[BUG][Go] undeclared name: isNil

[jonrosner]

Description

When generating Go structs with the latest docker container, a function isNil is used in the code but not generated.

openapi-generator version

v6.2.1

latest docker container (IMAGE ID: 0f04bb22fe23)

OpenAPI declaration file content or URL

Every file depends on this function.

Generation Details

func (o *MyObject) GetField() string {
	if o == nil || isNil(o.Field) {
		var ret string
		return ret
	}
	return *o.Field
}

Note that isNil(o.Field)

Steps to reproduce

$ docker run --rm -v \"${PWD}:/local\" \
	openapitools/openapi-generator-cli:latest  generate \
	-i openapi.yaml \
	-g go -o ${PWD}/gen/openapi \
	--global-property models,modelDocs=false \
	--additional-properties packageName=openapi"

Suggest a fix

Seems to be related to this MR: https://github.com/OpenAPITools/openapi-generator/pull/13843/files#diff-f85b9f51529f9922081dd92244891f831a26e126f4e27dd53bdaa03c7d55456c

My guess would be that because I only generate the models, this "utils" is not generated. So a fix would be to generate this utils anyway, even if only models are to be generated.

[wing328]

@jonrosner thanks for reporting the issue.

@NickUfer can you please take a look when you've time?

[NickUfer]

@wing328 Fix in this PR: #13918

https://openapi-generator.tech/docs/globals/#available-global-properties
@jonrosner another workaround for this would be to include the file in supportingFiles in --global-property

[AlHeamer]

As a user who is generating the utils.go file, I don't think the above pr will fully fix the issue.
The utils.go generated creates a definition func IsNil(i interface{}) bool however the generated files attempt to use isNil, so nothing will compile.

[gggrafff]

I have the same problem, I think it's an easy fix, and I wanted to do it, but I didn't find where exactly the isNil calls are generated.