BUG: Avoid bogus dependency on executable targets

When an executable target within the project is named in
target_link_libraries for another target, but the executable does not
have the ENABLE_EXPORTS property set, then the executable cannot really
be linked.  This is probably a case where the user intends to link to a
third-party library that happens to have the same name as an executable
target in the project (or else will get an error at build time).  We
need to avoid making the other target depend on the executable target
incorrectly, since the executable may actually want to link to that
target and this is not a circular depenency.

Source/cmComputeLinkDepends.cxx

@@ -292,7 +292,7 @@ int cmComputeLinkDepends::AddLinkEntry(std::string const& item)
   int index = lei->second;
   LinkEntry& entry = this->EntryList[index];
   entry.Item = item;
-  entry.Target = this->Makefile->FindTargetToUse(entry.Item.c_str());
+  entry.Target = this->FindTargetToLink(entry.Item.c_str());
 
   // If the item has dependencies queue it to follow them.
   if(entry.Target)
@@ -387,7 +387,7 @@ void cmComputeLinkDepends::HandleSharedDependency(SharedDepEntry const& dep)
     // Initialize the item entry.
     LinkEntry& entry = this->EntryList[lei->second];
     entry.Item = dep.Item;
-    entry.Target = this->Makefile->FindTargetToUse(dep.Item.c_str());
+    entry.Target = this->FindTargetToLink(dep.Item.c_str());
 
     // This item was added specifically because it is a dependent
     // shared library.  It may get special treatment
@@ -654,6 +654,25 @@ std::string cmComputeLinkDepends::CleanItemName(std::string const& item)
   return lib;
 }
 
+//----------------------------------------------------------------------------
+cmTarget* cmComputeLinkDepends::FindTargetToLink(const char* name)
+{
+  // Look for a target.
+  cmTarget* tgt = this->Makefile->FindTargetToUse(name);
+
+  // Skip targets that will not really be linked.  This is probably a
+  // name conflict between an external library and an executable
+  // within the project.
+  if(tgt && tgt->GetType() == cmTarget::EXECUTABLE &&
+     !tgt->IsExecutableWithExports())
+    {
+    tgt = 0;
+    }
+
+  // Return the target found, if any.
+  return tgt;
+}
+
 //----------------------------------------------------------------------------
 void cmComputeLinkDepends::InferDependencies()
 {
@@ -862,7 +881,7 @@ void cmComputeLinkDepends::CheckWrongConfigItem(std::string const& item)
   // For CMake 2.4 bug-compatibility we need to consider the output
   // directories of targets linked in another configuration as link
   // directories.
-  if(cmTarget* tgt = this->Makefile->FindTargetToUse(item.c_str()))
+  if(cmTarget* tgt = this->FindTargetToLink(item.c_str()))
     {
     if(!tgt->IsImported())
       {

Source/cmComputeLinkDepends.h

@@ -85,6 +85,7 @@ private:
   void AddLinkEntries(int depender_index,
                       std::vector<std::string> const& libs);
   std::string CleanItemName(std::string const& item);
+  cmTarget* FindTargetToLink(const char* name);
 
   // One entry for each unique item.
   std::vector<LinkEntry> EntryList;

Source/cmComputeTargetDepends.cxx

@@ -214,7 +214,7 @@ void cmComputeTargetDepends::CollectTargetDepends(int depender_index)
     // Don't emit the same library twice for this target.
     if(emitted.insert(lib->first).second)
       {
-      this->AddTargetDepend(depender_index, lib->first.c_str());
+      this->AddTargetDepend(depender_index, lib->first.c_str(), true);
       }
     }
 
@@ -226,14 +226,15 @@ void cmComputeTargetDepends::CollectTargetDepends(int depender_index)
     // Don't emit the same utility twice for this target.
     if(emitted.insert(*util).second)
       {
-      this->AddTargetDepend(depender_index, util->c_str());
+      this->AddTargetDepend(depender_index, util->c_str(), false);
       }
     }
 }
 
 //----------------------------------------------------------------------------
 void cmComputeTargetDepends::AddTargetDepend(int depender_index,
-                                             const char* dependee_name)
+                                             const char* dependee_name,
+                                             bool linking)
 {
   // Get the depender.
   cmTarget* depender = this->Targets[depender_index];
@@ -248,6 +249,16 @@ void cmComputeTargetDepends::AddTargetDepend(int depender_index,
     dependee = this->GlobalGenerator->FindTarget(0, dependee_name);
     }
 
+  // Skip targets that will not really be linked.  This is probably a
+  // name conflict between an external library and an executable
+  // within the project.
+  if(linking && dependee &&
+     dependee->GetType() == cmTarget::EXECUTABLE &&
+     !dependee->IsExecutableWithExports())
+    {
+    dependee = 0;
+    }
+
   // If not found then skip then the dependee.
   if(!dependee)
     {

Source/cmComputeTargetDepends.h

@@ -48,7 +48,8 @@ private:
   void CollectTargets();
   void CollectDepends();
   void CollectTargetDepends(int depender_index);
-  void AddTargetDepend(int depender_index, const char* dependee_name);
+  void AddTargetDepend(int depender_index, const char* dependee_name,
+                       bool linking);
   void ComputeFinalDepends(cmComputeComponentGraph const& ccg);
 
   cmGlobalGenerator* GlobalGenerator;