Compile error occurs when an arg name is same as a package name.

[yuzuy]

Actual behavior A clear and concise description of what the bug is.

Compile error occurs when an arg name is same as a package name.

import "github.com/yuzuy/xxx/pagination"

func (m *MockFooUseCase) Exec(ctx context.Context, pagination *pagination.Pagination) (*pagination.Page, error) {
	m.ctrl.T.Helper()
	ret := m.ctrl.Call(m, "Exec", ctx, pagination)
	ret0, _ := ret[0].(*pagination.Page) // pagination.Page is not a type
	ret1, _ := ret[1].(error)
	return ret0, ret1
}

Expected behavior A clear and concise description of what you expected to
happen.

Avoid a conflict between an arg name and a package name.

import "github.com/yuzuy/xxx/pagination"

func (m *MockFooUseCase) Exec(ctx context.Context, paginationArg *pagination.Pagination) (*pagination.Page, error) {
	m.ctrl.T.Helper()
	ret := m.ctrl.Call(m, "Exec", ctx, paginationArg)
	ret0, _ := ret[0].(*pagination.Page)
	ret1, _ := ret[1].(error)
	return ret0, ret1
}

To Reproduce Steps to reproduce the behavior

• Generate a mock of a method
  • that has an arg with the name that is same as the imported package name
  • that has a return value of the package type

Additional Information

• gomock mode (reflect or source): reflect
• gomock version or git ref: v0.5.0
• golang version: 1.23.1

Triage Notes for the Maintainers

[tompaz3]

I understand it's the issue for you (and probably for many others), but to be honest, I wouldn't personally introduce package name shadowing in the first place. Shadowing is unsafe on it's own and may lead to bugs eventually.

[rageagainsthepc]

@tompaz3 I agree, but unfortunately widely used packages like e.g. docker seem to shadow their package names quite often. Right now this probably breaks a lot of projects using mockgen.

[tompaz3]

@rageagainsthepc Ah, I see. It's still doable, but not without the extra hassle (like replacing it with custom consumer-side interface).
Definitely agree that this is a breaking change, anyway.

[cavus700]

#219 Seems like this will be fixed in the next release