Fix error messages from io:format and related functions

[juhlig]

Fixes #8568.

This PR introduces a new function erl_lint:check_format_string/2, where the second argument can be used to decide if the check should be strict (true, the default) or relaxed (false).

Strict checking, which is the same as in the current implementation, will check and complain about repeated (eg ~ttp), conflicting (eg ~kKp) or non-applicable (eg ~kb) modifiers in formatting sequences. Those do not cause errors, though, so while it is ok for linting to check and warn about them, it will cause wrong error messages.

Relaxed checking omits the above checks and only reports erroneous format sequences (eg ~q). Relaxed checking is used by erl_stdlib_errors to print out error reasons.

[github-actions]

CT Test Results

    2 files     95 suites   36m 7s ⏱️
2 142 tests 2 094 ✅ 48 💤 0 ❌
2 451 runs  2 401 ✅ 50 💤 0 ❌

Results for commit 4c6a99f.

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[garazdawi]

I was hoping this PR would arrive soon :)

Would you mind expanding the tests in https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/io_SUITE.erl#L3125-L3138 and https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/erl_lint_SUITE.erl#L3820-L3827 (https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/erl_lint_SUITE_data/format.erl) ?

[juhlig]

I was hoping this PR would arrive soon :)

😅

Would you mind expanding the tests in https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/io_SUITE.erl#L3125-L3138 and https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/erl_lint_SUITE.erl#L3820-L3827 (https://github.com/erlang/otp/blob/OTP-27.0/lib/stdlib/test/erl_lint_SUITE_data/format.erl) ?

Sure, but I probably won't get to it today.

[juhlig]

@garazdawi added some tests as requested, please take a look.

[garazdawi]

Looks good and test seem to pass. If you rebase to maint I will merge it for inclusion in 27.1.

[juhlig]

@garazdawi done, squashed the commits and rebased/retargeted to maint 👍

[garazdawi]

thanks!