xiaoxiang781216 opened a new pull request, #18886:
URL: https://github.com/apache/nuttx/pull/18886
## Summary
Replace the macOS sim C++ global constructor runtime hack
(`sim_macho_init.c`)
with a post-link Mach-O section patching scheme so dyld no longer auto-runs
constructors before NuttX is initialized.
## Impact
- **Area**: arch/sim (macOS host only). Linux behavior is unchanged.
## Testing
- **Build host**: macOS (Ventura VM)
- **Target**: sim:nsh with `CONFIG_HAVE_CXX=y` /
`CONFIG_HAVE_CXXINITIALIZE=y`
- Verified via standalone test (`test_sinit7`) that the C++ constructor is
deferred past `main()` and is only invoked when explicitly called through
the `_sinit[]/_einit[]` loop in `lib_cxx_initialize()`.
## Details
1. Link with `-Wl,-ld_classic,-no_fixup_chains` to keep the classic
`__mod_init_func` pointer format (prevents ld64 from converting it to
`__init_offsets`).
2. Post-link, run `patch_macho_initsection.py` (python3 + `lief`) to patch
the Mach-O section type flags from `MOD_INIT_FUNC_POINTERS` /
`INIT_FUNC_OFFSETS` to `REGULAR`, so dyld skips them.
3. Use the Mach-O auto-generated boundary symbols
`section$start$__DATA_CONST$__mod_init_func` /
`section$end$__DATA_CONST$__mod_init_func`, mapped via `__asm()` labels in
`arch/sim/include/arch.h` to the common `_sinit[]`/`_einit[]` names used
by `lib_cxx_initialize()`.
4. Delete the old `sim_macho_init.c` runtime hack and the macOS-specific
`macho_call_saved_init_funcs()` path in `lib_cxx_initialize.c`.
Dependency: `pip install lief` on the build host when
`CONFIG_HAVE_CXXINITIALIZE=y`.
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