allow protocol generators to declare error aliases (#1622)

Author: kuhe

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpBindingProtocolGenerator.java

@@ -533,7 +533,8 @@ public void generateResponseDeserializers(GenerationContext context) {
             this::writeErrorCodeParser,
             isErrorCodeInBody,
             this::getErrorBodyLocation,
-            this::getOperationErrors
+            this::getOperationErrors,
+            getErrorAliases(context, containedOperations)
         );
         deserializingErrorShapes.addAll(errorShapes);
     }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpProtocolGeneratorUtils.java

@@ -18,6 +18,7 @@
 import java.nio.file.Paths;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
@@ -318,7 +319,8 @@ public static Set<StructureShape> generateUnifiedErrorDispatcher(
         Consumer<GenerationContext> errorCodeGenerator,
         boolean shouldParseErrorBody,
         BiFunction<GenerationContext, String, String> bodyErrorLocationModifier,
-        BiFunction<GenerationContext, List<OperationShape>, Map<String, ShapeId>> operationErrorsToShapes
+        BiFunction<GenerationContext, List<OperationShape>, Map<String, ShapeId>> operationErrorsToShapes,
+        Map<String, TreeSet<String>> errorAliases
     ) {
         TypeScriptWriter writer = context.getWriter();
         SymbolProvider symbolProvider = context.getSymbolProvider();
@@ -385,6 +387,11 @@ public static Set<StructureShape> generateUnifiedErrorDispatcher(
                         String outputParam = shouldParseErrorBody ? "parsedOutput" : "output";
                         writer.write("case $S:", name);
                         writer.write("case $S:", errorId.toString());
+                        for (String alias : errorAliases.getOrDefault(errorId.toString(), new TreeSet<>())) {
+                            if (!Objects.equals(name, alias) && !Objects.equals(errorId.toString(), alias)) {
+                                writer.write("case $S:", alias);
+                            }
+                        }
                         writer.indent()
                             .write("throw await $L($L, context);", errorDeserMethodName, outputParam)
                             .dedent();

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpRpcProtocolGenerator.java

@@ -234,7 +234,8 @@ public void generateResponseDeserializers(GenerationContext context) {
             this::writeErrorCodeParser,
             isErrorCodeInBody,
             this::getErrorBodyLocation,
-            this::getOperationErrors
+            this::getOperationErrors,
+            getErrorAliases(context, containedOperations)
         );
         deserializingErrorShapes.addAll(errorShapes);
     }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/ProtocolGenerator.java

@@ -16,8 +16,10 @@
 package software.amazon.smithy.typescript.codegen.integration;
 
 import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.TreeSet;
 import java.util.stream.Collectors;
 import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.Symbol;
@@ -321,6 +323,15 @@ default Map<String, ShapeId> getOperationErrors(GenerationContext context, Colle
         return errors;
     }
 
+    /**
+     * @return map of fully qualified shape id to aliases and/or short names that should map to the same error.
+     */
+    default Map<String, TreeSet<String>> getErrorAliases(
+        GenerationContext context, Collection<OperationShape> operations
+    ) {
+        return Collections.emptyMap();
+    }
+
     /**
      * Context object used for service serialization and deserialization.
      */