refactor(params): auto-generate Fortran namelists from Python, eliminate toolchain duplication

.claude/rules/common-pitfalls.md

@@ -59,7 +59,7 @@ Before submitting a PR:
 - [ ] `./mfc.sh precheck -j 8` (5 CI lint checks)
 - [ ] `./mfc.sh build -j 8` (compiles)
 - [ ] `./mfc.sh test --only <relevant> -j 8` (tests pass)
-- [ ] If adding parameters: all 4 locations updated
+- [ ] If adding parameters: definitions.py (_r + _nv) updated; cmake reconfigured; case_validator.py if constraints
 - [ ] If modifying `src/common/`: all three targets tested
 - [ ] If changing output: golden files regenerated for affected tests
 - [ ] One logical change per commit

.claude/rules/parameter-system.md

@@ -23,20 +23,22 @@ MFC has ~3,400 simulation parameters defined in Python and read by Fortran via n
    - Reads `&user_inputs` namelist
    - Each parameter must be declared in the namelist statement
 
-## Adding a New Parameter (4-location checklist)
+## Adding a New Parameter (2-location checklist)
 
-YOU MUST update the first 3 locations. Missing any causes silent failures or compile errors.
-Location 4 is required only if the parameter has physics constraints.
+Fortran declarations and namelist bindings are now auto-generated from definitions.py
+at CMake configure time — no manual Fortran edits needed for simple scalar parameters.
 
-1. **`toolchain/mfc/params/definitions.py`**: Add parameter with type, default, constraints
-2. **`src/*/m_global_parameters.fpp`**: Declare the Fortran variable in the relevant
-   target(s). If the param is used by simulation only, add it there. If shared, add to
-   all three targets' m_global_parameters.fpp.
-3. **`src/*/m_start_up.fpp`**: Add to the Fortran `namelist` declaration in the relevant
-   target(s).
-4. **`toolchain/mfc/case_validator.py`**: Add validation rules if the parameter has
+1. **`toolchain/mfc/params/definitions.py`**: Add parameter with `_r()` (type, default,
+   constraints) AND add it to `NAMELIST_VARS` via `_nv()` for the relevant target(s).
+   After editing, re-run cmake (or `./mfc.sh build`) to regenerate the Fortran includes.
+2. **`toolchain/mfc/case_validator.py`**: Add validation rules if the parameter has
    physics constraints. Include `PHYSICS_DOCS` entry with title, category, explanation.
 
+**Exceptions — still require manual Fortran edits:**
+- Array variables (e.g. `logical, dimension(num_fluids_max)`) → declare in `src/*/m_global_parameters.fpp`
+- Derived-type members (`fluid_pp%attr`, `patch_icpp(i)%attr`) → declare in the relevant derived type
+- Case-optimization parameters → add to `CASE_OPT_PARAMS` and the `#:else` block in `src/simulation/m_global_parameters.fpp`
+
 ## Case Files
 - Case files are Python scripts (`.py`) that define a dict of parameters
 - Validated with `./mfc.sh validate case.py`

CLAUDE.md

@@ -139,11 +139,12 @@ NEVER use `stop` or `error stop`. Use `call s_mpi_abort()` or `@:PROHIBIT()`/`@:
 NEVER use `goto`, `COMMON` blocks, or global `save` variables.
 
 Every `@:ALLOCATE(...)` MUST have a matching `@:DEALLOCATE(...)`.
-Every new parameter MUST be added in at least 3 places (4 if it has constraints):
-  1. `toolchain/mfc/params/definitions.py` (parameter definition)
-  2. Fortran variable declaration in `src/*/m_global_parameters.fpp`
-  3. Fortran namelist in `src/*/m_start_up.fpp` (namelist binding)
-  4. `toolchain/mfc/case_validator.py` (only if parameter has physics constraints)
+Every new parameter MUST be added in at least 2 places (3 if it has constraints):
+  1. `toolchain/mfc/params/definitions.py` (parameter definition + NAMELIST_VARS target set)
+  2. `toolchain/mfc/case_validator.py` (only if parameter has physics constraints)
+  Note: Fortran declarations and namelist bindings are auto-generated from definitions.py
+  at CMake configure time. Simple scalars need no manual Fortran edits. Array/derived-type
+  variables still require a manual declaration in `src/*/m_global_parameters.fpp`.
 
 Changes to `src/common/` affect ALL three executables. Test comprehensively.
 

CMakeLists.txt

@@ -461,6 +461,39 @@ macro(HANDLE_SOURCES target useCommon)
 endmacro()
 
 
+# Generate Fortran parameter namelist/decl includes into the per-target build
+# include directories before HANDLE_SOURCES globs them for Fypp.
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+set(_mfc_gen_stamp "${CMAKE_BINARY_DIR}/mfc_params_gen.stamp")
+file(GLOB_RECURSE _mfc_gen_inputs
+    "${CMAKE_CURRENT_SOURCE_DIR}/toolchain/mfc/params/*.py"
+)
+set(_mfc_needs_regen FALSE)
+if(NOT EXISTS "${_mfc_gen_stamp}")
+    set(_mfc_needs_regen TRUE)
+else()
+    foreach(_input IN LISTS _mfc_gen_inputs)
+        if("${_input}" IS_NEWER_THAN "${_mfc_gen_stamp}")
+            set(_mfc_needs_regen TRUE)
+            break()
+        endif()
+    endforeach()
+endif()
+if(_mfc_needs_regen)
+    execute_process(
+        COMMAND "${Python3_EXECUTABLE}"
+                "${CMAKE_CURRENT_SOURCE_DIR}/toolchain/mfc/params/generators/cmake_gen.py"
+                "${CMAKE_BINARY_DIR}"
+        WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+        RESULT_VARIABLE _mfc_gen_result
+        ERROR_VARIABLE  _mfc_gen_error
+    )
+    if(NOT _mfc_gen_result EQUAL 0)
+        message(FATAL_ERROR "Fortran param generation failed:\n${_mfc_gen_error}")
+    endif()
+    file(TOUCH "${_mfc_gen_stamp}")
+endif()
+
 HANDLE_SOURCES(pre_process ON)
 HANDLE_SOURCES(simulation ON)
 HANDLE_SOURCES(post_process ON)

src/post_process/m_global_parameters.fpp

@@ -17,20 +17,19 @@ module m_global_parameters
 
     implicit none
 
+    #:include 'generated_decls.fpp'
+
     !> @name Logistics
     !> @{
-    integer                 :: num_procs  !< Number of processors
-    character(LEN=path_len) :: case_dir   !< Case folder location
+    integer :: num_procs  !< Number of processors
     !> @}
 
     ! Computational Domain Parameters
 
     integer :: proc_rank  !< Rank of the local processor
     !> @name Number of cells in the x-, y- and z-coordinate directions
     !> @{
-    integer :: m, m_root
-    integer :: n
-    integer :: p
+    integer :: m_root
     !> @}
 
     !> @name Max and min number of cells in a direction of each combination of x-,y-, and z-
@@ -39,7 +38,6 @@ module m_global_parameters
 
     !> @name Cylindrical coordinates (either axisymmetric or full 3D)
     !> @{
-    logical :: cyl_coord
     integer :: grid_geometry
     !> @}
 
@@ -66,50 +64,24 @@ module m_global_parameters
     real(wp), allocatable, dimension(:) :: dx, dy, dz
     !> @}
 
-    integer :: buff_size     !< Number of ghost cells for boundary condition storage
-    integer :: t_step_start  !< First time-step directory
-    integer :: t_step_stop   !< Last time-step directory
-    integer :: t_step_save   !< Interval between consecutive time-step directory
+    integer :: buff_size  !< Number of ghost cells for boundary condition storage
     !> @name IO options for adaptive time-stepping
     !> @{
-    logical  :: cfl_adap_dt, cfl_const_dt, cfl_dt
-    real(wp) :: t_save
-    real(wp) :: t_stop
-    real(wp) :: cfl_target
-    integer  :: n_save
-    integer  :: n_start
+    logical :: cfl_dt
+    integer :: n_save
     !> @}
 
     ! NOTE: m_root, x_root_cb, x_root_cc = defragmented grid (1D only; equals m, x_cb, x_cc in serial)
 
     !> @name Simulation Algorithm Parameters
     !> @{
-    integer            :: model_eqns                   !< Multicomponent flow model
-    integer            :: num_fluids                   !< Number of different fluids present in the flow
-    logical            :: relax                        !< phase change
-    integer            :: relax_model                  !< Phase change relaxation model
-    logical            :: mpp_lim                      !< Maximum volume fraction limiter
     integer            :: sys_size                     !< Number of unknowns in the system of equations
-    integer            :: recon_type                   !< Which type of reconstruction to use
-    integer            :: weno_order                   !< Order of accuracy for the WENO reconstruction
-    integer            :: muscl_order                  !< Order of accuracy for the MUSCL reconstruction
-    logical            :: mixture_err                  !< Mixture error limiter
-    logical            :: alt_soundspeed               !< Alternate sound speed
-    logical            :: mhd                          !< Magnetohydrodynamics
-    logical            :: relativity                   !< Relativity for RMHD
-    logical            :: hypoelasticity               !< Turn hypoelasticity on
-    logical            :: hyperelasticity              !< Turn hyperelasticity on
     logical            :: elasticity                   !< elasticity modeling, true for hyper or hypo
     integer            :: b_size                       !< Number of components in the b tensor
     integer            :: tensor_size                  !< Number of components in the nonsymmetric tensor
-    logical            :: cont_damage                  !< Continuum damage modeling
-    logical            :: hyper_cleaning               !< Hyperbolic cleaning for MHD
-    logical            :: igr                          !< enable IGR
-    integer            :: igr_order                    !< IGR reconstruction order
     logical, parameter :: chemistry = .${chemistry}$.  !< Chemistry modeling
     !> @}
 
-    integer :: avg_state  !< Average state evaluation method
     !> @name Annotations of the structure, i.e. the organization, of the state vectors
     !> @{
     type(eqn_idx_info)  :: eqn_idx   !< All conserved-variable equation index ranges and scalars.
@@ -122,7 +94,6 @@ module m_global_parameters
 
     ! Cell indices (InDices With BUFFer): includes buffer in simulation only
     type(int_bounds_info) :: idwbuff(1:3)
-    integer               :: num_bc_patches
     logical               :: bc_io
     !> @name Boundary conditions in the x-, y- and z-coordinate directions
     !> @{
@@ -133,12 +104,8 @@ module m_global_parameters
     integer, dimension(3)              :: shear_indices  !< Indices of the stress components that represent shear stress
     integer                            :: shear_BC_flip_num  !< Number of shear stress components to reflect for boundary conditions
     integer, dimension(3, 2)           :: shear_BC_flip_indices  !< Shear stress BC reflection indices (1:3, 1:shear_BC_flip_num)
-    logical                            :: parallel_io  !< Format of the data files
-    logical                            :: sim_data
-    logical                            :: file_per_process  !< output format
     integer, allocatable, dimension(:) :: proc_coords  !< Processor coordinates in MPI_CART_COMM
     integer, allocatable, dimension(:) :: start_idx  !< Starting cell-center index of local processor in global grid
-    integer                            :: num_ibs  !< Number of immersed boundaries
 #ifdef MFC_MPI
     type(mpi_io_var), public                      :: MPI_IO_DATA
     type(mpi_io_ib_var), public                   :: MPI_IO_IB_DATA
@@ -159,10 +126,6 @@ module m_global_parameters
     real(wp), allocatable, dimension(:)      :: adv  !< Advection variables
     ! Formatted Database File(s) Structure Parameters
 
-    integer               :: format                                    !< Format of the database file(s)
-    integer               :: precision                                 !< Floating point precision of the database file(s)
-    logical               :: down_sample                               !< down sampling of the database file(s)
-    logical               :: output_partial_domain                     !< Specify portion of domain to output for post-processing
     type(bounds_info)     :: x_output, y_output, z_output              !< Portion of domain to output for post-processing
     type(int_bounds_info) :: x_output_idx, y_output_idx, z_output_idx  !< Indices of domain to output for post-processing
     !> @name Size of the ghost zone layer in the x-, y- and z-coordinate directions. The definition of the ghost zone layers is only
@@ -172,101 +135,23 @@ module m_global_parameters
     type(int_bounds_info) :: offset_x, offset_y, offset_z
     !> @}
 
-    !> @name The list of all possible flow variables that may be written to a database file. It includes partial densities, density,
-    !! momentum, velocity, energy, pressure, volume fraction(s), specific heat ratio function, specific heat ratio, liquid stiffness
-    !! function, liquid stiffness, primitive variables, conservative variables, speed of sound, the vorticity, and the numerical
-    !! Schlieren function.
-    !> @{
-    logical, dimension(num_fluids_max) :: alpha_rho_wrt
-    logical                            :: rho_wrt
-    logical, dimension(3)              :: mom_wrt
-    logical, dimension(3)              :: vel_wrt
-    integer                            :: flux_lim
-    logical, dimension(3)              :: flux_wrt
-    logical                            :: E_wrt
-    logical, dimension(num_fluids_max) :: alpha_rho_e_wrt
-    logical                            :: fft_wrt
-    logical                            :: pres_wrt
-    logical, dimension(num_fluids_max) :: alpha_wrt
-    logical                            :: gamma_wrt
-    logical                            :: heat_ratio_wrt
-    logical                            :: pi_inf_wrt
-    logical                            :: pres_inf_wrt
-    logical                            :: prim_vars_wrt
-    logical                            :: cons_vars_wrt
-    logical                            :: c_wrt
-    logical, dimension(3)              :: omega_wrt
-    logical                            :: qm_wrt
-    logical                            :: liutex_wrt
-    logical                            :: schlieren_wrt
-    logical                            :: cf_wrt
-    logical                            :: ib
-    logical                            :: ib_state_wrt
-    logical                            :: chem_wrt_Y(1:num_species)
-    logical                            :: chem_wrt_T
-    logical                            :: lag_header
-    logical                            :: lag_txt_wrt
-    logical                            :: lag_db_wrt
-    logical                            :: lag_id_wrt
-    logical                            :: lag_pos_wrt
-    logical                            :: lag_pos_prev_wrt
-    logical                            :: lag_vel_wrt
-    logical                            :: lag_rad_wrt
-    logical                            :: lag_rvel_wrt
-    logical                            :: lag_r0_wrt
-    logical                            :: lag_rmax_wrt
-    logical                            :: lag_rmin_wrt
-    logical                            :: lag_dphidt_wrt
-    logical                            :: lag_pres_wrt
-    logical                            :: lag_mv_wrt
-    logical                            :: lag_mg_wrt
-    logical                            :: lag_betaT_wrt
-    logical                            :: lag_betaC_wrt
-    !> @}
-
-    real(wp), dimension(num_fluids_max) :: schlieren_alpha  !< Per-fluid Schlieren intensity amplitude coefficients
-    integer                             :: fd_order         !< Finite-difference order for vorticity and Schlieren derivatives
-    integer                             :: fd_number        !< Finite-difference half-stencil size: MAX(1, fd_order/2)
-    !> @name Reference parameters for Tait EOS
-    !> @{
-    real(wp) :: rhoref, pref
-    !> @}
-
+    ! alpha_rho_wrt, mom_wrt, vel_wrt, flux_wrt, alpha_rho_e_wrt, alpha_wrt,
+    ! omega_wrt, chem_wrt_Y, schlieren_alpha: auto-generated in generated_decls.fpp
+    integer                    :: fd_number  !< Finite-difference half-stencil size: MAX(1, fd_order/2)
     type(chemistry_parameters) :: chem_params
     !> @name Bubble modeling variables and parameters
     !> @{
-    integer :: nb
-    real(wp) :: Eu, Ca, Web, Re_inv
+    real(wp) :: Eu
     real(wp), dimension(:), allocatable :: weight, R0
-    logical :: bubbles_euler
-    logical :: qbmm
-    logical :: polytropic
-    logical :: polydisperse
-    logical :: adv_n
-    integer :: thermal  !< 1 = adiabatic, 2 = isotherm, 3 = transfer
     real(wp) :: phi_vg, phi_gv, Pe_c, Tw, k_vl, k_gl
     real(wp) :: gam_m
     real(wp), dimension(:), allocatable :: pb0, mass_g0, mass_v0, Pe_T, k_v, k_g
     real(wp), dimension(:), allocatable :: Re_trans_T, Re_trans_c, Im_trans_T, Im_trans_c, omegaN
-    real(wp) :: R0ref, p0ref, rho0ref, T0ref, ss, pv, vd, mu_l, mu_v, mu_g, gam_v, gam_g, M_v, M_g, cp_v, cp_g, R_v, R_g
+    real(wp) :: p0ref, rho0ref, T0ref, ss, pv, vd, mu_l, mu_v, mu_g, gam_v, gam_g, M_v, M_g, cp_v, cp_g, R_v, R_g
     real(wp) :: G
-    real(wp) :: poly_sigma
-    real(wp) :: sigR
     integer :: nmom
     !> @}
 
-    !> @name surface tension coefficient
-    !> @{
-    real(wp) :: sigma
-    logical  :: surface_tension
-    !> @}
-
-    !> @name Lagrangian bubbles
-    !> @{
-    logical :: bubbles_lagrange
-    !> @}
-
-    real(wp) :: Bx0                       !< Constant magnetic field in the x-direction (1D)
     real(wp) :: wall_time, wall_time_avg  !< Wall time measurements
 
 contains

src/post_process/m_start_up.fpp

@@ -59,18 +59,7 @@ contains
         integer                 :: iostatus
         character(len=1000)     :: line
 
-        namelist /user_inputs/ case_dir, m, n, p, t_step_start, t_step_stop, t_step_save, model_eqns, num_fluids, mpp_lim, &
-            & weno_order, bc_x, bc_y, bc_z, fluid_pp, bub_pp, format, precision, output_partial_domain, x_output, y_output, &
-            & z_output, hypoelasticity, G, mhd, chem_wrt_Y, chem_wrt_T, avg_state, alpha_rho_wrt, rho_wrt, mom_wrt, vel_wrt, &
-            & E_wrt, fft_wrt, pres_wrt, alpha_wrt, gamma_wrt, heat_ratio_wrt, pi_inf_wrt, pres_inf_wrt, cons_vars_wrt, &
-            & prim_vars_wrt, c_wrt, omega_wrt, qm_wrt, liutex_wrt, schlieren_wrt, schlieren_alpha, fd_order, mixture_err, &
-            & alt_soundspeed, flux_lim, flux_wrt, cyl_coord, parallel_io, rhoref, pref, bubbles_euler, qbmm, sigR, R0ref, nb, &
-            & polytropic, thermal, Ca, Web, Re_inv, polydisperse, poly_sigma, file_per_process, relax, relax_model, cf_wrt, &
-            & sigma, adv_n, ib, num_ibs, cfl_adap_dt, cfl_const_dt, t_save, t_stop, n_start, cfl_target, surface_tension, &
-            & bubbles_lagrange, sim_data, hyperelasticity, Bx0, relativity, cont_damage, hyper_cleaning, num_bc_patches, igr, &
-            & igr_order, down_sample, recon_type, muscl_order, lag_header, lag_txt_wrt, lag_db_wrt, lag_id_wrt, lag_pos_wrt, &
-            & lag_pos_prev_wrt, lag_vel_wrt, lag_rad_wrt, lag_rvel_wrt, lag_r0_wrt, lag_rmax_wrt, lag_rmin_wrt, lag_dphidt_wrt, &
-            & lag_pres_wrt, lag_mv_wrt, lag_mg_wrt, lag_betaT_wrt, lag_betaC_wrt, alpha_rho_e_wrt, ib_state_wrt
+        #:include 'generated_namelist.fpp'
 
         file_loc = 'post_process.inp'
         inquire (FILE=trim(file_loc), EXIST=file_check)