Nested module attribute is not resolved in recursive namespace

namespace rec Ns  

open System.Runtime.CompilerServices

  [<Extension>]   
module Module =
    [<Extension>]
    let ext1 (x: int) = x.ToString() 

 [<Extension>]
 type T() =
    class end

Linking to issue #5795 since it's a similar underlying problem

Just to note this is another case of attribute checking going awry in recursive scopes.

🤖 This is an automated response from Repo Assist.

Verified still present in F# 10.0 (F# Interactive 14.0.105.0, commit 251aaf2, 2026-03-26).

Minimal reproduction showing the difference between namespace and namespace rec:

// Without rec - compiles fine ✅
namespace Ns

open System.Runtime.CompilerServices

[(Extension)]
module Module =
    [(Extension)]
    let ext1 (x: int) = x.ToString()

// With rec - FS0039 error ❌
namespace rec Ns

open System.Runtime.CompilerServices

[(Extension)]   // error FS0039: The type 'Extension' is not defined.
module Module =
    [(Extension)]
    let ext1 (x: int) = x.ToString()

Error: FS0039: The type 'Extension' is not defined

The open System.Runtime.CompilerServices is in scope (as the non-recursive version proves), but attribute resolution in namespace rec doesn't see types from the opened namespace.

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