cmake --install produces an unusable tree (no export set/config; dependency headers absent); install rules unconditional; LICENSE not installed

[petlenz]

From the 2026-08-02 full-repo review (finding F-05 + F-18f). Verified by installing to a scratch prefix.

Evidence: CMakeLists.txt:216-232 installs include/ + libnumsim_codegen.a only. No export set, no *Config.cmake, no version file, no pkg-config, no LICENSE. The installed headers #include <numsim_cas/...> and <tmech/...>, which are not installed — so the tree cannot be consumed even by hand. find_package(NumSim_CodeGen) is impossible. (Export set is documented as blocked on numsim-cas exporting targets.)

Also: the install() rules are unconditional, so a superproject consuming this repo via add_subdirectory gets numsim-codegen headers/lib in its make install with no opt-out.

Impact: shipping install rules that produce a broken tree is worse than shipping none; and subproject consumers get install pollution.

Proposal (interim, until the numsim-cas export-set lands):

1. Gate install rules behind option(NUMSIM_CODEGEN_INSTALL "EXPERIMENTAL: no CMake package config yet" OFF) (or PROJECT_IS_TOP_LEVEL).
2. install(FILES LICENSE DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/doc/numsim-codegen).
3. README: state explicitly that add_subdirectory/FetchContent is the only supported consumption today.

Proposal (real fix, blocked upstream): install(TARGETS ... EXPORT NumSimCodegenTargets) + configure_package_config_file() with find_dependency(numsim_cas) + write_basic_package_version_file(... COMPATIBILITY SameMinorVersion); CI job that installs and configures a 3-line consumer.