compiler: count the number of variables correctly

pkg/compiler/analysis.go

@@ -70,16 +70,16 @@ func (c *codegen) traverseGlobals(f ast.Node) {
 
 // countGlobals counts the global variables in the program to add
 // them with the stack size of the function.
-func countGlobals(f ast.Node) (i int64) {
+func countGlobals(f ast.Node) (i int) {
 	ast.Inspect(f, func(node ast.Node) bool {
-		switch node.(type) {
+		switch n := node.(type) {
 		// Skip all function declarations.
 		case *ast.FuncDecl:
 			return false
 		// After skipping all funcDecls we are sure that each value spec
 		// is a global declared variable or constant.
 		case *ast.ValueSpec:
-			i++
+			i += len(n.Names)
 		}
 		return true
 	})

pkg/compiler/func_scope.go

@@ -102,13 +102,8 @@ func (c *funcScope) countLocals() int {
 		case *ast.ReturnStmt, *ast.IfStmt:
 			size++
 		// This handles the inline GenDecl like "var x = 2"
-		case *ast.GenDecl:
-			switch t := n.Specs[0].(type) {
-			case *ast.ValueSpec:
-				if len(t.Values) > 0 {
-					size++
-				}
-			}
+		case *ast.ValueSpec:
+			size += len(n.Names)
 		}
 		return true
 	})

pkg/compiler/global_test.go

@@ -19,3 +19,27 @@ func TestChangeGlobal(t *testing.T) {
 
 	eval(t, src, big.NewInt(42))
 }
+
+func TestMultiDeclaration(t *testing.T) {
+	src := `package foo
+	var a, b, c int
+	func Main() int {
+		a = 1
+		b = 2
+		c = 3
+		return a + b + c
+	}`
+	eval(t, src, big.NewInt(6))
+}
+
+func TestMultiDeclarationLocal(t *testing.T) {
+	src := `package foo
+	func Main() int {
+		var a, b, c int
+		a = 1
+		b = 2
+		c = 3
+		return a + b + c
+	}`
+	eval(t, src, big.NewInt(6))
+}