[Rust] set supportAsync to true as the default

• set supportAsync to true as the default

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

bin/rust-petstore.sh

@@ -40,7 +40,7 @@ for spec_path in \
                    --input-spec $spec_path
                    --generator-name rust
                    --output samples/client/petstore/rust/$library/$spec
-                   --additional-properties packageName=${spec}-${library}
+                   --additional-properties packageName=${spec}-${library},supportAsync=false
                    --library=$library $@"
     java ${JAVA_OPTS} -jar ${executable} ${args} || exit 1
   done

docs/generators/rust.md

@@ -6,10 +6,10 @@ sidebar_label: rust
 | Option | Description | Values | Default |
 | ------ | ----------- | ------ | ------- |
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
-|library|library template (sub-template) to use.|<dl><dt>**hyper**</dt><dd>HTTP client: Hyper.</dd><dt>**reqwest**</dt><dd>HTTP client: Reqwest.</dd></dl>|hyper|
+|library|library template (sub-template) to use.|<dl><dt>**hyper**</dt><dd>HTTP client: Hyper.</dd><dt>**reqwest**</dt><dd>HTTP client: Reqwest.</dd></dl>|reqwest|
 |packageName|Rust package name (convention: lowercase).| |openapi|
 |packageVersion|Rust package version.| |1.0.0|
-|supportAsync|If set, generate async function call instead| |false|
+|supportAsync|If set, generate async function call instead. This option is for 'reqwest' library only| |true|
 |useSingleRequestParameter|Setting this property to true will generate functions with a single argument containing all API endpoint parameters instead of one argument per parameter.| |false|
 
 ## IMPORT MAPPING

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

@@ -39,7 +39,7 @@ import static org.openapitools.codegen.utils.StringUtils.underscore;
 public class RustClientCodegen extends DefaultCodegen implements CodegenConfig {
     private static final Logger LOGGER = LoggerFactory.getLogger(RustClientCodegen.class);
     private boolean useSingleRequestParameter = false;
-    private boolean supportAsync = false;
+    private boolean supportAsync = true;
 
     public static final String PACKAGE_NAME = "packageName";
     public static final String PACKAGE_VERSION = "packageVersion";
@@ -173,18 +173,18 @@ public class RustClientCodegen extends DefaultCodegen implements CodegenConfig {
                 .defaultValue(Boolean.TRUE.toString()));
         cliOptions.add(new CliOption(CodegenConstants.USE_SINGLE_REQUEST_PARAMETER, CodegenConstants.USE_SINGLE_REQUEST_PARAMETER_DESC, SchemaTypeUtil.BOOLEAN_TYPE)
                 .defaultValue(Boolean.FALSE.toString()));
-        cliOptions.add(new CliOption(SUPPORT_ASYNC, "If set, generate async function call instead", SchemaTypeUtil.BOOLEAN_TYPE)
-                .defaultValue(Boolean.FALSE.toString()));
+        cliOptions.add(new CliOption(SUPPORT_ASYNC, "If set, generate async function call instead. This option is for 'reqwest' library only", SchemaTypeUtil.BOOLEAN_TYPE)
+                .defaultValue(Boolean.TRUE.toString()));
 
         supportedLibraries.put(HYPER_LIBRARY, "HTTP client: Hyper.");
         supportedLibraries.put(REQWEST_LIBRARY, "HTTP client: Reqwest.");
 
         CliOption libraryOption = new CliOption(CodegenConstants.LIBRARY, "library template (sub-template) to use.");
         libraryOption.setEnum(supportedLibraries);
-        // set hyper as the default
-        libraryOption.setDefault(HYPER_LIBRARY);
+        // set reqwest as the default
+        libraryOption.setDefault(REQWEST_LIBRARY);
         cliOptions.add(libraryOption);
-        setLibrary(HYPER_LIBRARY);
+        setLibrary(REQWEST_LIBRARY);
     }
 
     @Override