Keep classic Fortran on VS2022 and IFX on VS2026

[van_der_merwe__ben]

Does anyone know of a way to keep classic Fortran on Visual Studio 2019 and 2022 while  putting the newer IFX Fortran version only on 2026?

You have this situation:

• You have older code branches you have to support, ones that use Visual Studio 2019 and 2022 and Intel Classic Fortran 2023.2.1.7. You cant just migrate them, it is a major operation.
• You have that installed, all working well.
• For newer code branches, you want to use Visual Studio 2026 and Intel Fortran IFX 2025.3.2.26
• You install Visual Studio 2026.

When you install Intel Fortran IFX 2025.3.2.26, it asks about integration with Visual Studio 2019, 2022 and 2026. If you uncheck the 2022 integration, hoping it will mean "leave 2022 alone,  classic Fortran is there, leave it alone", then during the installation, you can see a step where it removes the Visual Studio 2022 integration even though it was not installed by this Intel Fortran but by the classic version. So then classic Fortran in 2022 no longer works. And running a repair on the classic Fortran does not fix it.

So.... you uninstall both Fortran versions. You run the newer Fortran installer and integrate it with all Visual Studio versions.  You manually delete the leftover folder "c:\program files(x86)\Intel\OneAPI" which prevents the installer from running. It also fails with "Details: Attempt 1 of 2 failed. Execution of C:\Program Files (x86)\Microsoft Visual Studio\Installer\resources\app\ServiceHub\Services\Microsoft.VisualStudio.Setup.Service\VSIXInstaller.exe failed with exit code -2146233088, output:
The product was modified outside of this installer. Please retry the operation." So you deleted these folders:

%LOCALAPPDATA%\Microsoft\VisualStudio\1*.*\ComponentModelCache 
%LOCALAPPDATA%\Microsoft\VisualStudio\1*.*\Extensions
And run the installer again with the repair option.

Now install the old classic compiler, and if you now open a solution containing classic Fortran projects in Visual Studio 2022, their status is "(incompatbile) (The application is not installed)"

Does anyone have any ideas how you can, on one machine have VS 2022 + Classic Fortran, and VS 2026 + IFX Fortran? Is that possible? This is on a test machine, so I can repair and try ideas.

Or is there a standalone Fortran installer that has both classic and IFX Fortran and support VS 2019,2022 and 2026?

[JohnNichols]

Ifort will remain on the setup as long as the setup string started with a 2024 or earlier offline installer.  

Once you have that installed and I kept one.  Then you can update as each version is released and the old IForts are still available.  

I only update from the control panel as has been normal for Intel for many years.  It used to automatically tell you, now you have to watch. 

So I have IFORT and IFX available in 2022, 2026 and 2026 Insider. This is 2022

IN 2022 you only use the select compiler on the solution explorer,  pick the one you want for each solution.  This is 2022

As seen above

on the much better 2026 Insider

If you change the X64 in debug to X32 it changes compiler.  

Really that is all you need, as long as you have a 2024 offline installer or you can get someone to load one into a drop box. 

I hope I answered your question,  IFX has some problems, it is getting better, the annoying issue of parameters in the watch window is all the annoys me.  

IFX does run jolly faster and 2026 Insider is so sweet, like a 40 year old Datsun 1200. 

John

[JohnNichols]

Sooner or later VS will not support IFORT, but based on history, I would say we have two more cycles or 8 years.  

[van_der_merwe__ben]

John.... Interesting... you say "2024 or earlier", so 2023.2 should work? If I currently have a machine with only VS2026 installed and only Fortran 2025.3, then if I install VS2022 and then Fortran 2023.2, should it all work then? I do not need ifort in VS2026, but I assuredly need ifort in VS2022 and VS2019. In VS2026 I only need ifx, not ifort.

What if you have a machine with VS2022 and Intel 2023.2 installed. If you then install VS2026 and then install Intel Fortran 2025.3, I guess you choose integration with all detected Visual Studio Studio versions when you install it, and hopefully VS2022 will still have ifort available?

(I am installing the standalone Fortran offline, not the entire oneAPI piece.)

[JohnNichols]

1. Clean out all the mess

2. Install VS 2022 and VS 2026 

3. Install the 2023.2 if you have it

4. then using CONTROL PANEL update the 2023.2 and everything will be kept

5. You can change IFX and IFORT in 2022 using the Compiler and in 2026 using debug, X64 or X32.  

They will all be there, just never remove anything after Step 1. Just add.

I assure you I use this every day and swap compilers all the time, although lately I have grown fond of IFX, much like a good Stoat.  

[van_der_merwe__ben]

I shall do some more experiments over the next week and see what works and post here.

When you say clean out the mess, just uninstall it all, or also clean out folders like: %LOCALAPPDATA%\Microsoft\VisualStudio\1*.*\ComponentModelCache, %LOCALAPPDATA%\Microsoft\VisualStudio\1*.*\Extensions

[JohnNichols]

Do not forget to add the FEE as it is not installed with the latest ONEAPI, although the version is old so it kept coming with the updates.  

Just because if says 2023 and 2025 does not mean all components updated, look at the CONTROL PANEL.  

Plus in IFX in debug mode watch does not pick up parameters, no matter what.