Keep `compiler.version` and used `emsdk` version consistent

[stevenwdv]

It seems that currently we manually need to keep the compiler.version setting consistent with the emsdk version in tool_requires. With conan-io/conan#19592, detect_api will have detect_emcc_compiler, but this will be ran too early. Would there be a way to automatically set compiler.version based on the version of the emsdk tool that is used?

If not, that would be unfortunate, because then there is no possibility of using a version pattern like emsdk/[~5], because the value of compiler.version will become outdated.
Maybe we could at least check in the recipe that its version is consistent with compiler.version?

[memsharded]

Hi @stevenwdv

I am not sure what you mean, if you have the detected emcc version ,why not using it directly in the [tool_requires]? it is not correlated to the emsdk version?

[stevenwdv]

Won't detect_api stuff in the profile be run before the emsdk package is loaded? Thus, if I don't have an existing separate EMSDK install, it won't pick it up?

[memsharded]

Won't detect_api stuff in the profile be run before the emsdk package is loaded? Thus, if I don't have an existing separate EMSDK install, it won't pick it up?

No, the rendering of the profile, including the evaluation of detect_api is a very early step, where the jinja2 syntax of the profile is loaded, and evaluated, replacing occurences, even before the profile contents are loaded to start computing the dependency graph.

If the profile has something as:

{%- set _, emsdk_version, _ = detect_api.detect_emcc_compiler("emcc") %}
[tool_requires]
emsdk/{{emsdk_version}}

then it should work

[stevenwdv]

Wait, I don't understand. The emsdk tool_requires will provide emcc much later than detect_emcc_compiler is evaluated, right? So then won't emsdk_version in that example be None?

[memsharded]

Wait, I don't understand. The emsdk tool_requires will provide emcc much later than detect_emcc_compiler is evaluated, right? So then won't emsdk_version in that example be None?

The detect_api only works for detecting things in the environment/system. It is impossible that it can detect something inside a tool_requires that hasn't been fetched yet from the server.

[stevenwdv]

Then I understood it correctly, but then how does your example work? As it has emsdk in the tool_requires, but also tries to detect it before that tool_requires is installed (unless we have a platform_tool_requires, but I'm talking about the case where we don't and we're using the recipe from this repo)

[stevenwdv]

Ah, I just stumbled upon conan-io/conan#13533 while searching for a different issue. It seems point (3) is what I'm asking for. But until we have that...

we could at least check in the recipe that its version is consistent with compiler.version?

[memsharded]

Then I understood it correctly, but then how does your example work? As it has emsdk in the tool_requires, but also tries to detect it before that tool_requires is installed (unless we have a platform_tool_requires, but I'm talking about the case where we don't and we're using the recipe from this repo)

That tool_requires in the profile could be a wrapper recipe around the system installed one that helps tracking and modeling the system version, as well as automating some of its configuration (like things in the recipe package_info()). I wasn't assuming it would detect the emcc inside the package, it is not uncommon to find this kind of system wrapper.

[stevenwdv]

Ah I see, that makes sense. As I understand it, that approach would not work for the emsdk recipe in this repo though, right? (Given I don't have EMSDK installed separately.)