[C++][Pistache-server] OpenApi properties starting with a number are not well handled

Created by: CyrilleBenard

Description

If the OpenApi file (YAML or JSON) defines a property name starting with a number, for example 5gItem, the generator produces a class member named m_5gItem (that's OK) BUT a method named 5gItemIsSet(). This syntax is not allowed in almost all languages, not only C++. No symbol names should start with a number.

One workaround would be to avoid the OpenApi property name starting with a number but I'm not sure of that. I read nothing in the standard about this constrain and I'm not convince with this. This wouldn't be my proposal.

As far as I know, the Java generator (lang : jaxrs-resteasy) uses the prefix underscore on all the members that start with a number. In C++ there is no issue on the members name 'cause they are prefixed with the characters 'm_' (for member). The issue scope is on the associated access method <property name>IsSet(). The accessors are not impacted because they are named get<property name> and set<property name>

Compile error looks like :

In file included from ./model/Content.h:24:0,
                 from api/CheckApi.h:29,
                 from api/CheckApi.cpp:13:
./model/_5gmmCapability.h:74:10: error: expected unqualified-id before numeric constant
     bool 5gItemIsSet() const;
          ^

Additional related issue : In case an OpenApi schema is defined also with a name starting with a number (under components/schemas), the pretty same issue is also generated :

• The protection against circular headers inclusions is impacted (see #ifndef xxxxx)
• The class name is generated with a number in the first position

To reproduce this current issue part, you can use the below yaml/json file after modifying the schema name (and reference) _5gmmCapability in 5gmmCapability

Errors look like :

In file included from ./model/Content.h:24:0,
                 from ./api/CheckApi.h:29,
                 from impl/CheckApiImpl.h:28,
                 from impl/CheckApiImpl.cpp:13:
./model/5gmmCapability.h:18:9: error: macro names must be identifiers
 #ifndef 5gmmCapability_H_
         ^

In file included from api/CheckApi.h:29:0,
                 from api/CheckApi.cpp:13:
./model/Content.h:58:5: error: expected unqualified-id before numeric constant
     5gmmCapability getType() const;
     ^
./model/Content.h:59:18: error: expected identifier before numeric constant
     void setType(5gmmCapability const& value);
                  ^

openapi-generator version

branch pr/497

OpenAPI declaration file content or url

openapi: "3.0.0"
info:
  version: 1.0.0
  title: Check 5gmmCapability
servers:
  - url: http://localhost:8080
paths:
  /Check5gmmCapability:
    get:
      summary: Check property beginning with a number
      operationId: list
      tags:
        - Check
      responses:
        '200':
          description: Everythings gonna be alright
          headers:
            x-next:
              description: A link to the next page of responses
              schema:
                type: string
          content:
            application/json:    
              schema:
                $ref: "#/components/schemas/Content"
      default:
        description: unexpected error
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/Content"

components:
  schemas:
    _5gmmCapability:
      type: object
      properties:
        item1:
          type: string
        item2:
          type: integer
        5gItem:
          type: integer


    Content:
      type: object
      properties:
        type:
          $ref: '#/components/schemas/_5gmmCapability'

{
  "openapi": "3.0.0",
  "info": {
    "version": "1.0.0",
    "title": "Check 5gmmCapability"
  },
  "servers": [
    {
      "url": "http://localhost:8080"
    }
  ],
  "paths": {
    "/Check5gmmCapability": {
      "get": {
        "summary": "Check property beginning with a number",
        "operationId": "list",
        "tags": [
          "Check"
        ],
        "responses": {
          "200": {
            "description": "Everythings gonna be alright",
            "headers": {
              "x-next": {
                "description": "A link to the next page of responses",
                "schema": {
                  "type": "string"
                }
              }
            },
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Content"
                }
              }
            }
          }
        },
        "default": {
          "description": "unexpected error",
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/Content"
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "_5gmmCapability": {
        "type": "object",
        "properties": {
          "item1": {
            "type": "string"
          },
          "item2": {
            "type": "integer"
          },
          "5gItem": {
            "type": "integer"
          }
        }
      },
      "Content": {
        "type": "object",
        "properties": {
          "type": {
            "$ref": "#/components/schemas/_5gmmCapability"
          }
        }
      }
    }
  }
}

Command line used for generation

Generate :

openapi-generator-cli.sh generate -i ./openapi.yaml -g cpp-pistache-server -c ./config.json -o .

Compile :

g++ -c  -I./api -I./model -I./impl -Wall -g -std=c++11 -o obj/api/CheckApi.o api/CheckApi.cpp

Steps to reproduce

Generate & compile has previously described

Related issues/PRs

N/A

Suggest a fix/enhancement

For all the access methods <symbol name>IsSet() one solution should be to rename them into a more "classical" way : Is<symbol name>Set() but I'm not really convinced (>_<)

Another solution would be to add the prefix underscore (like in Java) to all class/method/symbol that would have been generated with a number as a first character. It's not so elegant to read this kind of symbol name inside the code, but this situation may be encounter not so often.