From 70625002b6b3ba280c700636ed8314f20e1384a7 Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Wed, 19 Jun 2024 13:55:21 +0200
Subject: fix (parser): don't panic if assign of define untyped value

In case of defining or assigning to untyped value, the type has
to be taken from the source value instead of the target value.

The vm test coverage has also been slightly improved.
---
 parser/compiler.go         | 17 +++++++++++++----
 parser/interpreter_test.go |  2 ++
 2 files changed, 15 insertions(+), 4 deletions(-)

(limited to 'parser')

diff --git a/parser/compiler.go b/parser/compiler.go
index 3b9a32d..aa16888 100644
--- a/parser/compiler.go
+++ b/parser/compiler.go
@@ -61,13 +61,14 @@ func (c *Compiler) Codegen(tokens Tokens) (err error) {
 
 		case lang.String:
 			s := t.Block()
+			v := vm.Value{Data: reflect.ValueOf(s), Type: vm.TypeOf(s)}
 			i, ok := c.strings[s]
 			if !ok {
 				i = len(c.Data)
-				c.Data = append(c.Data, vm.ValueOf(s))
+				c.Data = append(c.Data, v)
 				c.strings[s] = i
 			}
-			push(&symbol{kind: symConst, value: vm.ValueOf(s)})
+			push(&symbol{kind: symConst, value: v})
 			emit(int64(t.Pos), vm.Dup, int64(i))
 
 		case lang.Add:
@@ -144,7 +145,11 @@ func (c *Compiler) Codegen(tokens Tokens) (err error) {
 			// TODO: support assignment to local, composite objects.
 			st := tokens[i-1]
 			l := len(c.Data)
-			typ := pop().Type
+			d := pop()
+			typ := d.Type
+			if typ == nil {
+				typ = d.value.Type
+			}
 			v := vm.NewValue(typ)
 			c.addSym(l, st.Str, v, symVar, typ, false)
 			c.Data = append(c.Data, v)
@@ -160,7 +165,11 @@ func (c *Compiler) Codegen(tokens Tokens) (err error) {
 			if !ok {
 				return fmt.Errorf("symbol not found: %s", st.Str)
 			}
-			typ := pop().Type
+			d := pop()
+			typ := d.Type
+			if typ == nil {
+				typ = d.value.Type
+			}
 			if s.Type == nil {
 				s.Type = typ
 				s.value = vm.NewValue(typ)
diff --git a/parser/interpreter_test.go b/parser/interpreter_test.go
index a6ad246..314f35b 100644
--- a/parser/interpreter_test.go
+++ b/parser/interpreter_test.go
@@ -69,6 +69,7 @@ func TestExpr(t *testing.T) {
 		{src: "-2 + 5", res: "3"},
 		{src: "5 + -2", res: "3"},
 		{src: "!false", res: "true"},
+		{src: `a := "hello"`, res: "hello"},
 	})
 }
 
@@ -233,6 +234,7 @@ func TestVar(t *testing.T) {
 		{src: "var a, b int = 2, 5; a+b", res: "7"},
 		{src: "var x = 5; x", res: "5"},
 		{src: "var a = 1; func f() int { var a, b int = 3, 4; return a+b}; a+f()", res: "8"},
+		{src: `var a = "hello"; a`, res: "hello"},
 		{src: `var (
 	a, b int = 4+1, 3
 	c = 8
-- 
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