Clang

When you need to squeeze more out of Clang than just dropping in GCC flags, this walks you through the LLVM-specific tooling that actually matters: optimization remarks that show you why loops didn't vectorize, clang-tidy for real static analysis, ThinLTO for sane link times on big codebases, and those superior diagnostics with fix-it hints. Covers the PGO workflow with llvm-profdata, flags like -Oz and -Rpass-missed, and the macOS/FreeBSD quirks where Clang is the system compiler. Honest take: if you're still just using -O2 -Wall, you're leaving a lot on the table.

skills.sh installs: 789
GitHub stars: 279
last updated: Aug 21, 2026

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Install

$ npx -y skills add mohitmishra786/low-level-dev-skills --skill clang --agent claude-code

Installs into .claude/skills of the current project.

Files

Clang

Purpose

Guide agents through Clang-specific features: superior diagnostics, sanitizer integration, optimization remarks, static analysis, and LLVM tooling. Covers divergences from GCC and Apple/FreeBSD specifics.

Triggers

"I want better compiler diagnostics/errors"
"How do I use clang-tidy / clang-format?"
"How do I see what the compiler optimised or didn't?"
"I'm on macOS / FreeBSD using clang"
"clang-cl for MSVC-compatible builds" — see skills/compilers/msvc-cl
Sanitizer queries — see skills/runtimes/sanitizers

Workflow

1. Build mode flags (identical to GCC)

Clang accepts most GCC flags. Key differences:

Feature	GCC	Clang
Min size	`-Os`	`-Os` or `-Oz` (more aggressive)
Optimise only hot	—	`-fprofile-instr-use` (LLVM PGO)
Thin LTO	`-flto`	`-flto=thin` (faster)
Static analyser	`-fanalyzer`	`clang --analyze` or `clang-tidy`

2. Clang-specific diagnostic flags

# Show fix-it hints inline
clang -Wall -Wextra --show-fixits src.c

# Limit error count
clang -ferror-limit=5 src.c

# Verbose template errors (disable elision)
clang -fno-elide-type src.cpp

SKILL.md on GitHub