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implement naked returns #189

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merged 2 commits into from
Jan 7, 2018
Merged

implement naked returns #189

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6fff279
typecheck: propagate return value names
sbinet Jan 6, 2018
a51db59
eval,typecheck: implement naked returns
sbinet Jan 6, 2018
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44 changes: 44 additions & 0 deletions eval/testdata/func10.ng
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Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
func f1() (i, j int) { return }

if v1, v2 := f1(); v1 != 0 || v2 != 0 {
panic("ERROR 1")
}

func f2() (i, j int) {
i = 1
j = 2
return
}

if v1, v2 := f2(); v1 != 1 || v2 != 2 {
panic("ERROR 2")
}

func f3(i int) (v int) {
if i == 0 {
return
}
if i == 1 {
v = 1
return
}
if i == 2 {
v = 2
return v
}
return
}

if v := f3(0); v != 0 {
panic("ERROR 3.1")
}

if v := f3(1); v != 1 {
panic("ERROR 3.2")
}

if v := f3(2); v != 2 {
panic("ERROR 3.3")
}

print("OK")
1 change: 1 addition & 0 deletions eval/testdata/func11_error.ng
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
func f() (i, j, k int) { return 1, 2 } // ERROR: not enough arguments to return
64 changes: 38 additions & 26 deletions typecheck/typecheck.go
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Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ func IsError(t tipe.Type) bool {
return Universe.Objs["error"].Type == t
}

func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple, retNames []string) tipe.Type {
switch s := s.(type) {
case *stmt.ConstSet:
for _, v := range s.Consts {
Expand Down Expand Up @@ -277,7 +277,7 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
c.pushScope()
defer c.popScope()
for _, s := range s.Stmts {
c.stmt(s, retType)
c.stmt(s, retType, retNames)
}
return nil

Expand All @@ -289,28 +289,28 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
if s.Init != nil {
c.pushScope()
defer c.popScope()
c.stmt(s.Init, retType)
c.stmt(s.Init, retType, retNames)
}
c.expr(s.Cond)
c.stmt(s.Body, retType)
c.stmt(s.Body, retType, retNames)
if s.Else != nil {
c.stmt(s.Else, retType)
c.stmt(s.Else, retType, retNames)
}
return nil

case *stmt.For:
if s.Init != nil {
c.pushScope()
defer c.popScope()
c.stmt(s.Init, retType)
c.stmt(s.Init, retType, retNames)
}
if s.Cond != nil {
c.expr(s.Cond)
}
if s.Post != nil {
c.stmt(s.Post, retType)
c.stmt(s.Post, retType, retNames)
}
c.stmt(s.Body, retType)
c.stmt(s.Body, retType, retNames)
return nil

case *stmt.Range:
Expand Down Expand Up @@ -365,7 +365,7 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
c.types[s.Val] = vt
}
}
c.stmt(s.Body, retType)
c.stmt(s.Body, retType, retNames)
return nil

case *stmt.TypeDecl:
Expand All @@ -383,7 +383,7 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {

case *stmt.TypeDeclSet:
for _, s := range s.TypeDecls {
c.stmt(s, retType)
c.stmt(s, retType, retNames)
}
return nil

Expand Down Expand Up @@ -453,13 +453,23 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
c.errorfmt("too many arguments to return")
return nil
case len(s.Exprs) < len(retType.Elems):
c.errorfmt("not enough arguments to return")
return nil
if !(len(s.Exprs) == 0 && len(retNames) == len(retType.Elems)) {
c.errorfmt("not enough arguments to return")
return nil
}
}
var partials []partial
for i, e := range s.Exprs {
partials = append(partials, c.expr(e))
c.constrainUntyped(&partials[i], retType.Elems[i])
switch len(s.Exprs) {
case 0:
partials = make([]partial, len(retType.Elems))
for i, t := range retType.Elems {
c.constrainUntyped(&partials[i], t)
}
default:
for i, e := range s.Exprs {
partials = append(partials, c.expr(e))
c.constrainUntyped(&partials[i], retType.Elems[i])
}
}
for _, p := range partials {
if p.mode == modeInvalid {
Expand Down Expand Up @@ -543,14 +553,14 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
return nil

case *stmt.Labeled:
c.stmt(s.Stmt, retType)
c.stmt(s.Stmt, retType, retNames)
return nil

case *stmt.Switch:
if s.Init != nil {
c.pushScope()
defer c.popScope()
c.stmt(s.Init, retType)
c.stmt(s.Init, retType, retNames)
}
var typ tipe.Type = tipe.Bool
if s.Cond != nil {
Expand Down Expand Up @@ -595,23 +605,23 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
c.constrainUntyped(&p, typ)
}
}
c.stmt(cse.Body, retType)
c.stmt(cse.Body, retType, retNames)
}
return nil

case *stmt.TypeSwitch:
if s.Init != nil {
c.pushScope()
defer c.popScope()
c.stmt(s.Init, retType)
c.stmt(s.Init, retType, retNames)
}
c.pushScope()
defer c.popScope()
if s.Assign == nil {
c.errorfmt("type switch needs a type switch guard")
return nil
}
c.stmt(s.Assign, retType)
c.stmt(s.Assign, retType, retNames)
var (
e *expr.TypeAssert
id expr.Expr
Expand Down Expand Up @@ -667,7 +677,7 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
)
}
}
c.stmt(cse.Body, retType)
c.stmt(cse.Body, retType, retNames)
}
return nil

Expand Down Expand Up @@ -716,9 +726,9 @@ func (c *Checker) stmt(s stmt.Stmt, retType *tipe.Tuple) tipe.Type {
if cse.Stmt != nil {
c.pushScope()
defer c.popScope()
c.stmt(cse.Stmt, retType)
c.stmt(cse.Stmt, retType, retNames)
}
c.stmt(cse.Body, retType)
c.stmt(cse.Body, retType, retNames)
}(&cse)
}
return nil
Expand Down Expand Up @@ -1292,7 +1302,7 @@ func (c *Checker) parseFile(filename string, source []byte) error {
c.curPkg.Syntax = f

for _, s := range f.Stmts {
c.stmt(s, nil)
c.stmt(s, nil, nil)
if len(c.errs) > 0 {
return c.errs[0]
}
Expand Down Expand Up @@ -2086,12 +2096,14 @@ func (c *Checker) exprPartial(e expr.Expr, hint typeHint) (p partial) {
}
}
}
var retNames []string
if e.Type.Results != nil {
for i, t := range e.Type.Results.Elems {
e.Type.Results.Elems[i], _ = c.resolve(t)
}
for i, rname := range e.ResultNames {
if rname != "" {
retNames = append(retNames, rname)
t := e.Type.Results.Elems[i]
c.addObj(&Obj{
Name: rname,
Expand All @@ -2102,7 +2114,7 @@ func (c *Checker) exprPartial(e expr.Expr, hint typeHint) (p partial) {
}
}
}
c.stmt(e.Body.(*stmt.Block), e.Type.Results)
c.stmt(e.Body.(*stmt.Block), e.Type.Results, retNames)
for _, pname := range e.ParamNames {
delete(c.cur.foundInParent, pname)
}
Expand Down Expand Up @@ -3468,7 +3480,7 @@ func round(v constant.Value, t tipe.Basic) constant.Value {
func (c *Checker) Add(s stmt.Stmt) tipe.Type {
c.mu.Lock()
defer c.mu.Unlock()
return c.stmt(s, nil)
return c.stmt(s, nil, nil)
}

func (c *Checker) Lookup(name string) *Obj {
Expand Down