testset inside "testset let" fails

[KnutAM]

Couldn't find any documentation that this should not be supported,
nor any related issues or PRs about the following.

@testset let a = 1
    @testset "for" for b in 1:2
        @test true
    end
end

gives

ERROR: MethodError: no method matching Test.ContextTestSet(::String)
The type `Test.ContextTestSet` exists, but no method is defined for this combination of argument types when trying to construct it.

The other way around (for outside let) works.

versioninfo

Julia Version 1.11.2
Commit 5e9a32e7af2 (2024-12-01 20:02 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin24.0.0)
  CPU: 11 × Apple M3 Pro
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, apple-m2)
Threads: 1 default, 0 interactive, 1 GC (on 5 virtual cores)
Environment:
  JULIA_EDITOR = code
  JULIA_NUM_THREADS = 

Full stack trace

Closest candidates are:
  Test.ContextTestSet(::Any, ::Any, ::Any)
   @ Test ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Test/src/Test.jl:1040
  Test.ContextTestSet(::Test.AbstractTestSet, ::Union{Expr, Symbol}, ::Any)
   @ Test ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Test/src/Test.jl:1040
  Test.ContextTestSet(::Union{Expr, Symbol}, ::Any)
   @ Test ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Test/src/Test.jl:1045

Stacktrace:
 [1] macro expansion
   @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Test/src/Test.jl:1788 [inlined]
 [2] macro expansion
   @ ./REPL[55]:2 [inlined]
 [3] top-level scope
   @ ~/.julia/juliaup/julia-1.11.2+0.aarch64.apple.darwin14/share/julia/stdlib/v1.11/Test/src/Test.jl:1655 [inlined]
 [4] top-level scope
   @ ./REPL[55]:0

[KnutAM]

Just realized that the error occurs even for a regular testset inside a let-block.

@testset let a = 1
    @testset "foo" begin
        @test true
    end
end

and only the nested let testsets work, e.g.

@testset let a = 1
    @testset let b = 2
        @test true
    end
end