Add (unsound) basic type-checking for resume statements

4 files changed, 34 insertions, 3 deletions

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
index 57a585a0..a79437ec 100644
--- a/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
@@ -1,5 +1,5 @@
 package org.shedlang.compiler.ast.typed;
 
-public sealed interface TypedFunctionStatementNode extends TypedNode permits TypedWhileNode, TypedAssignNode, TypedBlockReturnNode, TypedExpressionStatementNode, TypedFunctionReturnNode {
+public sealed interface TypedFunctionStatementNode extends TypedNode permits TypedAssignNode, TypedBlockReturnNode, TypedExpressionStatementNode, TypedFunctionReturnNode, TypedResumeNode, TypedWhileNode {
     TypedFunctionStatementBehaviour behaviour();
 }
diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedResumeNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedResumeNode.java
new file mode 100644
index 00000000..6511d3b6
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedResumeNode.java
@@ -0,0 +1,13 @@
+package org.shedlang.compiler.ast.typed;
+
+import org.shedlang.compiler.sources.Source;
+
+public record TypedResumeNode(
+    TypedExpressionNode expression,
+    Source source
+) implements TypedFunctionStatementNode {
+    @Override
+    public TypedFunctionStatementBehaviour behaviour() {
+        return TypedFunctionStatementBehaviour.TERMINATE;
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
index 8564a66d..0d467c0d 100644
--- a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
+++ b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
@@ -314,6 +314,9 @@ public class StackCompiler {
             case TypedFunctionReturnNode functionReturn ->
                 compileFunctionReturn(functionReturn, context);
 
+            case TypedResumeNode resume ->
+                throw new UnsupportedOperationException("TODO");
+
             case TypedWhileNode while_ ->
                 compileWhile(while_, context);
         };
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 8dbf0927..5e1fc6e2 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -611,7 +611,10 @@ public class TypeChecker {
                 returnType = implicitLowerBound.type();
             }
             case ReturnTypeState.ImplicitUnknown implicitUnknown -> {
-                throw new UnsupportedOperationException("TODO");
+                // If we've reached this point, then there are no returns
+                // statements, nor a block return, so this function must never
+                // return.
+                returnType = Types.BOTTOM;
             }
             case ReturnTypeState.NotInFunction notInFunction -> {
                 // TODO: better error
@@ -945,7 +948,7 @@ public class TypeChecker {
                 typeCheckAssign(assign, context);
 
             case UntypedResumeNode resume ->
-                throw new UnsupportedOperationException("TODO");
+                typeCheckResume(resume, context);
 
             case UntypedBlockReturnNode blockReturn ->
                 typeCheckBlockReturn(blockReturn, context);
@@ -1274,6 +1277,18 @@ public class TypeChecker {
         });
     }
 
+    private static TypeCheckerResult<TypedResumeNode> typeCheckResume(
+        UntypedResumeNode untyped,
+        TypeCheckerContext context
+    ) {
+        context = typeCheckFunctionReturnValue(Types.UNIT, untyped.source(), context);
+
+        return context.toResult(new TypedResumeNode(
+            new TypedUnitLiteralNode(untyped.source()),
+            untyped.source()
+        ));
+    }
+
     private static TypeCheckerResult<TypedStringLiteralNode> typeCheckStringLiteral(
         UntypedStringLiteralNode untyped,
         TypeCheckerContext context