Should target_link_options(staticLib PRIVATE -lfoo) pierce through static libs to the head target?

alcroito · June 29, 2021, 8:04am

Currently if one calls target_link_libraries(staticLib PRIVATE myLib) the implementation of target_link_libraries ensures to also add a $<LINK_ONLY:myLib> on staticLib’s INTERFACE_LINK_LIBRARIES.

github.com

Kitware/CMake/blob/master/Source/cmTargetLinkLibrariesCommand.cxx#L496


      
                                                    ? cmTarget::PlainTLLSignature
                                                    : cmTarget::KeywordTLLSignature);
              this->Makefile.IssueMessage(messageType, e.str());
              if (messageType == MessageType::FATAL_ERROR) {
                return false;
              }
            }
          }
          
          // Handle normal case where the command was called with another keyword than
          // INTERFACE / LINK_INTERFACE_LIBRARIES or none at all. (The "LINK_LIBRARIES"
          // property of the target on the LHS shall be populated.)
          if (currentProcessingState != ProcessingKeywordLinkInterface &&
              currentProcessingState != ProcessingPlainLinkInterface) {
          
            if (this->RejectRemoteLinking) {
              this->Makefile.IssueMessage(
                MessageType::FATAL_ERROR,
                cmStrCat("Attempt to add link library \"", lib, "\" to target \"",
                         this->Target->GetName(),
                         "\" which is not built in this "

Should the same be done for link options as well, given that link options don’t make sense / are not used when archiving a static library?

From docs:
https://cmake.org/cmake/help/latest/command/target_link_options.html

This command cannot be used to add options for static library targets, since they do not use a linker.

ben.boeckel · June 29, 2021, 1:34pm

Link options should be looked at when $<LINK_ONLY:> is used. Are they not?

@brad.king I would think it should, but I don’t see any tests for it. Would likely need a policy to change that though.

brad.king · June 29, 2021, 1:40pm

Cc: @marc.chevrier

See policy CMP0099.

alcroito · June 29, 2021, 2:04pm

Right. I couldn’t find relevant mentions of the behaviour in the docs of target_link_options / target_link_libraries and the associated properties
My test project was setting 3.14 as the minimum version.

Increasing the cmake minimum version which enables the policy does indeed propagate the link options.
Thanks!