Option 'minuit2' is no longer supported in ROOT 6.32.06 but still present in build instructions

[Ako_b]

Issue

According to Building ROOT from source, option minuit2 is a valid build option. However, during actual build with option -Dminuit2=ON CMake yields following error:
Option 'minuit2' is no longer supported in ROOT 6.32.06

I’ve found this thread:

I suspect it means that you will no longer be able to ‘disable’ minuit2. It will be always turned ON. See ROOT Version 6.30 Release Notes

— ferhue

So, I am confused, does ROOT built with -Dminimal=on contain minuit2 by default?
Also, I kindly ask to update the build instructions.

To Reproduce

git clone --branch v6-32-06 --depth=1 \
    https://github.com/root-project/root.git \
    /opt/root-minimal-v6.32.06-source
cmake -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_INSTALL_PREFIX=/opt/root-minimal-v6.32.06 \
    -Dminimal=ON -Dminuit2=ON \
    -B /opt/root-minimal-v6.32.06-build
    -S /opt/root-minimal-v6.32.06-source

Error in output:

CMake Error at cmake/modules/RootBuildOptions.cmake:402 (message):
  >>> Option 'minuit2' is no longer supported in ROOT 6.32.06.
Call Stack (most recent call first):
  CMakeLists.txt:107 (include)

Setup

ROOT Version: 6.32.06
Platform: AlmaLinux 9.4 (Seafoam Ocelot) x86-64
Compiler: g++ (GCC) 11.4.1 20231218 (Red Hat 11.4.1-3)

---

[jonas]

Thanks a lot! I’m fixing this.

Yes, ROOT builds always with Minuit2, because it’s now the default minimizer in all of ROOT. Therefore, it can’t be disabled anymore, even when building a minimal ROOT. The minimal ROOT includes fitting TH histograms, which now uses Minuit 2.

I hope that’s ok for you!

Cheers,
Jonas