Explicit return (#2657)

* Explicit `return`

* more

* one more

* format

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: Hendrik Ranocha <[email protected]>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: 3 people

src/callbacks_stage/positivity_zhang_shu.jl

@@ -64,7 +64,7 @@ end
 # terminate the type-stable iteration over tuples
 function limiter_zhang_shu!(u, thresholds::Tuple{}, variables::Tuple{},
                             mesh, equations, solver, cache)
-    nothing
+    return nothing
 end
 
 include("positivity_zhang_shu_dg1d.jl")

src/callbacks_step/analysis.jl

@@ -595,7 +595,7 @@ end
 
 # terminate the type-stable iteration over tuples
 function analyze_integrals(analysis_integrals::Tuple{}, io, du, u, t, semi)
-    nothing
+    return nothing
 end
 
 # used for error checks and EOC analysis

src/solvers/dgmulti/dg_parabolic.jl

@@ -257,7 +257,7 @@ end
 function calc_boundary_flux!(flux, u, t, operator_type,
                              boundary_conditions::NamedTuple{(), Tuple{}},
                              mesh, equations, dg::DGMulti, cache, cache_parabolic)
-    nothing
+    return nothing
 end
 
 function calc_single_boundary_flux!(flux_face_values, u_face_values, t,

src/solvers/dgsem_p4est/dg_3d.jl

@@ -26,7 +26,8 @@ function create_cache(mesh::Union{P4estMesh{3}, T8codeMesh{3}}, equations,
                          nnodes(mortar_l2), nnodes(mortar_l2))
                      for _ in 1:Threads.maxthreadid()] |> VecOfArrays
 
-    (; fstar_primary_threaded, fstar_secondary_threaded, fstar_tmp_threaded, u_threaded)
+    return (; fstar_primary_threaded, fstar_secondary_threaded, fstar_tmp_threaded,
+            u_threaded)
 end
 
 #     index_to_start_step_3d(index::Symbol, index_range)

src/solvers/dgsem_unstructured/dg_2d.jl

@@ -358,7 +358,7 @@ function calc_boundary_flux_by_type!(cache, t, BCs::Tuple{}, BC_indices::Tuple{}
                                      mesh::Union{UnstructuredMesh2D, P4estMesh,
                                                  T8codeMesh},
                                      equations, surface_integral, dg::DG)
-    nothing
+    return nothing
 end
 
 function calc_boundary_flux!(cache, t, boundary_condition::BC, boundary_indexing,