Don't panic on unrecognised enum variant tag

3 files changed, 17 insertions, 2 deletions

diff --git a/examples/14-transient-0/output/rust/src/gen/data/transient_0.rs b/examples/14-transient-0/output/rust/src/gen/data/transient_0.rs
index 765341e..541d9eb 100644
--- a/examples/14-transient-0/output/rust/src/gen/data/transient_0.rs
+++ b/examples/14-transient-0/output/rust/src/gen/data/transient_0.rs
@@ -172,7 +172,7 @@ pub fn decode_enum_with_variants(reader: &mut impl std::io::Read, shared_values:
         0 => crate::data::EnumWithVariants::Zero,
         1 => crate::data::EnumWithVariants::One,
         2 => crate::data::EnumWithVariants::Two,
-        _ => todo!(),
+        _ => ::std::result::Result::Err(::std::io::Error::new(::std::io::ErrorKind::InvalidData, "unrecognised variant tag"))?,
     })
 }
 
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttransient0/RustTransient0Generator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttransient0/RustTransient0Generator.java
index 20b21de..ec39245 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttransient0/RustTransient0Generator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttransient0/RustTransient0Generator.java
@@ -379,7 +379,19 @@ public class RustTransient0Generator implements Generator {
 
         decodeMatchArms.add(new RustMatchArm(
             new RustWildcardPattern(),
-            generateTodo()
+            new RustTryPropagationExpression(new RustCallExpression(
+                RustTypes.RESULT_ERR,
+                List.of(
+                    new RustCallExpression(
+                        RustTypes.IO_ERROR.addSegment(RustPathSegment.of("new")),
+                        List.of(
+                            RustTypes.IO_ERROR_KIND_INVALID_DATA,
+                            // TODO: include variant tag
+                            new RustStringLiteral("unrecognised variant tag")
+                        )
+                    )
+                )
+            ))
         ));
 
         return generateDecodeFunction(
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustTypes.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustTypes.java
index 5e6303a..3c5ab6c 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustTypes.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustTypes.java
@@ -49,6 +49,9 @@ public class RustTypes {
     public static RustPath NONE = RustPath.global("std", "option", "Option", "None");
     public static RustPath SOME = RustPath.global("std", "option", "Option", "Some");
 
+    public static RustPath RESULT = RustPath.global("std", "result", "Result");
+    public static RustPath RESULT_ERR = RESULT.addSegment(RustPathSegment.of("Err"));
+
     public static RustPath STRING = RustPath.global("std", "string", "String");
 
     public static RustPath ARC = RustPath.global("std", "sync", "Arc");