[tcgc] add void and never handling for parameter and return types

.chronus/changes/fix_void-2024-4-8-13-39-22.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+add void and never handling for parameter and return types

packages/typespec-client-generator-core/src/http.ts

@@ -44,6 +44,7 @@ import {
   getLocationOfOperation,
   isAcceptHeader,
   isContentTypeHeader,
+  isNeverOrVoidType,
   isNullable,
   isSubscriptionId,
 } from "./internal-utils.js";
@@ -108,6 +109,7 @@ function getSdkHttpParameters(
     bodyParam: undefined,
   };
   retval.parameters = httpOperation.parameters.parameters
+    .filter((x) => !isNeverOrVoidType(x.param.type))
     .map((x) =>
       diagnostics.pipe(getSdkHttpParameter(context, x.param, httpOperation.operation, x.type))
     )
@@ -124,7 +126,7 @@ function getSdkHttpParameters(
   const correspondingMethodParams: SdkModelPropertyType[] = [];
   if (tspBody) {
     // if there's a param on the body, we can just rely on getSdkHttpParameter
-    if (tspBody.parameter) {
+    if (tspBody.parameter && !isNeverOrVoidType(tspBody.parameter.type)) {
       const getParamResponse = diagnostics.pipe(
         getSdkHttpParameter(context, tspBody.parameter, httpOperation.operation, "body")
       );
@@ -143,7 +145,7 @@ function getSdkHttpParameters(
         return diagnostics.wrap(retval);
       }
       retval.bodyParam = getParamResponse;
-    } else {
+    } else if (!isNeverOrVoidType(tspBody.type)) {
       const type = diagnostics.pipe(
         getClientTypeWithDiagnostics(context, tspBody.type, httpOperation.operation)
       );
@@ -170,15 +172,17 @@ function getSdkHttpParameters(
         correspondingMethodParams,
       };
     }
-    addContentTypeInfoToBodyParam(context, httpOperation, retval.bodyParam);
-    retval.bodyParam.correspondingMethodParams = diagnostics.pipe(
-      getCorrespondingMethodParams(
-        context,
-        httpOperation.operation,
-        methodParameters,
-        retval.bodyParam
-      )
-    );
+    if (retval.bodyParam) {
+      addContentTypeInfoToBodyParam(context, httpOperation, retval.bodyParam);
+      retval.bodyParam.correspondingMethodParams = diagnostics.pipe(
+        getCorrespondingMethodParams(
+          context,
+          httpOperation.operation,
+          methodParameters,
+          retval.bodyParam
+        )
+      );
+    }
   }
   if (retval.bodyParam && !headerParams.some((h) => isContentTypeHeader(h))) {
     // if we have a body param and no content type header, we add one
@@ -380,6 +384,7 @@ function getSdkHttpResponseAndExceptions(
 
     for (const innerResponse of response.responses) {
       for (const header of Object.values(innerResponse.headers || [])) {
+        if (isNeverOrVoidType(header.type)) continue;
         const clientType = diagnostics.pipe(getClientTypeWithDiagnostics(context, header.type));
         const defaultContentType = innerResponse.body?.contentTypes.includes("application/json")
           ? "application/json"
@@ -395,7 +400,7 @@ function getSdkHttpResponseAndExceptions(
           nullable: isNullable(header.type),
         });
       }
-      if (innerResponse.body) {
+      if (innerResponse.body && !isNeverOrVoidType(innerResponse.body.type)) {
         if (body && body !== innerResponse.body.type) {
           diagnostics.add(
             createDiagnostic({

packages/typespec-client-generator-core/src/internal-utils.ts

@@ -15,7 +15,9 @@ import {
   getNamespaceFullName,
   getSummary,
   ignoreDiagnostics,
+  isNeverType,
   isNullType,
+  isVoidType,
 } from "@typespec/compiler";
 import { HttpOperation, HttpStatusCodeRange } from "@typespec/http";
 import { getAddedOnVersions, getRemovedOnVersions, getVersions } from "@typespec/versioning";
@@ -407,3 +409,7 @@ export function getLocationOfOperation(operation: Operation): Namespace | Interf
   // have to check interface first, because interfaces are more granular than namespaces
   return (operation.interface || operation.namespace)!;
 }
+
+export function isNeverOrVoidType(type: Type): boolean {
+  return isNeverType(type) || isVoidType(type);
+}

packages/typespec-client-generator-core/src/package.ts

@@ -56,6 +56,7 @@ import {
   getHashForType,
   getLocationOfOperation,
   getSdkTypeBaseHelper,
+  isNeverOrVoidType,
   isNullable,
   updateWithApiVersionInformation,
 } from "./internal-utils.js";
@@ -241,14 +242,15 @@ function getSdkBasicServiceMethod<
   const parameters = httpOperation.parameters;
   // path/query/header parameters
   for (const param of parameters.parameters) {
+    if (isNeverOrVoidType(param.param.type)) continue;
     methodParameters.push(diagnostics.pipe(getSdkMethodParameter(context, param.param, operation)));
   }
   // body parameters
-  if (parameters.body?.parameter) {
+  if (parameters.body?.parameter && !isNeverOrVoidType(parameters.body.parameter.type)) {
     methodParameters.push(
       diagnostics.pipe(getSdkMethodParameter(context, parameters.body?.parameter, operation))
     );
-  } else if (parameters.body) {
+  } else if (parameters.body && !isNeverOrVoidType(parameters.body.type)) {
     if (parameters.body.type.kind === "Model") {
       const type = getEffectivePayloadType(context, parameters.body.type);
       // spread case

packages/typespec-client-generator-core/src/types.ts

@@ -85,6 +85,7 @@ import {
   isAzureCoreModel,
   isMultipartFormData,
   isMultipartOperation,
+  isNeverOrVoidType,
   isNullable,
   updateWithApiVersionInformation,
 } from "./internal-utils.js";
@@ -1044,7 +1045,7 @@ function addPropertiesToModelType(
   for (const property of type.properties.values()) {
     if (
       isStatusCode(context.program, property) ||
-      isNeverType(property.type) ||
+      isNeverOrVoidType(property.type) ||
       sdkType.kind !== "model"
     ) {
       continue;
@@ -1240,6 +1241,7 @@ function updateTypesFromOperation(
   const httpOperation = getHttpOperationWithCache(context, operation);
   const generateConvenient = shouldGenerateConvenient(context, operation);
   for (const param of operation.parameters.properties.values()) {
+    if (isNeverOrVoidType(param.type)) continue;
     const paramTypes = diagnostics.pipe(checkAndGetClientType(context, param.type, operation));
     if (generateConvenient) {
       paramTypes.forEach((paramType) => {
@@ -1248,6 +1250,7 @@ function updateTypesFromOperation(
     }
   }
   for (const param of httpOperation.parameters.parameters) {
+    if (isNeverOrVoidType(param.param.type)) continue;
     const paramTypes = diagnostics.pipe(
       checkAndGetClientType(context, param.param.type, operation)
     );
@@ -1258,7 +1261,7 @@ function updateTypesFromOperation(
     }
   }
   const httpBody = httpOperation.parameters.body;
-  if (httpBody) {
+  if (httpBody && !isNeverOrVoidType(httpBody.type)) {
     const bodies = diagnostics.pipe(checkAndGetClientType(context, httpBody.type, operation));
     if (generateConvenient) {
       bodies.forEach((body) => {
@@ -1282,7 +1285,7 @@ function updateTypesFromOperation(
   }
   for (const response of httpOperation.responses) {
     for (const innerResponse of response.responses) {
-      if (innerResponse.body?.type) {
+      if (innerResponse.body?.type && !isNeverOrVoidType(innerResponse.body.type)) {
         const responseBodies = diagnostics.pipe(
           checkAndGetClientType(context, innerResponse.body.type, operation)
         );

packages/typespec-client-generator-core/test/package.test.ts

@@ -1679,6 +1679,29 @@ describe("typespec-client-generator-core: package", () => {
         ["apiVersion", "generationOptions", "contentType", "accept"]
       );
     });
+
+    it("never void parameter or response", async () => {
+      await runner.compileWithBuiltInService(`
+        op TestTemplate<
+          headerType,
+          queryType,
+          bodyType,
+          responseHeaderType,
+          responseBodyType
+        >(@header h: headerType, @query q: queryType, @body b: bodyType): {
+          @header h: responseHeaderType;
+          @body b: responseBodyType;
+        };
+        op test is TestTemplate<void, void, void, void, void>;
+      `);
+      const sdkPackage = runner.context.experimental_sdkPackage;
+      const method = getServiceMethodOfClient(sdkPackage);
+      strictEqual(method.parameters.length, 0);
+      strictEqual(method.response.type, undefined);
+      strictEqual(method.operation.parameters.length, 0);
+      strictEqual(method.operation.responses.get(200)?.headers.length, 0);
+      strictEqual(method.operation.responses.get(200)?.type, undefined);
+    });
   });
 
   describe("Responses", () => {

packages/typespec-client-generator-core/test/types.test.ts

@@ -3282,6 +3282,26 @@ describe("typespec-client-generator-core: types", () => {
         ["ValidResponse"]
       );
     });
+
+    it("never or void property", async () => {
+      await runner.compileAndDiagnose(`
+        @service({})
+        @test namespace MyService {
+          @test
+          @usage(Usage.input | Usage.output)
+          @access(Access.public)
+          model Test{
+            prop1: never;
+            prop2: void;
+          }
+        }
+      `);
+
+      const models = runner.context.experimental_sdkPackage.models;
+      strictEqual(models.length, 1);
+      strictEqual(models[0].name, "Test");
+      strictEqual(models[0].properties.length, 0);
+    });
   });
 
   describe("SdkArrayType", () => {