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, 7 insertions, 4 deletions

diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index d8ffb5e..504c6e7 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -239,10 +239,12 @@ because this need be done only for shared libraries without soname-s.
 
 //----------------------------------------------------------------------------
 cmComputeLinkInformation
-::cmComputeLinkInformation(cmTarget* target, const char* config)
+::cmComputeLinkInformation(cmTarget* target, const char* config,
+                           cmTarget *headTarget)
 {
   // Store context information.
   this->Target = target;
+  this->HeadTarget = headTarget;
   this->Makefile = this->Target->GetMakefile();
   this->LocalGenerator = this->Makefile->GetLocalGenerator();
   this->GlobalGenerator = this->LocalGenerator->GetGlobalGenerator();
@@ -265,7 +267,7 @@ cmComputeLinkInformation
   this->OrderDependentRPath = 0;
 
   // Get the language used for linking this target.
-  this->LinkLanguage = this->Target->GetLinkerLanguage(config);
+  this->LinkLanguage = this->Target->GetLinkerLanguage(config, headTarget);
   if(!this->LinkLanguage)
     {
     // The Compute method will do nothing, so skip the rest of the
@@ -503,7 +505,7 @@ bool cmComputeLinkInformation::Compute()
     }
 
   // Compute the ordered link line items.
-  cmComputeLinkDepends cld(this->Target, this->Config);
+  cmComputeLinkDepends cld(this->Target, this->Config, this->HeadTarget);
   cld.SetOldLinkDirMode(this->OldLinkDirMode);
   cmComputeLinkDepends::EntryVector const& linkEntries = cld.Compute();
 
@@ -569,7 +571,8 @@ bool cmComputeLinkInformation::Compute()
 void cmComputeLinkInformation::AddImplicitLinkInfo()
 {
   // The link closure lists all languages whose implicit info is needed.
-  cmTarget::LinkClosure const* lc=this->Target->GetLinkClosure(this->Config);
+  cmTarget::LinkClosure const* lc=this->Target->GetLinkClosure(this->Config,
+                                                          this->HeadTarget);
   for(std::vector<std::string>::const_iterator li = lc->Languages.begin();
       li != lc->Languages.end(); ++li)
     {