Throw exception when variant tag is unrecognised

2 files changed, 14 insertions, 2 deletions

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
index ac38727..b1533d2 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
@@ -462,8 +462,18 @@ public class JavaTransient0Generator implements Generator {
 
                 cases.add(new JavaSwitchRule(
                     new JavaCaseDefault(),
-                    // TODO: throw an exception
-                    new JavaBlock(List.of(new JavaReturn(new JavaNullLiteral())))
+                    new JavaBlock(List.of(
+                        new JavaThrowStatement(new JavaNewExpression(
+                            JavaTypeRef.RUNTIME_EXCEPTION,
+                            List.of(
+                                new JavaBinaryOperation(
+                                    JavaBinaryOperator.ADD,
+                                    new JavaStringLiteral("unexpected " + sumDefinition.type().describe() + " variant tag: "),
+                                    new JavaRef(variantTag)
+                                )
+                            )
+                        ))
+                    ))
                 ));
 
                 decodeStatements.add(new JavaSwitchStatement(
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeRef.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeRef.java
index 8dbca61..81e0acc 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeRef.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeRef.java
@@ -85,6 +85,8 @@ public record JavaTypeRef(JavaPackageName packageName, List<JavaIdentifier> type
 
     public static final JavaTypeRef OUTPUT_STREAM = topLevel(JavaPackages.JAVA_IO, JavaIdentifier.of("OutputStream"));
 
+    public static final JavaTypeRef RUNTIME_EXCEPTION = topLevel(JavaPackages.JAVA_LANG, JavaIdentifier.of("RuntimeException"));
+
     public static final JavaTypeRef STANDARD_CHARSETS = topLevel(JavaPackages.JAVA_NIO_CHARSET, JavaIdentifier.of("StandardCharsets"));
 
     public static final JavaTypeRef STREAM = topLevel(JavaPackages.JAVA_UTIL_STREAM, JavaIdentifier.of("Stream"));