Qt/C++ generated code crashes if response is of type string · swagger-api/swagger-codegen#4835

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Client: QTIssue: Bughelp wanted

Description

Qt/C++ code crashes during the API callback when output is cast to QString*

On Mac, this causes a fatal SIGSEGV exception in QtCore at QString::append(QString const&) + 17 according to the crash log.

Current version used by http://editor.swagger.io/#/ at time of posting.

Include the following in the yaml:

      responses:
        '200':
          description: OK
          schema:
            type: string
            title: jsonData

then:

Generate Qt/C++ code
Create a slot corresponding to the callback and connect the callback signal to it
Instantiate the API interface class (e.g. SWGDefaultApi) and call the endpoint

I believe the problem is this line of code:

I believe the solution is to detect when {{returnType}} is QString* and in this case just replace the line with:

{{{returnType}}} output = &json;

I have tested this locally by replacing (in the generated code)

QString* output = static_cast<QString*>(create(json, QString("QString")));

with

QString* output = &json;

Tech stack: cpp
Domain: apitooling
Issue type: bug
Difficulty: 3
Estimated time: under 1 hour
Activity status: stale
Clarity: clear
Prerequisites: basic C++ knowledgeunderstanding of mustache templates
Newbie friendliness: 70
Research direction: Examine the file `modules/swagger codegen/src/main/resources/qt5cpp/api body.mustache` at line 169. Understand the current code that casts response to QString* using `create` function. Implement the suggested fix by checking if the return type is `QString*` and using direct assignment `QString* output = &json;`. Test with a Swagger spec that includes a response with `type: string`. Look for existing tests for Qt/C++ generation to ensure no regressions.