type.Etype != TBLANK {
aop = assignop(r.Type, l.Type, nil)
if aop != 0 {
if l.Type.IsInterface() && !r.Type.IsInterface() && !IsComparable(r.Type) {
yyerror("invalid operation: %v (operator %v not defined on %s)", n, op, typekind(r.Type))
n.Type = nil
return n
}
dowidth(r.Type)
if r.Type.IsInterface() == l.Type.IsInterface() || r.Type.Width >= 1<<16 {
r = nod(aop, r, nil)
r.Type = l.Type
r.SetTypecheck(1)
n.Right = r
}
t = l.Type
}
}
et = t.Etype
}
if t.Etype != TIDEAL && !types.Identical(l.Type, r.Type) {
l, r = defaultlit2(l, r, true)
if r.Type.IsInterface() == l.Type.IsInterface() || aop == 0 {
yyerror("invalid operation: %v (mismatched types %v and %v)", n, l.Type, r.Type)
n.Type = nil
return n
}
}
if !okfor[op][et] {
yyerror("invalid operation: %v (operator %v not defined on %s)", n, op, typekind(t))
n.Type = nil
return n
}
// okfor allows any array == array, map == map, func == func.
// restrict to slice/map/func == nil and nil == slice/map/func.
if l.Type.IsArray() && !IsComparable(l.Type) {
yyerror("invalid operation: %v (%v cannot be compared)", n, l.Type)
n.Type = nil
return n
}
if l.Type.IsSlice() && !l.isNil() && !r.isNil() {
yyerror("invalid operation: %v (slice can only be compared to nil)", n)
n.Type = nil
return n
}
if l.Type.IsMap() && !l.isNil() && !r.isNil() {
yyerror("invalid operation: %v (map can only be compared to nil)", n)
n.Type = nil
return n
}
if l.Type.Etype == TFUNC && !l.isNil() && !r.isNil() {
yyerror("invalid operation: %v (func can only be compared to nil)", n)
n.Type = nil
return n
}
if l.Type.IsStruct() {
if f := IncomparableField(l.Type); f != nil {
yyerror("invalid operation: %v (struct containing %v cannot be compared)", n, f.Type)
n.Type = nil
return n
}
}
t = l.Type
if iscmp[n.Op] {
evconst(n)
t = types.Idealbool
if n.Op != OLITERAL {
l, r = defaultlit2(l, r, true)
n.Left = l
n.Right = r
}
}
if et == TSTRING && n.Op == OADD {
// create OADDSTR node with list of strings in x + y + z + (w + v) + ...
n.Op = OADDSTR
if l.Op == OADDSTR {
n.List.Set(l.List.Slice())
} else {
n.List.Set1(l)
}
if r.Op == OADDSTR {
n.List.AppendNodes(&r.List)
} else {
n.List.Append(r)
}
n.Left = nil
n.Right = nil
}
if (op == ODIV || op == OMOD) && Isconst(r, CTINT) {
if r.Val().U.(*Mpint).CmpInt64(0) == 0 {
yyerror("division by zero")
n.Type = nil
return n
}
}
n.Type = t
case OBITNOT, ONEG, ONOT, OPLUS:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
if !okfor[n.Op][t.Etype] {
yyerror("invalid operation: %v %v", n.Op, t)
n.Type = nil
return n
}
n.Type = t
// exprs
case OADDR:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
if n.Left.Type == nil {
n.Type = nil
return n
}
checklvalue(n.Left, "take the address of")
r := outervalue(n.Left)
var l *Node
for l = n.Left; l != r; l = l.Left {
l.SetAddrtaken(true)
if l.IsClosureVar() && !capturevarscomplete {
// Mark the original variable as Addrtaken so that capturevars
// knows not to pass it by value.
// But if the capturevars phase is complete, don't touch it,
// in case l.Name's containing function has not yet been compiled.
l.Name.Defn.SetAddrtaken(true)
}
}
if l.Orig != l && l.Op == ONAME {
Fatalf("found non-orig name node %v", l)
}
l.SetAddrtaken(true)
if l.IsClosureVar() && !capturevarscomplete {
// See comments above about closure variables.
l.Name.Defn.SetAddrtaken(true)
}
n.Left = defaultlit(n.Left, nil)
l = n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
n.Type = types.NewPtr(t)
case OCOMPLIT:
ok |= ctxExpr
n = typecheckcomplit(n)
if n.Type == nil {
return n
}
case OXDOT, ODOT:
if n.Op == OXDOT {
n = adddot(n)
n.Op = ODOT
if n.Left == nil {
n.Type = nil
return n
}
}
n.Left = typecheck(n.Left, ctxExpr|Etype)
n.Left = defaultlit(n.Left, nil)
t := n.Left.Type
if t == nil {
adderrorname(n)
n.Type = nil
return n
}
s := n.Sym
if n.Left.Op == OTYPE {
n = typecheckMethodExpr(n)
if n.Type == nil {
return n
}
ok = ctxExpr
break
}
if t.IsPtr() && !t.Elem().IsInterface() {
t = t.Elem()
if t == nil {
n.Type = nil
return n
}
n.Op = ODOTPTR
checkwidth(t)
}
if n.Sym.IsBlank() {
yyerror("cannot refer to blank field or method")
n.Type = nil
return n
}
if lookdot(n, t, 0) == nil {
// Legitimate field or method lookup failed, try to explain the error
switch {
case t.IsEmptyInterface():
yyerror("%v undefined (type %v is interface with no methods)", n, n.Left.Type)
case t.IsPtr() && t.Elem().IsInterface():
// Pointer to interface is almost always a mistake.
yyerror("%v undefined (type %v is pointer to interface, not interface)", n, n.Left.Type)
case lookdot(n, t, 1) != nil:
// Field or method matches by name, but it is not exported.
yyerror("%v undefined (cannot refer to unexported field or method %v)", n, n.Sym)
default:
if mt := lookdot(n, t, 2); mt != nil && visible(mt.Sym) { // Case-insensitive lookup.
yyerror("%v undefined (type %v has no field or method %v, but does have %v)", n, n.Left.Type, n.Sym, mt.Sym)
} else {
yyerror("%v undefined (type %v has no field or method %v)", n, n.Left.Type, n.Sym)
}
}
n.Type = nil
return n
}
switch n.Op {
case ODOTINTER, ODOTMETH:
if top&ctxCallee != 0 {
ok |= ctxCallee
} else {
typecheckpartialcall(n, s)
ok |= ctxExpr
}
default:
ok |= ctxExpr
}
case ODOTTYPE:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsInterface() {
yyerror("invalid type assertion: %v (non-interface type %v on left)", n, t)
n.Type = nil
return n
}
if n.Right != nil {
n.Right = typecheck(n.Right, Etype)
n.Type = n.Right.Type
n.Right = nil
if n.Type == nil {
return n
}
}
if n.Type != nil && !n.Type.IsInterface() {
var missing, have *types.Field
var ptr int
if !implements(n.Type, t, &missing, &have, &ptr) {
if have != nil && have.Sym == missing.Sym {
yyerror("impossible type assertion:\n\t%v does not implement %v (wrong type for %v method)\n"+
"\t\thave %v%0S\n\t\twant %v%0S", n.Type, t, missing.Sym, have.Sym, have.Type, missing.Sym, missing.Type)
} else if ptr != 0 {
yyerror("impossible type assertion:\n\t%v does not implement %v (%v method has pointer receiver)", n.Type, t, missing.Sym)
} else if have != nil {
yyerror("impossible type assertion:\n\t%v does not implement %v (missing %v method)\n"+
"\t\thave %v%0S\n\t\twant %v%0S", n.Type, t, missing.Sym, have.Sym, have.Type, missing.Sym, missing.Type)
} else {
yyerror("impossible type assertion:\n\t%v does not implement %v (missing %v method)", n.Type, t, missing.Sym)
}
n.Type = nil
return n
}
}
case OINDEX:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
n.Left = implicitstar(n.Left)
l := n.Left
n.Right = typecheck(n.Right, ctxExpr)
r := n.Right
t := l.Type
if t == nil || r.Type == nil {
n.Type = nil
return n
}
switch t.Etype {
default:
yyerror("invalid operation: %v (type %v does not support indexing)", n, t)
n.Type = nil
return n
case TSTRING, TARRAY, TSLICE:
n.Right = indexlit(n.Right)
if t.IsString() {
n.Type = types.Bytetype
} else {
n.Type = t.Elem()
}
why := "string"
if t.IsArray() {
why = "array"
} else if t.IsSlice() {
why = "slice"
}
if n.Right.Type != nil && !n.Right.Type.IsInteger() {
yyerror("non-integer %s index %v", why, n.Right)
break
}
if !n.Bounded() && Isconst(n.Right, CTINT) {
x := n.Right.Int64()
if x < 0 {
yyerror("invalid %s index %v (index must be non-negative)", why, n.Right)
} else if t.IsArray() && x >= t.NumElem() {
yyerror("invalid array index %v (out of bounds for %d-element array)", n.Right, t.NumElem())
} else if Isconst(n.Left, CTSTR) && x >= int64(len(n.Left.Val().U.(string))) {
yyerror("invalid string index %v (out of bounds for %d-byte string)", n.Right, len(n.Left.Val().U.(string)))
} else if n.Right.Val().U.(*Mpint).Cmp(maxintval[TINT]) > 0 {
yyerror("invalid %s index %v (index too large)", why, n.Right)
}
}
case TMAP:
n.Right = defaultlit(n.Right, t.Key())
if n.Right.Type != nil {
n.Right = assignconv(n.Right, t.Key(), "map index")
}
n.Type = t.Elem()
n.Op = OINDEXMAP
n.ResetAux()
}
case ORECV:
ok |= ctxStmt | ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsChan() {
yyerror("invalid operation: %v (receive from non-chan type %v)", n, t)
n.Type = nil
return n
}
if !t.ChanDir().CanRecv() {
yyerror("invalid operation: %v (receive from send-only type %v)", n, t)
n.Type = nil
return n
}
n.Type = t.Elem()
case OSEND:
ok |= ctxStmt
n.Left = typecheck(n.Left, ctxExpr)
n.Right = typecheck(n.Right, ctxExpr)
n.Left = defaultlit(n.Left, nil)
t := n.Left.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsChan() {
yyerror("invalid operation: %v (send to non-chan type %v)", n, t)
n.Type = nil
return n
}
if !t.ChanDir().CanSend() {
yyerror("invalid operation: %v (send to receive-only type %v)", n, t)
n.Type = nil
return n
}
n.Right = defaultlit(n.Right, t.Elem())
r := n.Right
if r.Type == nil {
n.Type = nil
return n
}
n.Right = assignconv(r, t.Elem(), "send")
n.Type = nil
case OSLICEHEADER:
// Errors here are Fatalf instead of yyerror because only the compiler
// can construct an OSLICEHEADER node.
// Components used in OSLICEHEADER that are supplied by parsed source code
// have already been typechecked in e.g. OMAKESLICE earlier.
ok |= ctxExpr
t := n.Type
if t == nil {
Fatalf("no type specified for OSLICEHEADER")
}
if !t.IsSlice() {
Fatalf("invalid type %v for OSLICEHEADER", n.Type)
}
if n.Left == nil || n.Left.Type == nil || !n.Left.Type.IsUnsafePtr() {
Fatalf("need unsafe.Pointer for OSLICEHEADER")
}
if x := n.List.Len(); x != 2 {
Fatalf("expected 2 params (len, cap) for OSLICEHEADER, got %d", x)
}
n.Left = typecheck(n.Left, ctxExpr)
l := typecheck(n.List.First(), ctxExpr)
c := typecheck(n.List.Second(), ctxExpr)
l = defaultlit(l, types.Types[TINT])
c = defaultlit(c, types.Types[TINT])
if Isconst(l, CTINT) && l.Int64() < 0 {
Fatalf("len for OSLICEHEADER must be non-negative")
}
if Isconst(c, CTINT) && c.Int64() < 0 {
Fatalf("cap for OSLICEHEADER must be non-negative")
}
if Isconst(l, CTINT) && Isconst(c, CTINT) && l.Val().U.(*Mpint).Cmp(c.Val().U.(*Mpint)) > 0 {
Fatalf("len larger than cap for OSLICEHEADER")
}
n.List.SetFirst(l)
n.List.SetSecond(c)
case OSLICE, OSLICE3:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
low, high, max := n.SliceBounds()
hasmax := n.Op.IsSlice3()
low = typecheck(low, ctxExpr)
high = typecheck(high, ctxExpr)
max = typecheck(max, ctxExpr)
n.Left = defaultlit(n.Left, nil)
low = indexlit(low)
high = indexlit(high)
max = indexlit(max)
n.SetSliceBounds(low, high, max)
l := n.Left
if l.Type == nil {
n.Type = nil
return n
}
if l.Type.IsArray() {
if !islvalue(n.Left) {
yyerror("invalid operation %v (slice of unaddressable value)", n)
n.Type = nil
return n
}
n.Left = nod(OADDR, n.Left, nil)
n.Left.SetImplicit(true)
n.Left = typecheck(n.Left, ctxExpr)
l = n.Left
}
t := l.Type
var tp *types.Type
if t.IsString() {
if hasmax {
yyerror("invalid operation %v (3-index slice of string)", n)
n.Type = nil
return n
}
n.Type = t
n.Op = OSLICESTR
} else if t.IsPtr() && t.Elem().IsArray() {
tp = t.Elem()
n.Type = types.NewSlice(tp.Elem())
dowidth(n.Type)
if hasmax {
n.Op = OSLICE3ARR
} else {
n.Op = OSLICEARR
}
} else if t.IsSlice() {
n.Type = t
} else {
yyerror("cannot slice %v (type %v)", l, t)
n.Type = nil
return n
}
if low != nil && !checksliceindex(l, low, tp) {
n.Type = nil
return n
}
if high != nil && !checksliceindex(l, high, tp) {
n.Type = nil
return n
}
if max != nil && !checksliceindex(l, max, tp) {
n.Type = nil
return n
}
if !checksliceconst(low, high) || !checksliceconst(low, max) || !checksliceconst(high, max) {
n.Type = nil
return n
}
// call and call like
case OCALL:
typecheckslice(n.Ninit.Slice(), ctxStmt) // imported rewritten f(g()) calls (#30907)
n.Left = typecheck(n.Left, ctxExpr|Etype|ctxCallee)
if n.Left.Diag() {
n.SetDiag(true)
}
l := n.Left
if l.Op == ONAME && l.SubOp() != 0 {
if n.IsDDD() && l.SubOp() != OAPPEND {
yyerror("invalid use of ... with builtin %v", l)
}
// builtin: OLEN, OCAP, etc.
n.Op = l.SubOp()
n.Left = n.Right
n.Right = nil
n = typecheck1(n, top)
return n
}
n.Left = defaultlit(n.Left, nil)
l = n.Left
if l.Op == OTYPE {
if n.IsDDD() || l.Type.IsDDDArray() {
if !l.Type.Broke() {
yyerror("invalid use of ... in type conversion to %v", l.Type)
}
n.SetDiag(true)
}
// pick off before type-checking arguments
ok |= ctxExpr
// turn CALL(type, arg) into CONV(arg) w/ type
n.Left = nil
n.Op = OCONV
n.Type = l.Type
if !onearg(n, "conversion to %v", l.Type) {
n.Type = nil
return n
}
n = typecheck1(n, top)
return n
}
typecheckargs(n)
t := l.Type
if t == nil {
n.Type = nil
return n
}
checkwidth(t)
switch l.Op {
case ODOTINTER:
n.Op = OCALLINTER
case ODOTMETH:
n.Op = OCALLMETH
// typecheckaste was used here but there wasn't enough
// information further down the call chain to know if we
// were testing a method receiver for unexported fields.
// It isn't necessary, so just do a sanity check.
tp := t.Recv().Type
if l.Left == nil || !types.Identical(l.Left.Type, tp) {
Fatalf("method receiver")
}
default:
n.Op = OCALLFUNC
if t.Etype != TFUNC {
name := l.String()
if isBuiltinFuncName(name) && l.Name.Defn != nil {
// be more specific when the function
// name matches a predeclared function
yyerror("cannot call non-function %s (type %v), declared at %s",
name, t, linestr(l.Name.Defn.Pos))
} else {
yyerror("cannot call non-function %s (type %v)", name, t)
}
n.Type = nil
return n
}
}
typecheckaste(OCALL, n.Left, n.IsDDD(), t.Params(), n.List, func() string { return fmt.Sprintf("argument to %v", n.Left) })
ok |= ctxStmt
if t.NumResults() == 0 {
break
}
ok |= ctxExpr
if t.NumResults() == 1 {
n.Type = l.Type.Results().Field(0).Type
if n.Op == OCALLFUNC && n.Left.Op == ONAME && isRuntimePkg(n.Left.Sym.Pkg) && n.Left.Sym.Name == "getg" {
// Emit code for runtime.getg() directly instead of calling function.
// Most such rewrites (for example the similar one for math.Sqrt) should be done in walk,
// so that the ordering pass can make sure to preserve the semantics of the original code
// (in particular, the exact time of the function call) by introducing temporaries.
// In this case, we know getg() always returns the same result within a given function
// and we want to avoid the temporaries, so we do the rewrite earlier than is typical.
n.Op = OGETG
}
break
}
// multiple return
if top&(ctxMultiOK|ctxStmt) == 0 {
yyerror("multiple-value %v() in single-value context", l)
break
}
n.Type = l.Type.Results()
case OALIGNOF, OOFFSETOF, OSIZEOF:
ok |= ctxExpr
if !onearg(n, "%v", n.Op) {
n.Type = nil
return n
}
n.Type = types.Types[TUINTPTR]
case OCAP, OLEN:
ok |= ctxExpr
if !onearg(n, "%v", n.Op) {
n.Type = nil
return n
}
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
n.Left = implicitstar(n.Left)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
var ok bool
if n.Op == OLEN {
ok = okforlen[t.Etype]
} else {
ok = okforcap[t.Etype]
}
if !ok {
yyerror("invalid argument %L for %v", l, n.Op)
n.Type = nil
return n
}
n.Type = types.Types[TINT]
case OREAL, OIMAG:
ok |= ctxExpr
if !onearg(n, "%v", n.Op) {
n.Type = nil
return n
}
n.Left = typecheck(n.Left, ctxExpr)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
// Determine result type.
et := t.Etype
switch et {
case TIDEAL:
// result is ideal
case TCOMPLEX64:
et = TFLOAT32
case TCOMPLEX128:
et = TFLOAT64
default:
yyerror("invalid argument %L for %v", l, n.Op)
n.Type = nil
return n
}
n.Type = types.Types[et]
case OCOMPLEX:
ok |= ctxExpr
typecheckargs(n)
if !twoarg(n) {
n.Type = nil
return n
}
l := n.Left
r := n.Right
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
l, r = defaultlit2(l, r, false)
if l.Type == nil || r.Type == nil {
n.Type = nil
return n
}
n.Left = l
n.Right = r
if !types.Identical(l.Type, r.Type) {
yyerror("invalid operation: %v (mismatched types %v and %v)", n, l.Type, r.Type)
n.Type = nil
return n
}
var t *types.Type
switch l.Type.Etype {
default:
yyerror("invalid operation: %v (arguments have type %v, expected floating-point)", n, l.Type)
n.Type = nil
return n
case TIDEAL:
t = types.Types[TIDEAL]
case TFLOAT32:
t = types.Types[TCOMPLEX64]
case TFLOAT64:
t = types.Types[TCOMPLEX128]
}
n.Type = t
case OCLOSE:
if !onearg(n, "%v", n.Op) {
n.Type = nil
return n
}
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
l := n.Left
t := l.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsChan() {
yyerror("invalid operation: %v (non-chan type %v)", n, t)
n.Type = nil
return n
}
if !t.ChanDir().CanSend() {
yyerror("invalid operation: %v (cannot close receive-only channel)", n)
n.Type = nil
return n
}
ok |= ctxStmt
case ODELETE:
ok |= ctxStmt
typecheckargs(n)
args := n.List
if args.Len() == 0 {
yyerror("missing arguments to delete")
n.Type = nil
return n
}
if args.Len() == 1 {
yyerror("missing second (key) argument to delete")
n.Type = nil
return n
}
if args.Len() != 2 {
yyerror("too many arguments to delete")
n.Type = nil
return n
}
l := args.First()
r := args.Second()
if l.Type != nil && !l.Type.IsMap() {
yyerror("first argument to delete must be map; have %L", l.Type)
n.Type = nil
return n
}
args.SetSecond(assignconv(r, l.Type.Key(), "delete"))
case OAPPEND:
ok |= ctxExpr
typecheckargs(n)
args := n.List
if args.Len() == 0 {
yyerror("missing arguments to append")
n.Type = nil
return n
}
t := args.First().Type
if t == nil {
n.Type = nil
return n
}
n.Type = t
if !t.IsSlice() {
if Isconst(args.First(), CTNIL) {
yyerror("first argument to append must be typed slice; have untyped nil")
n.Type = nil
return n
}
yyerror("first argument to append must be slice; have %L", t)
n.Type = nil
return n
}
if n.IsDDD() {
if args.Len() == 1 {
yyerror("cannot use ... on first argument to append")
n.Type = nil
return n
}
if args.Len() != 2 {
yyerror("too many arguments to append")
n.Type = nil
return n
}
if t.Elem().IsKind(TUINT8) && args.Second().Type.IsString() {
args.SetSecond(defaultlit(args.Second(), types.Types[TSTRING]))
break
}
args.SetSecond(assignconv(args.Second(), t.Orig, "append"))
break
}
as := args.Slice()[1:]
for i, n := range as {
if n.Type == nil {
continue
}
as[i] = assignconv(n, t.Elem(), "append")
checkwidth(as[i].Type) // ensure width is calculated for backend
}
case OCOPY:
ok |= ctxStmt | ctxExpr
typecheckargs(n)
if !twoarg(n) {
n.Type = nil
return n
}
n.Type = types.Types[TINT]
if n.Left.Type == nil || n.Right.Type == nil {
n.Type = nil
return n
}
n.Left = defaultlit(n.Left, nil)
n.Right = defaultlit(n.Right, nil)
if n.Left.Type == nil || n.Right.Type == nil {
n.Type = nil
return n
}
// copy([]byte, string)
if n.Left.Type.IsSlice() && n.Right.Type.IsString() {
if types.Identical(n.Left.Type.Elem(), types.Bytetype) {
break
}
yyerror("arguments to copy have different element types: %L and string", n.Left.Type)
n.Type = nil
return n
}
if !n.Left.Type.IsSlice() || !n.Right.Type.IsSlice() {
if !n.Left.Type.IsSlice() && !n.Right.Type.IsSlice() {
yyerror("arguments to copy must be slices; have %L, %L", n.Left.Type, n.Right.Type)
} else if !n.Left.Type.IsSlice() {
yyerror("first argument to copy should be slice; have %L", n.Left.Type)
} else {
yyerror("second argument to copy should be slice or string; have %L", n.Right.Type)
}
n.Type = nil
return n
}
if !types.Identical(n.Left.Type.Elem(), n.Right.Type.Elem()) {
yyerror("arguments to copy have different element types: %L and %L", n.Left.Type, n.Right.Type)
n.Type = nil
return n
}
case OCONV:
ok |= ctxExpr
checkwidth(n.Type) // ensure width is calculated for backend
n.Left = typecheck(n.Left, ctxExpr)
n.Left = convlit1(n.Left, n.Type, true, noReuse)
t := n.Left.Type
if t == nil || n.Type == nil {
n.Type = nil
return n
}
var why string
n.Op = convertop(t, n.Type, &why)
if n.Op == 0 {
if !n.Diag() && !n.Type.Broke() && !n.Left.Diag() {
yyerror("cannot convert %L to type %v%s", n.Left, n.Type, why)
n.SetDiag(true)
}
n.Op = OCONV
n.Type = nil
return n
}
switch n.Op {
case OCONVNOP:
if t.Etype == n.Type.Etype {
switch t.Etype {
case TFLOAT32, TFLOAT64, TCOMPLEX64, TCOMPLEX128:
// Floating point casts imply rounding and
// so the conversion must be kept.
n.Op = OCONV
}
}
// do not convert to []byte literal. See CL 125796.
// generated code and compiler memory footprint is better without it.
case OSTR2BYTES:
break
case OSTR2RUNES:
if n.Left.Op == OLITERAL {
n = stringtoruneslit(n)
}
}
case OMAKE:
ok |= ctxExpr
args := n.List.Slice()
if len(args) == 0 {
yyerror("missing argument to make")
n.Type = nil
return n
}
n.List.Set(nil)
l := args[0]
l = typecheck(l, Etype)
t := l.Type
if t == nil {
n.Type = nil
return n
}
i := 1
switch t.Etype {
default:
yyerror("cannot make type %v", t)
n.Type = nil
return n
case TSLICE:
if i >= len(args) {
yyerror("missing len argument to make(%v)", t)
n.Type = nil
return n
}
l = args[i]
i++
l = typecheck(l, ctxExpr)
var r *Node
if i < len(args) {
r = args[i]
i++
r = typecheck(r, ctxExpr)
}
if l.Type == nil || (r != nil && r.Type == nil) {
n.Type = nil
return n
}
if !checkmake(t, "len", l) || r != nil && !checkmake(t, "cap", r) {
n.Type = nil
return n
}
if Isconst(l, CTINT) && r != nil && Isconst(r, CTINT) && l.Val().U.(*Mpint).Cmp(r.Val().U.(*Mpint)) > 0 {
yyerror("len larger than cap in make(%v)", t)
n.Type = nil
return n
}
n.Left = l
n.Right = r
n.Op = OMAKESLICE
case TMAP:
if i < len(args) {
l = args[i]
i++
l = typecheck(l, ctxExpr)
l = defaultlit(l, types.Types[TINT])
if l.Type == nil {
n.Type = nil
return n
}
if !checkmake(t, "size", l) {
n.Type = nil
return n
}
n.Left = l
} else {
n.Left = nodintconst(0)
}
n.Op = OMAKEMAP
case TCHAN:
l = nil
if i < len(args) {
l = args[i]
i++
l = typecheck(l, ctxExpr)
l = defaultlit(l, types.Types[TINT])
if l.Type == nil {
n.Type = nil
return n
}
if !checkmake(t, "buffer", l) {
n.Type = nil
return n
}
n.Left = l
} else {
n.Left = nodintconst(0)
}
n.Op = OMAKECHAN
}
if i < len(args) {
yyerror("too many arguments to make(%v)", t)
n.Op = OMAKE
n.Type = nil
return n
}
n.Type = t
case ONEW:
ok |= ctxExpr
args := n.List
if args.Len() == 0 {
yyerror("missing argument to new")
n.Type = nil
return n
}
l := args.First()
l = typecheck(l, Etype)
t := l.Type
if t == nil {
n.Type = nil
return n
}
if args.Len() > 1 {
yyerror("too many arguments to new(%v)", t)
n.Type = nil
return n
}
n.Left = l
n.Type = types.NewPtr(t)
case OPRINT, OPRINTN:
ok |= ctxStmt
typecheckslice(n.List.Slice(), ctxExpr)
ls := n.List.Slice()
for i1, n1 := range ls {
// Special case for print: int constant is int64, not int.
if Isconst(n1, CTINT) {
ls[i1] = defaultlit(ls[i1], types.Types[TINT64])
} else {
ls[i1] = defaultlit(ls[i1], nil)
}
}
case OPANIC:
ok |= ctxStmt
if !onearg(n, "panic") {
n.Type = nil
return n
}
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, types.Types[TINTER])
if n.Left.Type == nil {
n.Type = nil
return n
}
case ORECOVER:
ok |= ctxExpr | ctxStmt
if n.List.Len() != 0 {
yyerror("too many arguments to recover")
n.Type = nil
return n
}
n.Type = types.Types[TINTER]
case OCLOSURE:
ok |= ctxExpr
typecheckclosure(n, top)
if n.Type == nil {
return n
}
case OITAB:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
t := n.Left.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsInterface() {
Fatalf("OITAB of %v", t)
}
n.Type = types.NewPtr(types.Types[TUINTPTR])
case OIDATA:
// Whoever creates the OIDATA node must know a priori the concrete type at that moment,
// usually by just having checked the OITAB.
Fatalf("cannot typecheck interface data %v", n)
case OSPTR:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
t := n.Left.Type
if t == nil {
n.Type = nil
return n
}
if !t.IsSlice() && !t.IsString() {
Fatalf("OSPTR of %v", t)
}
if t.IsString() {
n.Type = types.NewPtr(types.Types[TUINT8])
} else {
n.Type = types.NewPtr(t.Elem())
}
case OCLOSUREVAR:
ok |= ctxExpr
case OCFUNC:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
n.Type = types.Types[TUINTPTR]
case OCONVNOP:
ok |= ctxExpr
n.Left = typecheck(n.Left, ctxExpr)
// statements
case OAS:
ok |= ctxStmt
typecheckas(n)
// Code that creates temps does not bother to set defn, so do it here.
if n.Left.Op == ONAME && n.Left.IsAutoTmp() {
n.Left.Name.Defn = n
}
case OAS2:
ok |= ctxStmt
typecheckas2(n)
case OBREAK,
OCONTINUE,
ODCL,
OEMPTY,
OGOTO,
OFALL,
OVARKILL,
OVARLIVE:
ok |= ctxStmt
case OLABEL:
ok |= ctxStmt
decldepth++
if n.Sym.IsBlank() {
// Empty identifier is valid but useless.
// Eliminate now to simplify life later.
// See issues 7538, 11589, 11593.
n.Op = OEMPTY
n.Left = nil
}
case ODEFER:
ok |= ctxStmt
n.Left = typecheck(n.Left, ctxStmt|ctxExpr)
if !n.Left.Diag() {
checkdefergo(n)
}
case OGO:
ok |= ctxStmt
n.Left = typecheck(n.Left, ctxStmt|ctxExpr)
checkdefergo(n)
case OFOR, OFORUNTIL:
ok |= ctxStmt
typecheckslice(n.Ninit.Slice(), ctxStmt)
decldepth++
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
if n.Left != nil {
t := n.Left.Type
if t != nil && !t.IsBoolean() {
yyerror("non-bool %L used as for condition", n.Left)
}
}
n.Right = typecheck(n.Right, ctxStmt)
if n.Op == OFORUNTIL {
typecheckslice(n.List.Slice(), ctxStmt)
}
typecheckslice(n.Nbody.Slice(), ctxStmt)
decldepth--
case OIF:
ok |= ctxStmt
typecheckslice(n.Ninit.Slice(), ctxStmt)
n.Left = typecheck(n.Left, ctxExpr)
n.Left = defaultlit(n.Left, nil)
if n.Left != nil {
t := n.Left.Type
if t != nil && !t.IsBoolean() {
yyerror("non-bool %L used as if condition", n.Left)
}
}
typecheckslice(n.Nbody.Slice(), ctxStmt)
typecheckslice(n.Rlist.Slice(), ctxStmt)
case ORETURN:
ok |= ctxStmt
typecheckargs(n)
if Curfn == nil {
yyerror("return outside function")
n.Type = nil
return n
}
if Curfn.Type.FuncType().Outnamed && n.List.Len() == 0 {
break
}
typecheckaste(ORETURN, nil, false, Curfn.Type.Results(), n.List, func() string { return "return argument" })
case ORETJMP:
ok |= ctxStmt
case OSELECT:
ok |= ctxStmt
typecheckselect(n)
case OSWITCH:
ok |= ctxStmt
typecheckswitch(n)
case ORANGE:
ok |= ctxStmt
typecheckrange(n)
case OTYPESW:
yyerror("use of .(type) outside type switch")
n.Type = nil
return n
case OXCASE:
ok |= ctxStmt
typecheckslice(n.List.Slice(), ctxExpr)
typecheckslice(n.Nbody.Slice(), ctxStmt)
case ODCLFUNC:
ok |= ctxStmt
typecheckfunc(n)
case ODCLCONST:
ok |= ctxStmt
n.Left = typecheck(n.Left, ctxExpr)
case ODCLTYPE:
ok |= ctxStmt
n.Left = typecheck(n.Left, Etype)
checkwidth(n.Left.Type)
if n.Left.Type != nil && n.Left.Type.NotInHeap() && n.Left.Name.Param.Pragma&NotInHeap == 0 {
// The type contains go:notinheap types, so it
// must be marked as such (alternatively, we
// could silently propagate go:notinheap).
yyerror("type %v must be go:notinheap", n.Left.Type)
}
}
t := n.Type
if t != nil && !t.IsFuncArgStruct() && n.Op != OTYPE {
switch t.Etype {
case TFUNC, // might have TANY; wait until it's called
TANY, TFORW, TIDEAL, TNIL, TBLANK:
break
default:
checkwidth(t)
}
}
evconst(n)
if n.Op == OTYPE && top&Etype == 0 {
if !n.Type.Broke() {
yyerror("type %v is not an expression", n.Type)
}
n.Type = nil
return n
}
if top&(ctxExpr|Etype) == Etype && n.Op != OTYPE {
yyerror("%v is not a type", n)
n.Type = nil
return n
}
// TODO(rsc): simplify
if (top&(ctxCallee|ctxExpr|Etype) != 0) && top&ctxStmt == 0 && ok&(ctxExpr|Etype|ctxCallee) == 0 {
yyerror("%v used as value", n)
n.Type = nil
return n
}
if (top&ctxStmt != 0) && top&(ctxCallee|ctxExpr|Etype) == 0 && ok&ctxStmt == 0 {
if !n.Diag() {
yyerror("%v evaluated but not used", n)
n.SetDiag(true)
}
n.Type = nil
return n
}
return n
}
func typecheckargs(n *Node) {
if n.List.Len() != 1 || n.IsDDD() {
typecheckslice(n.List.Slice(), ctxExpr)
return
}
typecheckslice(n.List.Slice(), ctxExpr|ctxMultiOK)
t := n.List.First().Type
if t == nil || !t.IsFuncArgStruct() {
return
}
// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
// Save n as n.Orig for fmt.go.
if n.Orig == n {
n.Orig = n.sepcopy()
}
as := nod(OAS2, nil, nil)
as.Rlist.AppendNodes(&n.List)
// 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 dummyInitFn for now, and init.go
// will reassociate them later when it's appropriate.
static := Curfn == nil
if static {
Curfn = dummyInitFn
}
for _, f := range t.FieldSlice() {
t := temp(f.Type)
as.Ninit.Append(nod(ODCL, t, nil))
as.List.Append(t)
n.List.Append(t)
}
if static {
Curfn = nil
}
as = typecheck(as, ctxStmt)
n.Ninit.Append(as)
}
func checksliceindex(l *Node, r *Node, tp *types.Type) bool {
t := r.Type
if t == nil {
return false
}
if !t.IsInteger() {
yyerror("invalid slice index %v (type %v)", r, t)
return false
}
if r.Op == OLITERAL {
if r.Int64() < 0 {
yyerror("invalid slice index %v (index must be non-negative)", r)
return false
} else if tp != nil && tp.NumElem() >= 0 && r.Int64() > tp.NumElem() {
yyerror("invalid slice index %v (out of bounds for %d-element array)", r, tp.NumElem())
return false
} else if Isconst(l, CTSTR) && r.Int64() > int64(len(l.Val().U.(string))) {
yyerror("invalid slice index %v (out of bounds for %d-byte string)", r, len(l.Val().U.(string)))
return false
} else if r.Val().U.(*Mpint).Cmp(maxintval[TINT]) > 0 {
yyerror("invalid slice index %v (index too large)", r)
return false
}
}
return true
}
func checksliceconst(lo *Node, hi *Node) bool {
if lo != nil && hi != nil && lo.Op == OLITERAL && hi.Op == OLITERAL && lo.Val().U.(*Mpint).Cmp(hi.Val().U.(*Mpint)) > 0 {
yyerror("invalid slice index: %v > %v", lo, hi)
return false
}
return true
}
func checkdefergo(n *Node) {
what := "defer"
if n.Op == OGO {
what = "go"
}
switch n.Left.Op {
// ok
case OCALLINTER,
OCALLMETH,
OCALLFUNC,
OCLOSE,
OCOPY,
ODELETE,
OPANIC,
OPRINT,
OPRINTN,
ORECOVER:
return
case OAPPEND,
OCAP,
OCOMPLEX,
OIMAG,
OLEN,
OMAKE,
OMAKESLICE,
OMAKECHAN,
OMAKEMAP,
ONEW,
OREAL,
OLITERAL: // conversion or unsafe.Alignof, Offsetof, Sizeof
if n.Left.Orig != nil && n.Left.Orig.Op == OCONV {
break
}
yyerror("%s discards result of %v", what, n.Left)
return
}
// type is broken or missing, most likely a method call on a broken type
// we will warn about the broken type elsewhere. no need to emit a potentially confusing error
if n.Left.Type == nil || n.Left.Type.Broke() {
return
}
if !n.Diag() {
// The syntax made sure it was a call, so this must be
// a conversion.
n.SetDiag(true)
yyerror("%s requires function call, not conversion", what)
}
}
// The result of implicitstar MUST be assigned back to n, e.g.
// n.Left = implicitstar(n.Left)
func implicitstar(n *Node) *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
}
n = nod(ODEREF, n, nil)
n.SetImplicit(true)
n = typecheck(n, ctxExpr)
return n
}
func onearg(n *Node, f string, args ...interface{}) bool {
if n.Left != nil {
return true
}
if n.List.Len() == 0 {
p := fmt.Sprintf(f, args...)
yyerror("missing argument to %s: %v", p, n)
return false
}
if n.List.Len() > 1 {
p := fmt.Sprintf(f, args...)
yyerror("too many arguments to %s: %v", p, n)
n.Left = n.List.First()
n.List.Set(nil)
return false
}
n.Left = n.List.First()
n.List.Set(nil)
return true
}
func twoarg(n *Node) bool {
if n.Left != nil {
return true
}
if n.List.Len() != 2 {
if n.List.Len() < 2 {
yyerror("not enough arguments in call to %v", n)
} else {
yyerror("too many arguments in call to %v", n)
}
return false
}
n.Left = n.List.First()
n.Right = n.List.Second()
n.List.Set(nil)
return true
}
func lookdot1(errnode *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 {
yyerror("ambiguous selector %v", errnode)
} else if t.IsPtr() {
yyerror("ambiguous selector (%v).%v", t, s)
} else {
yyerror("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 *Node) (res *Node) {
if enableTrace && trace {
defer tracePrint("typecheckMethodExpr", n)(&res)
}
t := n.Left.Type
// Compute the method set for t.
var ms *types.Fields
if t.IsInterface() {
ms = t.Fields()
} else {
mt := methtype(t)
if mt == nil {
yyerror("%v undefined (type %v has no method %v)", n, t, n.Sym)
n.Type = nil
return n
}
expandmeth(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 {
addsignat(t)
}
}
s := n.Sym
m := lookdot1(n, s, t, ms, 0)
if m == nil {
if lookdot1(n, s, t, ms, 1) != nil {
yyerror("%v undefined (cannot refer to unexported method %v)", n, s)
} else if _, ambig := dotpath(s, t, nil, false); ambig {
yyerror("%v undefined (ambiguous selector)", n) // method or field
} else {
yyerror("%v undefined (type %v has no method %v)", n, t, s)
}
n.Type = nil
return n
}
if !isMethodApplicable(t, m) {
yyerror("invalid method expression %v (needs pointer receiver: (*%v).%S)", n, t, s)
n.Type = nil
return n
}
n.Op = ONAME
if n.Name == nil {
n.Name = new(Name)
}
n.Right = newname(n.Sym)
n.Sym = methodSym(t, n.Sym)
n.Type = methodfunc(m.Type, n.Left.Type)
n.Xoffset = 0
n.SetClass(PFUNC)
// methodSym already marked n.Sym as a function.
// Issue 25065. Make sure that we emit the symbol for a local method.
if Ctxt.Flag_dynlink && !inimport && (t.Sym == nil || t.Sym.Pkg == localpkg) {
makefuncsym(n.Sym)
}
return n
}
// isMethodApplicable reports whether method m can be called on a
// value of type t. This is necessary because we compute a single
// method set for both T and *T, but some *T methods are not
// applicable to T receivers.
func isMethodApplicable(t *types.Type, m *types.Field) bool {
return t.IsPtr() || !m.Type.Recv().Type.IsPtr() || isifacemethod(m.Type) || m.Embedded == 2
}
func derefall(t *types.Type) *types.Type {
for t != nil && t.IsPtr() {
t = t.Elem()
}
return t
}
type typeSymKey struct {
t *types.Type
s *types.Sym
}
// dotField maps (*types.Type, *types.Sym) pairs to the corresponding struct field (*types.Type with Etype==TFIELD).
// It is a cache for use during usefield in walk.go, only enabled when field tracking.
var dotField = map[typeSymKey]*types.Field{}
func lookdot(n *Node, t *types.Type, dostrcmp int) *types.Field {
s := n.Sym
dowidth(t)
var f1 *types.Field
if t.IsStruct() || t.IsInterface() {
f1 = lookdot1(n, s, t, t.Fields(), dostrcmp)
}
var f2 *types.Field
if n.Left.Type == t || n.Left.Type.Sym == nil {
mt := methtype(t)
if mt != nil {
f2 = lookdot1(n, s, mt, mt.Methods(), dostrcmp)
}
}
if f1 != nil {
if dostrcmp > 1 || f1.Broke() {
// Already in the process of diagnosing an error.
return f1
}
if f2 != nil {
yyerror("%v is both field and method", n.Sym)
}
if f1.Offset == BADWIDTH {
Fatalf("lookdot badwidth %v %p", f1, f1)
}
n.Xoffset = f1.Offset
n.Type = f1.Type
if objabi.Fieldtrack_enabled > 0 {
dotField[typeSymKey{t.Orig, s}] = f1
}
if t.IsInterface() {
if n.Left.Type.IsPtr() {
n.Left = nod(ODEREF, n.Left, nil) // implicitstar
n.Left.SetImplicit(true)
n.Left = typecheck(n.Left, ctxExpr)
}
n.Op = ODOTINTER
}
return f1
}
if f2 != nil {
if dostrcmp > 1 {
// Already in the process of diagnosing an error.
return f2
}
tt := n.Left.Type
dowidth(tt)
rcvr := f2.Type.Recv().Type
if !types.Identical(rcvr, tt) {
if rcvr.IsPtr() && types.Identical(rcvr.Elem(), tt) {
checklvalue(n.Left, "call pointer method on")
n.Left = nod(OADDR, n.Left, nil)
n.Left.SetImplicit(true)
n.Left = typecheck(n.Left, Etype|ctxExpr)
} else if tt.IsPtr() && !rcvr.IsPtr() && types.Identical(tt.Elem(), rcvr) {
n.Left = nod(ODEREF, n.Left, nil)
n.Left.SetImplicit(true)
n.Left = typecheck(n.Left, Etype|ctxExpr)
} else if tt.IsPtr() && tt.Elem().IsPtr() && types.Identical(derefall(tt), derefall(rcvr)) {
yyerror("calling method %v with receiver %L requires explicit dereference", n.Sym, n.Left)
for tt.IsPtr() {
// Stop one level early for method with pointer receiver.
if rcvr.IsPtr() && !tt.Elem().IsPtr() {
break
}
n.Left = nod(ODEREF, n.Left, nil)
n.Left.SetImplicit(true)
n.Left = typecheck(n.Left, Etype|ctxExpr)
tt = tt.Elem()
}
} else {
Fatalf("method mismatch: %v for %v", rcvr, tt)
}
}
pll := n
ll := n.Left
for ll.Left != nil && (ll.Op == ODOT || ll.Op == ODOTPTR || ll.Op == ODEREF) {
pll = ll
ll = ll.Left
}
if pll.Implicit() && ll.Type.IsPtr() && ll.Type.Sym != nil && asNode(ll.Type.Sym.Def) != nil && asNode(ll.Type.Sym.Def).Op == OTYPE {
// It is invalid to automatically dereference a named pointer type when selecting a method.
// Make n.Left == ll to clarify error message.
n.Left = ll
return nil
}
n.Sym = methodSym(n.Left.Type, f2.Sym)
n.Xoffset = f2.Offset
n.Type = f2.Type
n.Op = ODOTMETH
return f2
}
return nil
}
func nokeys(l Nodes) bool {
for _, n := range l.Slice() {
if n.Op == OKEY || n.Op == 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 Op, call *Node, isddd bool, tstruct *types.Type, nl Nodes, desc func() string) {
var t *types.Type
var i int
lno := lineno
defer func() { lineno = lno }()
if tstruct.Broke() {
return
}
var n *Node
if nl.Len() == 1 {
n = nl.First()
}
n1 := tstruct.NumFields()
n2 := nl.Len()
if !hasddd(tstruct) {
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 >= nl.Len() {
goto notenough
}
if nl.Len()-i > 1 {
goto toomany
}
n = nl.Index(i)
setlineno(n)
if n.Type != nil {
nl.SetIndex(i, assignconvfn(n, t, desc))
}
return
}
// TODO(mdempsky): Make into ... call with implicit slice.
for ; i < nl.Len(); i++ {
n = nl.Index(i)
setlineno(n)
if n.Type != nil {
nl.SetIndex(i, assignconvfn(n, t.Elem(), desc))
}
}
return
}
if i >= nl.Len() {
goto notenough
}
n = nl.Index(i)
setlineno(n)
if n.Type != nil {
nl.SetIndex(i, assignconvfn(n, t, desc))
}
i++
}
if i < nl.Len() {
goto toomany
}
if isddd {
if call != nil {
yyerror("invalid use of ... in call to %v", call)
} else {
yyerror("invalid use of ... in %v", op)
}
}
return
notenough:
if n == nil || !n.Diag() {
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.isMethodExpression() {
yyerror("not enough arguments in call to method expression %v%s", call, details)
} else {
yyerror("not enough arguments in call to %v%s", call, details)
}
} else {
yyerror("not enough arguments to %v%s", op, details)
}
if n != nil {
n.SetDiag(true)
}
}
return
toomany:
details := errorDetails(nl, tstruct, isddd)
if call != nil {
yyerror("too many arguments in call to %v%s", call, details)
} else {
yyerror("too many arguments to %v%s", op, details)
}
}
func errorDetails(nl Nodes, tstruct *types.Type, isddd bool) string {
// If we don't know any type at a call site, let's suppress any return
// message signatures. See Issue https://golang.org/issues/19012.
if tstruct == nil {
return ""
}
// If any node has an unknown type, suppress it as well
for _, n := range nl.Slice() {
if n.Type == nil {
return ""
}
}
return fmt.Sprintf("\n\thave %s\n\twant %v", nl.retsigerr(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) string {
switch t {
default:
return t.String()
case types.Types[TIDEAL]:
// "untyped number" is not commonly used
// outside of the compiler, so let's use "number".
return "number"
case types.Idealstring:
return "string"
case types.Idealbool:
return "bool"
}
}
// retsigerr returns the signature of the types
// at the respective return call site of a function.
func (nl Nodes) retsigerr(isddd bool) string {
if nl.Len() < 1 {
return "()"
}
var typeStrings []string
for _, n := range nl.Slice() {
typeStrings = append(typeStrings, sigrepr(n.Type))
}
ddd := ""
if isddd {
ddd = "..."
}
return fmt.Sprintf("(%s%s)", strings.Join(typeStrings, ", "), ddd)
}
// type check composite
func fielddup(name string, hash map[string]bool) {
if hash[name] {
yyerror("duplicate field name in struct literal: %s", name)
return
}
hash[name] = true
}
// iscomptype reports whether type t is a composite literal type
// or a pointer to one.
func iscomptype(t *types.Type) bool {
if t.IsPtr() {
t = t.Elem()
}
switch t.Etype {
case TARRAY, TSLICE, TSTRUCT, TMAP:
return true
default:
return false
}
}
func pushtype(n *Node, t *types.Type) {
if n == nil || n.Op != OCOMPLIT || !iscomptype(t) {
return
}
if n.Right == nil {
n.Right = typenod(t)
n.SetImplicit(true) // don't print
n.Right.SetImplicit(true) // * is okay
} else if Debug['s'] != 0 {
n.Right = typecheck(n.Right, Etype)
if n.Right.Type != nil && types.Identical(n.Right.Type, t) {
fmt.Printf("%v: redundant type: %v\n", n.Line(), t)
}
}
}
// The result of typecheckcomplit MUST be assigned back to n, e.g.
// n.Left = typecheckcomplit(n.Left)
func typecheckcomplit(n *Node) (res *Node) {
if enableTrace && trace {
defer tracePrint("typecheckcomplit", n)(&res)
}
lno := lineno
defer func() {
lineno = lno
}()
if n.Right == nil {
yyerrorl(n.Pos, "missing type in composite literal")
n.Type = nil
return n
}
// Save original node (including n.Right)
norig := n.copy()
setlineno(n.Right)
n.Right = typecheck(n.Right, Etype|ctxCompLit)
l := n.Right // sic
t := l.Type
if t == nil {
n.Type = nil
return n
}
nerr := nerrors
n.Type = t
if t.IsPtr() {
// For better or worse, we don't allow pointers as the composite literal type,
// except when using the &T syntax, which sets implicit on the ODEREF.
if !n.Right.Implicit() {
yyerror("invalid pointer type %v for composite literal (use &%v instead)", t, t.Elem())
n.Type = nil
return n
}
// Also, the underlying type must be a struct, map, slice, or array.
if !iscomptype(t) {
yyerror("invalid pointer type %v for composite literal", t)
n.Type = nil
return n
}
t = t.Elem()
}
switch t.Etype {
default:
yyerror("invalid type for composite literal: %v", t)
n.Type = nil
case TARRAY, TSLICE:
// 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 _, n1 := range n.List.Slice() {
if n1.Op == OKEY {
indices = make(map[int64]bool)
break
}
}
var length, i int64
checkBounds := t.IsArray() && !t.IsDDDArray()
nl := n.List.Slice()
for i2, l := range nl {
setlineno(l)
vp := &nl[i2]
if l.Op == OKEY {
l.Left = typecheck(l.Left, ctxExpr)
evconst(l.Left)
i = indexconst(l.Left)
if i < 0 {
if !l.Left.Diag() {
if i == -2 {
yyerror("index too large")
} else {
yyerror("index must be non-negative integer constant")
}
l.Left.SetDiag(true)
}
i = -(1 << 30) // stay negative for a while
}
vp = &l.Right
}
if i >= 0 && indices != nil {
if indices[i] {
yyerror("duplicate index in array literal: %d", i)
} else {
indices[i] = true
}
}
r := *vp
pushtype(r, t.Elem())
r = typecheck(r, ctxExpr)
r = defaultlit(r, t.Elem())
*vp = assignconv(r, t.Elem(), "array or slice literal")
i++
if i > length {
length = i
if checkBounds && length > t.NumElem() {
setlineno(l)
yyerror("array index %d out of bounds [0:%d]", length-1, t.NumElem())
checkBounds = false
}
}
}
if t.IsDDDArray() {
t.SetNumElem(length)
}
if t.IsSlice() {
n.Op = OSLICELIT
n.Right = nodintconst(length)
} else {
n.Op = OARRAYLIT
n.Right = nil
}
case TMAP:
var cs constSet
for i3, l := range n.List.Slice() {
setlineno(l)
if l.Op != OKEY {
n.List.SetIndex(i3, typecheck(l, ctxExpr))
yyerror("missing key in map literal")
continue
}
r := l.Left
pushtype(r, t.Key())
r = typecheck(r, ctxExpr)
r = defaultlit(r, t.Key())
l.Left = assignconv(r, t.Key(), "map key")
if cs.add(l.Left) != nil {
yyerror("duplicate key %v in map literal", l.Left)
}
r = l.Right
pushtype(r, t.Elem())
r = typecheck(r, ctxExpr)
r = defaultlit(r, t.Elem())
l.Right = assignconv(r, t.Elem(), "map value")
}
n.Op = OMAPLIT
n.Right = nil
case TSTRUCT:
// Need valid field offsets for Xoffset below.
dowidth(t)
errored := false
if n.List.Len() != 0 && nokeys(n.List) {
// simple list of variables
ls := n.List.Slice()
for i, n1 := range ls {
setlineno(n1)
n1 = typecheck(n1, ctxExpr)
ls[i] = n1
if i >= t.NumFields() {
if !errored {
yyerror("too many values in %v", n)
errored = true
}
continue
}
f := t.Field(i)
s := f.Sym
if s != nil && !types.IsExported(s.Name) && s.Pkg != localpkg {
yyerror("implicit assignment of unexported field '%s' in %v literal", s.Name, t)
}
// No pushtype allowed here. Must name fields for that.
n1 = assignconv(n1, f.Type, "field value")
n1 = nodSym(OSTRUCTKEY, n1, f.Sym)
n1.Xoffset = f.Offset
ls[i] = n1
}
if len(ls) < t.NumFields() {
yyerror("too few values in %v", n)
}
} else {
hash := make(map[string]bool)
// keyed list
ls := n.List.Slice()
for i, l := range ls {
setlineno(l)
if l.Op == OKEY {
key := l.Left
l.Op = OSTRUCTKEY
l.Left = l.Right
l.Right = nil
// An OXDOT uses the Sym field to hold
// the field to the right of the dot,
// so s will be non-nil, but an OXDOT
// is never a valid struct literal key.
if key.Sym == nil || key.Op == OXDOT || key.Sym.IsBlank() {
yyerror("invalid field name %v in struct initializer", key)
l.Left = typecheck(l.Left, ctxExpr)
continue
}
// Sym might have resolved to name in other top-level
// package, because of import dot. Redirect to correct sym
// before we do the lookup.
s := key.Sym
if s.Pkg != localpkg && types.IsExported(s.Name) {
s1 := lookup(s.Name)
if s1.Origpkg == s.Pkg {
s = s1
}
}
l.Sym = s
}
if l.Op != OSTRUCTKEY {
if !errored {
yyerror("mixture of field:value and value initializers")
errored = true
}
ls[i] = typecheck(ls[i], ctxExpr)
continue
}
f := lookdot1(nil, l.Sym, t, t.Fields(), 0)
if f == nil {
if ci := lookdot1(nil, l.Sym, t, t.Fields(), 2); ci != nil { // Case-insensitive lookup.
if visible(ci.Sym) {
yyerror("unknown field '%v' in struct literal of type %v (but does have %v)", l.Sym, t, ci.Sym)
} else {
yyerror("unknown field '%v' in struct literal of type %v", l.Sym, t)
}
continue
}
var f *types.Field
p, _ := dotpath(l.Sym, t, &f, true)
if p == nil || f.IsMethod() {
yyerror("unknown field '%v' in struct literal of type %v", l.Sym, t)
continue
}
// dotpath returns the parent embedded types in reverse order.
var ep []string
for ei := len(p) - 1; ei >= 0; ei-- {
ep = append(ep, p[ei].field.Sym.Name)
}
ep = append(ep, l.Sym.Name)
yyerror("cannot use promoted field %v in struct literal of type %v", strings.Join(ep, "."), t)
continue
}
fielddup(f.Sym.Name, hash)
l.Xoffset = f.Offset
// No pushtype allowed here. Tried and rejected.
l.Left = typecheck(l.Left, ctxExpr)
l.Left = assignconv(l.Left, f.Type, "field value")
}
}
n.Op = OSTRUCTLIT
n.Right = nil
}
if nerr != nerrors {
return n
}
n.Orig = norig
if n.Type.IsPtr() {
n = nod(OPTRLIT, n, nil)
n.SetTypecheck(1)
n.Type = n.Left.Type
n.Left.Type = t
n.Left.SetTypecheck(1)
}
n.Orig = norig
return n
}
// visible reports whether sym is exported or locally defined.
func visible(sym *types.Sym) bool {
return sym != nil && (types.IsExported(sym.Name) || sym.Pkg == localpkg)
}
// lvalue etc
func islvalue(n *Node) bool {
switch n.Op {
case OINDEX:
if n.Left.Type != nil && n.Left.Type.IsArray() {
return islvalue(n.Left)
}
if n.Left.Type != nil && n.Left.Type.IsString() {
return false
}
fallthrough
case ODEREF, ODOTPTR, OCLOSUREVAR:
return true
case ODOT:
return islvalue(n.Left)
case ONAME:
if n.Class() == PFUNC {
return false
}
return true
}
return false
}
func checklvalue(n *Node, verb string) {
if !islvalue(n) {
yyerror("cannot %s %v", verb, n)
}
}
func checkassign(stmt *Node, n *Node) {
// Variables declared in ORANGE are assigned on every iteration.
if n.Name == nil || n.Name.Defn != stmt || stmt.Op == ORANGE {
r := outervalue(n)
var l *Node
for l = n; l != r; l = l.Left {
l.SetAssigned(true)
if l.IsClosureVar() {
l.Name.Defn.SetAssigned(true)
}
}
l.SetAssigned(true)
if l.IsClosureVar() {
l.Name.Defn.SetAssigned(true)
}
}
if islvalue(n) {
return
}
if n.Op == OINDEXMAP {
n.SetIndexMapLValue(true)
return
}
// have already complained about n being invalid
if n.Type == nil {
return
}
if n.Op == ODOT && n.Left.Op == OINDEXMAP {
yyerror("cannot assign to struct field %v in map", n)
} else {
yyerror("cannot assign to %v", n)
}
n.Type = nil
}
func checkassignlist(stmt *Node, l Nodes) {
for _, n := range l.Slice() {
checkassign(stmt, n)
}
}
// samesafeexpr checks whether it is safe to reuse one of l and r
// instead of computing both. samesafeexpr assumes that l and r are
// used in the same statement or expression. In order for it to be
// safe to reuse l or r, they must:
// * be the same expression
// * not have side-effects (no function calls, no channel ops);
// however, panics are ok
// * not cause inappropriate aliasing; e.g. two string to []byte
// conversions, must result in two distinct slices
//
// The handling of OINDEXMAP is subtle. OINDEXMAP can occur both
// as an lvalue (map assignment) and an rvalue (map access). This is
// currently OK, since the only place samesafeexpr gets used on an
// lvalue expression is for OSLICE and OAPPEND optimizations, and it
// is correct in those settings.
func samesafeexpr(l *Node, r *Node) bool {
if l.Op != r.Op || !types.Identical(l.Type, r.Type) {
return false
}
switch l.Op {
case ONAME, OCLOSUREVAR:
return l == r
case ODOT, ODOTPTR:
return l.Sym != nil && r.Sym != nil && l.Sym == r.Sym && samesafeexpr(l.Left, r.Left)
case ODEREF, OCONVNOP,
ONOT, OBITNOT, OPLUS, ONEG:
return samesafeexpr(l.Left, r.Left)
case OCONV:
// Some conversions can't be reused, such as []byte(str).
// Allow only numeric-ish types. This is a bit conservative.
return issimple[l.Type.Etype] && samesafeexpr(l.Left, r.Left)
case OINDEX, OINDEXMAP,
OADD, OSUB, OOR, OXOR, OMUL, OLSH, ORSH, OAND, OANDNOT, ODIV, OMOD:
return samesafeexpr(l.Left, r.Left) && samesafeexpr(l.Right, r.Right)
case OLITERAL:
return eqval(l.Val(), r.Val())
}
return false
}
// type check assignment.
// if this assignment is the definition of a var on the left side,
// fill in the var's type.
func typecheckas(n *Node) {
if enableTrace && trace {
defer tracePrint("typecheckas", n)(nil)
}
// delicate little dance.
// the definition of n may refer to this assignment
// as its definition, in which case it will call typecheckas.
// in that case, do not call typecheck back, or it will cycle.
// if the variable has a type (ntype) then typechecking
// will not look at defn, so it is okay (and desirable,
// so that the conversion below happens).
n.Left = resolve(n.Left)
if n.Left.Name == nil || n.Left.Name.Defn != n || n.Left.Name.Param.Ntype != nil {
n.Left = typecheck(n.Left, ctxExpr|ctxAssign)
}
// Use ctxMultiOK so we can emit an "N variables but M values" error
// to be consistent with typecheckas2 (#26616).
n.Right = typecheck(n.Right, ctxExpr|ctxMultiOK)
checkassign(n, n.Left)
if n.Right != nil && n.Right.Type != nil {
if n.Right.Type.IsFuncArgStruct() {
yyerror("assignment mismatch: 1 variable but %v returns %d values", n.Right.Left, n.Right.Type.NumFields())
// Multi-value RHS isn't actually valid for OAS; nil out
// to indicate failed typechecking.
n.Right.Type = nil
} else if n.Left.Type != nil {
n.Right = assignconv(n.Right, n.Left.Type, "assignment")
}
}
if n.Left.Name != nil && n.Left.Name.Defn == n && n.Left.Name.Param.Ntype == nil {
n.Right = defaultlit(n.Right, nil)
n.Left.Type = n.Right.Type
}
// second half of dance.
// now that right is done, typecheck the left
// just to get it over with. see dance above.
n.SetTypecheck(1)
if n.Left.Typecheck() == 0 {
n.Left = typecheck(n.Left, ctxExpr|ctxAssign)
}
if !n.Left.isBlank() {
checkwidth(n.Left.Type) // ensure width is calculated for backend
}
}
func checkassignto(src *types.Type, dst *Node) {
var why string
if assignop(src, dst.Type, &why) == 0 {
yyerror("cannot assign %v to %L in multiple assignment%s", src, dst, why)
return
}
}
func typecheckas2(n *Node) {
if enableTrace && trace {
defer tracePrint("typecheckas2", n)(nil)
}
ls := n.List.Slice()
for i1, n1 := range ls {
// delicate little dance.
n1 = resolve(n1)
ls[i1] = n1
if n1.Name == nil || n1.Name.Defn != n || n1.Name.Param.Ntype != nil {
ls[i1] = typecheck(ls[i1], ctxExpr|ctxAssign)
}
}
cl := n.List.Len()
cr := n.Rlist.Len()
if cl > 1 && cr == 1 {
n.Rlist.SetFirst(typecheck(n.Rlist.First(), ctxExpr|ctxMultiOK))
} else {
typecheckslice(n.Rlist.Slice(), ctxExpr)
}
checkassignlist(n, n.List)
var l *Node
var r *Node
if cl == cr {
// easy
ls := n.List.Slice()
rs := n.Rlist.Slice()
for il, nl := range ls {
nr := rs[il]
if nl.Type != nil && nr.Type != nil {
rs[il] = assignconv(nr, nl.Type, "assignment")
}
if nl.Name != nil && nl.Name.Defn == n && nl.Name.Param.Ntype == nil {
rs[il] = defaultlit(rs[il], nil)
nl.Type = rs[il].Type
}
}
goto out
}
l = n.List.First()
r = n.Rlist.First()
// x,y,z = f()
if cr == 1 {
if r.Type == nil {
goto out
}
switch r.Op {
case OCALLMETH, OCALLINTER, OCALLFUNC:
if !r.Type.IsFuncArgStruct() {
break
}
cr = r.Type.NumFields()
if cr != cl {
goto mismatch
}
n.Op = OAS2FUNC
for i, l := range n.List.Slice() {
f := r.Type.Field(i)
if f.Type != nil && l.Type != nil {
checkassignto(f.Type, l)
}
if l.Name != nil && l.Name.Defn == n && l.Name.Param.Ntype == nil {
l.Type = f.Type
}
}
goto out
}
}
// x, ok = y
if cl == 2 && cr == 1 {
if r.Type == nil {
goto out
}
switch r.Op {
case OINDEXMAP, ORECV, ODOTTYPE:
switch r.Op {
case OINDEXMAP:
n.Op = OAS2MAPR
case ORECV:
n.Op = OAS2RECV
case ODOTTYPE:
n.Op = OAS2DOTTYPE
r.Op = ODOTTYPE2
}
if l.Type != nil {
checkassignto(r.Type, l)
}
if l.Name != nil && l.Name.Defn == n {
l.Type = r.Type
}
l := n.List.Second()
if l.Type != nil && !l.Type.IsBoolean() {
checkassignto(types.Types[TBOOL], l)
}
if l.Name != nil && l.Name.Defn == n && l.Name.Param.Ntype == nil {
l.Type = types.Types[TBOOL]
}
goto out
}
}
mismatch:
switch r.Op {
default:
yyerror("assignment mismatch: %d variables but %d values", cl, cr)
case OCALLFUNC, OCALLMETH, OCALLINTER:
yyerror("assignment mismatch: %d variables but %v returns %d values", cl, r.Left, cr)
}
// second half of dance
out:
n.SetTypecheck(1)
ls = n.List.Slice()
for i1, n1 := range ls {
if n1.Typecheck() == 0 {
ls[i1] = typecheck(ls[i1], ctxExpr|ctxAssign)
}
}
}
// type check function definition
func typecheckfunc(n *Node) {
if enableTrace && trace {
defer tracePrint("typecheckfunc", n)(nil)
}
for _, ln := range n.Func.Dcl {
if ln.Op == ONAME && (ln.Class() == PPARAM || ln.Class() == PPARAMOUT) {
ln.Name.Decldepth = 1
}
}
n.Func.Nname = typecheck(n.Func.Nname, ctxExpr|ctxAssign)
t := n.Func.Nname.Type
if t == nil {
return
}
n.Type = t
t.FuncType().Nname = asTypesNode(n.Func.Nname)
rcvr := t.Recv()
if rcvr != nil && n.Func.Shortname != nil {
m := addmethod(n.Func.Shortname, t, true, n.Func.Pragma&Nointerface != 0)
if m == nil {
return
}
n.Func.Nname.Sym = methodSym(rcvr.Type, n.Func.Shortname)
declare(n.Func.Nname, PFUNC)
}
if Ctxt.Flag_dynlink && !inimport && n.Func.Nname != nil {
makefuncsym(n.Func.Nname.Sym)
}
}
// The result of stringtoruneslit MUST be assigned back to n, e.g.
// n.Left = stringtoruneslit(n.Left)
func stringtoruneslit(n *Node) *Node {
if n.Left.Op != OLITERAL || n.Left.Val().Ctype() != CTSTR {
Fatalf("stringtoarraylit %v", n)
}
var l []*Node
s := n.Left.Val().U.(string)
i := 0
for _, r := range s {
l = append(l, nod(OKEY, nodintconst(int64(i)), nodintconst(int64(r))))
i++
}
nn := nod(OCOMPLIT, nil, typenod(n.Type))
nn.List.Set(l)
nn = typecheck(nn, ctxExpr)
return nn
}
var mapqueue []*Node
func checkMapKeys() {
for _, n := range mapqueue {
k := n.Type.MapType().Key
if !k.Broke() && !IsComparable(k) {
yyerrorl(n.Pos, "invalid map key type %v", k)
}
}
mapqueue = nil
}
func copytype(n *Node, t *types.Type) {
if t.Etype == TFORW {
// This type isn't computed yet; when it is, update n.
t.ForwardType().Copyto = append(t.ForwardType().Copyto, asTypesNode(n))
return
}
embedlineno := n.Type.ForwardType().Embedlineno
l := n.Type.ForwardType().Copyto
cache := n.Type.Cache
// TODO(mdempsky): Fix Type rekinding.
*n.Type = *t
t = n.Type
t.Sym = n.Sym
if n.Name != nil {
t.Vargen = n.Name.Vargen
}
// spec: "The declared type does not inherit any methods bound
// to the existing type, but the method set of an interface
// type [...] remains unchanged."
if !t.IsInterface() {
*t.Methods() = types.Fields{}
*t.AllMethods() = types.Fields{}
}
t.Nod = asTypesNode(n)
t.SetDeferwidth(false)
t.Cache = cache
// Propagate go:notinheap pragma from the Name to the Type.
if n.Name != nil && n.Name.Param != nil && n.Name.Param.Pragma&NotInHeap != 0 {
t.SetNotInHeap(true)
}
// Update nodes waiting on this type.
for _, n := range l {
copytype(asNode(n), t)
}
// Double-check use of type as embedded type.
if embedlineno.IsKnown() {
if t.IsPtr() || t.IsUnsafePtr() {
yyerrorl(embedlineno, "embedded type cannot be a pointer")
}
}
}
func typecheckdeftype(n *Node) {
if enableTrace && trace {
defer tracePrint("typecheckdeftype", n)(nil)
}
n.Type.Sym = n.Sym
n.SetTypecheck(1)
n.Name.Param.Ntype = typecheck(n.Name.Param.Ntype, Etype)
t := n.Name.Param.Ntype.Type
if t == nil {
n.SetDiag(true)
n.Type = nil
} else if n.Type == nil {
n.SetDiag(true)
} else {
// copy new type and clear fields
// that don't come along.
copytype(n, t)
}
}
func typecheckdef(n *Node) {
if enableTrace && trace {
defer tracePrint("typecheckdef", n)(nil)
}
lno := setlineno(n)
if n.Op == ONONAME {
if !n.Diag() {
n.SetDiag(true)
// Note: adderrorname looks for this string and
// adds context about the outer expression
yyerrorl(lineno, "undefined: %v", n.Sym)
}
lineno = lno
return
}
if n.Walkdef() == 1 {
lineno = lno
return
}
typecheckdefstack = append(typecheckdefstack, n)
if n.Walkdef() == 2 {
flusherrors()
fmt.Printf("typecheckdef loop:")
for i := len(typecheckdefstack) - 1; i >= 0; i-- {
n := typecheckdefstack[i]
fmt.Printf(" %v", n.Sym)
}
fmt.Printf("\n")
Fatalf("typecheckdef loop")
}
n.SetWalkdef(2)
if n.Type != nil || n.Sym == nil { // builtin or no name
goto ret
}
switch n.Op {
default:
Fatalf("typecheckdef %v", n.Op)
case OLITERAL:
if n.Name.Param.Ntype != nil {
n.Name.Param.Ntype = typecheck(n.Name.Param.Ntype, Etype)
n.Type = n.Name.Param.Ntype.Type
n.Name.Param.Ntype = nil
if n.Type == nil {
n.SetDiag(true)
goto ret
}
}
e := n.Name.Defn
n.Name.Defn = nil
if e == nil {
Dump("typecheckdef nil defn", n)
yyerrorl(n.Pos, "xxx")
}
e = typecheck(e, ctxExpr)
if e.Type == nil {
goto ret
}
if !e.isGoConst() {
if !e.Diag() {
if Isconst(e, CTNIL) {
yyerrorl(n.Pos, "const initializer cannot be nil")
} else {
yyerrorl(n.Pos, "const initializer %v is not a constant", e)
}
e.SetDiag(true)
}
goto ret
}
t := n.Type
if t != nil {
if !okforconst[t.Etype] {
yyerrorl(n.Pos, "invalid constant type %v", t)
goto ret
}
if !e.Type.IsUntyped() && !types.Identical(t, e.Type) {
yyerrorl(n.Pos, "cannot use %L as type %v in const initializer", e, t)
goto ret
}
e = convlit(e, t)
}
n.SetVal(e.Val())
n.Type = e.Type
case ONAME:
if n.Name.Param.Ntype != nil {
n.Name.Param.Ntype = typecheck(n.Name.Param.Ntype, Etype)
n.Type = n.Name.Param.Ntype.Type
if n.Type == nil {
n.SetDiag(true)
goto ret
}
}
if n.Type != nil {
break
}
if n.Name.Defn == nil {
if n.SubOp() != 0 { // like OPRINTN
break
}
if nsavederrors+nerrors > 0 {
// Can have undefined variables in x := foo
// that make x have an n.name.Defn == nil.
// If there are other errors anyway, don't
// bother adding to the noise.
break
}
Fatalf("var without type, init: %v", n.Sym)
}
if n.Name.Defn.Op == ONAME {
n.Name.Defn = typecheck(n.Name.Defn, ctxExpr)
n.Type = n.Name.Defn.Type
break
}
n.Name.Defn = typecheck(n.Name.Defn, ctxStmt) // fills in n.Type
case OTYPE:
if p := n.Name.Param; p.Alias {
// Type alias declaration: Simply use the rhs type - no need
// to create a new type.
// If we have a syntax error, p.Ntype may be nil.
if p.Ntype != nil {
p.Ntype = typecheck(p.Ntype, Etype)
n.Type = p.Ntype.Type
if n.Type == nil {
n.SetDiag(true)
goto ret
}
// For package-level type aliases, set n.Sym.Def so we can identify
// it as a type alias during export. See also #31959.
if n.Name.Curfn == nil {
n.Sym.Def = asTypesNode(p.Ntype)
}
}
break
}
// regular type declaration
if Curfn != nil {
defercheckwidth()
}
n.SetWalkdef(1)
n.Type = types.New(TFORW)
n.Type.Nod = asTypesNode(n)
n.Type.Sym = n.Sym // TODO(gri) this also happens in typecheckdeftype(n) - where should it happen?
nerrors0 := nerrors
typecheckdeftype(n)
if n.Type.Etype == TFORW && nerrors > nerrors0 {
// Something went wrong during type-checking,
// but it was reported. Silence future errors.
n.Type.SetBroke(true)
}
if Curfn != nil {
resumecheckwidth()
}
}
ret:
if n.Op != OLITERAL && n.Type != nil && n.Type.IsUntyped() {
Fatalf("got %v for %v", n.Type, n)
}
last := len(typecheckdefstack) - 1
if typecheckdefstack[last] != n {
Fatalf("typecheckdefstack mismatch")
}
typecheckdefstack[last] = nil
typecheckdefstack = typecheckdefstack[:last]
lineno = lno
n.SetWalkdef(1)
}
func checkmake(t *types.Type, arg string, n *Node) bool {
if !n.Type.IsInteger() && n.Type.Etype != TIDEAL {
yyerror("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.
switch consttype(n) {
case CTINT, CTRUNE, CTFLT, CTCPLX:
n.SetVal(toint(n.Val()))
if n.Val().U.(*Mpint).CmpInt64(0) < 0 {
yyerror("negative %s argument in make(%v)", arg, t)
return false
}
if n.Val().U.(*Mpint).Cmp(maxintval[TINT]) > 0 {
yyerror("%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[TINT])
return true
}
func markbreak(n *Node, implicit *Node) {
if n == nil {
return
}
switch n.Op {
case OBREAK:
if n.Sym == nil {
if implicit != nil {
implicit.SetHasBreak(true)
}
} else {
lab := asNode(n.Sym.Label)
if lab != nil {
lab.SetHasBreak(true)
}
}
case OFOR, OFORUNTIL, OSWITCH, OTYPESW, OSELECT, ORANGE:
implicit = n
fallthrough
default:
markbreak(n.Left, implicit)
markbreak(n.Right, implicit)
markbreaklist(n.Ninit, implicit)
markbreaklist(n.Nbody, implicit)
markbreaklist(n.List, implicit)
markbreaklist(n.Rlist, implicit)
}
}
func markbreaklist(l Nodes, implicit *Node) {
s := l.Slice()
for i := 0; i < len(s); i++ {
n := s[i]
if n == nil {
continue
}
if n.Op == OLABEL && i+1 < len(s) && n.Name.Defn == s[i+1] {
switch n.Name.Defn.Op {
case OFOR, OFORUNTIL, OSWITCH, OTYPESW, OSELECT, ORANGE:
n.Sym.Label = asTypesNode(n.Name.Defn)
markbreak(n.Name.Defn, n.Name.Defn)
n.Sym.Label = nil
i++
continue
}
}
markbreak(n, implicit)
}
}
// isterminating reports whether the Nodes list ends with a terminating statement.
func (l Nodes) isterminating() bool {
s := l.Slice()
c := len(s)
if c == 0 {
return false
}
return s[c-1].isterminating()
}
// Isterminating reports whether the node n, the last one in a
// statement list, is a terminating statement.
func (n *Node) isterminating() 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 OBLOCK:
return n.List.isterminating()
case OGOTO, ORETURN, ORETJMP, OPANIC, OFALL:
return true
case OFOR, OFORUNTIL:
if n.Left != nil {
return false
}
if n.HasBreak() {
return false
}
return true
case OIF:
return n.Nbody.isterminating() && n.Rlist.isterminating()
case OSWITCH, OTYPESW, OSELECT:
if n.HasBreak() {
return false
}
def := false
for _, n1 := range n.List.Slice() {
if !n1.Nbody.isterminating() {
return false
}
if n1.List.Len() == 0 { // default
def = true
}
}
if n.Op != OSELECT && !def {
return false
}
return true
}
return false
}
// checkreturn makes sure that fn terminates appropriately.
func checkreturn(fn *Node) {
if fn.Type.NumResults() != 0 && fn.Nbody.Len() != 0 {
markbreaklist(fn.Nbody, nil)
if !fn.Nbody.isterminating() {
yyerrorl(fn.Func.Endlineno, "missing return at end of function")
}
}
}
func deadcode(fn *Node) {
deadcodeslice(fn.Nbody)
}
func deadcodeslice(nn Nodes) {
var lastLabel = -1
for i, n := range nn.Slice() {
if n != nil && n.Op == OLABEL {
lastLabel = i
}
}
for i, n := range nn.Slice() {
// Cut is set to true when all nodes after i'th position
// should be removed.
// In other words, it marks whole slice "tail" as dead.
cut := false
if n == nil {
continue
}
if n.Op == OIF {
n.Left = deadcodeexpr(n.Left)
if Isconst(n.Left, CTBOOL) {
var body Nodes
if n.Left.Bool() {
n.Rlist = Nodes{}
body = n.Nbody
} else {
n.Nbody = Nodes{}
body = n.Rlist
}
// If "then" or "else" branch ends with panic or return statement,
// it is safe to remove all statements after this node.
// isterminating is not used to avoid goto-related complications.
// We must be careful not to deadcode-remove labels, as they
// might be the target of a goto. See issue 28616.
if body := body.Slice(); len(body) != 0 {
switch body[(len(body) - 1)].Op {
case ORETURN, ORETJMP, OPANIC:
if i > lastLabel {
cut = true
}
}
}
}
}
deadcodeslice(n.Ninit)
deadcodeslice(n.Nbody)
deadcodeslice(n.List)
deadcodeslice(n.Rlist)
if cut {
*nn.slice = nn.Slice()[:i+1]
break
}
}
}
func deadcodeexpr(n *Node) *Node {
// Perform dead-code elimination on short-circuited boolean
// expressions involving constants with the intent of
// producing a constant 'if' condition.
switch n.Op {
case OANDAND:
n.Left = deadcodeexpr(n.Left)
n.Right = deadcodeexpr(n.Right)
if Isconst(n.Left, CTBOOL) {
if n.Left.Bool() {
return n.Right // true && x => x
} else {
return n.Left // false && x => false
}
}
case OOROR:
n.Left = deadcodeexpr(n.Left)
n.Right = deadcodeexpr(n.Right)
if Isconst(n.Left, CTBOOL) {
if n.Left.Bool() {
return n.Left // true || x => true
} else {
return n.Right // false || x => x
}
}
}
return n
}
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