docs/C++-Standard-Libraries.md
C++ libraries must use a compatible compiler, C++ standard library and application binary interface across their dependency graph. Mixing incompatible C++ runtimes can cause link failures, missing symbols or crashes that are not resolved by changing header or library search paths.
Apple Clang and Homebrew bottles on supported macOS versions use libc++.
Formulae should use the compiler and standard library selected by Homebrew unless upstream has a documented requirement that cannot be met by the default toolchain.
GNU GCC normally uses its own libstdc++.
A formula built with GNU GCC must not pass C++ objects across a dependency boundary that was built with an incompatible runtime unless upstream explicitly supports that combination.
Homebrew's Linux toolchain normally uses libstdc++.
The same compatibility rule applies: a formula and the C++ libraries whose interfaces it consumes must agree on their runtime and ABI.
After an operating system, compiler or C++ runtime upgrade, reinstall the affected formula and its C++ dependencies with the current Homebrew toolchain. Do not create replacement symlinks for missing versioned C++ libraries because doing so can load an ABI-incompatible library.
Formula authors should inspect the complete compiler and linker commands before overriding Homebrew's compiler selection. If upstream requires a specific compiler, declare it as a dependency and test the complete dependency graph on every supported platform.
See the Formula Cookbook for build and dependency guidance.