Fixed/inc dec

compiler.go

@@ -664,11 +664,23 @@ func (c *Compiler) compileAssign(
 		if depth == 0 && exists {
 			return c.errorf(node, "'%s' redeclared in this block", ident)
 		}
-		symbol = c.symbolTable.Define(ident)
+		symbol = c.symbolTable.Define(ident, rhs[0])
 	} else {
 		if !exists {
 			return c.errorf(node, "unresolved reference '%s'", ident)
+		} else {
+			symbol, ok := c.symbolTable.store[ident]
+			if ok {
+				switch symbol.Expr.(type) {
+				case *parser.IntLit, *parser.FloatLit, *parser.CharLit:
+					break
+				default:
+					return c.errorf(node, "invalid operation: ++/-- (non-numeric type)")
+
+				}
+			}
 		}
+
 	}
 
 	// +=, -=, *=, /=

symbol_table.go

@@ -1,5 +1,7 @@
 package tengo
 
+import "github.com/d5/tengo/v2/parser"
+
 // SymbolScope represents a symbol scope.
 type SymbolScope string
 
@@ -17,6 +19,7 @@ type Symbol struct {
 	Scope         SymbolScope
 	Index         int
 	LocalAssigned bool // if the local symbol is assigned at least once
+	Expr          parser.Expr
 }
 
 // SymbolTable represents a symbol table.
@@ -38,7 +41,7 @@ func NewSymbolTable() *SymbolTable {
 }
 
 // Define adds a new symbol in the current scope.
-func (t *SymbolTable) Define(name string) *Symbol {
+func (t *SymbolTable) Define(name string, expr ...parser.Expr) *Symbol {
 	symbol := &Symbol{Name: name, Index: t.nextIndex()}
 	t.numDefinition++
 
@@ -58,6 +61,9 @@ func (t *SymbolTable) Define(name string) *Symbol {
 	} else {
 		symbol.Scope = ScopeLocal
 	}
+	if len(expr) > 0 {
+		symbol.Expr = expr[0]
+	}
 	t.store[name] = symbol
 	t.updateMaxDefs(symbol.Index + 1)
 	return symbol