From b019bf9cebdea64773836f74c5d7db7623d11b18 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 7 Jul 2023 18:55:57 +0100
Subject: Check operand types for binary operation

---
 .../shedlang/compiler/typechecker/TypeChecker.java | 38 +++++++++++++++-------
 .../errors/UnsupportedBinaryOperationError.java    | 31 ++++++++++++++++++
 2 files changed, 57 insertions(+), 12 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/typechecker/errors/UnsupportedBinaryOperationError.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 89650a53..db7becc3 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -158,7 +158,12 @@ public class TypeChecker {
         var right = rightResult.value();
         context = rightResult.context();
         
-        var operator = typeCheckBinaryOperator(untyped.operator(), left.type(), right.type());
+        var operator = typeCheckBinaryOperator(
+            untyped.operator(),
+            left.type(),
+            right.type(),
+            untyped.source()
+        );
 
         return context.toResult(new TypedBinaryOperationNode(
             operator,
@@ -168,20 +173,29 @@ public class TypeChecker {
         ));
     }
 
-    private static TypedBinaryOperator typeCheckBinaryOperator(UntypedBinaryOperator operator, Type left, Type right) {
-        return switch (operator) {
-            case ADD ->
-                TypedBinaryOperator.INT_ADD;
+    private static TypedBinaryOperator typeCheckBinaryOperator(
+        UntypedBinaryOperator operator,
+        Type left,
+        Type right,
+        Source source
+    ) {
+        if (left.equals(Types.INT) && right.equals(Types.INT)) {
+            return switch (operator) {
+                case ADD ->
+                    TypedBinaryOperator.INT_ADD;
 
-            case EQUALS ->
-                TypedBinaryOperator.INT_EQUALS;
+                case EQUALS ->
+                    TypedBinaryOperator.INT_EQUALS;
 
-            case NOT_EQUAL ->
-                TypedBinaryOperator.INT_NOT_EQUAL;
+                case NOT_EQUAL ->
+                    TypedBinaryOperator.INT_NOT_EQUAL;
 
-            case SUB ->
-                TypedBinaryOperator.INT_SUB;
-        };
+                case SUB ->
+                    TypedBinaryOperator.INT_SUB;
+            };
+        } else {
+            throw new UnsupportedBinaryOperationError(operator, left, right, source);
+        }
     }
 
     public static TypeCheckerResult<TypedExpressionNode> typeCheckBoolLiteral(
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/UnsupportedBinaryOperationError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/UnsupportedBinaryOperationError.java
new file mode 100644
index 00000000..fe826531
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/UnsupportedBinaryOperationError.java
@@ -0,0 +1,31 @@
+package org.shedlang.compiler.typechecker.errors;
+
+import org.shedlang.compiler.ast.untyped.UntypedBinaryOperator;
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.types.Type;
+
+public class UnsupportedBinaryOperationError extends SourceError {
+    private final UntypedBinaryOperator operator;
+    private final Type left;
+    private final Type right;
+
+    public UnsupportedBinaryOperationError(UntypedBinaryOperator operator, Type left, Type right, Source source) {
+        super("Unsupported binary operation: " + operator + " " + left + " " + right, source);
+        this.operator = operator;
+        this.left = left;
+        this.right = right;
+    }
+
+    public UntypedBinaryOperator operator() {
+        return operator;
+    }
+
+    public Type left() {
+        return left;
+    }
+
+    public Type right() {
+        return right;
+    }
+}
-- 
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