Skill: c-cpp

Purpose

Apply the shared engineering style to C and C++ projects while respecting safety, ABI, build configuration, resource ownership, and platform constraints.

Inspect First

Before changing C/C++ code, inspect relevant files when present:

• CMakeLists.txt
• Makefile
• build scripts
• compiler flags
• toolchain files
• compile_commands.json
• formatter/linter config
• existing headers/source/tests
• target platform constraints

Infer:

• C/C++ standard;
• compiler/toolchain;
• warning policy;
• memory ownership style;
• test framework;
• embedded constraints if relevant.

Do not assume language standard or ABI expectations.

General Rules

• Preserve ABI when relevant.
• Avoid undefined behavior.
• Keep ownership explicit.
• Keep headers minimal and stable.
• Avoid unnecessary dynamic allocation.
• Avoid global mutable state.
• Prefer small translation units with cohesive responsibility.
• Do not create giant headers full of unrelated code.

C++ Rules

• Prefer RAII.
• Avoid raw owning pointers.
• Use const correctly.
• Prefer value semantics when appropriate.
• Use smart pointers only when ownership requires them.
• Avoid inheritance unless polymorphism is real.
• Prefer composition over inheritance.
• Avoid exceptions if the project forbids them; otherwise follow project convention.
• Do not use modern features unsupported by configured standard.

C Rules

• Make ownership and lifetime explicit in names/docs.
• Check allocation and I/O failures.
• Avoid buffer overflows.
• Prefer bounded operations.
• Keep error paths correct.
• Do not hide resource ownership in vague helper functions.

Embedded / Firmware Awareness

When code may run on constrained hardware:

• avoid blocking critical loops;
• avoid unbounded allocation;
• consider stack usage;
• consider ISR constraints;
• avoid unsafe boot states;
• preserve watchdog behavior;
• be careful with volatile/hardware registers;
• isolate platform-specific code.

Tests and Validation

Use existing build/test system.

Common commands, only when configured or clearly available:

cmake --build <build-dir>
ctest --test-dir <build-dir>
make
make test
ninja

Report exact commands and results.

Shared Cross-Ecosystem Style

Apply the shared engineering style from:

• ../../engineering/05_design_principles.md
• ../../engineering/06_responsibility_model.md
• ../../engineering/07_complexity_budget.md
• ../../engineering/12_naming_bible.md

Language-specific idioms control syntax and ecosystem details, but they must not weaken the core rules: small cohesive units, explicit boundaries, honest validation, no dumping grounds, and no fake placeholders.