Return multiple values from Patio functions

5 files changed, 14 insertions, 82 deletions

diff --git a/src/test/java/org/shedlang/compiler/backends/cranelift/PatioToCraneliftAmd64Tests.java b/src/test/java/org/shedlang/compiler/backends/cranelift/PatioToCraneliftAmd64Tests.java
index 3d258e0f..f8814ba7 100644
--- a/src/test/java/org/shedlang/compiler/backends/cranelift/PatioToCraneliftAmd64Tests.java
+++ b/src/test/java/org/shedlang/compiler/backends/cranelift/PatioToCraneliftAmd64Tests.java
@@ -29,7 +29,7 @@ public class PatioToCraneliftAmd64Tests extends PatioExampleTests {
             "main",
             PatioVisibility.PUBLIC,
             List.of(),
-            PatioTypes.INT32,
+            List.of(PatioTypes.INT32),
             List.of(
                 Patio.call(
                     Optional.empty(),
diff --git a/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java b/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
index 8267a13a..eed0e9f3 100644
--- a/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
+++ b/src/test/java/org/shedlang/compiler/patio/PatioExampleTests.java
@@ -26,7 +26,6 @@ public abstract class PatioExampleTests {
     public void intConstCreatesConstantIntValue() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addBodyInstruction(emitInt(Patio.intConst(42)))
             .addBodyInstruction(Patio.returnVoid())
             .build();
@@ -45,7 +44,6 @@ public abstract class PatioExampleTests {
     public void localsAreStoredByName() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(PatioLocal.val("a", PatioTypes.INT))
             .addLocal(PatioLocal.val("b", PatioTypes.INT))
             .addBodyInstruction(Patio.localStore(Patio.localRef("a"), Patio.intConst(42)))
@@ -76,7 +74,6 @@ public abstract class PatioExampleTests {
         );
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.memoryLoad(
                 Patio.localRef("x"),
@@ -115,7 +112,6 @@ public abstract class PatioExampleTests {
         );
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.memoryLoad(
                 Patio.localRef("x"),
@@ -152,7 +148,6 @@ public abstract class PatioExampleTests {
         );
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.memoryStore(
                 Patio.dataPtrConst("answer"),
@@ -192,7 +187,6 @@ public abstract class PatioExampleTests {
         );
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.memoryLoad(
                 Patio.localRef("x"),
@@ -226,7 +220,6 @@ public abstract class PatioExampleTests {
                 Patio.localRef("x"),
                 Patio.dataPtrConst(Patio.dataPtrValueNull())
             ))
-            .withReturnType(PatioTypes.VOID)
             .addBodyInstruction(Patio.returnVoid())
             .build();
         var patio = Patio.compilationUnit(List.of(
@@ -248,7 +241,6 @@ public abstract class PatioExampleTests {
         );
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("ptr_int", PatioTypes.INT))
             .addLocal(Patio.val("ptr", PatioTypes.DATA_PTR))
@@ -281,7 +273,6 @@ public abstract class PatioExampleTests {
     public void blockSingleResult() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.block(
                 List.of(
@@ -308,7 +299,6 @@ public abstract class PatioExampleTests {
     public void blockMultipleResults() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addBodyInstruction(Patio.block(
@@ -342,7 +332,6 @@ public abstract class PatioExampleTests {
     public void ifCanHaveOneResult() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.if_(
                 List.of(Patio.localRef("x")),
@@ -366,7 +355,6 @@ public abstract class PatioExampleTests {
     public void ifCanHaveMultipleResults() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addBodyInstruction(Patio.if_(
@@ -393,7 +381,6 @@ public abstract class PatioExampleTests {
     public void loopRunsUntilEndIsReachedWithoutContinue() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("c", PatioTypes.BOOL))
             .addLocal(Patio.var("x_var", PatioTypes.INT))
             .addLocal(Patio.val("x_current", PatioTypes.INT))
@@ -428,7 +415,6 @@ public abstract class PatioExampleTests {
     public void loopCanExitEarlyWithBreak() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("c", PatioTypes.BOOL))
             .addLocal(Patio.var("x_var", PatioTypes.INT))
             .addLocal(Patio.val("x_current", PatioTypes.INT))
@@ -464,7 +450,6 @@ public abstract class PatioExampleTests {
     public void boolToIntToBoolIsIdentityForFalse() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.BOOL))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z", PatioTypes.BOOL))
@@ -503,7 +488,6 @@ public abstract class PatioExampleTests {
     public void boolToIntToBoolIsIdentityForTrue() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.BOOL))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z", PatioTypes.BOOL))
@@ -542,7 +526,6 @@ public abstract class PatioExampleTests {
     public void intAdd() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z", PatioTypes.INT))
@@ -584,7 +567,6 @@ public abstract class PatioExampleTests {
     ) throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z_bool", PatioTypes.BOOL))
@@ -631,7 +613,6 @@ public abstract class PatioExampleTests {
     ) throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z_bool", PatioTypes.BOOL))
@@ -669,7 +650,6 @@ public abstract class PatioExampleTests {
     public void intSub() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z", PatioTypes.INT))
@@ -702,7 +682,6 @@ public abstract class PatioExampleTests {
     public void switchWithUnreachableDefault() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("x1", PatioTypes.INT))
             .addLocal(Patio.val("x2", PatioTypes.INT))
@@ -750,7 +729,6 @@ public abstract class PatioExampleTests {
     public void switchWithReachableDefault() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addLocal(Patio.val("x1", PatioTypes.INT))
             .addLocal(Patio.val("x2", PatioTypes.INT))
@@ -791,13 +769,12 @@ public abstract class PatioExampleTests {
     public void canCallFunctionWithoutArgsDefinedInModule() throws IOException, InterruptedException {
         var calledFunction = PatioFunctionDefinition.builder()
             .withName("get")
-            .withReturnType(PatioTypes.INT)
+            .addReturnType(PatioTypes.INT)
             .addBodyInstruction(Patio.return_(Patio.intConst(42)))
             .build();
 
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.call(
                 Optional.of(Patio.localRef("x")),
@@ -821,13 +798,12 @@ public abstract class PatioExampleTests {
         var calledFunction = PatioFunctionDefinition.builder()
             .withName("identity")
             .addLocal(PatioLocal.param("x", PatioTypes.INT))
-            .withReturnType(PatioTypes.INT)
+            .addReturnType(PatioTypes.INT)
             .addBodyInstruction(Patio.return_(Patio.localRef("x")))
             .build();
 
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.call(
                 Optional.of(Patio.localRef("x")),
@@ -850,13 +826,12 @@ public abstract class PatioExampleTests {
     public void canCallPointerToFunctionDefinedInModule() throws IOException, InterruptedException {
         var calledFunction = PatioFunctionDefinition.builder()
             .withName("get")
-            .withReturnType(PatioTypes.INT)
+            .addReturnType(PatioTypes.INT)
             .addBodyInstruction(Patio.return_(Patio.intConst(42)))
             .build();
 
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.callPointer(
                 Patio.localRef("x"),
@@ -879,7 +854,6 @@ public abstract class PatioExampleTests {
     public void whenExceptionIsNotThrownThenTryReturnsFromBody() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -920,7 +894,6 @@ public abstract class PatioExampleTests {
     public void whenExceptionIsThrownThenFirstMatchingExceptionHandlerIsUsed() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -981,7 +954,6 @@ public abstract class PatioExampleTests {
     public void multipleCatchClausesCanBeAttachedToSameTry() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -1033,7 +1005,6 @@ public abstract class PatioExampleTests {
     public void whenExceptionIsThrownThenExceptionHandlerForOtherExceptionsIsIgnored() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -1095,7 +1066,6 @@ public abstract class PatioExampleTests {
     public void catchClauseCanThrow() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -1158,7 +1128,6 @@ public abstract class PatioExampleTests {
     public void exceptionHandlerIsDiscardedAfterTry() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -1218,7 +1187,6 @@ public abstract class PatioExampleTests {
     public void thrownValueIsPassedToCatchClause() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r", PatioTypes.INT))
             .addLocal(Patio.val("e", PatioTypes.INT))
             .addBodyInstruction(Patio.try_(
@@ -1259,7 +1227,6 @@ public abstract class PatioExampleTests {
     public void tryCanHaveMultipleResults() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("r1", PatioTypes.INT))
             .addLocal(Patio.val("r2", PatioTypes.INT))
             .addLocal(Patio.val("e1", PatioTypes.INT))
@@ -1302,7 +1269,6 @@ public abstract class PatioExampleTests {
     public void vars() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.var("x", PatioTypes.INT))
             .addLocal(Patio.val("y", PatioTypes.INT))
             .addLocal(Patio.val("z", PatioTypes.INT))
@@ -1344,7 +1310,6 @@ public abstract class PatioExampleTests {
     public void canGetByteOffsetOf() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.localStore(
                 Patio.localRef("x"),
@@ -1383,7 +1348,6 @@ public abstract class PatioExampleTests {
     public void canGetByteSizeOf() throws IOException, InterruptedException {
         var patioFunction = PatioFunctionDefinition.builder()
             .withName(FUNCTION_NAME)
-            .withReturnType(PatioTypes.VOID)
             .addLocal(Patio.val("x", PatioTypes.INT))
             .addBodyInstruction(Patio.localStore(
                 Patio.localRef("x"),
@@ -1432,7 +1396,6 @@ public abstract class PatioExampleTests {
         var emitIntDeclaration = PatioFunctionDeclaration.builder()
             .withName("patio__test__emit_int")
             .addParam(PatioLocal.param("value", PatioTypes.INT))
-            .withReturnType(PatioTypes.VOID)
             .build();
 
         var result = executeCompilationUnit(new PatioCompilationUnit(
diff --git a/src/test/java/org/shedlang/compiler/patio/PatioSerializerTests.java b/src/test/java/org/shedlang/compiler/patio/PatioSerializerTests.java
index 5cf44a1a..76b336ea 100644
--- a/src/test/java/org/shedlang/compiler/patio/PatioSerializerTests.java
+++ b/src/test/java/org/shedlang/compiler/patio/PatioSerializerTests.java
@@ -19,7 +19,6 @@ public class PatioSerializerTests {
     public void canSerializeCompilationUnit() {
         var element = PatioFunctionDefinition.builder()
             .withName("f")
-            .withReturnType(PatioTypes.VOID)
             .build();
         var compilationUnit = Patio.compilationUnit(List.of(element));
 
@@ -32,7 +31,7 @@ public class PatioSerializerTests {
                     "f"
                     visibility=private
                     locals=()
-                    return-type=void
+                    return-types=()
                     body=(
                     )
                 )
@@ -106,7 +105,7 @@ public class PatioSerializerTests {
             .withName("f")
             .addParam(Patio.param("param1", PatioTypes.INT))
             .addParam(Patio.param("param2", PatioTypes.DATA_PTR))
-            .withReturnType(PatioTypes.VOID)
+            .addReturnType(PatioTypes.INT32)
             .build();
 
         var string = PatioTesting.serializeCompilationUnitElement(element);
@@ -116,7 +115,7 @@ public class PatioSerializerTests {
                 function-decl
                 "f"
                 params=((param "param1" int) (param "param2" data-ptr))
-                return-type=void
+                return-types=(int32)
             )"""
         ));
     }
@@ -130,7 +129,7 @@ public class PatioSerializerTests {
             .addLocal(Patio.param("param2", PatioTypes.DATA_PTR))
             .addLocal(Patio.val("local1", PatioTypes.FUNCTION_PTR))
             .addLocal(Patio.val("local2", PatioTypes.INT))
-            .withReturnType(PatioTypes.VOID)
+            .addReturnType(PatioTypes.INT32)
             .addBodyInstruction(Patio.localStore(Patio.localRef("local2"), Patio.intConst(2)))
             .build();
 
@@ -142,7 +141,7 @@ public class PatioSerializerTests {
                 "f"
                 visibility=private
                 locals=((param "param1" int) (param "param2" data-ptr) (val "local1" function-ptr) (val "local2" int))
-                return-type=void
+                return-types=(int32)
                 body=(
                     (local-store (local "local2") (int-const 2))
                 )
@@ -479,16 +478,7 @@ public class PatioSerializerTests {
 
         var string = PatioTesting.serializeInstruction(instruction);
 
-        assertThat(string, equalTo("(return (local \"value\"))"));
-    }
-
-    @Test
-    public void canSerializeReturnVoid() {
-        var instruction = Patio.returnVoid();
-
-        var string = PatioTesting.serializeInstruction(instruction);
-
-        assertThat(string, equalTo("(return-void)"));
+        assertThat(string, equalTo("(return ((local \"value\")))"));
     }
 
     @Test
@@ -889,15 +879,6 @@ public class PatioSerializerTests {
         assertThat(string, equalTo("int32"));
     }
 
-    @Test
-    public void canSerializeVoidType() {
-        var type = PatioTypes.VOID;
-
-        var string = PatioTesting.serializeType(type);
-
-        assertThat(string, equalTo("void"));
-    }
-
     // == Data layouts ==
 
     @Test
diff --git a/src/test/java/org/shedlang/compiler/patio/instructions/Patio.java b/src/test/java/org/shedlang/compiler/patio/instructions/Patio.java
index 5bdd24df..0c0de429 100644
--- a/src/test/java/org/shedlang/compiler/patio/instructions/Patio.java
+++ b/src/test/java/org/shedlang/compiler/patio/instructions/Patio.java
@@ -299,11 +299,11 @@ public class Patio {
     }
 
     public static PatioInstruction return_(PatioOperand value) {
-        return new PatioReturn(value, Sources.NULL);
+        return new PatioReturn(List.of(value), Sources.NULL);
     }
 
     public static PatioInstruction returnVoid() {
-        return new PatioReturnVoid(Sources.NULL);
+        return new PatioReturn(List.of(), Sources.NULL);
     }
 
     public static PatioInstruction switch_(
diff --git a/src/test/java/org/shedlang/compiler/patio/serialization/PatioSerializationTests.java b/src/test/java/org/shedlang/compiler/patio/serialization/PatioSerializationTests.java
index be71c7ce..2f2990bb 100644
--- a/src/test/java/org/shedlang/compiler/patio/serialization/PatioSerializationTests.java
+++ b/src/test/java/org/shedlang/compiler/patio/serialization/PatioSerializationTests.java
@@ -28,7 +28,6 @@ public abstract class PatioSerializationTests {
     public void canSerializeCompilationUnit() {
         var element = PatioFunctionDefinition.builder()
             .withName("f")
-            .withReturnType(PatioTypes.VOID)
             .build();
         var compilationUnit = Patio.compilationUnit(List.of(element));
 
@@ -112,7 +111,7 @@ public abstract class PatioSerializationTests {
             .withName("f")
             .addParam(Patio.param("param1", PatioTypes.INT))
             .addParam(Patio.param("param2", PatioTypes.DATA_PTR))
-            .withReturnType(PatioTypes.VOID)
+            .addReturnType(PatioTypes.INT32)
             .build();
 
         var deserializedElement = deserializeCompilationUnitElement(
@@ -132,7 +131,7 @@ public abstract class PatioSerializationTests {
             .addLocal(Patio.param("param2", PatioTypes.DATA_PTR))
             .addLocal(Patio.val("local1", PatioTypes.FUNCTION_PTR))
             .addLocal(Patio.val("local2", PatioTypes.INT))
-            .withReturnType(PatioTypes.VOID)
+            .addReturnType(PatioTypes.INT32)
             .addBodyInstruction(Patio.localStore(Patio.localRef("local2"), Patio.intConst(2)))
             .build();
 
@@ -868,17 +867,6 @@ public abstract class PatioSerializationTests {
         assertThat(deserializedType, equalTo(type));
     }
 
-    @Test
-    public void canSerializeVoidType() {
-        var type = PatioTypes.VOID;
-
-        var deserializedType = deserializeType(
-            serializeType(type)
-        );
-
-        assertThat(deserializedType, equalTo(type));
-    }
-
     // == Data layouts ==
 
     protected abstract PatioDataLayout deserializeDataLayout(byte[] buffer);