Check that variable is declared and defined in same scope

3 files changed, 39 insertions, 11 deletions

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 391d8e0c..8758ad6a 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -226,19 +226,16 @@ public class TypeChecker {
         UntypedBlockNode untyped,
         TypeCheckerContext context
     ) {
-        // TODO: get environment and pass to enterBlock()
-        var bodyContext = context.enterBlock(P.map());
-
-        var typedStatementsResult = bodyContext.mapWithContext(
+        var typedStatementsResult = context.mapWithContext(
             untyped.statements(),
             TypeChecker::typeCheckFunctionStatement
         );
         var typedStatements = typedStatementsResult.value();
-        bodyContext = typedStatementsResult.context();
+        context = typedStatementsResult.context();
 
         var typed = new TypedBlockNode(typedStatements, untyped.source());
 
-        return context.exit(bodyContext).toResult(typed);
+        return context.toResult(typed);
     }
 
     private static TypeCheckerResult<TypedFunctionStatementNode> typeCheckBlockReturn(
@@ -320,9 +317,14 @@ public class TypeChecker {
 
         checkExpressionType(typedCondition, Types.BOOL, context);
 
-        var typedBodyResult = typeCheckBlock(conditionalBranch.body(), context);
+        // TODO: get environment and pass to enterBlock()
+        var bodyContext = context.enterBlock(P.map());
+
+        var typedBodyResult = typeCheckBlock(conditionalBranch.body(), bodyContext);
         var typedBody = typedBodyResult.value();
-        context = typedBodyResult.context();
+        bodyContext = typedBodyResult.context();
+
+        context = context.exit(bodyContext);
 
         return context.toResult(new TypedConditionalBranchNode(
             typedCondition,
@@ -506,9 +508,14 @@ public class TypeChecker {
         var typedConditionalBranches = typedConditionalBranchesResult.value();
         context = typedConditionalBranchesResult.context();
 
-        var typedElseBodyResult = typeCheckBlock(untyped.elseBody(), context);
+        // TODO: get environment and pass to enterBlock()
+        var bodyContext = context.enterBlock(P.map());
+
+        var typedElseBodyResult = typeCheckBlock(untyped.elseBody(), bodyContext);
         var typedElseBody = typedElseBodyResult.value();
-        context = typedElseBodyResult.context();
+        bodyContext = typedElseBodyResult.context();
+
+        context = context.exit(bodyContext);
 
         var branchTypes = Stream.concat(
             typedConditionalBranches.stream()
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
index 6f626725..2a5423db 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
@@ -4,6 +4,7 @@ import org.pcollections.Empty;
 import org.pcollections.PMap;
 import org.shedlang.compiler.ast.typed.FreeVariables;
 import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.typechecker.errors.CannotDefineVariableDeclaredInOuterScopeError;
 import org.shedlang.compiler.typechecker.errors.UnknownVariableError;
 import org.shedlang.compiler.typechecker.errors.VariableIsAlreadyDefinedError;
 import org.shedlang.compiler.types.*;
@@ -142,7 +143,10 @@ public class TypeCheckerContext {
                 throw new VariableIsAlreadyDefinedError(name, source);
             }
             case Variable.Undefined undefined -> {
-                // TODO: check is declared in this scope
+                if (!this.boundVariables.contains(name)) {
+                    throw new CannotDefineVariableDeclaredInOuterScopeError(name, source);
+                }
+
                 return new TypeCheckerContext(
                     this.environment.plus(name, new Variable.Defined(type)),
                     this.effect,
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineVariableDeclaredInOuterScopeError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineVariableDeclaredInOuterScopeError.java
new file mode 100644
index 00000000..7002c637
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineVariableDeclaredInOuterScopeError.java
@@ -0,0 +1,17 @@
+package org.shedlang.compiler.typechecker.errors;
+
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Source;
+
+public class CannotDefineVariableDeclaredInOuterScopeError extends SourceError {
+    private final String variableName;
+
+    public CannotDefineVariableDeclaredInOuterScopeError(String variableName, Source source) {
+        super("Cannot define variable declared in outer scope: " + variableName, source);
+        this.variableName = variableName;
+    }
+
+    public String variableName() {
+        return variableName;
+    }
+}