MVSC fails compiling Minuit2 with OpenMP enabled

[AdrianDBS]

Check duplicate issues.

• Checked for duplicates

Description

Compiling Minuit2 with minuit2_omp=ON when using MVSC raises error C3016: 'i': index variable in OpenMP 'for' statement must have signed integral type

Source of the error is line 102 in math/minuit2/src/Numerical2PGradientCalculator.cxx where (in commit 95035e2) the for-loop variable type was changed from integer to unsigned integer. While this is no problem for GCC, MVSC apparently strictly forbids this.

Reproducer

Just compile Minuit2 with minuit2_omp=ON using MVSC.

ROOT version

Affected version: v6-38-00
More specifically: Every revision downstream of commit 95035e2

Installation method

Build from source

Operating system

Windows

Additional context

No response

[guitargeek]

Thanks for the report! Can you let us know if it would work with this fix? Thanks!

• [Minuit2] Use signed integer as index variable in OpenMP 'for' statement #20587

[AdrianDBS]

It works again :-)
Thanks for the quick fix!