From 623c8a2542cf071b59aebe4811d7d61c762db774 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 27 Aug 2023 20:27:49 +0100
Subject: Check while loop body does not yield value

---
 .../java/org/shedlang/compiler/typechecker/TypeChecker.java    | 10 ++++++++++
 .../typechecker/errors/LoopBodyCannotYieldValueError.java      | 10 ++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 src/main/java/org/shedlang/compiler/typechecker/errors/LoopBodyCannotYieldValueError.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 651a4f79..5302ee6c 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -900,6 +900,16 @@ public class TypeChecker {
         var typedBody = typedBodyResult.value();
         context = typedBodyResult.context();
 
+        switch (typedBody.behaviour()) {
+            case TypedFunctionStatementBehaviour.BlockReturn blockReturn -> {
+                throw new LoopBodyCannotYieldValueError(untyped.body().source());
+            }
+            case TypedFunctionStatementBehaviour.Continue continue_ -> {
+            }
+            case TypedFunctionStatementBehaviour.Terminate terminate -> {
+            }
+        }
+
         return context.toResult(new TypedWhileNode(
             typedCondition,
             typedBody,
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/LoopBodyCannotYieldValueError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/LoopBodyCannotYieldValueError.java
new file mode 100644
index 00000000..2c80338e
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/LoopBodyCannotYieldValueError.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.typechecker.errors;
+
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Source;
+
+public class LoopBodyCannotYieldValueError extends SourceError {
+    public LoopBodyCannotYieldValueError(Source source) {
+        super("Loop body cannot yield value", source);
+    }
+}
-- 
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