Fix decoding of LangError (#919)

* Decode enum variants using discriminant * Clippy
use-ink · Jan 25, 2023 · 30ba1ec · 30ba1ec
1 parent 2e8e4eb
commit 30ba1ec
Show file tree

Hide file tree

Showing 3 changed files with 32 additions and 2 deletions.
diff --git a/crates/cargo-contract/src/cmd/extrinsics/call.rs b/crates/cargo-contract/src/cmd/extrinsics/call.rs
@@ -44,6 +44,7 @@ use contract_build::name_value_println;
 
 use anyhow::{
     anyhow,
+    Context,
     Result,
 };
 
@@ -112,7 +113,11 @@ impl CallCommand {
                 match result.result {
                     Ok(ref ret_val) => {
                         let value = transcoder
-                            .decode_return(&self.message, &mut &ret_val.data[..])?;
+                            .decode_return(&self.message, &mut &ret_val.data[..])
+                            .context(format!(
+                                "Failed to decode return value {:?}",
+                                &ret_val
+                            ))?;
                         let dry_run_result = CallDryRunResult {
                             result: String::from("Success!"),
                             reverted: ret_val.did_revert(),

diff --git a/crates/transcode/src/decode.rs b/crates/transcode/src/decode.rs
@@ -180,7 +180,8 @@ impl<'a> Decoder<'a> {
         let discriminant = input.read_byte()?;
         let variant = variant_type
             .variants()
-            .get(discriminant as usize)
+            .iter()
+            .find(|v| v.index == discriminant)
             .ok_or_else(|| {
                 anyhow::anyhow!("No variant found with discriminant {}", discriminant)
             })?;

diff --git a/crates/transcode/src/lib.rs b/crates/transcode/src/lib.rs
@@ -629,6 +629,30 @@ mod tests {
         assert_eq!(expected, decoded);
     }
 
+    #[test]
+    fn decode_lang_error() {
+        use ink::primitives::LangError;
+
+        let metadata = generate_metadata();
+        let transcoder = ContractMessageTranscoder::new(metadata);
+
+        let encoded =
+            Result::<bool, LangError>::Err(LangError::CouldNotReadInput).encode();
+        let decoded = transcoder
+            .decode_return("get", &mut &encoded[..])
+            .unwrap_or_else(|e| panic!("Error decoding return value {}", e));
+
+        let expected = Value::Tuple(Tuple::new(
+            "Err".into(),
+            [Value::Tuple(Tuple::new(
+                Some("CouldNotReadInput"),
+                Vec::new(),
+            ))]
+            .to_vec(),
+        ));
+        assert_eq!(expected, decoded);
+    }
+
     #[test]
     fn decode_contract_event() -> Result<()> {
         let metadata = generate_metadata();