Add 1st draft of the compiler warning set required to support MISRA C++:2023 compliance.

[nradakovic]

Summary

This task introduces a new Bazel cc_feature named misra_cpp_2023_warnings. The feature shall enable the compiler warnings identified in the S-CORE MISRA C++:2023 Guideline Enforcement Plan (GEP) as applicable to GCC and Clang.

The initial implementation is intended as a first draft of the warning set. The mapping and selected warnings may be refined as the MISRA enforcement strategy and compiler support evolve.

Goal

Provide a reusable Bazel C/C++ feature that enables compiler diagnostics relevant to the enforcement of MISRA C++:2023 guidelines.

The initial warning set shall be derived from the compiler-warning mappings defined in the S-CORE MISRA C++:2023 GEP:
https://github.com/eclipse-score/communication/blob/main/quality/static_analysis/misra_gep.md

The feature should provide a single, consistent entry point for enabling the MISRA C++:2023-oriented compiler warnings in supported C/C++ builds.

Scope

The implementation should cover:

• Adding the misra_cpp_2023_warnings cc_feature
• Adding the GCC warnings identified in the MISRA C++:2023 GEP
• Adding the corresponding Clang warnings where applicable
• Handling compiler-specific warning availability appropriately
• Integrating the feature into the existing C/C++ warning policy infrastructure
• Validating the feature with representative C/C++ targets

The first draft should focus specifically on compiler warnings listed in the GEP. MISRA rules covered exclusively by CodeQL or other static-analysis tools are outside the scope of this task.

Proposed Implementation

• Add a new cc_feature named misra_cpp_2023_warnings
• Map the warning options from the MISRA C++:2023 GEP to the corresponding compiler configuration
• Provide GCC-specific warning options where defined by the GEP
• Provide Clang-specific warning options where defined by the GEP
• Ensure unsupported compiler-specific warnings do not break toolchain configuration
• Make the feature independently selectable from other warning sets
• Integrate the feature with the existing C/C++ policy configuration

Validation Expectations

Before closing this task, verify:

• The misra_cpp_2023_warnings feature is correctly recognized by the Bazel C/C++ toolchain configuration
• GCC builds successfully when the feature is enabled
• Clang builds successfully when the feature is enabled
• The expected warning options are passed to the compiler
• Compiler-specific warnings are only enabled for compilers that support them
• Representative code violating applicable MISRA-related compiler diagnostics produces the expected warnings
• The feature does not introduce unrelated compiler options
• Existing warning sets and configurations remain unaffected when the feature is not enabled

Acceptance Criteria

• A misra_cpp_2023_warnings cc_feature is implemented
• The feature contains the first-draft set of GCC warnings identified in the S-CORE MISRA C++:2023 GEP
• The corresponding applicable Clang warnings are included
• Compiler-specific differences are handled correctly
• The feature can be enabled independently through the existing Bazel C/C++ configuration
• The implementation is validated with representative GCC and Clang builds
• The implemented warning mapping is documented and traceable to the MISRA C++:2023 GEP
• It is explicitly documented that this compiler warning set provides only partial MISRA C++:2023 enforcement and does not constitute complete MISRA compliance

Checklist

• Review GCC warning mappings in the MISRA C++:2023 GEP
• Review Clang warning mappings in the MISRA C++:2023 GEP
• Define the initial misra_cpp_2023_warnings feature
• Add applicable GCC warning options
• Add applicable Clang warning options
• Handle compiler-specific warning availability
• Integrate the feature into the existing C/C++ policy configuration
• Add/extend test coverage for the feature
• Validate GCC configuration
• Validate Clang configuration
• Verify expected diagnostics with representative MISRA-related violations
• Document the initial warning mapping
• Document known gaps and rules requiring CodeQL or other static-analysis tooling