C/C++ Backend Guide

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Fish coordinates C and C++ projects using modern compilers (GCC, Clang, MSVC) and CMake.

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Detection & Discovery

Fish detects C/C++ projects by looking for CMakeLists.txt, Makefile, meson.build, or root C/C++ header/source structures.

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Fast Linker Integration

Fish automatically queries your environment for modern high-speed linkers:

• Linux: Automatically uses mold or ld.lld via -fuse-ld=mold.
• Windows: Uses lld-link or MSVC linker.
• macOS: Uses ld64.lld or Apple ld.

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Response File Support

When compiling large C/C++ projects with thousands of source files, Fish writes argument vectors exceeding OS length limits into @fish_args.rsp response files automatically.

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Compilation Database (compile_commands.json)

Fish automatically generates and exports standard compile_commands.json compilation databases for Clangd, Neovim, VS Code, and CLion, mapping compiler include directories and definitions directly from the workspace DAG.