Update docs about possible MOD files compilation errors with >=9.0 (#…

…3106)

- Add a table with all models and MOD files so that it would be
  easy for users to find the changed mod file.
- Change the sphinx version to >= 9.0
- Add a link in  the top-level README

fixes #1876

README.md

@@ -14,11 +14,16 @@ Linux and Mac you can install the official Python 3 wheel with:
 pip3 install neuron
 ```
 
-If you want to build the latest version from source, we support **CMake** as build system. **Autotools** build system has been removed after 8.0 release.
+If you want to build the latest version from source, we support **CMake** as build system.
 See detailed installation instructions: [docs/install/install_instructions.md](docs/install/install_instructions.md).
 
 It is possible to install the Linux Python wheels on Windows via the Windows Subsystem for Linux (WSL) - check the installation instructions above.
 
+> [!NOTE]
+> **About NEURON >= 9.0**: If you are experiencing compilation errors while using
+> `nrnivmodl` with NEURON >=9.0, but not with previous 8.x releases, see
+> [Adapting MOD files for C++ with NEURON >= 9.0](docs/guide/porting_mechanisms_to_cpp.rst).
+
 ## Documentation
 
 * See documentation section of the [NEURON website](https://neuron.yale.edu/neuron/docs)

bin/nrnivmodl.in

@@ -274,5 +274,15 @@ if [ "$LinkCoreNEURON" = true ] ; then
   fi
 fi
 
-make -j 4 -f "${bindir}/nrnmech_makefile" "ROOT=${prefix}" "MODOBJFILES=$MODOBJS" "UserLDFLAGS=$UserLDFLAGS" "UserINCFLAGS=$UserINCFLAGS" "LinkCoreNEURON=$LinkCoreNEURON" "UserNMODLBIN=$UserNMODLBIN" "UserNMODLFLAGS=$UserNMODLFLAGS" special &&
-echo "Successfully created $MODSUBDIR/special"
+set +e
+
+make -j 4 -f "${bindir}/nrnmech_makefile" "ROOT=${prefix}" "MODOBJFILES=$MODOBJS" "UserLDFLAGS=$UserLDFLAGS" "UserINCFLAGS=$UserINCFLAGS" "LinkCoreNEURON=$LinkCoreNEURON" "UserNMODLBIN=$UserNMODLBIN" "UserNMODLFLAGS=$UserNMODLFLAGS" special
+
+ MAKE_STATUS=$?
+
+ if [ $MAKE_STATUS -eq 0 ]; then
+     echo "Successfully created $MODSUBDIR/special"
+ else
+     printf "\nNOTE: If you are encountering MOD file compilation errors only with NEURON version 9.0 or later\n"
+     printf "refer to the C++ migration guide at https://nrn.readthedocs.io/en/9.0.0/guide/porting_mechanisms_to_cpp.html\n\n"
+ fi