Feature/package id cmake checks

[memsharded]

Changelog: Bugfix: Use the real settings value to check the compiler and compiler version in the cmake generator local flow when the package_id() method changes values.
Docs: Omit

Fix: #6658

[jgsogo]

Probably this change makes no difference as we are unsing only CMAKE_MATCH_1 , but at least it matches the comment and the previous block of code... although MATCH will probably run faster.

[jgsogo]

Wow, sorry, I was looking to one commit of the changeset (not my best day).

I don't see how this change fixes the issue, the regex continues to be the same, does the CMAKE_MATCH_1 stores the last match when using MATCHALL?

[jgsogo]

Ok, according to CMake docs: https://cmake.org/cmake/help/v3.17/variable/CMAKE_MATCH_n.html

CMAKE_MATCH_: Capture group <n> matched by the last regular expression

[memsharded]

Changed, so instead of using MATCHALL, looks first for full_settings. Please re-review.

[jgsogo]

If we are going to match the full_settings, why not using a regex that will match only that block like \[full_settings((?!\[full_).)*?

And really important now, how does CMake's regex engine work with new lines? With this approach the .* pattern needs to match also new lines (usually it needs to activate a flag s), but I see that tests are passing so it should be the default. Do we trust CMake about this?

[memsharded]

Yes, that is the problem. Trying to write such a regex is pretty ugly, like needing \\\\[full_settings\\\\] and still the problem of new lines. So I preferred to do the search for full_settings, and just capture the remaining of the file, that should work for this issue, and in any case is something that will start to change soon.