Error compiling C++ with flag (-Wmissing-field-initializers)

[yperess]

Describe the bug
When using -Wmissing-field-initializers to compile Zephyr we get and error for SYS_INIT since it doesn't initialize the dev field

To Reproduce
Steps to reproduce the behavior:

1. Add -Wmissing-field-initializers to the compile options and build any app with SYS_INIT

Expected behavior
Should build

Impact
Breaks build

[yperess]

Fixed in #68125

[marc-hb]

Re-opening because this flag broke again:

• drivers: adc: fix warning when using ADC_DT_SPEC_GET macro on C++ #69419

If this policy is not formally agreed and regularly enforced in CI then it will keep breaking. From #68118 (comment)

@barnas-michal not related to this being the right way to "fix" or not, but we should not be fixing issues of compiler warnings only enabled outside of the project, if this compiler flag is useful we should enable it in zephyr as well and fix issues everywhere and deal with it within the project for all toolchains and support this accordingly.

More relevant discussion in

• Revert "init: add missing initialization of dev pointer in SYS_INIT (alternative to PR68125) #68118

[github-actions]

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[marc-hb]

init.h fixed for good in a portable way in:

• init.h: restore designated initializers in SYS_INIT_NAMED() v2 #69486

Solution thoroughly documented in:

• doc: languages: add new section "headers and C/C++ compatibility" #74047

Note that new documentation does NOT say anything about -Wmissing-field-initializers, which is not required by any C or C++ version. Both languages guarantee that missing fields will be initialized to zero (or equivalent).

@ceolin is -Wmissing-field-initializers something MISRA requires?