What does 'inline' mean?

[Walter Bright]

On 6/11/2020 10:39 AM, kinke wrote:
> Internal linkage (C(++) static), AFAIK, means that you may end up with multiple 
> identical functions in the final linked binary. Some linkers may be able to 
> still fold them, such as the MS linker and lld with /OPT:ICF (identical COMDAT 
> folding).
> 
> Linkonce_odr linkage (C++ templates and `inline` functions) on the other hand 
> means that you end up with either 0 or 1 function in the final binary, even when 
> multiple object files define it; AFAIK, without having to rely on /OPT:REF or 
> --gc-sections etc. At least for LLVM, linkonce_odr additionally means that the 
> definition is discarded early if unused and might not make it to the object file 
> at all.
> 
> Weak_odr linkage (current D templates) is similar to linkonce_odr but not 
> 'officially' discardable (if unreferenced) for the final binary (and thus always 
> making it to the object file). This can be overridden by /OPT:REF and 
> --gc-sections etc., the success of which also depends on symbol visibility 
> and/or --export-dynamic etc.

gc-sections isn't about merging multiple definitions, it's about discarding 
unreferenced sections.