Change Details

In GNU ld and ld.lld, -dc is used with -r to allocate space to COMMON symbols. It is presumably to work around legacy code which cannot handle COMMON symbols in relocatable output. -dc is not needed if -fno-common is used. The original -dc comment is wrong. By using -dc -r, two relocatable output may have duplicate STB_GLOBAL definitions which will lead to a duplicate definition error in the final link. By keeping COMMON symbols in the relocatable output, one can actually link the pieces together without an error. See https://maskray.me/blog/2022-02-06-all-about-common-symbols for detail. ld.lld may remove -dc or make it a no-op for the 15.0.0 release. --- Hope that someone tests this for me. Note: -nostdlib can be removed if FreeBSD Clang picks https://reviews.llvm.org/D117388

In GNU ld and ld.lld, -dc is used with -r to allocate space to COMMON symbols. It is presumably to work around legacy code which cannot handle COMMON symbols in relocatable output. -dc has no effect if -fno-common is used. See https://maskray.me/blog/2022-02-06-all-about-common-symbols for detail. ld.lld may remove -dc or make it a no-op for the 15.0.0 release. See emaste's comment: -dc is just not needed, for both -fcommon and -fno-common code. --- Hope that someone tests this for me. Note: -nostdlib can be removed if FreeBSD Clang picks https://reviews.llvm.org/D117388

In GNU ld and ld.lld, -dc is used with -r to allocate space to COMMON symbols. It is presumably to work around legacy code which cannot handle COMMON symbols in relocatable output. -dc ihas not needed effect if -fno-common is used. The original -dc comment is wrong. By using -dc -r, two relocatable output may have duplicate STB_GLOBAL definitions which will lead to a duplicate definition error in the final link. By keeping COMMON symbols in the relocatable output, one can actually link the pieces together without an error. See https://maskray.me/blog/2022-02-06-all-about-common-symbols for detail. ld.lld may remove -dc or make it a no-op for the 15.0.0 release. See emaste's comment: -dc is just not needed, for both -fcommon and -fno-common code. --- Hope that someone tests this for me. Note: -nostdlib can be removed if FreeBSD Clang picks https://reviews.llvm.org/D117388