-Wl,--no-copy-dt-needed-entries is not universally understood! Depends on the BFD linker.

[exoosh]

docs/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.md should contain a warning in the section "TL;DR: What compiler options should I use?":

**NB:** `-Wl,--no-copy-dt-needed-entries` is not understood by `lld`, so if you use `-fuse-ld=lld` this flag needs to be dropped.

In fact I don't know which other linkers support this linker switch besides the BFD linker. But since the section starts out with:

[...] on compilers such as GCC and clang

it would make sense to point it out.

[exoosh]

Somewhere below the table it says:

Note that support for some options may differ between different compilers [...]

Perhaps it's sufficient, although of course -Wl passes these through to the linker, so technically it depends on the linker and compiler in tandem.

[thomasnyman]

Thanks for reporting this. We have so far only really considered BFD in the guide, but that scoping is not really clearly documented. I would address this at this point by adding an explicit mention that, unless otherwise noted, any linker options given in the guide only apply for BFD.

[thomasnyman]

Suggested some text to this effect in #927