Make linking APIs aware of 'head' target

The 'head' is the dependent target to be linked with the current target.
It will be used to evaluate generator expressions with proper handling
of mapped configurations and is used as the source target of properties.

This requires that memoization is done with a key of a pair of target
and config, instead of just config, because now the result also depends
on the target.  Removing the memoization entirely is not an option
because it slows cmake down considerably.

1 files changed, 6 insertions, 5 deletions

diff --git a/Source/cmComputeLinkDepends.cxx b/Source/cmComputeLinkDepends.cxx
index 055aab0..dec2b54 100644
--- a/Source/cmComputeLinkDepends.cxx
+++ b/Source/cmComputeLinkDepends.cxx
@@ -172,10 +172,11 @@ satisfy dependencies.
 
 //----------------------------------------------------------------------------
 cmComputeLinkDepends
-::cmComputeLinkDepends(cmTarget* target, const char* config)
+::cmComputeLinkDepends(cmTarget* target, const char* config, cmTarget* head)
 {
   // Store context information.
   this->Target = target;
+  this->HeadTarget = head;
   this->Makefile = this->Target->GetMakefile();
   this->LocalGenerator = this->Makefile->GetLocalGenerator();
   this->GlobalGenerator = this->LocalGenerator->GetGlobalGenerator();
@@ -352,7 +353,7 @@ void cmComputeLinkDepends::FollowLinkEntry(BFSEntry const& qe)
     {
     // Follow the target dependencies.
     if(cmTarget::LinkInterface const* iface =
-       entry.Target->GetLinkInterface(this->Config))
+       entry.Target->GetLinkInterface(this->Config, this->HeadTarget))
       {
       // This target provides its own link interface information.
       this->AddLinkEntries(depender_index, iface->Libraries);
@@ -444,7 +445,7 @@ void cmComputeLinkDepends::HandleSharedDependency(SharedDepEntry const& dep)
   if(entry.Target)
     {
     if(cmTarget::LinkInterface const* iface =
-       entry.Target->GetLinkInterface(this->Config))
+       entry.Target->GetLinkInterface(this->Config, this->HeadTarget))
       {
       // Follow public and private dependencies transitively.
       this->FollowSharedDeps(index, iface, true);
@@ -533,7 +534,7 @@ void cmComputeLinkDepends::AddDirectLinkEntries()
 {
   // Add direct link dependencies in this configuration.
   cmTarget::LinkImplementation const* impl =
-    this->Target->GetLinkImplementation(this->Config);
+    this->Target->GetLinkImplementation(this->Config, this->HeadTarget);
   this->AddLinkEntries(-1, impl->Libraries);
   for(std::vector<std::string>::const_iterator
         wi = impl->WrongConfigLibraries.begin();
@@ -944,7 +945,7 @@ int cmComputeLinkDepends::ComputeComponentCount(NodeList const& nl)
     if(cmTarget* target = this->EntryList[*ni].Target)
       {
       if(cmTarget::LinkInterface const* iface =
-         target->GetLinkInterface(this->Config))
+         target->GetLinkInterface(this->Config, this->HeadTarget))
         {
         if(iface->Multiplicity > count)
           {