Louis Dionne
Principal Software Engineer (C Standard Library) at Apple
Quebec, Canada
Summary
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Rockstar🎓
Top SchoolLouis Dionne is a Principal Software Engineer based in Quebec with 13 years of experience specializing in C and C++ standard library implementation and compiler internals. As technical lead and code owner of libc++ at Apple and a member of the C++ Standards Committee, he shapes the standard library used on billions of devices and drives standards-conformance across major toolchains like LLVM/Clang. He is the author of Boost.Hana and a long-time contributor to high-profile projects such as LLVM, Clang, and Apple's libc++, with a track record of hardening, refactoring, and modernizing core library and compiler code. His background in mathematics and formal metaprogramming informs a rigorous approach to API design, correctness, and performance. He has also applied C++ expertise to machine learning infrastructure work, modernizing legacy code and build processes at scale. Colleagues rely on him for deep technical judgment in areas where language standards, performance, and safety intersect.
13 years of coding experience
6 years of employment as a software developer
Mathematics, Mathematics at Université LavalDES Programme d'Éducation Internationale, DES Programme d'Éducation Internationale at École secondaire De RochebelleDEC Natural Sciences, DEC Natural Sciences at Collège François-Xavier-Garneau
French, English
Stackoverflow
3,104reputation
45kreached
53answers
7questions
boost
top-5%
Github Skills (37)
unit-testing10
cpp-library10
c-language10
template-metaprogramming10
compiler-development10
testing10
machine-learning10
cmake10
data-structure10
standard-library10
compiler-compiler10
deep-learning10
exception-handling10
performance-optimization10
c-libraries10
Programming languages (20)
Github contributions (5)
boostorg/hana
Jun 2013 - Oct 2022
Your standard library for metaprogramming
Role in this project:
Back-end Developer
Back-end DeveloperContributions:16 releases, 7 reviews, 2275 commits in 9 years 6 months
Contributions summary:Louis was primarily involved in implementing and refactoring the core data structures and algorithms for a metaprogramming library, as seen in the changes to the closure and the removal of deprecated features. The user appears to have focused on efficiency and standards-conformance by making significant changes to the tuple structure, including improvements to the copy and move constructors, the underlying EBO storage mechanism, and the addition of set-theoretic operations. Their contributions also included adding and testing new features, like `take_back_c`.
cppmetaprogrammingheader-onlystandard-libraryboost
llvm/llvm-project
Oct 2021 - Jan 2023
The LLVM Project is a collection of modular and reusable compiler and toolchain technologies.
Role in this project:Back-end Developer
Back-end DeveloperContributions:2575 reviews, 25 commits, 1252 PRs in 1 year 3 months
Contributions summary:Louis contributed to the core C++ Standard Library implementation by adding test coverage for the implementation of expected, fixing a -Wgnu-include-next warning in stddef.h, introducing CPU traits for the PSTL, adding a utility to check for a valid range, renaming __cpu_traits functions and introducing an ABI setting to harden unique_ptr<T[]>::operator[]. They also deprecated the C++20 synchronization library before C++20, fixed several bugs, and refactored a number of tests. Their work focused on enhancing the functionality, stability, and correctness of the standard library's components.
compilerstechnologiesclangsubmittoolchain
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