Add strict variables mode.

tests/options.rs

@@ -1,7 +1,7 @@
 use rhai::{Engine, EvalAltResult};
 
 #[test]
-fn test_options() -> Result<(), Box<EvalAltResult>> {
+fn test_options_allow() -> Result<(), Box<EvalAltResult>> {
     let mut engine = Engine::new();
 
     engine.compile("let x = if y { z } else { w };")?;
@@ -33,3 +33,59 @@ fn test_options() -> Result<(), Box<EvalAltResult>> {
 
     Ok(())
 }
+
+#[test]
+fn test_options_strict_var() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+
+    engine.compile("let x = if y { z } else { w };")?;
+
+    #[cfg(not(feature = "no_function"))]
+    engine.compile("fn foo(x) { x + y }")?;
+
+    #[cfg(not(feature = "no_module"))]
+    engine.compile("print(h::y::z);")?;
+
+    #[cfg(not(feature = "no_module"))]
+    engine.compile("let x = h::y::foo();")?;
+
+    #[cfg(not(feature = "no_function"))]
+    #[cfg(not(feature = "no_module"))]
+    engine.compile("fn foo() { h::y::foo() }")?;
+
+    #[cfg(not(feature = "no_function"))]
+    engine.compile("let f = |y| x * y;")?;
+
+    engine.set_strict_variables(true);
+
+    assert!(engine.compile("let x = if y { z } else { w };").is_err());
+    engine.compile("let y = 42; let x = y;")?;
+
+    #[cfg(not(feature = "no_function"))]
+    assert!(engine.compile("fn foo(x) { x + y }").is_err());
+
+    #[cfg(not(feature = "no_module"))]
+    {
+        assert!(engine.compile("print(h::y::z);").is_err());
+        engine.compile(r#"import "hello" as h; print(h::y::z);"#)?;
+        assert!(engine.compile("let x = h::y::foo();").is_err());
+        engine.compile(r#"import "hello" as h; let x = h::y::foo();"#)?;
+    }
+
+    #[cfg(not(feature = "no_function"))]
+    #[cfg(not(feature = "no_module"))]
+    engine.compile("fn foo() { h::y::foo() }")?;
+
+    #[cfg(not(feature = "no_function"))]
+    {
+        assert!(engine.compile("let f = |y| x * y;").is_err());
+        #[cfg(not(feature = "no_closure"))]
+        {
+            engine.compile("let x = 42; let f = |y| x * y;")?;
+            engine.compile("let x = 42; let f = |y| { || x + y };")?;
+            assert!(engine.compile("fn foo() { |y| { || x + y } }").is_err());
+        }
+    }
+
+    Ok(())
+}