Merge pull request #5402 from Luv-Ray/short-circuit

`expr`: short-circuit evaluation for `&`

src/uu/expr/src/syntax_tree.rs

@@ -166,17 +166,27 @@ impl AstNode {
         {
             let mut out = Vec::with_capacity(operands.len());
             let mut operands = operands.iter();
-            // check the first value before `|`, stop evaluate and return directly if it is true.
+
-            // push dummy to pass the check of `len() == 2`
-            if op_type == "|" {
             if let Some(value) = operands.next() {
                 let value = value.evaluate()?;
                 out.push(value.clone());
+                // short-circuit evaluation for `|` and `&`
+                // push dummy to pass `assert!(values.len() == 2);`
+                match op_type.as_ref() {
+                    "|" => {
                         if value_as_bool(&value) {
                             out.push(String::from("dummy"));
                             return Ok(out);
                         }
                     }
+                    "&" => {
+                        if !value_as_bool(&value) {
+                            out.push(String::from("dummy"));
+                            return Ok(out);
+                        }
+                    }
+                    _ => {}
+                }
             }
 
             for operand in operands {

tests/by-util/test_expr.rs

@@ -155,6 +155,21 @@ fn test_and() {
         .args(&["-14", "&", "1"])
         .run()
         .stdout_is("-14\n");
+
+    new_ucmd!()
+        .args(&["0", "&", "a", "/", "5"])
+        .run()
+        .stdout_only("0\n");
+
+    new_ucmd!()
+        .args(&["", "&", "a", "/", "5"])
+        .run()
+        .stdout_only("0\n");
+
+    new_ucmd!()
+        .args(&["-1", "&", "10", "/", "5"])
+        .succeeds()
+        .stdout_only("-1\n");
 }
 
 #[test]