Changing Intel Fortran compiler option /fpconstant

Usage
1

Hi,

I am new to CMake although I have been aware of its existence for several years.

I am trying to use CMake to build a static library project in Visual Studio Community 2015. I have to pass compiler flag /fpconstant. Here is how I have prepared my CMakeLists.txt:

cmake_minimum_required(VERSION 3.19.4 FATAL_ERROR)
set(ENV{FC} "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries_2016.2.180/windows/bin/ia32/ifort.exe")

project(plybck LANGUAGES Fortran)

add_compile_options(/fpconstant)

add_library("${PROJECT_NAME}" STATIC plybckutils.f90)

However, after the project is built by CMake and I open the sln solution in Visual Studio, the flag has not changed (Fortran>Floating Point > Extend Precision of Single-Precision Constants).

I opened .vfproj in a text editor and verified that /fpconstant is in the string AdditionalOptions, so it seems like the add_compile_options is doing its job.

Then, I manually changed the flag in Visual Studio GUI to /fpconstant, and saved the project. I can see that ExtendSinglePrecisionConstants=“true” has been subsequently added to .vfproj which was not there before.

How can I change get CMake to do this change for me?

2

CMake uses some flag tables to map flags to .vcproj file properties. Not all flags are mapped though. Does it work with the way CMake generates the project as-is at least?

Cc: @brad.king

3

For reference, the Fortran flag table for VS is in the code here.

4

Thanks for the info @ben.boeckel and @brad.king
So yes CMake generates the Visual Studio project. Then I have to change a few flags (/fpconstant is one of them) as the main application for which I am building the static library uses certain compiler flags that affect code generation.
I went over the Fortran flag table. Maybe I can add a few flags to it and compile from source? I have never done this before and have no idea how challenging it can be!

5

Yes, try adding some flags and building from source. If you get it working, please see CONTRIBUTING.rst and open a merge request to add the entries.