target_link_libraries: Add LINK_(PUBLIC|PRIVATE) options

Makes it possible to specify the link dependencies and link
interfaces in one command without repetition.

2 files changed, 62 insertions, 11 deletions

diff --git a/Source/cmTargetLinkLibrariesCommand.cxx b/Source/cmTargetLinkLibrariesCommand.cxx
index 805959d..0db5943 100644
--- a/Source/cmTargetLinkLibrariesCommand.cxx
+++ b/Source/cmTargetLinkLibrariesCommand.cxx
@@ -95,8 +95,8 @@ bool cmTargetLinkLibrariesCommand
   bool haveLLT = false;
 
   // Start with primary linking and switch to link interface
-  // specification when the keyword is encountered.
-  this->DoingInterface = false;
+  // specification if the keyword is encountered as the first argument.
+  this->CurrentProcessingState = ProcessingLinkLibraries;
 
   // add libraries, nothe that there is an optional prefix
   // of debug and optimized than can be used
@@ -104,7 +104,7 @@ bool cmTargetLinkLibrariesCommand
     {
     if(args[i] == "LINK_INTERFACE_LIBRARIES")
       {
-      this->DoingInterface = true;
+      this->CurrentProcessingState = ProcessingLinkInterface;
       if(i != 1)
         {
         this->Makefile->IssueMessage(
@@ -115,6 +115,32 @@ bool cmTargetLinkLibrariesCommand
         return true;
         }
       }
+    else if(args[i] == "LINK_PUBLIC")
+      {
+      if(i != 1 && this->CurrentProcessingState != ProcessingPrivateInterface)
+        {
+        this->Makefile->IssueMessage(
+          cmake::FATAL_ERROR,
+          "The LINK_PUBLIC or LINK_PRIVATE option must appear as the second "
+          "argument, just after the target name."
+          );
+        return true;
+        }
+      this->CurrentProcessingState = ProcessingPublicInterface;
+      }
+    else if(args[i] == "LINK_PRIVATE")
+      {
+      if(i != 1 && this->CurrentProcessingState != ProcessingPublicInterface)
+        {
+        this->Makefile->IssueMessage(
+          cmake::FATAL_ERROR,
+          "The LINK_PUBLIC or LINK_PRIVATE option must appear as the second "
+          "argument, just after the target name."
+          );
+        return true;
+        }
+      this->CurrentProcessingState = ProcessingPrivateInterface;
+      }
     else if(args[i] == "debug")
       {
       if(haveLLT)
@@ -186,11 +212,13 @@ bool cmTargetLinkLibrariesCommand
     cmSystemTools::SetFatalErrorOccured();
     }
 
-  // If the INTERFACE option was given, make sure the
-  // LINK_INTERFACE_LIBRARIES property exists.  This allows the
-  // command to be used to specify an empty link interface.
-  if(this->DoingInterface &&
-     !this->Target->GetProperty("LINK_INTERFACE_LIBRARIES"))
+  // If any of the LINK_ options were given, make sure the
+  // LINK_INTERFACE_LIBRARIES target property exists.
+  // Use of any of the new keywords implies awareness of
+  // this property. And if no libraries are named, it should
+  // result in an empty link interface.
+  if((this->CurrentProcessingState != ProcessingLinkLibraries)
+    && !this->Target->GetProperty("LINK_INTERFACE_LIBRARIES"))
     {
     this->Target->SetProperty("LINK_INTERFACE_LIBRARIES", "");
     }
@@ -217,11 +245,15 @@ cmTargetLinkLibrariesCommand::HandleLibrary(const char* lib,
                                             cmTarget::LinkLibraryType llt)
 {
   // Handle normal case first.
-  if(!this->DoingInterface)
+  if(this->CurrentProcessingState != ProcessingLinkInterface)
     {
     this->Makefile
       ->AddLinkLibraryForTarget(this->Target->GetName(), lib, llt);
-    return;
+    if (this->CurrentProcessingState != ProcessingPublicInterface
+        || this->CurrentProcessingState == ProcessingPrivateInterface)
+      {
+      return;
+      }
     }
 
   // Get the list of configurations considered to be DEBUG.
diff --git a/Source/cmTargetLinkLibrariesCommand.h b/Source/cmTargetLinkLibrariesCommand.h
index a9b5d8b..e91c46d 100644
--- a/Source/cmTargetLinkLibrariesCommand.h
+++ b/Source/cmTargetLinkLibrariesCommand.h
@@ -107,6 +107,18 @@ public:
       "Libraries specified as \"general\" (or without any keyword) are "
       "treated as if specified for both \"debug\" and \"optimized\"."
       "\n"
+      "  target_link_libraries(<target>\n"
+      "                        <LINK_PRIVATE|LINK_PUBLIC>\n"
+      "                          [[debug|optimized|general] <lib>] ...\n"
+      "                        [<LINK_PRIVATE|LINK_PUBLIC>\n"
+      "                          [[debug|optimized|general] <lib>] ...])\n"
+      "The LINK_PUBLIC and LINK_PRIVATE modes can be used to specify both the"
+      "link dependencies and the link interface in one command.  "
+      "Libraries and targets following LINK_PUBLIC are linked to, and are "
+      "made part of the LINK_INTERFACE_LIBRARIES. Libraries and targets "
+      "following LINK_PRIVATE are linked to, but are not made part of the "
+      "LINK_INTERFACE_LIBRARIES.  "
+      "\n"
       "The library dependency graph is normally acyclic (a DAG), but in the "
       "case of mutually-dependent STATIC libraries CMake allows the graph "
       "to contain cycles (strongly connected components).  "
@@ -137,7 +149,14 @@ private:
   static const char* LinkLibraryTypeNames[3];
 
   cmTarget* Target;
-  bool DoingInterface;
+  enum ProcessingState {
+    ProcessingLinkLibraries,
+    ProcessingLinkInterface,
+    ProcessingPublicInterface,
+    ProcessingPrivateInterface
+  };
+
+  ProcessingState CurrentProcessingState;
 
   void HandleLibrary(const char* lib, cmTarget::LinkLibraryType llt);
 };