There is no shadowing, this is a Golang reporting bug.
On Monday, September 8, 2025 at 5:09:42 AM UTC+2 Mike Schinkel wrote:
> Hi Gophers,
>
> I have some code that is not working as I expect it to and wanted to see
> if I was misunderstanding something or if there is in fact a bug in the
> compiler. I have tried this in v1.24.5 and 1.25.1.
>
> Here is a version of the code — heavily cut down to provide a minimal
> example — that is not acting as I expect it to:
>
> func ensureRootConfig(cs cfgutil.ConfigStore) (root *RootConfigV1, err error)
> {
> if cs != nil {
> root = &RootConfigV1{}
> err = cs.LoadJSON(&root)
> } else {
> root = NewRootConfigV1(RootConfigV1Args{})
> err = cs.SaveJSON(root)
> }
> return root, err
> }
>
> When I run the above code the assignment to `root` gets shadowed and the
> return variable is null. I have confirmed this using Goland and the Delve
> debugger.
>
> The following does not shadow `root`:
>
> func ensureRootConfig(cs cfgutil.ConfigStore) (*RootConfigV1, error) {
> var root *RootConfigV1
> var err error
> if cs != nil {
> root = &RootConfigV1{}
> err = cs.LoadJSON(&root)
> } else {
> root = NewRootConfigV1(RootConfigV1Args{})
> err = cs.SaveJSON(root)
> }
> return root, err
> }
>
>
> This code, of course also works, too, but with multiple returns is not the
> style of code we want use:
>
> func ensureRootConfig(cs cfgutil.ConfigStore) (*RootConfigV1, error) {
> if cs != nil {
> root := &RootConfigV1{}
> err := cs.LoadJSON(&root)
> return root, err
> }
> root := NewRootConfigV1(RootConfigV1Args{})
> err := cs.SaveJSON(root)
> return root, err
> }
>
>
> I do understand that some might want to say “just use the other
> approaches” but if this is a bug it still needs to be reported and ideally
> fixed given how the language should allow this, right? That is unless I
> misunderstand something about how named return variables work with
> shadowing.
>
> -Mike
>
>
>
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