missing-make-j-flag

Detects workflow steps that run make, gmake, or cmake --build without any parallelization mechanism.

Why this rule exists:

• these tools default to serial execution
• runner minutes add up when a build uses only one core
• -j$(nproc) is a zero-risk change that cuts build wall time

What is checked:

• run: commands containing make, gmake, or cmake --build
• the command itself is checked for -j, --jobs, or --parallel flags
• workflow-level, job-level, and step-level env: maps are checked for MAKEFLAGS containing a -j flag, and for CMAKE_BUILD_PARALLEL_LEVEL
• for cmake --build only: all steps in the same job are scanned for Ninja references; if Ninja is the generator, cmake --build already parallelizes

Typical remediation:

• add -j$(nproc) to the make / gmake / cmake --build invocation
• or set MAKEFLAGS: -j$(nproc) in workflow, job, or step env
• or set CMAKE_BUILD_PARALLEL_LEVEL: $(nproc) for cmake-based builds
• or switch to Ninja as the CMake generator, which parallelizes by default