Agent skill

Clang

by mohitmishra786 in mohitmishra786/low-level-dev-skills

Clang/LLVM compiler skill for C/C++ projects. An agent skill from mohitmishra786/low-level-dev-skills.

MITAuto-check passedSecurity

Install Clang

skills CLI

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

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/compilers/clang .claude/skills/clang && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .claude/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill clang -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/compilers/clang .agents/skills/clang && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .agents/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill clang -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/compilers/clang .cursor/skills/clang && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .cursor/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/mohitmishra786/low-level-dev-skills.git --path skills/compilers/clang

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill clang -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/compilers/clang .gemini/skills/clang && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .gemini/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill clang -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/compilers/clang .github/skills/clang && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .github/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add mohitmishra786/low-level-dev-skills --skill clang -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install mohitmishra786/low-level-dev-skills clang --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/compilers/clang .opencode/skills/clang && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "clang" agent skill from https://github.com/mohitmishra786/low-level-dev-skills/tree/main/skills/compilers/clang into .opencode/skills/clang/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "clang", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: clang
GitHub stars: 252
Token cost: ~1.4k tokens
SKILL.md length: 401 words
Files: 3 (incl. references)
Skills in repo: 138
Repo updated: Jun 27, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Clang/LLVM compiler skill for C/C++ projects. An agent skill from mohitmishra786/low-level-dev-skills.

Works in 8 steps: Build mode flags (identical to GCC) → Clang-specific diagnostic flags → Optimization remarks → …
Working with clang
SKILL.md covers Purpose, Triggers, Workflow and Related skills
Calls xcrun

What it does

Clang is an agent skill from mohitmishra786/low-level-dev-skills. Clang/LLVM compiler skill for C/C++ projects. Use when working with clang or clang++ for diagnostics, sanitizer instrumentation, optimization remarks, static analysis with clang-tidy, LTO via lld, or when migrating from GCC to Clang. Activates on queries about clang flags, clang-tidy, clang-format, better error messages, Apple/FreeBSD toolchains, or LLVM-specific optimizations. Covers flag selection, diagnostic tuning, and integration with LLVM tooling.

Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files, including reference files (for example `references/clang-tidy.md` and `references/flags.md`).

It sits in Security, covering Static analysis and SAST. It works with C++. The repository describes itself as: A curated suite of AI agent skills for systems and low-level programming with C/C++, Rust, and Zig toolchains, covering compilers, debuggers, profilers, build systems…. The licence is MIT.

When your agent uses it

Working with clang
Clang++ for diagnostics
Sanitizer instrumentation
Optimization remarks

Example prompts

“/clang”

Workflow steps

8 steps, taken from the step headings in SKILL.md.

Build mode flags (identical to GCC)
Clang-specific diagnostic flags
Optimization remarks
Static analysis
LTO with lld
PGO (LLVM instrumentation)
GCC compatibility
macOS specifics

What it can do on your machine

Read from SKILL.md and the folder at commit bdc5847. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- xcrun
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Clang loads about 1.4k tokens when it runs, and up to ~2.9k if it reads all its reference files. Until then it costs about 116 tokens; SKILL.md has 401 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~116
When it runs · the whole SKILL.md, loaded when a task matches: ~1.4k
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~2.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from mohitmishra786/low-level-dev-skills at commit bdc5847, republished under its MIT licence (© mohitmishra786). 401 words, ~1,377 tokens.

Download SKILL.mdSave it as .claude/skills/clang/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.

name: clang
description: Clang/LLVM compiler skill for C/C++ projects. Use when working with clang or clang++ for diagnostics, sanitizer instrumentation, optimization remarks, static analysis with clang-tidy, LTO via lld, or when migrating from GCC to Clang. Activates on queries about clang flags, clang-tidy, clang-format, better error messages, Apple/FreeBSD toolchains, or LLVM-specific optimizations. Covers flag selection, diagnostic tuning, and integration with LLVM tooling.

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

bash

# 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

# Show tree diff for template mismatch
clang -fdiagnostics-show-template-tree src.cpp

Clang's diagnostics include exact range highlighting and fix-it suggestions that GCC lacks.

3. Optimization remarks

Optimization remarks let you see what Clang did or refused to do:

bash

# Inliner decisions
clang -O2 -Rpass=inline src.c

# Missed vectorisation
clang -O2 -Rpass-missed=loop-vectorize src.c

# Why a loop was not vectorized
clang -O2 -Rpass-analysis=loop-vectorize src.c

# Save all remarks to YAML for post-processing
clang -O2 -fsave-optimization-record src.c
# Produces src.opt.yaml

Interpret remarks:

remark: foo inlined into bar — inlining happened; good for hot paths
remark: loop not vectorized: loop control flow is not understood — restructure the loop
remark: not vectorized: cannot prove it is safe to reorder... — add __restrict__ or #pragma clang loop vectorize(assume_safety)

4. Static analysis

bash

# Built-in analyser (CSA)
clang --analyze -Xanalyzer -analyzer-output=text src.c

# clang-tidy (separate tool, richer checks)
clang-tidy src.c -- -std=c++17 -I/usr/include

# Enable specific check families
clang-tidy -checks='clang-analyzer-*,modernize-*,bugprone-*' src.cpp --

# Apply fixits automatically
clang-tidy -fix src.cpp --

Common clang-tidy check families:

bugprone-*: real bugs (use-after-move, dangling, etc.)
clang-analyzer-*: CSA checks (memory, null deref)
modernize-*: C++11/14/17 modernisation
performance-*: unnecessary copies, move candidates
readability-*: naming, complexity

5. LTO with lld

bash

# Full LTO
clang -O2 -flto -fuse-ld=lld src.c -o prog

# Thin LTO (faster link, nearly same quality)
clang -O2 -flto=thin -fuse-ld=lld src.c -o prog

# Check lld is available
clang -fuse-ld=lld -Wl,--version 2>&1 | head -1

For large projects, ThinLTO is preferred: link times 5-10x faster than full LTO with comparable code quality.

Show full SKILL.md (169 more words)Show less

6. PGO (LLVM instrumentation)

bash

# Step 1: instrument
clang -O2 -fprofile-instr-generate prog.c -o prog_inst

# Step 2: run with representative input
./prog_inst < workload.input
# Generates default.profraw

# Step 3: merge profiles
llvm-profdata merge -output=prog.profdata default.profraw

# Step 4: use profile
clang -O2 -fprofile-instr-use=prog.profdata prog.c -o prog

AutoFDO (sampling-based, less intrusive): collect with perf, convert with create_llvm_prof, use with -fprofile-sample-use. See skills/profilers/linux-perf.

7. GCC compatibility

Clang is intentionally GCC-compatible for driver flags. Key differences:

Clang does not support all GCC-specific attributes; check with __has_attribute(foo)
-Weverything enables all Clang warnings (no GCC equivalent); too noisy for production, useful for one-off audits
Some GCC intrinsics need #include <x86intrin.h> on Clang too
__int128 is supported; __float128 requires -lquadmath on some targets

8. macOS specifics

On macOS, clang is the system compiler (Apple LLVM). Key points:

ld64 is the default linker; lld requires explicit -fuse-ld=lld and Homebrew LLVM
Use -mmacosx-version-min=X.Y to set deployment target
Sanitizers on macOS use DYLD_INSERT_LIBRARIES; do not strip the binary
xcrun clang resolves to the Xcode toolchain clang

For flag reference, see references/flags.md. For clang-tidy config examples, see references/clang-tidy.md.

Use skills/compilers/gcc for GCC-equivalent flag mapping
Use skills/runtimes/sanitizers for -fsanitize=* workflows
Use skills/compilers/llvm for IR-level work (opt, llc, llvm-dis)
Use skills/compilers/msvc-cl for clang-cl on Windows
Use skills/binaries/linkers-lto for linker-level LTO details

Files

SKILL.md and 2 other files (references) in skills/compilers/clang of mohitmishra786/low-level-dev-skills.

SKILL.md
references/clang-tidy.md
references/flags.md

Open the folder on GitHubat commit bdc5847

Compare with similar skills

Clang next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Clang compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Clang this skillmohitmishra786/low-level-dev-skills	252	—	~1.4k	Automated safety check: Pass	MIT	3 mo ago
Cpp StyleLuisaGroup/LuisaCompute	1.1k	—	~1.1k	Automated safety check: Pass	Apache-2.0	today
Static AnalysisLeoKemp223/embed-ai-tool	991	—	~402	Automated safety check: Pass	None	1 mo ago
CodeQL Security Scantrailofbits/skills	7.5k	—	~4.6k	Automated safety check: Notes	CC-BY-SA-4.0	yesterday
Zeroization Audittrailofbits/skills	7.5k	4 repos	~5.9k	Automated safety check: Notes	CC-BY-SA-4.0	yesterday
Constant-Time Analysistrailofbits/skills	7.5k	—	~3.3k	Automated safety check: Notes	CC-BY-SA-4.0	yesterday

Similar skills

Cpp Style
LuisaGroup/LuisaCompute
C++ naming, formatting, static analysis, and RTTI rules for LuisaCompute.
1.1k GitHub stars~1.1k tokensUpdated today
SecurityAuto-check passed
Static Analysis
LeoKemp223/embed-ai-tool
当需要对嵌入式 C/C++ 代码运行 cppcheck、clang-tidy 或 GCC analyzer 静态分析，或进行 MISRA-C 合规检查时使用。
991 GitHub stars~402 tokensUpdated 1 mo ago
SecurityAuto-check passed
CodeQL Security Scan
trailofbits/skills
Official
Scans a codebase for vulnerabilities with CodeQL's data flow and taint tracking in run-all or important-only modes, including data extensions for project-specific sources and sinks.
7.5k GitHub stars~4.6k tokensUpdated yesterday
SecurityAuto-check: notes
Zeroization Audit
trailofbits/skills
Official
Finds sensitive data that C, C++ or Rust code never wipes from memory, including wipes the compiler optimizes away, using source, assembly and control-flow analysis.
7.5k GitHub starsUsed in 4 repos~5.9k tokens
SecurityAuto-check: notes
Constant-Time Analysis
trailofbits/skills
Official
Compiles cryptographic code and inspects the assembly or bytecode for variable-time instructions, then triages which flagged operations actually touch secrets.
7.5k GitHub stars~3.3k tokensUpdated yesterday
SecurityAuto-check: notes
Taint Instrumentation Assistant
ArabelaTso/Skills-4-SE
Instruments code to track the flow of untrusted or sensitive data at runtime, enabling detection of injection vulnerabilities, data leaks, and privilege violations.
253 GitHub stars~2.9k tokensUpdated 1 mo ago
SecurityAuto-check passed

Questions about Clang

What does Clang do?

Clang/LLVM compiler skill for C/C++ projects. An agent skill from mohitmishra786/low-level-dev-skills. Clang is an agent skill from mohitmishra786/low-level-dev-skills. Clang/LLVM compiler skill for C/C++ projects.

When should I use Clang?

Clang fits situations like: working with clang; clang++ for diagnostics; sanitizer instrumentation; optimization remarks.

How do I install Clang in Claude Code?

Run `npx skills add mohitmishra786/low-level-dev-skills --skill clang -a claude-code`. Or copy the skill folder (skills/compilers/clang in mohitmishra786/low-level-dev-skills) into .claude/skills/clang in your project. Claude Code loads it when a task matches its description.

How do I install Clang in Codex?

Run `npx skills add mohitmishra786/low-level-dev-skills --skill clang -a codex`. Or copy the skill folder (skills/compilers/clang in mohitmishra786/low-level-dev-skills) into .agents/skills/clang in your project. Codex loads it when a task matches its description.

Can I use Clang in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mohitmishra786/low-level-dev-skills --skill clang -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/clang, .gemini/skills/clang, .github/skills/clang and .opencode/skills/clang in your project.

What does Clang need to run?

Going by SKILL.md and its folder, Clang needs the command-line tools its instructions call (xcrun).

Does Clang access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Clang safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Clang use?

Clang is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Clang use?

About 1.4k tokens (SKILL.md is roughly 5.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.5k tokens, read only when the agent opens those files.

What are the alternatives to Clang?

Skills that share tags, products or a category with Clang: Cpp Style (LuisaGroup/LuisaCompute, 1.1k stars), Static Analysis (LeoKemp223/embed-ai-tool, 991 stars), CodeQL Security Scan (trailofbits/skills, 7.5k stars) and Zeroization Audit (trailofbits/skills, 7.5k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Clang?

mohitmishra786 (a GitHub user) maintains it in mohitmishra786/low-level-dev-skills, which has 252 GitHub stars. The repository holds 138 skills in this directory. The repository was last updated on June 27, 2026.

Source: mohitmishra786/low-level-dev-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Clang

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Clang

Purpose

Triggers

Workflow

1. Build mode flags (identical to GCC)

2. Clang-specific diagnostic flags

3. Optimization remarks

4. Static analysis

5. LTO with lld

6. PGO (LLVM instrumentation)

7. GCC compatibility

8. macOS specifics

Related skills

Files

Compare with similar skills

Similar skills

More from mohitmishra786/low-level-dev-skills

Related

Questions about Clang