fix: correctly init variables from index expressions

_test/type18.go

@@ -0,0 +1,20 @@
+package main
+
+type T struct {
+	name string
+	size int
+}
+
+var table = []*T{{
+	name: "foo",
+	size: 2,
+}}
+
+var s = table[0].size
+
+func main() {
+	println(s)
+}
+
+// Output:
+// 2

_test/type19.go

@@ -0,0 +1,21 @@
+package main
+
+type T struct {
+	name string
+	size int
+}
+
+var table = map[int]*T{
+	0: {
+		name: "foo",
+		size: 2,
+	}}
+
+var s = table[0].size
+
+func main() {
+	println(s)
+}
+
+// Output:
+// 2

interp/cfg.go

@@ -840,7 +840,7 @@ func (interp *Interpreter) cfg(root *node, pkgID string) ([]*node, error) {
 				n.findex = sc.add(n.typ)
 			}
 			// TODO: Check that composite literal expr matches corresponding type
-			n.gen = compositeGenerator(n)
+			n.gen = compositeGenerator(n, sc)
 
 		case fallthroughtStmt:
 			if n.anc.kind != caseBody {
@@ -1869,21 +1869,32 @@ func gotoLabel(s *symbol) {
 	}
 }
 
-func compositeGenerator(n *node) (gen bltnGenerator) {
+func compositeGenerator(n *node, sc *scope) (gen bltnGenerator) {
 	switch n.typ.cat {
 	case aliasT, ptrT:
 		n.typ.val.untyped = n.typ.untyped
 		n.typ = n.typ.val
-		gen = compositeGenerator(n)
+		gen = compositeGenerator(n, sc)
 	case arrayT:
 		gen = arrayLit
 	case mapT:
 		gen = mapLit
 	case structT:
-		if len(n.child) > 0 && n.lastChild().kind == keyValueExpr {
-			gen = compositeSparse
-		} else {
-			gen = compositeLit
+		switch {
+		case len(n.child) == 0:
+			gen = compositeLitNotype
+		case n.lastChild().kind == keyValueExpr:
+			if n.child[0].isType(sc) {
+				gen = compositeSparse
+			} else {
+				gen = compositeSparseNotype
+			}
+		default:
+			if n.child[0].isType(sc) {
+				gen = compositeLit
+			} else {
+				gen = compositeLitNotype
+			}
 		}
 	case valueT:
 		switch k := n.typ.rtype.Kind(); k {
@@ -1895,7 +1906,7 @@ func compositeGenerator(n *node) (gen bltnGenerator) {
 			log.Panic(n.cfgErrorf("compositeGenerator not implemented for type kind: %s", k))
 		}
 	}
-	return
+	return gen
 }
 
 // arrayTypeLen returns the node's array length. If the expression is an

interp/run.go

@@ -1680,12 +1680,12 @@ func destType(n *node) *itype {
 	}
 }
 
-// compositeLit creates and populates a struct object
-func compositeLit(n *node) {
+// doCompositeLit creates and populates a struct object
+func doCompositeLit(n *node, hasType bool) {
 	value := valueGenerator(n, n.findex)
 	next := getExec(n.tnext)
 	child := n.child
-	if !n.typ.untyped {
+	if hasType {
 		child = n.child[1:]
 	}
 	destInterface := destType(n).cat == interfaceT
@@ -1717,12 +1717,15 @@ func compositeLit(n *node) {
 	}
 }
 
-// compositeSparse creates a struct Object, filling fields from sparse key-values
-func compositeSparse(n *node) {
+func compositeLit(n *node)       { doCompositeLit(n, true) }
+func compositeLitNotype(n *node) { doCompositeLit(n, false) }
+
+// doCompositeSparse creates a struct Object, filling fields from sparse key-values
+func doCompositeSparse(n *node, hasType bool) {
 	value := valueGenerator(n, n.findex)
 	next := getExec(n.tnext)
 	child := n.child
-	if !n.typ.untyped {
+	if hasType {
 		child = n.child[1:]
 	}
 
@@ -1752,6 +1755,9 @@ func compositeSparse(n *node) {
 	}
 }
 
+func compositeSparse(n *node)       { doCompositeSparse(n, true) }
+func compositeSparseNotype(n *node) { doCompositeSparse(n, false) }
+
 func empty(n *node) {}
 
 var rat = reflect.ValueOf((*[]rune)(nil)).Type().Elem() // runes array type

interp/type.go

@@ -406,6 +406,20 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 			sc.sym[n.ident] = &symbol{kind: typeSym, typ: t}
 		}
 
+	case indexExpr:
+		var lt *itype
+		if lt, err = nodeType(interp, sc, n.child[0]); err != nil {
+			return nil, err
+		}
+		if lt.incomplete {
+			t.incomplete = true
+			break
+		}
+		switch lt.cat {
+		case arrayT, mapT:
+			t = lt.val
+		}
+
 	case interfaceType:
 		t.cat = interfaceT
 		if sname := typeName(n); sname != "" {