[DOC]: List compiler support matrix in README

[bernhardmgruber]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this bug and that I agree to the Code of Conduct

Is this for new documentation, or an update to existing docs?

Update

Describe the incorrect/future/missing documentation

We should explicitly list the supported compilers for CCCL in the README's corresponding section.

Currently, the README refers to the CTK documentation for host compiler support, but the oldest supported CTK 11.1 is fairly vague. For example, it specifies that "the minimum recommended GCC compiler is at least GCC 5", suggestion that g++ below 5 is also somewhat supported. However, we have no devcontainers nor CI runs for g++ below 6, suggesting support for g++ 4.x and 5.x is partial, untested, ... ?

Ideally, we could add a table like the one in CTK 12.5. Maintenance of that table should be rare, but must be done each time support for a CTK is added or removed. However, IMO the benefit of being explicit and easily discoverable outweights that cost.

Adding warnings to cmake or compilation when an unsupported compiler is used could be a follow-up step, but this is not proposed by this issue.

If this is a correction, please provide a link to the incorrect documentation. If this is a new documentation request, please link to where you have looked.

No response

[jrhemstad]

I really don't want to have to maintain this table. This is the kind of thing that immediately goes out of date. The table from the CTK should be the source of truth.

[bernhardmgruber]

@jrhemstad so, what's the minimum g++ version we support?

[wmaxey]

@jrhemstad We can't support what the CTK supports as we don't test everything the compiler supports. q++ on QNX or GCC 4-5 for example.

[jrhemstad]

@jrhemstad so, what's the minimum g++ version we support?

gcc6

https://docs.nvidia.com/cuda/cuda-installation-guide-linux/index.html#host-compiler-support-policy

[jrhemstad]

@jrhemstad We can't support what the CTK supports as we don't test everything the compiler supports. q++ on QNX or GCC 4-5 for example.

Why do we think the CTK supports gcc4-5?

QNX is a special case that I'm content to ignore for the time being.

[bernhardmgruber]

@jrhemstad We can't support what the CTK supports as we don't test everything the compiler supports. q++ on QNX or GCC 4-5 for example.

Why do we think the CTK supports gcc4-5?

Because CCCL supports CTK 11.1, which supports GCC 4 and 5. The matrix you posted is from CTK 12.5. Are you telling me we only support what the latest CTK supports?