MSVC compiler.version is not allowed to contain `.`

[tru]

We needed to keep track of subversions of MSVC, i.e. 16.8 vs 16.9. Why? because MSVC LTCG (LTO) is not compatible between minor versions. So if you compile a static library with LTCG in 16.8 you can't link it to with 16.9.

We thought this was a easy solution - just change compiler.version to 16.8 instead of 16. But there are several assumptions in the conan codebase about the value of this setting, here is one: https://github.com/conan-io/conan/blob/develop/conans/client/tools/win.py#L429

For now I am adding compiler.minorversion but maybe this should be fixed.

[danimtb]

Hi @tru,

Would you mind providing me with more information about the topic? Did the MSVC team provide information about this incompatibility between minor versions? I believe this will be useful to improve our current msvc compiler support.

Thank you

[tru]

guessing this is the best source of the information: https://docs.microsoft.com/en-us/cpp/error-messages/compiler-errors-1/fatal-error-c1047?view=msvc-160

For example, you can't link a /LTCG library built by using Visual Studio 2019 version 16.7 to an app built by using Visual Studio 2019 version 16.8

But basically this is the same for GCC and Clang LTO as well. When using LTO/LTCG static libraries will contain the .o files that are NOT objects - they are just "bitcode" that is only supposed to be consumed by the same compiler that created it.

[memsharded]

Hi @tru

Are you aware that the new msvc compiler setting definition contains the minor compiler version? Also the CMakeToolchain from 1.36 (due today) will be able to define the specific msvc minor version (or fail otherwise, protecting from setup errors).

I know it is a big change, not easy to change recipes and existing builds to use it, but just to let you know that in the new build system integrations we are aiming to improve many of these issues.

[tru]

No I was not aware of that - we are a bit behind on our conan versions. But that sounds good.

[memsharded]

For reference for other users as well: https://docs.conan.io/en/latest/reference/config_files/settings.yml.html?#msvc

[AbrilRBS]

Closing as Conan 1-specific, which is no longer supported.

In Conan 2, the settings handling has been improved and errors like this should not show up, and a new msvc compiler was added to replace the old Visual Studio one, with more keys to specify extra information if needed