Expand ${#unset_variable} to 0

magicant · Apr 23, 2024 · 82704c2 · 82704c2
1 parent 90c18ec
commit 82704c2
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Showing 3 changed files with 15 additions and 2 deletions.
diff --git a/yash-cli/tests/scripted_test/param-p.sh b/yash-cli/tests/scripted_test/param-p.sh
@@ -253,7 +253,6 @@ __IN__
 ${#?} 1
 __OUT__
 
-: TODO yash is broken <<\__OUT__
 test_oE -e 0 'length of unset variables, success'
 unset u
 echoraw ${#u}

diff --git a/yash-semantics/CHANGELOG.md b/yash-semantics/CHANGELOG.md
@@ -28,6 +28,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `<TextUnit as Expand>::expand` now correctly expands an unset parameter with a
   switch to an empty string regardless of the `Unset` shell option. Previously,
   it would expand to an empty string only if the `Unset` shell option was on.
+- The parameter expansion of an unset variable with a `Length` modifier now
+  correctly expands to `0` rather than an empty string.
 
 ## [0.1.0] - 2024-04-13
 

diff --git a/yash-semantics/src/expansion/initial/param.rs b/yash-semantics/src/expansion/initial/param.rs
@@ -99,7 +99,7 @@ impl Expand for ParamRef<'_> {
             Modifier::Length => {
                 // TODO Reject ${#*} and ${#@} in POSIX mode
                 match &mut value {
-                    None => (),
+                    None => value = Some(Value::scalar("0")),
                     Some(Value::Scalar(v)) => to_length(v),
                     Some(Value::Array(vs)) => vs.iter_mut().for_each(to_length),
                 }
@@ -189,6 +189,18 @@ pub mod tests {
         assert_eq!(phrase, Phrase::Field(to_field("a1\u{30A4}")));
     }
 
+    #[test]
+    fn length_of_unset() {
+        let mut env = yash_env::Env::new_virtual();
+        let mut env = Env::new(&mut env);
+        let mut param = param("foo");
+        param.modifier = Modifier::Length;
+        let param = ParamRef::from(&param);
+
+        let phrase = param.expand(&mut env).now_or_never().unwrap().unwrap();
+        assert_eq!(phrase, Phrase::Field(to_field("0")));
+    }
+
     #[test]
     fn length_of_scalar() {
         let mut env = yash_env::Env::new_virtual();