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typecheck.go
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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"os"
"strings"
"github.com/andybalholm/c2go/cc"
)
// rewriteTypes rewrites C types appearing in the program to equivalent Go types.
func rewriteTypes(cfg *Config, prog cc.Syntax) {
// Cache is needed to cut off translation of recursive types.
cache := make(map[*cc.Type]*cc.Type)
cc.Postorder(prog, func(x cc.Syntax) {
if t, ok := x.(*cc.Type); ok {
if t.Kind == cc.Struct || t.Kind == cc.Enum {
for _, d := range t.Decls {
d.OuterType = t
}
}
if t.Kind == cc.Func && len(t.Decls) == 1 && t.Decls[0].Type.Is(cc.Void) {
t.Decls = nil
}
}
if d, ok := x.(*cc.Decl); ok {
if d.Type != nil && d.Type.Kind == cc.Func {
for _, d1 := range d.Type.Decls {
d1.CurFn = d
// Check for array passed as parameter. Doesn't translate well.
if d1.Type != nil && d1.Type.Kind == cc.Array {
d1.Type.Kind = cc.Ptr
d1.Indexed = true
}
}
if d.Body != nil {
for _, s := range d.Body.Block {
if s.Op == cc.StmtDecl {
s.Decl.CurFn = d
}
}
}
}
}
})
cc.Postorder(prog, func(x cc.Syntax) {
switch x := x.(type) {
case *cc.Decl:
d := x
if d.Name == "..." || d.Type == nil {
return
}
if d.Name == "" && d.Type.Is(cc.Enum) && len(d.Type.Decls) > 0 {
for _, dd := range d.Type.Decls {
dd.Type = idealType
}
return
}
if d.Init != nil && len(d.Init.Braced) > 0 && d.Type != nil && d.Type.Kind == cc.Array {
// Initialization of array - do not override type.
// But if size is not given explicitly, change to slice.
d.Type.Base = toGoType(cfg, nil, d.Type.Base, cache)
if d.Type.Width == nil {
d.Type.Kind = Slice
}
return
}
d.Type = toGoType(cfg, d, d.Type, cache)
case *cc.Expr:
if x.Type != nil {
t := toGoType(cfg, nil, x.Type, cache)
if t == nil {
fprintf(x.Span, "cannot convert %v to go type\n", GoString(x.Type))
}
x.Type = t
}
}
})
}
var (
boolType = &cc.Type{Kind: Bool}
byteType = &cc.Type{Kind: Byte}
intType = &cc.Type{Kind: Int}
uintType = &cc.Type{Kind: Uint}
int32Type = &cc.Type{Kind: Int32}
uint32Type = &cc.Type{Kind: Uint32}
int64Type = &cc.Type{Kind: Int64}
uint64Type = &cc.Type{Kind: Uint64}
idealType = &cc.Type{Kind: Ideal}
stringType = &cc.Type{Kind: String}
runeType = &cc.Type{Kind: Rune}
float64Type = &cc.Type{Kind: Float64}
)
var c2goKind = map[cc.TypeKind]cc.TypeKind{
cc.Char: Int8,
cc.Uchar: Byte,
cc.Short: Int16,
cc.Ushort: Uint16,
cc.Int32: Int32,
cc.Uint32: Uint32,
cc.Int: Int,
cc.Uint: Uint,
cc.Long: Int, // long is used too indiscriminately to assign 32-bit meaning to it
cc.Ulong: Uint,
cc.Longlong: Int64,
cc.Ulonglong: Uint64,
cc.Float: Float32,
cc.Double: Float64,
cc.Enum: Int,
}
var c2goName = map[string]cc.TypeKind{
"uchar": Byte,
"int32": Int32,
"uint32": Uint32,
"int64": Int64,
"uint64": Uint64,
"bool": Bool,
"BOOL": Bool,
}
func toGoType(cfg *Config, x cc.Syntax, typ *cc.Type, cache map[*cc.Type]*cc.Type) *cc.Type {
if typ == nil {
return nil
}
if cache[typ] != nil {
return cache[typ]
}
switch typ.Kind {
default:
panic(fmt.Sprintf("unexpected C type %s", typ))
case Ideal:
return typ
case cc.Void:
return &cc.Type{Kind: cc.Struct} // struct{}
case cc.Char, cc.Uchar, cc.Short, cc.Ushort, cc.Int32, cc.Uint32, cc.Int, cc.Uint, cc.Long, cc.Ulong, cc.Longlong, cc.Ulonglong, cc.Float, cc.Double, cc.Enum:
t := &cc.Type{Kind: c2goKind[typ.Kind]}
t.Decls = typ.Decls
t.Tag = typ.Tag
if d, ok := x.(*cc.Decl); ok {
if cfg.bool[declKey(d)] {
t.Kind = Bool
}
}
return t
case cc.TypedefType:
if cfg != nil && cfg.typeMap[typ.Name] != "" {
t := &cc.Type{Kind: cc.TypedefType, Name: cfg.typeMap[typ.Name], TypeDecl: typ.TypeDecl}
cache[typ] = t
return t
}
// If this is a typedef like uchar, translate the type by name.
// Otherwise fall back to base.
def := typ.Base
if def != nil && cc.Char <= def.Kind && def.Kind <= cc.Enum {
var t *cc.Type
if c2goName[typ.Name] != 0 {
t = &cc.Type{Kind: c2goName[typ.Name]}
} else {
t = &cc.Type{Kind: c2goKind[typ.Base.Kind]}
}
if d, ok := x.(*cc.Decl); ok {
if cfg.bool[declKey(d)] {
t.Kind = Bool
}
}
return t
}
if typ.Name == "va_list" {
return &cc.Type{Kind: cc.TypedefType, Name: "[]interface{}"}
}
if def != nil && def.Kind == cc.Ptr {
// The base is a pointer type; unwrap it.
// Converting pointers to slices works better that way.
return toGoType(cfg, x, def, cache)
}
if def != nil && def.Tag != "" {
// If we have a typedef of a tagged union, use the union tag
// instead of the typedef name.
return toGoType(cfg, x, def, cache)
}
// Otherwise assume it is a struct or some such,
// and preserve the name but translate the base.
t := &cc.Type{Kind: cc.TypedefType, Name: typ.Name, TypeDecl: typ.TypeDecl}
cache[typ] = t
t.Base = toGoType(cfg, nil, typ.Base, cache)
return t
case cc.Array:
if typ.Base.Def().Kind == cc.Char && typ.Width == nil {
if d, ok := x.(*cc.Decl); ok && cfg.slice[declKey(d)] {
return &cc.Type{Kind: Slice, Base: byteType}
}
return &cc.Type{Kind: String}
}
t := &cc.Type{Kind: cc.Array, Width: typ.Width}
cache[typ] = t
if typ.Base.Def().Kind == cc.Char {
t.Base = byteType
} else {
t.Base = toGoType(cfg, nil, typ.Base, cache)
}
return t
case cc.Ptr:
t := &cc.Type{Kind: cc.Ptr}
cache[typ] = t
base := x
if typ.Base.Kind != cc.Func {
base = nil
}
t.Base = toGoType(cfg, base, typ.Base, cache)
// Convert void* to interface{}.
if typ.Base.Kind == cc.Void {
t.Base = nil
t.Kind = cc.TypedefType
t.Name = "interface{}"
return t
}
d, ok := x.(*cc.Decl)
if typ.Base.Kind == cc.Char {
if ok && cfg.slice[declKey(d)] {
t.Kind = Slice
t.Base = byteType
return t
}
t.Kind = String
t.Base = nil
return t
}
if typ.Base.Def().Kind == cc.Uchar && (!ok || !cfg.ptr[declKey(d)]) {
t.Kind = Slice
t.Base = byteType
}
if ok && (cfg.slice[declKey(d)] || d.Indexed) {
t.Kind = Slice
}
if ok && typ.Base.Kind == cc.Ptr && cfg.slice["*"+declKey(d)] {
t.Base.Kind = Slice
}
return t
case cc.Func:
// A func Type contains Decls, and we don't fork the Decls, so don't fork the Type.
// The Decls themselves appear in the group lists, so they'll be handled by rewriteTypes.
// The return value has no Decl and needs to be converted.
if !typ.Base.Is(cc.Void) {
if d, ok := x.(*cc.Decl); ok {
x = &cc.Decl{
Name: "return",
CurFn: d,
}
} else {
x = nil
}
typ.Base = toGoType(cfg, x, typ.Base, cache)
}
return typ
case cc.Struct:
// A struct Type contains Decls, and we don't fork the Decls, so don't fork the Type.
// The Decls themselves appear in the group lists, so they'll be handled by rewriteTypes.
return typ
}
}
// fixGoTypes corrects type errors in Go programs by applying the rules for implicit C conversions.
// It is basically a Go type checker that rewrites the program instead of printing errors.
func fixGoTypes(cfg *Config, prog *cc.Prog) {
// prog.Decls may contain duplicates, due to forward declarations.
// TODO(rsc): Should probably remove them.
did := make(map[*cc.Decl]bool)
for i := 0; i < len(prog.Decls); i++ {
decl := prog.Decls[i]
if did[decl] {
continue
}
did[decl] = true
if decl.Init != nil {
fixGoTypesInit(decl, decl.Init)
}
if decl.Body != nil {
t := decl.Type
if t != nil && t.Kind == cc.Func && t.Base.Is(Int) && len(t.Decls) >= 1 && t.Decls[0].Type.String() == "Fmt*" {
fixFormatter(decl)
}
fixGoTypesStmt(prog, decl, decl.Body)
}
}
// fixGoTypes might have introduced an (x = fmt.Sprintf(...)) in a larger expression.
// rewrite it out.
rewriteSyntax(cfg, prog)
}
func fixGoTypesInit(decl *cc.Decl, x *cc.Init) {
if x.Expr != nil {
fixGoTypesExpr(nil, x.Expr, x.XType)
}
for _, init := range x.Braced {
fixGoTypesInit(decl, init)
}
}
func fixGoTypesStmt(prog *cc.Prog, fn *cc.Decl, x *cc.Stmt) {
if x == nil {
return
}
fixFormatStmt(fn, x)
switch x.Op {
case cc.StmtDecl:
fixGoTypesExpr(fn, x.Expr, nil)
if x.Decl.Init != nil && x.Decl.Init.Expr != nil {
forceGoType(fn, x.Decl.Init.Expr, x.Decl.Type)
}
case cc.StmtExpr:
if x.Expr != nil && x.Expr.Op == cc.Call && x.Expr.Left.Op == cc.Name {
switch x.Expr.Left.Text {
case "qsort":
fixQsort(prog, x.Expr)
return
case "memset", "__builtin___memset_chk":
fixMemset(prog, fn, x)
return
case "free":
x.Op = cc.Empty
x.Expr = nil
return
}
}
fixGoTypesExpr(fn, x.Expr, nil)
case cc.If, cc.For:
fixGoTypesExpr(fn, x.Pre, nil)
fixGoTypesExpr(fn, x.Post, nil)
fixGoTypesExpr(fn, x.Expr, boolType)
if x.Decl != nil && x.Decl.Init != nil && x.Decl.Init.Expr != nil {
fixGoTypesExpr(fn, x.Decl.Init.Expr, x.Decl.Type)
}
case cc.Switch:
fixGoTypesExpr(fn, x.Expr, nil)
case cc.Return:
if x.Expr != nil {
forceGoType(fn, x.Expr, fn.Type.Base)
}
}
for _, stmt := range x.Block {
fixGoTypesStmt(prog, fn, stmt)
}
if len(x.Block) > 0 && x.Body != nil {
panic("block and body")
}
fixGoTypesStmt(prog, fn, x.Body)
fixGoTypesStmt(prog, fn, x.Else)
for _, lab := range x.Labels {
// TODO: use correct type
fixGoTypesExpr(fn, lab.Expr, nil)
}
}
func fixGoTypesExpr(fn *cc.Decl, x *cc.Expr, targ *cc.Type) (ret *cc.Type) {
if x == nil {
return nil
}
defer func() {
x.XType = ret
}()
if x.Op == cc.Paren {
return fixGoTypesExpr(fn, x.Left, targ)
}
// Make explicit C's implicit conversions from boolean to non-boolean and vice versa.
switch x.Op {
case cc.AndAnd, cc.OrOr, cc.Not, cc.EqEq, cc.Lt, cc.LtEq, cc.Gt, cc.GtEq, cc.NotEq:
if targ != nil && targ.Kind != Bool {
old := copyExpr(x)
if targ.Kind == Int {
x.Op = cc.Call
x.Left = &cc.Expr{Op: cc.Name, Text: "bool2int"}
x.List = []*cc.Expr{old}
x.Right = nil
} else {
x.Op = cc.Cast
x.Left = &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: "bool2int"}, List: []*cc.Expr{old}}
x.Type = targ
}
fixGoTypesExpr(fn, old, boolType)
return targ
}
default:
if targ != nil && targ.Kind == Bool || targ == boolType {
left := fixGoTypesExpr(fn, x, nil)
old := copyExpr(x)
if left == nil || left.Kind == Bool {
return targ
}
if old.Op == cc.Number {
switch old.Text {
case "1":
x.Op = cc.Name
x.Text = "true"
return targ
case "0":
x.Op = cc.Name
x.Text = "false"
return targ
}
}
x.Op = cc.NotEq
x.Left = old
x.Right = zeroFor(left)
fixSpecialCompare(fn, x)
return targ
}
}
switch x.Op {
default:
panic(fmt.Sprintf("unexpected construct %v in fixGoTypesExpr - %v - %v", GoString(x), x.Op, x.Span))
case ExprType:
// inserted by a rewrite
return nil
case ExprSlice:
// inserted by rewriteLen
left := fixGoTypesExpr(fn, x.List[0], targ)
fixGoTypesExpr(fn, x.List[1], nil)
fixGoTypesExpr(fn, x.List[2], nil)
return left
case cc.Comma:
for i, y := range x.List {
t := targ
if i+1 < len(x.List) {
t = nil
}
fixGoTypesExpr(fn, y, t)
}
return nil
case ExprBlock:
for _, stmt := range x.Block {
fixGoTypesStmt(nil, fn, stmt)
}
return nil
case cc.Add, cc.And, cc.Div, cc.Mod, cc.Mul, cc.Or, cc.Sub, cc.Xor:
if x.Op == cc.Sub && isPtrSliceOrArray(x.Left.XType) && isPtrSliceOrArray(x.Right.XType) {
left := fixGoTypesExpr(fn, x.Left, nil)
right := fixGoTypesExpr(fn, x.Right, nil)
if left != nil && right != nil && left.Kind != right.Kind {
if left.Kind == Slice {
forceConvert(fn, x.Right, right, left)
} else {
forceConvert(fn, x.Left, left, right)
}
}
fnName := "cap"
if x.Left.XType.Kind == String && x.Right.XType.Kind == String {
fnName = "len"
}
x.Left = &cc.Expr{Op: cc.Minus, Left: &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: fnName}, List: []*cc.Expr{x.Left}}}
x.Right = &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: fnName}, List: []*cc.Expr{x.Right}}
x.Op = cc.Add
return intType
}
left := fixGoTypesExpr(fn, x.Left, targ)
if x.Op == cc.And && x.Right.Op == cc.Twid {
x.Op = AndNot
x.Right = x.Right.Left
}
if x.Op == cc.Add && isSliceStringOrArray(left) {
fixGoTypesExpr(fn, x.Right, nil)
x.Op = ExprSlice
x.List = []*cc.Expr{x.Left, x.Right, nil}
x.Left = nil
x.Right = nil
if left.Kind == cc.Array {
left = &cc.Type{Kind: Slice, Base: left.Base}
}
return left
}
right := fixGoTypesExpr(fn, x.Right, targ)
if x.Op == cc.Div && x.Left.Op == cc.SizeofExpr && x.Right.Op == cc.SizeofExpr {
// Probably it's dividing the size of an array by the size of an element to find
// the length of the array.
lx := x.Left.Left
for lx.Op == cc.Paren {
lx = lx.Left
}
rx := x.Right.Left
for rx.Op == cc.Paren {
rx = rx.Left
}
if rx.String() == lx.String()+"[0]" {
x.Op = cc.Call
x.List = []*cc.Expr{lx}
x.Left = &cc.Expr{Op: cc.Name, Text: "len"}
return intType
}
}
if x.Op == cc.Div && x.Left.Op == cc.SizeofExpr && x.Right.Op == cc.SizeofType {
// Finding the length of an array again, but this time the argument of sizeof
// is the type rather than the first element.
lx := x.Left.Left
for lx.Op == cc.Paren {
lx = lx.Left
}
if lx.XType != nil && GoString(lx.XType.Base) == GoString(x.Right.Type) {
x.Op = cc.Call
x.List = []*cc.Expr{lx}
x.Left = &cc.Expr{Op: cc.Name, Text: "len"}
return intType
}
}
return fixBinary(fn, x, left, right, targ)
case cc.AddEq, cc.AndEq, cc.DivEq, cc.Eq, cc.ModEq, cc.MulEq, cc.OrEq, cc.SubEq, cc.XorEq:
left := fixGoTypesExpr(fn, x.Left, nil)
if x.Op == cc.AndEq && x.Right.Op == cc.Twid {
x.Op = AndNotEq
x.Right = x.Right.Left
}
if x.Op == cc.AddEq && isSliceOrString(left) {
fixGoTypesExpr(fn, x.Right, nil)
old := copyExpr(x.Left)
x.Op = cc.Eq
x.Right = &cc.Expr{Op: ExprSlice, List: []*cc.Expr{old, x.Right, nil}}
return left
}
if x.Op == cc.Eq && x.Left.Op == cc.Index && sameType(x.Left.Left.XType, stringType) && GoString(x.Left.Right) == "0" && GoString(x.Right) == "0" {
x.Left = x.Left.Left
x.Right = &cc.Expr{Op: cc.Name, Text: `""`}
return x.Left.XType
}
forceGoType(fn, x.Right, left)
if x.Op == cc.Eq && x.Left != nil && x.Right != nil && x.Right.XType != nil && isCall(x.Right, "make") && x.Left.XDecl != nil && x.Left.XDecl.Type != nil && x.Left.XDecl.Type.Kind == cc.Ptr && sameType(x.Left.XDecl.Type.Base, x.Right.XType.Base) {
x.Left.XDecl.Type = x.Right.XType
x.Left.XType = x.Right.XType
left = x.Right.XType
}
return left
case ColonEq:
left := fixGoTypesExpr(fn, x.Right, nil)
x.Left.XType = left
x.Left.XDecl.Type = left
return left
case cc.Addr:
left := fixGoTypesExpr(fn, x.Left, nil)
if left == nil {
return nil
}
if targ != nil && targ.Kind == Slice && sameType(targ.Base, left) {
l := x.Left
l.Op = ExprSlice
l.List = []*cc.Expr{l.Left, l.Right, nil}
l.Left = nil
l.Right = nil
fixMerge(x, l)
return targ
}
return &cc.Type{Kind: cc.Ptr, Base: left}
case cc.AndAnd, cc.OrOr, cc.Not:
fixGoTypesExpr(fn, x.Left, boolType)
if x.Right != nil {
fixGoTypesExpr(fn, x.Right, boolType)
}
return boolType
case cc.Arrow, cc.Dot:
left := fixGoTypesExpr(fn, x.Left, nil)
if x.Op == cc.Arrow && isSliceOrString(left) {
x.Left = &cc.Expr{Op: cc.Index, Left: x.Left, Right: &cc.Expr{Op: cc.Number, Text: "0"}}
}
if x.XDecl == nil {
return nil
}
return x.XDecl.Type
case cc.Call:
if fixPrintf(fn, x) {
return x.XType
}
if fixSpecialCall(fn, x, targ) {
return x.XType
}
left := fixGoTypesExpr(fn, x.Left, nil)
if left != nil && left.Kind == cc.Ptr && left.Base.Kind == cc.Func {
left = left.Base
}
for i, y := range x.List {
if left != nil && left.Kind == cc.Func && i < len(left.Decls) {
forceGoType(fn, y, left.Decls[i].Type)
} else {
fixGoTypesExpr(fn, y, nil)
}
}
if left != nil && left.Kind == cc.Func {
return left.Base
}
return nil
case cc.Cast:
if x.Left.Op == cc.Call && x.Left.Left.Op == cc.Name {
switch x.Left.Left.Text {
case "malloc", "calloc":
// Casting the return value of malloc does more harm than good,
// so remove the cast.
typ := fixGoTypesExpr(fn, x.Left, nil)
*x = *x.Left
return typ
}
}
if x.Type.Kind == cc.Struct && len(x.Type.Decls) == 0 {
// If we're casting to struct{}, it must have been a cast to void in C.
// The best way to translate that is just to remove the cast.
typ := fixGoTypesExpr(fn, x.Left, nil)
*x = *x.Left
return typ
}
if (x.Type.Kind == cc.Ptr || x.Type.Name == "interface{}") && x.Left.Op == cc.Number && x.Left.Text == "0" {
// Casting 0 to a pointer type should be translated as nil.
*x = cc.Expr{Op: cc.Name, Text: "nil"}
return nil
}
fixGoTypesExpr(fn, x.Left, nil)
if isEmptyInterface(x.Left.XType) {
x.Op = TypeAssert
}
return x.Type
case cc.CastInit:
fixGoTypesInit(nil, x.Init)
return x.Type
case cc.EqEq, cc.Gt, cc.GtEq, cc.Lt, cc.LtEq, cc.NotEq:
if fixSpecialCompare(fn, x) {
return boolType
}
left := fixGoTypesExpr(fn, x.Left, nil)
if x.Right.Op == cc.Number && x.Right.Text == "0" || x.Right.Op == cc.Name && (x.Right.Text == "nil" || x.Right.Text == "NULL") {
if isSliceOrPtr(left) {
x.Right.Op = cc.Name
x.Right.Text = "nil"
return boolType
}
if left != nil && left.Kind == String {
x.Right.Op = cc.String
x.Right.Texts = []string{`""`}
return boolType
}
}
right := fixGoTypesExpr(fn, x.Right, nil)
if isSliceOrArray(x.Left.XType) && isSliceOrArray(x.Right.XType) {
x.Left = &cc.Expr{Op: cc.Minus, Left: &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: "cap"}, List: []*cc.Expr{x.Left}}}
x.Right = &cc.Expr{Op: cc.Minus, Left: &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: "cap"}, List: []*cc.Expr{x.Right}}}
return boolType
}
fixBinary(fn, x, left, right, nil)
return boolType
case cc.Index, cc.Indir:
left := fixGoTypesExpr(fn, x.Left, nil)
if x.Right != nil {
fixGoTypesExpr(fn, x.Right, nil)
}
if left == nil {
return nil
}
if isSliceOrString(left) && x.Op == cc.Indir {
x.Op = cc.Index
x.Right = &cc.Expr{Op: cc.Number, Text: "0"}
}
switch left.Kind {
case cc.Ptr, Slice, cc.Array:
if x.Op == cc.Indir && left.Kind == cc.Ptr && left.Base.Kind == cc.Func {
*x = *x.Left
}
return left.Base
case String:
return byteType
}
return nil
case cc.Lsh, cc.Rsh:
left := fixGoTypesExpr(fn, x.Left, targ)
if left != nil && targ != nil && Int8 <= left.Kind && left.Kind <= Float64 && targ.Kind > left.Kind {
forceConvert(fn, x.Left, left, targ)
left = targ
}
fixShiftCount(fn, x.Right)
return left
case cc.LshEq, cc.RshEq:
left := fixGoTypesExpr(fn, x.Left, nil)
fixShiftCount(fn, x.Right)
return left
case cc.Name:
switch x.Text {
case "len":
return &cc.Type{Kind: cc.Func, Base: intType}
}
if x.XDecl == nil {
if x.Text == "true" || x.Text == "false" {
return x.XType
}
return nil
}
return x.XDecl.Type
case cc.Number:
return idealType
case cc.Minus, cc.Plus, cc.Twid:
return fixGoTypesExpr(fn, x.Left, targ)
case cc.Offsetof:
// TODO
return nil
case cc.Paren:
return fixGoTypesExpr(fn, x.Left, targ)
case cc.PostDec, cc.PostInc:
left := fixGoTypesExpr(fn, x.Left, nil)
if x.Op == cc.PostInc && isSliceOrString(left) {
old := copyExpr(x.Left)
x.Op = cc.Eq
x.Right = &cc.Expr{Op: ExprSlice, List: []*cc.Expr{old, &cc.Expr{Op: cc.Number, Text: "1"}, nil}}
}
return nil
case cc.SizeofExpr:
left := fixGoTypesExpr(fn, x.Left, nil)
if left != nil && (left.Kind == cc.Array || left.Kind == Slice) && left.Base.Def().Is(Byte) {
x.Op = cc.Call
x.List = []*cc.Expr{x.Left}
x.Left = &cc.Expr{Op: cc.Name, Text: "len"}
return intType
}
return nil
case cc.SizeofType:
return nil
case cc.String:
return &cc.Type{Kind: String}
case cc.VaArg:
// TODO
return nil
case cc.Cond:
// Conditional expressions should have been eliminated by the time we get here,
// but in the initializer of a variable declaration there's not much we can do with them.
return nil
}
}
func forceGoType(fn *cc.Decl, x *cc.Expr, targ *cc.Type) {
actual := fixGoTypesExpr(fn, x, targ)
forceConvert(fn, x, actual, targ)
}
func forceConvert(fn *cc.Decl, x *cc.Expr, actual, targ *cc.Type) {
if isEmptyInterface(targ) {
return
}
if isEmptyInterface(actual) {
old := copyExpr(x)
x.Op = TypeAssert
x.Left = old
x.Right = nil
x.List = nil
x.Type = targ
x.XType = targ
return
}
if isNumericConst(x) && targ != nil {
switch targ.Kind {
case cc.Ptr, Slice:
if x.Op == cc.Number && x.Text == "0" {
x.Op = cc.Name
x.Text = "nil"
x.XType = targ
}
case String:
if x.Op == cc.Number && x.Text == "0" {
x.Op = cc.Name
x.Text = `""`
x.XType = targ
}
}
return
}
if x.Op == cc.Name && (x.Text == "nil" || x.Text == "NULL") && targ != nil {
switch targ.Kind {
case cc.Func, cc.Ptr, Slice:
x.Text = "nil"
return
case String:
x.Text = `""`
x.XType = targ
x.XDecl = nil
return
}
}
if actual == nil || targ == nil {
return
}
if actual.Kind == Ideal && Int8 <= targ.Kind && targ.Kind <= Float64 {
return
}
if x != nil && x.Op == cc.Name && (x.Text == "nil" || x.Text == "NULL") {
if targ.Kind == cc.Func || targ.Kind == cc.Ptr || targ.Kind == Slice {
return
}
}
// Func conversions are never useful.
// If the func types are different, the conversion will fail;
// if not, the conversion is unnecessary.
// Either way the conversion is an eyesore.
if targ.Kind == cc.Func || targ.Kind == cc.Ptr && targ.Base.Kind == cc.Func {
return
}
if actual.Kind == Bool && Int8 <= targ.Kind && targ.Kind <= Float64 {
old := copyExpr(x)
if targ.Kind == Int {
x.Op = cc.Call
x.Left = &cc.Expr{Op: cc.Name, Text: "bool2int"}
x.List = []*cc.Expr{old}
x.Right = nil
} else {
x.Op = cc.Cast
x.Left = &cc.Expr{Op: cc.Call, Left: &cc.Expr{Op: cc.Name, Text: "bool2int"}, List: []*cc.Expr{old}}
x.Type = targ
}
return
}
if actual.Kind == cc.Array && targ.Kind == Slice && sameType(actual.Base, targ.Base) {
old := copyExpr(x)
x.Op = ExprSlice
x.List = []*cc.Expr{old, nil, nil}
x.Left = nil
x.Right = nil
return
}
if actual.Kind == Slice && targ.Kind == cc.Ptr && sameType(actual.Base, targ.Base) {
if isCall(x, "make") {
return
}
old := copyExpr(x)
x.Op = cc.Addr
x.Left = &cc.Expr{Op: cc.Index, Left: old, Right: &cc.Expr{Op: cc.Number, Text: "0"}}
return
}
if !sameType(actual, targ) {
if x.Op == cc.Twid {
forceConvert(fn, x.Left, actual, targ)
x.XType = targ
return
}
old := copyExpr(x)
// for debugging:
// old = &cc.Expr{Op: cc.Cast, Left: old, Type: actual, XType: actual}
x.Op = cc.Cast
x.Left = old
x.Right = nil
x.List = nil
x.Type = targ
x.XType = targ
if actual.Kind == cc.Array && targ.Kind == Slice {
x.Op = ExprSlice
x.List = []*cc.Expr{old, nil, nil}
x.Left = nil
x.Type = nil
}
}
}
func fixShiftCount(fn *cc.Decl, x *cc.Expr) {
typ := fixGoTypesExpr(fn, x, nil)
if typ == nil {
return
}
switch typ.Kind {
case Uint16, Uint32, Uint64, Uint, Uintptr, Byte:
return
}
if typ.Kind == Int64 {
forceConvert(fn, x, typ, uint64Type)
return
}
forceConvert(fn, x, typ, uintType)
}
func fixBinary(fn *cc.Decl, x *cc.Expr, left, right, targ *cc.Type) *cc.Type {
if left == nil || right == nil {
return nil
}
if left.Kind != Ideal && (left.Kind < Int8 || left.Kind > Float64) {
return nil
}
if right.Kind != Ideal && (right.Kind < Int8 || right.Kind > Float64) {
return nil
}
if targ != nil && (targ.Kind < Int8 || targ.Kind > Float64) {
return nil
}
// Want to do everything at as high a precision as possible for as long as possible.
// If target is wider, convert early.
// If target is narrower, don't convert at all - let next step do it.
// Must make left and right match.
// Convert to largest of three.
t := left
if t.Kind == Ideal || t.Kind < right.Kind && right.Kind != Ideal {
t = right
}
if targ != nil && (t.Kind == Ideal || t.Kind < targ.Kind && targ.Kind != Ideal) {
t = targ
}
if !sameType(t, left) {