Hovering doesn't show interface in "external" subroutine

[mcdc64]

Hi,

I am working on a project that uses LAPACK (a linear algebra library) and used fortls's "source_dirs" to include the relevant paths to the directory:

VSCode Settings:

{
"fortran.fortls.directories": ["/home/cian/lapack/SRC/**","home/cian/lapack/BLAS/SRC/**","home/cian/sims/*"]
}

This works well to call subroutines from LAPACK and allow the subroutine's interface to be seen on hover, thus saving me having to look it up online. See snippet below:

! HOVER WORKS!
module implicitIntegrator
contains
    subroutine singleImplicitStep(dt, derivMatrix, phivals)
        implicit none(type, external)
        real dt
        real, allocatable, dimension(:) :: phivals, pivot
        real, allocatable, dimension(:, :) :: derivMatrix, identity, diffMatrix
        integer N, j
        integer rc

        call dgesv(N + 1, 1, diffMatrix, N + 1, pivot, phivals, N + 1, rc)

    end subroutine
end module

This snippet shows the subroutine's interface when I hover, as seen in this image:

The problem, obviously, is that the actual code is missing a declaration for the subroutine, even though fortls knows where it is. And since the library I'm calling from has no mod files, I need to declare the subroutine as external to avoid compiler errors. So we add a line below implicit none(type, external):

! HOVER DOESN'T WORK
module implicitIntegrator
contains
    subroutine singleImplicitStep(dt, derivMatrix, phivals)
        implicit none(type, external)
        external dgesv
        real dt
        real, allocatable, dimension(:) :: phivals, pivot
        real, allocatable, dimension(:, :) :: derivMatrix, identity, diffMatrix
        integer N, j
        integer rc

        call dgesv(N + 1, 1, diffMatrix, N + 1, pivot, phivals, N + 1, rc)

    end subroutine
end module

But declaring it as external seems to prevent fortls from accessing the interface when I hover, either on the actual call or on the "external" declaration.

Is this known behaviour? I haven't seen any issues that look similar; if this is a duplicate please close.