[scala][http4s] fix codegen for using reserved words in openapi (#21518)

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaHttp4sServerCodegen.java

@@ -16,10 +16,14 @@
 
 package org.openapitools.codegen.languages;
 
+import com.google.common.collect.ImmutableMap;
+import com.samskivert.mustache.Escapers;
+import com.samskivert.mustache.Mustache;
 import io.swagger.v3.oas.models.media.Schema;
 import org.openapitools.codegen.*;
 import org.openapitools.codegen.meta.features.*;
 import org.openapitools.codegen.model.*;
+import org.openapitools.codegen.templating.mustache.EscapeKeywordLambda;
 import org.openapitools.codegen.utils.ModelUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -140,7 +144,7 @@ public class ScalaHttp4sServerCodegen extends DefaultCodegen implements CodegenC
         additionalProperties.put("infoEmail", "team@openapitools.org");
         additionalProperties.put("licenseInfo", "Apache 2.0");
         additionalProperties.put("licenseUrl", "http://apache.org/licenses/LICENSE-2.0.html");
-
+        additionalProperties.put("fnEscapeBacktick", new EscapeBacktickLambda());
 
         languageSpecificPrimitives = new HashSet<>(
                 Arrays.asList(
@@ -557,7 +561,12 @@ public class ScalaHttp4sServerCodegen extends DefaultCodegen implements CodegenC
 
     @Override
     public String escapeReservedWord(String name) {
-        return "_" + name;
+        if (this.reservedWordsMappings().containsKey(name)) {
+            return this.reservedWordsMappings().get(name);
+        }
+        // Reserved words will be further escaped at the mustache compiler level.
+        // Scala escaping done here (via `, without compiler escaping) would otherwise be HTML encoded.
+        return "`" + name + "`";
     }
 
     @Override
@@ -807,12 +816,12 @@ public class ScalaHttp4sServerCodegen extends DefaultCodegen implements CodegenC
 
         if (_vendorExtensions.size() == 1) { // only `x-type`
             if ("String".equals(cp.getDataType())) {
-                return cp.paramName;
+                return escapeReservedWordUnapply(cp.baseName);
             } else {
-                return cp.dataType + "Varr(" + cp.paramName + ")";
+                return cp.dataType + "Varr(" + escapeReservedWordUnapply(cp.baseName) + ")";
             }
         } else {
-            return cp.baseName + "Varr(" + cp.paramName + ")";
+            return cp.baseName + "Varr(" + escapeReservedWordUnapply(cp.baseName) + ")";
         }
     }
 
@@ -844,11 +853,34 @@ public class ScalaHttp4sServerCodegen extends DefaultCodegen implements CodegenC
         }
 
         vendorExtensions.putAll(refineProp(cp, imports));
-        return cp.baseName + "QueryParam(" + cp.paramName + ")";
+        return cp.baseName + "QueryParam(" + escapeReservedWordUnapply(cp.baseName) + ")";
     }
 
     @Override
     public GeneratorLanguage generatorLanguage() {
         return GeneratorLanguage.SCALA;
     }
+
+    @Override
+    protected ImmutableMap.Builder<String, Mustache.Lambda> addMustacheLambdas() {
+        return super.addMustacheLambdas()
+                .put("escapeReservedWordUnapply", new EscapeKeywordLambda(this::escapeReservedWordUnapply));
+    }
+
+    private String escapeReservedWordUnapply(String value) {
+        // The unapply method doesn’t allow you to work with reserved variables via backticks;
+        // in such cases you should use the variable via a placeholder instead.
+        return isReservedWord(value) ? "_" + value : value;
+    }
+
+    private static class EscapeBacktickLambda extends AbstractScalaCodegen.CustomLambda {
+        @Override
+        public String formatFragment(String fragment) {
+            if (fragment.startsWith("`") && fragment.endsWith("`")) {
+                String unescaped = fragment.substring(1, fragment.length() - 1);
+                return "`" + Escapers.HTML.escape(unescaped) + "`";
+            }
+            return Escapers.HTML.escape(fragment);
+        }
+    }
 }

modules/openapi-generator/src/main/resources/scala-http4s-server/delegateArgs.mustache

@@ -1,21 +1,21 @@
 {{#pathParams}}
-      {{paramName}}: {{{vendorExtensions.x-type}}},
+      {{#fnEscapeBacktick}}{{{paramName}}}{{/fnEscapeBacktick}}: {{{vendorExtensions.x-type}}},
 {{/pathParams}}
 {{#queryParams}}
   {{#isArray}}
     {{#required}}
-      {{paramName}}: List[{{{items.vendorExtensions.x-type}}}],
+      {{#fnEscapeBacktick}}{{{paramName}}}{{/fnEscapeBacktick}}: List[{{{items.vendorExtensions.x-type}}}],
     {{/required}}
     {{^required}}
-      {{paramName}}: Option[List[{{{items.vendorExtensions.x-type}}}]],
+      {{#fnEscapeBacktick}}{{{paramName}}}{{/fnEscapeBacktick}}: Option[List[{{{items.vendorExtensions.x-type}}}]],
     {{/required}}
   {{/isArray}}
   {{^isArray}}
     {{#required}}
-      {{paramName}}: {{{vendorExtensions.x-type}}},
+      {{#fnEscapeBacktick}}{{{paramName}}}{{/fnEscapeBacktick}}: {{{vendorExtensions.x-type}}},
     {{/required}}
     {{^required}}
-      {{paramName}}: Option[{{{vendorExtensions.x-type}}}],
+      {{#fnEscapeBacktick}}{{{paramName}}}{{/fnEscapeBacktick}}: Option[{{{vendorExtensions.x-type}}}],
     {{/required}}
   {{/isArray}}
 {{/queryParams}}

modules/openapi-generator/src/main/resources/scala-http4s-server/delegateCallGeneric.mustache

@@ -1,6 +1,6 @@
 {{^authName}}
-delegate.{{operationId}}.handle(req, {{#pathParams}}{{paramName}}, {{/pathParams}}{{#queryParams}}{{paramName}}, {{/queryParams}}responses)
+delegate.{{operationId}}.handle(req, {{#pathParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/pathParams}}{{#queryParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/queryParams}}responses)
 {{/authName}}
 {{#authName}}
-delegate.{{operationId}}.handle_{{authName}}(auth, req, {{#pathParams}}{{paramName}}, {{/pathParams}}{{#queryParams}}{{paramName}}, {{/queryParams}}responses)
+delegate.{{operationId}}.handle_{{authName}}(auth, req, {{#pathParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/pathParams}}{{#queryParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/queryParams}}responses)
 {{/authName}}

modules/openapi-generator/src/main/resources/scala-http4s-server/delegateCallJson.mustache

@@ -1,6 +1,6 @@
 {{^authName}}
-  delegate.{{operationId}}.handle(req, req.asJsonDecode[{{{bodyParam.dataType}}}] , {{#pathParams}}{{paramName}}, {{/pathParams}}{{#queryParams}}{{paramName}}, {{/queryParams}}responses)
+  delegate.{{operationId}}.handle(req, req.asJsonDecode[{{{bodyParam.dataType}}}] , {{#pathParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/pathParams}}{{#queryParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/queryParams}}responses)
 {{/authName}}
 {{#authName}}
-  delegate.{{operationId}}.handle_{{authName}}(auth, req, req.asJsonDecode[{{{bodyParam.dataType}}}] , {{#pathParams}}{{paramName}}, {{/pathParams}}{{#queryParams}}{{paramName}}, {{/queryParams}}responses)
+  delegate.{{operationId}}.handle_{{authName}}(auth, req, req.asJsonDecode[{{{bodyParam.dataType}}}] , {{#pathParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/pathParams}}{{#queryParams}}{{#lambda.escapeReservedWordUnapply}}{{baseName}}{{/lambda.escapeReservedWordUnapply}}, {{/queryParams}}responses)
 {{/authName}}

modules/openapi-generator/src/main/resources/scala-http4s-server/types.mustache

@@ -23,7 +23,7 @@ import {{modelPackage}}.{{classname}}.{{classname}}
 /**
 * {{{description}}}
 {{#vars}}
-* @param {{name}} {{{description}}}
+* @param {{#fnEscapeBacktick}}{{{name}}}{{/fnEscapeBacktick}} {{{description}}}
 {{/vars}}
 */
 {{#vendorExtensions.x-isSealedTrait}}
@@ -104,7 +104,7 @@ object {{classname}} extends Enumeration {
 {{#vendorExtensions.x-another}}
 case class {{classname}}(
 {{#vars}}
-  {{name}}: {{^required}}Option[{{{vendorExtensions.x-type}}}]{{/required}}{{#required}}{{{vendorExtensions.x-type}}}{{/required}}{{^-last}},{{/-last}}
+  {{#fnEscapeBacktick}}{{{name}}}{{/fnEscapeBacktick}}: {{^required}}Option[{{{vendorExtensions.x-type}}}]{{/required}}{{#required}}{{{vendorExtensions.x-type}}}{{/required}}{{^-last}},{{/-last}}
 {{/vars}}
 ){{#vendorExtensions.x-extends}} extends {{.}}{{/vendorExtensions.x-extends}}{{#vendorExtensions.x-extendsWith}} with {{.}}{{/vendorExtensions.x-extendsWith}}
 object {{classname}} {

samples/server/petstore/scala-http4s-server/src/main/scala/org/openapitools/apis/FakeApi.scala

@@ -57,8 +57,8 @@ trait FakeApiDelegate[F[_]] {
 
     def handle(
       req: Request[F],
-      _type: String,
+      `type`: String,
-      _var: Option[String],
+      `var`: Option[String],
       responses: reservedWordsResponses[F]
     ): F[Response[F]]
 

samples/server/petstore/scala-http4s-server/src/main/scala/org/openapitools/models/types.scala

@@ -15,13 +15,13 @@ import java.time.ZonedDateTime
 /**
 * Describes the result of uploading an image resource
 * @param code 
-* @param _type 
+* @param `type` 
 * @param message 
 */
 
 case class ApiResponse(
   code: Option[Int],
-  _type: Option[String],
+  `type`: Option[String],
   message: Option[String]
 )
 object ApiResponse {