OpenROAD Coding Patterns

Style Rules

General C++ Guidelines

Follow the Google C++ Style Guide.
Use modern C++20 style and features.
Apply const qualifiers whenever possible.

Type Declarations

Use C++ casts, not C-style casts

Braces

Use {...} even for single-line statements

Comments

Do not remove existing comments
Recommend adding a single line comment for each important code block
All comments must be in English

Function Length

Factor out into multiple functions if a function exceeds 100 lines
- Exception: Unit tests can have long functions

Null Safety

Avoid adding too defensive null checks if the object cannot be null

Service Interfaces

Abstract interfaces published through utl::ServiceRegistry use the Service suffix (e.g. est::ParasiticsService, drt::PinAccessService). Each interface lives in its owning module's public include/<module>/ directory and is exposed as a small header-only Bazel target that consumers can depend on without pulling in the full implementation library. This keeps module dependency graphs acyclic and the decoupling visible at the build layer.

Note that this is distinct from the Abstract* prefix used for graphics/visualization mock-swappable classes (e.g. AbstractSteinerRenderer); those are inherited for test/headless modes rather than looked up through a registry.

Common Coding Mistakes

OpenROAD Message ID Duplicate Checker

etc/find_messages.py uses regex to match literal numeric IDs in logger->xxx(MODULE, NNNN, ...) calls. When duplicating a message across modules, use named constants to bypass the checker:

constexpr int kMsgIdBufferInserted = 1234;
logger_->info(RSZ, kMsgIdBufferInserted, "...");