Thank you for this pull request, looks relevant. I will double check this and merge if OK in a couple of days.

Reviewed for security and consistency. Looks good overall — no security concerns, sensible packaging fixes. A few notes:

GetGitVersion.cmake — The PROJECT_VERSION fallback and moving the dirty check inside the else (successful git describe) branch are both correct. Previously, a failed git describe would still run the dirty check against a potentially absent HEAD, which could produce confusing errors in tarball builds.

config/CMakeLists.txt — Changing generated from add_library(INTERFACE) to add_custom_target(DEPENDS ...) is the right call. The old target_sources(generated PRIVATE bugs.c authors.c) on an INTERFACE library is questionable CMake — INTERFACE libraries shouldn't own source files. A custom target purely expressing the dependency is cleaner.

locale/CMakeLists.txt — Using get_filename_component() to resolve absolute path and adding add_dependencies(${GETTEXT_TARGET} generated) fixes the build order issue where gettext might try to scan authors.c/bugs.c before they're generated. Correct.

man/CMakeLists.txt — Removing the file(ARCHIVE_CREATE) gzip step and installing the uncompressed .1 file directly. This delegates compression to the packaging system (dpkg, rpm, etc.) which is the standard approach. Clean.

src/CMakeLists.txt — Replacing target_link_libraries(... generated) with add_dependencies(gerbv-app generated) is consistent with the config/ change. The macOS INSTALL_RPATH addition is correct for Homebrew's lib layout.

CMakeLists.txt — QUARTZ define on APPLE is needed — callbacks.c and render.c use #if defined(QUARTZ) for macOS-specific paths, and the CMake build was not defining it (commit ae525ba changed the checks from #if QUARTZ to #if defined(QUARTZ) in anticipation of this). _GNU_SOURCE on Linux is used by lrealpath.c for canonicalize_file_name.

No issues found. LGTM.

Additional note: the _GNU_SOURCE define on Linux also fixes pre-existing undeclared-identifier errors for M_PI_2 and M_1_PI.

These are POSIX/XSI math constants (not C standard), and the project sets CMAKE_C_EXTENSIONS OFF which produces -std=c23 instead of -std=gnu23. Without a feature-test macro, <math.h> on glibc won't expose them.

_GNU_SOURCE implies _XOPEN_SOURCE on glibc, which gates all three constants in <math.h>. On macOS they're available by default, so the Linux-only scope is correct. This PR effectively fixes the build on strict-C toolchains.

Thanks for the merge, also log a pr to add macos CI, #327.