fix: apply automatic type conversion to constant expressions (#484)

CONTRIBUTING.md

@@ -13,7 +13,12 @@ discussions.
 Once the proposal is approved, a Pull Request can be opened. If you want
 to provide early visibility to reviewers, create a [Draft Pull Request].
 
+We will also require you to sign the [Containous Contributor License Agreement]
+after you submit your first pull request to this project. The link to sign the
+agreement will be presented to you in the web interface of the pull request.
+
 [Issues]: https://github.com/containous/yaegi/issues
 [Pull Requests]: https://github.com/containous/yaegi/issues
 [Feature Request]: https://github.com/containous/yaegi/issues/new?template=feature_request.md
 [Draft Pull Request]: https://github.blog/2019-02-14-introducing-draft-pull-requests/
+[Containous Contributor License Agreement]: https://cla-assistant.io/containous/yaegi

_test/bin2.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func main() {
+	fmt.Println(math.Abs(-5))
+}
+
+// Output:
+// 5

_test/nil1.go

@@ -0,0 +1,12 @@
+package main
+
+func main() {
+	var a error = nil
+
+	if a == nil || a.Error() == "nil" {
+		println("a is nil")
+	}
+}
+
+// Output:
+// a is nil

_test/or0.go

@@ -0,0 +1,9 @@
+package main
+
+func main() {
+	c := false
+	println(c || !c)
+}
+
+// Output:
+// true

_test/or1.go

@@ -0,0 +1,9 @@
+package main
+
+func main() {
+	c := false
+	println(!c || c)
+}
+
+// Output:
+// true

internal/genop/genop.go

@@ -352,6 +352,30 @@ func {{$name}}(n *node) {
 	}
 }
 {{end}}
+{{range $name, $op := .Unary}}
+func {{$name}}Const(n *node) {
+	t := n.typ.rtype
+	v := n.child[0].rval
+	n.rval = reflect.New(t).Elem()
+
+	{{- if $op.Bool}}
+	n.rval.SetBool({{$op.Name}} v.Bool())
+	{{- else}}
+	switch t.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n.rval.SetInt({{$op.Name}} v.Int())
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.rval.SetUint({{$op.Name}} v.Uint())
+	{{- if $op.Float}}
+	case reflect.Float32, reflect.Float64:
+		n.rval.SetFloat({{$op.Name}} v.Float())
+	case reflect.Complex64, reflect.Complex128:
+		n.rval.SetComplex({{$op.Name}} v.Complex())
+	{{- end}}
+	}
+	{{- end}}
+}
+{{end}}
 {{range $name, $op := .Comparison}}
 func {{$name}}(n *node) {
 	tnext := getExec(n.tnext)
@@ -793,6 +817,7 @@ type Op struct {
 	Float   bool   // true if operator applies to float
 	Complex bool   // true if operator applies to complex
 	Shift   bool   // true if operator is a shift operation
+	Bool    bool   // true if operator applies to bool
 }
 
 func main() {
@@ -805,17 +830,17 @@ func main() {
 	b := &bytes.Buffer{}
 	data := map[string]interface{}{
 		"Arithmetic": map[string]Op{
-			"add":    {"+", true, true, true, false},
-			"sub":    {"-", false, true, true, false},
-			"mul":    {"*", false, true, true, false},
-			"quo":    {"/", false, true, true, false},
-			"rem":    {"%", false, false, false, false},
-			"shl":    {"<<", false, false, false, true},
-			"shr":    {">>", false, false, false, true},
-			"and":    {"&", false, false, false, false},
-			"or":     {"|", false, false, false, false},
-			"xor":    {"^", false, false, false, false},
-			"andNot": {"&^", false, false, false, false},
+			"add":    {"+", true, true, true, false, false},
+			"sub":    {"-", false, true, true, false, false},
+			"mul":    {"*", false, true, true, false, false},
+			"quo":    {"/", false, true, true, false, false},
+			"rem":    {"%", false, false, false, false, false},
+			"shl":    {"<<", false, false, false, true, false},
+			"shr":    {">>", false, false, false, true, false},
+			"and":    {"&", false, false, false, false, false},
+			"or":     {"|", false, false, false, false, false},
+			"xor":    {"^", false, false, false, false, false},
+			"andNot": {"&^", false, false, false, false, false},
 		},
 		"IncDec": map[string]Op{
 			"inc": {Name: "+"},
@@ -829,6 +854,12 @@ func main() {
 			"lowerEqual":   {Name: "<=", Complex: false},
 			"notEqual":     {Name: "!=", Complex: true},
 		},
+		"Unary": map[string]Op{
+			"not":    {Name: "!", Float: false, Bool: true},
+			"neg":    {Name: "-", Float: true, Bool: false},
+			"pos":    {Name: "+", Float: true, Bool: false},
+			"bitNot": {Name: "^", Float: false, Bool: false},
+		},
 	}
 	if err = parse.Execute(b, data); err != nil {
 		log.Fatal(err)

interp/ast.go

@@ -199,6 +199,7 @@ const (
 	aAndAssign
 	aAndNot
 	aAndNotAssign
+	aBitNot
 	aCall
 	aCase
 	aCompositeLit
@@ -217,11 +218,12 @@ const (
 	aMethod
 	aMul
 	aMulAssign
-	aNegate
+	aNeg
 	aNot
 	aNotEqual
 	aOr
 	aOrAssign
+	aPos
 	aQuo
 	aQuoAssign
 	aRange
@@ -255,6 +257,7 @@ var actions = [...]string{
 	aAndAssign:    "&=",
 	aAndNot:       "&^",
 	aAndNotAssign: "&^=",
+	aBitNot:       "^",
 	aCall:         "call",
 	aCase:         "case",
 	aCompositeLit: "compositeLit",
@@ -271,11 +274,12 @@ var actions = [...]string{
 	aMethod:       "Method",
 	aMul:          "*",
 	aMulAssign:    "*=",
-	aNegate:       "-",
+	aNeg:          "-",
 	aNot:          "!",
 	aNotEqual:     "!=",
 	aOr:           "|",
 	aOrAssign:     "|=",
+	aPos:          "+",
 	aQuo:          "/",
 	aQuoAssign:    "/=",
 	aRange:        "range",
@@ -771,6 +775,8 @@ func (interp *Interpreter) ast(src, name string) (string, *node, error) {
 			var kind = unaryExpr
 			var act action
 			switch a.Op {
+			case token.ADD:
+				act = aPos
 			case token.AND:
 				kind = addressExpr
 				act = aAddr
@@ -779,7 +785,9 @@ func (interp *Interpreter) ast(src, name string) (string, *node, error) {
 			case token.NOT:
 				act = aNot
 			case token.SUB:
-				act = aNegate
+				act = aNeg
+			case token.XOR:
+				act = aBitNot
 			}
 			st.push(addChild(&root, anc, pos, kind, act), nod)
 

interp/cfg.go

@@ -24,6 +24,10 @@ var constOp = map[action]func(*node){
 	aShr:    shrConst,
 	aAndNot: andNotConst,
 	aXor:    xorConst,
+	aNot:    notConst,
+	aBitNot: bitNotConst,
+	aNeg:    negConst,
+	aPos:    posConst,
 }
 
 var constBltn = map[string]func(*node){
@@ -1019,6 +1023,9 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			n.child[1].tnext = n
 			n.typ = n.child[0].typ
 			n.findex = sc.add(n.typ)
+			if n.start.action == aNop {
+				n.start.gen = branch
+			}
 
 		case lorExpr:
 			n.start = n.child[0].start
@@ -1027,6 +1034,9 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			n.child[1].tnext = n
 			n.typ = n.child[0].typ
 			n.findex = sc.add(n.typ)
+			if n.start.action == aNop {
+				n.start.gen = branch
+			}
 
 		case parenExpr:
 			wireChild(n)
@@ -1375,16 +1385,60 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 		case unaryExpr:
 			wireChild(n)
 			n.typ = n.child[0].typ
-			if n.action == aRecv {
+			switch n.action {
+			case aRecv:
 				// Channel receive operation: set type to the channel data type
 				if n.typ.cat == valueT {
 					n.typ = &itype{cat: valueT, rtype: n.typ.rtype.Elem()}
 				} else {
 					n.typ = n.typ.val
 				}
+			case aBitNot:
+				if !isInt(n.typ.TypeOf()) {
+					err = n.cfgErrorf("illegal operand type for '^' operator")
+					return
+				}
+			case aNot:
+				if !isBool(n.typ) {
+					err = n.cfgErrorf("illegal operand type for '!' operator")
+					return
+				}
+			case aNeg, aPos:
+				if !isNumber(n.typ.TypeOf()) {
+					err = n.cfgErrorf("illegal operand type for '%v' operator", n.action)
+					return
+				}
 			}
 			// TODO: Optimisation: avoid allocation if boolean branch op (i.e. '!' in an 'if' expr)
-			n.findex = sc.add(n.typ)
+			if n.child[0].rval.IsValid() && constOp[n.action] != nil {
+				if n.typ == nil {
+					if n.typ, err = nodeType(interp, sc, n); err != nil {
+						return
+					}
+				}
+				n.typ.TypeOf() // init reflect type
+				constOp[n.action](n)
+			}
+			switch {
+			case n.rval.IsValid():
+				n.gen = nop
+				n.findex = -1
+			case n.anc.kind == assignStmt && n.anc.action == aAssign:
+				dest := n.anc.child[childPos(n)-n.anc.nright]
+				n.typ = dest.typ
+				n.findex = dest.findex
+			case n.anc.kind == returnStmt:
+				pos := childPos(n)
+				n.typ = sc.def.typ.ret[pos]
+				n.findex = pos
+			default:
+				if n.typ == nil {
+					if n.typ, err = nodeType(interp, sc, n); err != nil {
+						return
+					}
+				}
+				n.findex = sc.add(n.typ)
+			}
 
 		case valueSpec:
 			n.gen = reset

interp/doc.go

@@ -4,6 +4,18 @@ Package interp provides a complete Go interpreter.
 For the Go language itself, refer to the official Go specification
 https://golang.org/ref/spec.
 
+Importing packages
+
+Packages can be imported in source or binary form, using the standard
+Go import statement. In source form, packages are searched first in the
+vendor directory, the preferred way to store source dependencies. If not
+found in vendor, sources modules will be searched in GOPATH. Go modules
+are not supported yet by yaegi.
+
+Binary form packages are compiled and linked with the interpreter
+executable, and exposed to scripts with the Use method. The goexports
+command can be used to generate package wrappers.
+
 Custom build tags
 
 Custom build tags allow to control which files in imported source

interp/dot.go

@@ -38,7 +38,7 @@ func (n *node) astDot(out io.Writer, name string) {
 func (n *node) cfgDot(out io.Writer) {
 	fmt.Fprintf(out, "digraph cfg {\n")
 	n.Walk(nil, func(n *node) {
-		if n.kind == basicLit || n.kind == identExpr || n.tnext == nil {
+		if n.kind == basicLit || n.tnext == nil {
 			return
 		}
 		var label string

interp/interp_eval_test.go

@@ -47,11 +47,17 @@ func TestEvalArithmetic(t *testing.T) {
 		{desc: "shl_IN", src: "1 << -1", err: "1:28: illegal operand types for '<<' operator"},
 		{desc: "shl_IF", src: "1 << 1.0", res: "2"},
 		{desc: "shl_IF1", src: "1 << 1.1", err: "1:28: illegal operand types for '<<' operator"},
-		{desc: "shl_IF", src: "1.0 << 1", res: "2"},
+		{desc: "shl_IF2", src: "1.0 << 1", res: "2"},
 		{desc: "shr_II", src: "1 >> 8", res: "0"},
 		{desc: "shr_IN", src: "1 >> -1", err: "1:28: illegal operand types for '>>' operator"},
 		{desc: "shr_IF", src: "1 >> 1.0", res: "0"},
 		{desc: "shr_IF1", src: "1 >> 1.1", err: "1:28: illegal operand types for '>>' operator"},
+		{desc: "neg_I", src: "-2", res: "-2"},
+		{desc: "pos_I", src: "+2", res: "2"},
+		{desc: "bitnot_I", src: "^2", res: "-3"},
+		{desc: "bitnot_F", src: "^0.2", err: "1:28: illegal operand type for '^' operator"},
+		{desc: "not_B", src: "!false", res: "true"},
+		{desc: "not_I", src: "!0", err: "1:28: illegal operand type for '!' operator"},
 	})
 }
 

interp/op.go

@@ -1864,6 +1864,57 @@ func inc(n *node) {
 	}
 }
 
+func bitNotConst(n *node) {
+	t := n.typ.rtype
+	v := n.child[0].rval
+	n.rval = reflect.New(t).Elem()
+	switch t.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n.rval.SetInt(^v.Int())
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.rval.SetUint(^v.Uint())
+	}
+}
+
+func negConst(n *node) {
+	t := n.typ.rtype
+	v := n.child[0].rval
+	n.rval = reflect.New(t).Elem()
+	switch t.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n.rval.SetInt(-v.Int())
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.rval.SetUint(-v.Uint())
+	case reflect.Float32, reflect.Float64:
+		n.rval.SetFloat(-v.Float())
+	case reflect.Complex64, reflect.Complex128:
+		n.rval.SetComplex(-v.Complex())
+	}
+}
+
+func notConst(n *node) {
+	t := n.typ.rtype
+	v := n.child[0].rval
+	n.rval = reflect.New(t).Elem()
+	n.rval.SetBool(!v.Bool())
+}
+
+func posConst(n *node) {
+	t := n.typ.rtype
+	v := n.child[0].rval
+	n.rval = reflect.New(t).Elem()
+	switch t.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n.rval.SetInt(+v.Int())
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.rval.SetUint(+v.Uint())
+	case reflect.Float32, reflect.Float64:
+		n.rval.SetFloat(+v.Float())
+	case reflect.Complex64, reflect.Complex128:
+		n.rval.SetComplex(+v.Complex())
+	}
+}
+
 func equal(n *node) {
 	tnext := getExec(n.tnext)
 	dest := genValue(n)

interp/run.go

@@ -24,6 +24,7 @@ var builtin = [...]bltnGenerator{
 	aAndAssign:    andAssign,
 	aAndNot:       andNot,
 	aAndNotAssign: andNotAssign,
+	aBitNot:       bitNot,
 	aCall:         call,
 	aCase:         _case,
 	aCompositeLit: arrayLit,
@@ -40,11 +41,12 @@ var builtin = [...]bltnGenerator{
 	aLowerEqual:   lowerEqual,
 	aMul:          mul,
 	aMulAssign:    mulAssign,
-	aNegate:       negate,
+	aNeg:          neg,
 	aNot:          not,
 	aNotEqual:     notEqual,
 	aOr:           or,
 	aOrAssign:     orAssign,
+	aPos:          pos,
 	aQuo:          quo,
 	aQuoAssign:    quoAssign,
 	aRange:        _range,
@@ -340,21 +342,24 @@ func assign(n *node) {
 }
 
 func not(n *node) {
+	dest := genValue(n)
 	value := genValue(n.child[0])
 	tnext := getExec(n.tnext)
+	i := n.findex
 
 	if n.fnext != nil {
 		fnext := getExec(n.fnext)
 		n.exec = func(f *frame) bltn {
 			if !value(f).Bool() {
+				f.data[i].SetBool(true)
 				return tnext
 			}
+			f.data[i].SetBool(false)
 			return fnext
 		}
 	} else {
-		i := n.findex
 		n.exec = func(f *frame) bltn {
-			f.data[i].SetBool(!value(f).Bool())
+			dest(f).SetBool(!value(f).Bool())
 			return tnext
 		}
 	}
@@ -658,7 +663,7 @@ func call(n *node) {
 				values = append(values, func(f *frame) reflect.Value { return f.data[ind] })
 			}
 		default:
-			if c.kind == basicLit {
+			if c.kind == basicLit || c.rval.IsValid() {
 				var argType reflect.Type
 				if variadic >= 0 && i >= variadic {
 					argType = n.child[0].typ.arg[variadic].val.TypeOf()
@@ -843,7 +848,7 @@ func callBin(n *node) {
 				values = append(values, func(f *frame) reflect.Value { return f.data[ind] })
 			}
 		default:
-			if c.kind == basicLit {
+			if c.kind == basicLit || c.rval.IsValid() {
 				// Convert literal value (untyped) to function argument type (if not an interface{})
 				var argType reflect.Type
 				if variadic >= 0 && i >= variadic {
@@ -1246,7 +1251,7 @@ func getIndexSeqMethod(n *node) {
 	}
 }
 
-func negate(n *node) {
+func neg(n *node) {
 	dest := genValue(n)
 	value := genValue(n.child[0])
 	next := getExec(n.tnext)
@@ -1270,6 +1275,37 @@ func negate(n *node) {
 	}
 }
 
+func pos(n *node) {
+	dest := genValue(n)
+	value := genValue(n.child[0])
+	next := getExec(n.tnext)
+
+	n.exec = func(f *frame) bltn {
+		dest(f).Set(value(f))
+		return next
+	}
+}
+
+func bitNot(n *node) {
+	dest := genValue(n)
+	value := genValue(n.child[0])
+	next := getExec(n.tnext)
+	typ := n.typ.TypeOf()
+
+	switch typ.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		n.exec = func(f *frame) bltn {
+			dest(f).SetInt(^value(f).Int())
+			return next
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.exec = func(f *frame) bltn {
+			dest(f).SetUint(^value(f).Uint())
+			return next
+		}
+	}
+}
+
 func land(n *node) {
 	value0 := genValue(n.child[0])
 	value1 := genValue(n.child[1])
@@ -1946,7 +1982,7 @@ func _close(n *node) {
 }
 
 func _complex(n *node) {
-	i := n.findex
+	dest := genValue(n)
 	c1, c2 := n.child[1], n.child[2]
 	convertLiteralValue(c1, floatType)
 	convertLiteralValue(c2, floatType)
@@ -1956,38 +1992,38 @@ func _complex(n *node) {
 
 	if typ := n.typ.TypeOf(); isComplex(typ) {
 		n.exec = func(f *frame) bltn {
-			f.data[i].SetComplex(complex(value0(f).Float(), value1(f).Float()))
+			dest(f).SetComplex(complex(value0(f).Float(), value1(f).Float()))
 			return next
 		}
 	} else {
 		// Not a complex type: ignore imaginary part
 		n.exec = func(f *frame) bltn {
-			f.data[i].Set(value0(f).Convert(typ))
+			dest(f).Set(value0(f).Convert(typ))
 			return next
 		}
 	}
 }
 
 func _imag(n *node) {
-	i := n.findex
+	dest := genValue(n)
 	convertLiteralValue(n.child[1], complexType)
 	value := genValue(n.child[1])
 	next := getExec(n.tnext)
 
 	n.exec = func(f *frame) bltn {
-		f.data[i].SetFloat(imag(value(f).Complex()))
+		dest(f).SetFloat(imag(value(f).Complex()))
 		return next
 	}
 }
 
 func _real(n *node) {
-	i := n.findex
+	dest := genValue(n)
 	convertLiteralValue(n.child[1], complexType)
 	value := genValue(n.child[1])
 	next := getExec(n.tnext)
 
 	n.exec = func(f *frame) bltn {
-		f.data[i].SetFloat(real(value(f).Complex()))
+		dest(f).SetFloat(real(value(f).Complex()))
 		return next
 	}
 }
@@ -2005,12 +2041,12 @@ func _delete(n *node) {
 }
 
 func _len(n *node) {
-	i := n.findex
+	dest := genValue(n)
 	value := genValue(n.child[1])
 	next := getExec(n.tnext)
 
 	n.exec = func(f *frame) bltn {
-		f.data[i].SetInt(int64(value(f).Len()))
+		dest(f).SetInt(int64(value(f).Len()))
 		return next
 	}
 }
@@ -2222,13 +2258,16 @@ func recv2(n *node) {
 }
 
 func convertLiteralValue(n *node, t reflect.Type) {
-	if n.kind != basicLit || t == nil || t.Kind() == reflect.Interface {
+	// Skip non-constant values, undefined target type or interface target type.
+	if !(n.kind == basicLit || n.rval.IsValid()) || t == nil || t.Kind() == reflect.Interface {
 		return
 	}
 	if n.rval.IsValid() {
+		// Convert constant value to target type.
 		n.rval = n.rval.Convert(t)
 	} else {
-		n.rval = reflect.New(t).Elem() // convert to type nil value
+		// Create a zero value of target type.
+		n.rval = reflect.New(t).Elem()
 	}
 }
 
@@ -2420,19 +2459,21 @@ func isNil(n *node) {
 		value = genValue(n.child[0])
 	}
 	tnext := getExec(n.tnext)
+	dest := genValue(n)
 
 	if n.fnext != nil {
 		fnext := getExec(n.fnext)
 		n.exec = func(f *frame) bltn {
 			if value(f).IsNil() {
+				dest(f).SetBool(true)
 				return tnext
 			}
+			dest(f).SetBool(false)
 			return fnext
 		}
 	} else {
-		i := n.findex
 		n.exec = func(f *frame) bltn {
-			f.data[i].SetBool(value(f).IsNil())
+			dest(f).SetBool(value(f).IsNil())
 			return tnext
 		}
 	}
@@ -2446,19 +2487,21 @@ func isNotNil(n *node) {
 		value = genValue(n.child[0])
 	}
 	tnext := getExec(n.tnext)
+	dest := genValue(n)
 
 	if n.fnext != nil {
 		fnext := getExec(n.fnext)
 		n.exec = func(f *frame) bltn {
 			if value(f).IsNil() {
+				dest(f).SetBool(false)
 				return fnext
 			}
+			dest(f).SetBool(true)
 			return tnext
 		}
 	} else {
-		i := n.findex
 		n.exec = func(f *frame) bltn {
-			f.data[i].SetBool(!value(f).IsNil())
+			dest(f).SetBool(!value(f).IsNil())
 			return tnext
 		}
 	}

stdlib/stdlib.go

@@ -1,5 +1,6 @@
 // +build go1.12,!go1.14
 
+// Package stdlib provides wrappers of standard library packages to be imported natively in Yaegi.
 package stdlib
 
 import "reflect"

stdlib/syscall/syscall.go

@@ -1,5 +1,6 @@
 // +build go1.12,!go1.14
 
+// Package syscall provide wrapper of standard library syscall package for native import in Yaegi.
 package syscall
 
 import "reflect"

stdlib/unsafe/unsafe.go

@@ -1,5 +1,6 @@
 // +build go1.12,!go1.14
 
+// Package unsafe provides wrapper of standard library unsafe package to be imported natively in Yaegi.
 package unsafe
 
 import "reflect"