Check vars can't be captured for specific function nodes

2 files changed, 51 insertions, 8 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
index 590beb7f..47813c25 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
@@ -3,10 +3,12 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
+import org.shedlang.compiler.typechecker.errors.CannotCaptureVarError;
 import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingParamTypeError;
 import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingReturnTypeError;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.FunctionType;
+import org.shedlang.compiler.types.NamespaceName;
 import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;
 
@@ -18,8 +20,7 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
 import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
-import static org.zwobble.precisely.Matchers.isOptionalEmpty;
-import static org.zwobble.precisely.Matchers.isSequence;
+import static org.zwobble.precisely.Matchers.*;
 
 public class TypeCheckerFunctionDefinitionTests {
     @Test
@@ -72,4 +73,27 @@ public class TypeCheckerFunctionDefinitionTests {
             () -> typeCheckNamespaceStatement(untyped, context)
         );
     }
+
+    @Test
+    public void varsCannotBeCaptured() {
+        var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnType(Untyped.typeLevelReference("Unit"))
+            .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(NamespaceName.of("Example"), P.map(
+                Map.entry("Unit", Variable.defined(Types.metaType(Types.UNIT), VariableType.CONSTANT)),
+                Map.entry("x", Variable.defined(Types.STRING, VariableType.VAR))
+            ));
+
+        var error = assertThrows(
+            CannotCaptureVarError.class,
+            () -> typeCheckNamespaceStatement(
+                untyped,
+                context
+            )
+        );
+
+        assertThat(error.name(), equalTo("x"));
+    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
index ce2a0570..27b5b444 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
@@ -3,11 +3,9 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionExpressionNode;
+import org.shedlang.compiler.typechecker.errors.CannotCaptureVarError;
 import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingParamTypeError;
-import org.shedlang.compiler.types.Effects;
-import org.shedlang.compiler.types.FunctionType;
-import org.shedlang.compiler.types.NamedParam;
-import org.shedlang.compiler.types.Types;
+import org.shedlang.compiler.types.*;
 import org.shedlang.compiler.util.P;
 
 import java.util.List;
@@ -17,8 +15,7 @@ import java.util.Optional;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
 import static org.zwobble.precisely.AssertThat.assertThat;
-import static org.zwobble.precisely.Matchers.isOptionalEmpty;
-import static org.zwobble.precisely.Matchers.isSequence;
+import static org.zwobble.precisely.Matchers.*;
 
 public class TypeCheckerFunctionExpressionTests {
     @Test
@@ -132,4 +129,26 @@ public class TypeCheckerFunctionExpressionTests {
             )
         );
     }
+
+    @Test
+    public void varsCannotBeCaptured() {
+        var untyped = UntypedFunctionExpressionNode.builder()
+            .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(NamespaceName.of("Example"), P.map(
+                Map.entry("x", Variable.defined(Types.STRING, VariableType.VAR))
+            ));
+
+        var error = assertThrows(
+            CannotCaptureVarError.class,
+            () -> TypeChecker.typeCheckExpression(
+                untyped,
+                Optional.empty(),
+                context
+            )
+        );
+
+        assertThat(error.name(), equalTo("x"));
+    }
 }