Check for consistency in compilation unit elements

4 files changed, 55 insertions, 5 deletions

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenContext.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenContext.java
index da417cf5..c6f9b11d 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenContext.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenContext.java
@@ -11,6 +11,7 @@ import org.shedlang.compiler.patio.ast.instructions.PatioLocalStore;
 import org.shedlang.compiler.patio.ast.operands.PatioLocalRef;
 import org.shedlang.compiler.patio.ast.types.PatioDataLayout;
 import org.shedlang.compiler.patio.ast.types.PatioType;
+import org.shedlang.compiler.patio.errors.DuplicateCompilationUnitElementName;
 import org.shedlang.compiler.sources.Source;
 import org.shedlang.compiler.typechecker.TypeInfos;
 import org.shedlang.compiler.types.*;
@@ -150,11 +151,33 @@ public record PatioCodeGenContext(
         public CompilationUnitContext addCompilationUnitElement(
             PatioCompilationUnitElement element
         ) {
+            if (this.elementsByName.containsKey(element.name())) {
+                throw new DuplicateCompilationUnitElementName(element.name(), element.source());
+            }
+
             return new CompilationUnitContext(
                 this.elementsByName.plus(element.name(), element)
             );
         }
 
+        @CheckReturnValue
+        public CompilationUnitContext ensureCompilationUnitElement(
+            PatioCompilationUnitElement element
+        ) {
+            var existingElement = this.elementsByName.get(element.name());
+
+            if (existingElement == null) {
+                return new CompilationUnitContext(
+                    this.elementsByName.plus(element.name(), element)
+                );
+            } else if (existingElement.equals(element)) {
+                return this;
+            } else {
+                throw new DuplicateCompilationUnitElementName(element.name(), element.source());
+            }
+
+        }
+
         public record Result<T>(T value, CompilationUnitContext context) {}
     }
 
@@ -389,6 +412,15 @@ public record PatioCodeGenContext(
     }
 
     @CheckReturnValue
+    public PatioCodeGenContext ensureCompilationUnitElement(
+        PatioCompilationUnitElement element
+    ) {
+        return withCompilationUnitContext(
+            this.compilationUnitContext.ensureCompilationUnitElement(element)
+        );
+    }
+
+    @CheckReturnValue
     public PatioCodeGenResult<PatioLocalRef> temporaryPop() {
         var result = this.functionContext.temporaryPop();
 
diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenEffects.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenEffects.java
index dd1f414b..6d6e0476 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenEffects.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenEffects.java
@@ -11,6 +11,7 @@ import org.shedlang.compiler.patio.ast.types.PatioDataLayouts;
 import org.shedlang.compiler.patio.ast.types.PatioType;
 import org.shedlang.compiler.patio.ast.types.PatioTypes;
 import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.sources.Sources;
 import org.shedlang.compiler.stackir.instructions.DefineFunctionInstruction;
 import org.shedlang.compiler.types.UserDefinedEffect;
 import org.shedlang.compiler.util.Lists;
@@ -75,15 +76,14 @@ public class PatioCodeGenEffects {
                 bodyContext -> {
                     var runtimeFindHandlerMethodName = "shed__runtime__effects_find_handler_method";
 
-                    // TODO: check if element already exists?
-                    bodyContext = bodyContext.addCompilationUnitElement(new PatioFunctionDeclaration(
+                    bodyContext = bodyContext.ensureCompilationUnitElement(new PatioFunctionDeclaration(
                         runtimeFindHandlerMethodName,
                         List.of(
                             new PatioLocal.Param("effectTag", EFFECT_TAG_TYPE),
                             new PatioLocal.Param("methodIndex", EFFECT_METHOD_INDEX_TYPE)
                         ),
                         PatioCodeGenTypes.VALUE_TYPE,
-                        source
+                        Sources.RUNTIME
                     ));
 
                     var handlerMethodResult = bodyContext.allocateVal(
diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenStrings.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenStrings.java
index a1de8092..2e62202d 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGenStrings.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGenStrings.java
@@ -10,6 +10,7 @@ import org.shedlang.compiler.patio.ast.types.PatioDataLayouts;
 import org.shedlang.compiler.patio.ast.types.PatioDataValue;
 import org.shedlang.compiler.patio.ast.types.PatioDataValues;
 import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.sources.Sources;
 
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
@@ -60,14 +61,14 @@ public class PatioCodeGenStrings {
     ) {
         var runtimeAddName = "shed__runtime__string_add";
 
-        context = context.addCompilationUnitElement(new PatioFunctionDeclaration(
+        context = context.ensureCompilationUnitElement(new PatioFunctionDeclaration(
             runtimeAddName,
             List.of(
                 new PatioLocal.Param("left", PatioCodeGenTypes.VALUE_TYPE),
                 new PatioLocal.Param("right", PatioCodeGenTypes.VALUE_TYPE)
             ),
             PatioCodeGenTypes.VALUE_TYPE,
-            source
+            Sources.RUNTIME
         ));
 
         context = context.addInstruction(new PatioCall(
diff --git a/src/main/java/org/shedlang/compiler/patio/errors/DuplicateCompilationUnitElementName.java b/src/main/java/org/shedlang/compiler/patio/errors/DuplicateCompilationUnitElementName.java
new file mode 100644
index 00000000..264d7da8
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/patio/errors/DuplicateCompilationUnitElementName.java
@@ -0,0 +1,17 @@
+package org.shedlang.compiler.patio.errors;
+
+import org.shedlang.compiler.errors.InternalCompilerError;
+import org.shedlang.compiler.sources.Source;
+
+public class DuplicateCompilationUnitElementName extends InternalCompilerError {
+    private final String elementName;
+
+    public DuplicateCompilationUnitElementName(String elementName, Source source) {
+        super("Duplicate compilation unit element name: " + elementName, source);
+        this.elementName = elementName;
+    }
+
+    public String elementName() {
+        return elementName;
+    }
+}