dcr/docs/dependencies-and-build/compilers-and-linking.md

Compilers & linking

Compiler backend selection

DCR picks a backend from build.compiler:

• contains clang-cl -> MSVC backend
• equals as or contains gas -> GAS backend (standalone assembler)
• contains gcc or g++ -> GCC backend
• contains clang or clang++ -> Clang backend
• equals cl or contains msvc -> MSVC backend
• contains nasm -> NASM backend
• otherwise -> Clang backend fallback

Compilation model

• Source files are found recursively in src/ based on build.language.
• build.roots and build.src_disable can replace the default src/ root.
• Mixed language builds use arrays, for example build.language = ["c", "asm"].
• Each source is compiled to target/<profile>/obj/<relative-path>.o (.obj on MSVC).
• Recompile happens when source mtime is newer than object mtime.
• build.exclude removes paths from source/header collection; build.include re-allows matching paths and has priority over exclude.

Default build flags

These flags are applied automatically based on profile and compiler backend.

GCC/Clang:

• debug: -O0 -g -Wall -Wextra -fno-omit-frame-pointer -DDCR_DEBUG
• release: -O3 -DNDEBUG

MSVC:

• debug: /Od /Zi /W4 /DDCR_DEBUG /Oy-
• release: /O2 /DNDEBUG

Platform hint

If build.platform is set, DCR passes it as an architecture hint:

• GCC/Clang: -march=<platform>
• MSVC: maps to /arch:* for known values (x86, i386, i486, i586, i686, sse2, avx, avx2)

Toolchain overrides

If [toolchain] is set, DCR uses its values to override compiler/linker tools:

• cc, cxx, as override compilers for C/C++/ASM
• ar overrides the archiver (used for staticlib)
• ld overrides the linker (used by GCC/Clang/NASM/GAS backends)
• uic, moc, rcc override Qt tools used in build.steps

Environment overrides (highest priority):

• DCR_COMPILER (all languages)
• DCR_CC, DCR_CXX, DCR_AS, DCR_AR, DCR_LD
• DCR_DEBUG enables verbose build logging

Linking

For kind = "bin":

• Object files are linked into executable artifact.
• Dependency lib dirs and library names are passed to linker.
• build.ldflags are appended to link command.

For kind = "staticlib":

• Linux/macOS (GCC/Clang): ar rcs creates .a archive.
• Windows (MSVC): lib creates .lib archive.

For kind = "sharedlib":

• Linux (GCC/Clang): -shared with output .so.
• macOS (Clang): -dynamiclib with output .dylib.
• Windows (MSVC): /LD with output .dll.