Fix crash when inspecting a CHRSXP (#701)

* Fix crash when inspecting a `CHRSXP`

* Skip if rlang is not installed.

crates/ark/src/variables/variable.rs

@@ -99,6 +99,7 @@ impl WorkspaceVariableDisplayValue {
             CLOSXP => Self::from_closure(value),
             ENVSXP => Self::from_env(value),
             LANGSXP => Self::from_language(value),
+            CHARSXP => Self::from_charsxp(value),
             _ if r_is_matrix(value) => Self::from_matrix(value)?,
             RAWSXP | LGLSXP | INTSXP | REALSXP | STRSXP | CPLXSXP => Self::from_default(value)?,
             _ if r_is_s4(value) => Self::from_s4(value)?,
@@ -356,6 +357,10 @@ impl WorkspaceVariableDisplayValue {
         Ok(Self::new(display_value, false))
     }
 
+    fn from_charsxp(_: SEXP) -> Self {
+        Self::new(String::from("<CHARSXP>"), false)
+    }
+
     fn from_default(value: SEXP) -> anyhow::Result<Self> {
         let formatted = FormattedVector::new(RObject::from(value))?;
 
@@ -445,6 +450,11 @@ impl WorkspaceVariableDisplayType {
             return Self::from_class(value, String::from("S4"));
         }
 
+        // We can't check attributes of CHARSXP, so we just short-circuit here
+        if r_typeof(value) == CHARSXP {
+            return Self::simple(String::from("CHARSXP"));
+        }
+
         if r_is_simple_vector(value) {
             let display_type = match include_length {
                 true => match r_vec_is_single_dimension_with_single_value(value) {
@@ -2078,4 +2088,26 @@ mod tests {
             assert!(vars[0].display_value.starts_with("<S4 class"),);
         })
     }
+
+    #[test]
+    fn test_charsxp() {
+        r_task(|| {
+            // Skip test if rlang is not installed
+            if let Ok(false) = harp::parse_eval_global(r#".ps.is_installed("rlang")"#)
+                .unwrap()
+                .try_into()
+            {
+                return;
+            }
+
+            let env = Environment::new_empty().unwrap();
+            let value = harp::parse_eval_base(r#"rlang:::chr_get("foo", 0L)"#).unwrap();
+            env.bind("x".into(), &value);
+
+            let path = vec![];
+            let vars = PositronVariable::inspect(env.into(), &path).unwrap();
+            assert_eq!(vars.len(), 1);
+            assert_eq!(vars[0].display_value, "<CHARSXP>");
+        })
+    }
 }

crates/harp/src/utils.rs

@@ -158,6 +158,11 @@ pub fn r_is_simple_vector(value: SEXP) -> bool {
 ///
 /// Notably returns `false` for 1D arrays and >=3D arrays.
 pub fn r_is_matrix(object: SEXP) -> bool {
+    // We can't check the `dim` attribute for CHARSXP's
+    if r_typeof(object) == CHARSXP {
+        return false;
+    }
+
     let dim = r_dim(object);
 
     if dim == r_null() {