cmMakefile: Implement LinkLibraries as an internal property

cmMakefile should not have logic particular to individual cmake
commands.  The link_libraries() command is generally obsolete in favor
of target_link_libraries().  An alternative language for CMake probably
would not offer the former.  The quirks and historical behaviors of the
current language should be separate from the core classes of CMake to
allow replacing the language.

Source/cmLinkLibrariesCommand.cxx

@@ -20,7 +20,7 @@ bool cmLinkLibrariesCommand::InitialPass(std::vector<std::string> const& args,
                        "a library");
         return false;
       }
-      this->Makefile->AddLinkLibrary(*i, DEBUG_LibraryType);
+      this->Makefile->AppendProperty("LINK_LIBRARIES", "debug");
     } else if (*i == "optimized") {
       ++i;
       if (i == args.end()) {
@@ -28,10 +28,9 @@ bool cmLinkLibrariesCommand::InitialPass(std::vector<std::string> const& args,
                        "a library");
         return false;
       }
-      this->Makefile->AddLinkLibrary(*i, OPTIMIZED_LibraryType);
-    } else {
-      this->Makefile->AddLinkLibrary(*i, GENERAL_LibraryType);
+      this->Makefile->AppendProperty("LINK_LIBRARIES", "optimized");
     }
+    this->Makefile->AppendProperty("LINK_LIBRARIES", i->c_str());
   }
 
   return true;

Source/cmMakefile.cxx

@@ -1207,15 +1207,6 @@ bool cmMakefile::ParseDefineFlag(std::string const& def, bool remove)
   return true;
 }
 
-void cmMakefile::AddLinkLibrary(const std::string& lib,
-                                cmTargetLinkLibraryType llt)
-{
-  cmTarget::LibraryID tmp;
-  tmp.first = lib;
-  tmp.second = llt;
-  this->LinkLibraries.push_back(tmp);
-}
-
 void cmMakefile::InitializeFromParent(cmMakefile* parent)
 {
   this->SystemIncludeDirectories = parent->SystemIncludeDirectories;
@@ -1247,7 +1238,7 @@ void cmMakefile::InitializeFromParent(cmMakefile* parent)
   }
 
   // link libraries
-  this->LinkLibraries = parent->LinkLibraries;
+  this->SetProperty("LINK_LIBRARIES", parent->GetProperty("LINK_LIBRARIES"));
 
   // link directories
   this->SetProperty("LINK_DIRECTORIES",
@@ -1804,14 +1795,29 @@ void cmMakefile::AddGlobalLinkInformation(cmTarget& target)
     }
   }
 
-  cmTarget::LinkLibraryVectorType::const_iterator i =
-    this->LinkLibraries.begin();
-  for (; i != this->LinkLibraries.end(); ++i) {
-    // This is equivalent to the target_link_libraries plain signature.
-    target.AddLinkLibrary(*this, i->first, i->second);
-    target.AppendProperty(
-      "INTERFACE_LINK_LIBRARIES",
-      target.GetDebugGeneratorExpressions(i->first, i->second).c_str());
+  if (const char* linkLibsProp = this->GetProperty("LINK_LIBRARIES")) {
+    std::vector<std::string> linkLibs;
+    cmSystemTools::ExpandListArgument(linkLibsProp, linkLibs);
+
+    for (std::vector<std::string>::iterator j = linkLibs.begin();
+         j != linkLibs.end(); ++j) {
+      std::string libraryName = *j;
+      cmTargetLinkLibraryType libType = GENERAL_LibraryType;
+      if (libraryName == "optimized") {
+        libType = OPTIMIZED_LibraryType;
+        ++j;
+        libraryName = *j;
+      } else if (libraryName == "debug") {
+        libType = DEBUG_LibraryType;
+        ++j;
+        libraryName = *j;
+      }
+      // This is equivalent to the target_link_libraries plain signature.
+      target.AddLinkLibrary(*this, libraryName, libType);
+      target.AppendProperty(
+        "INTERFACE_LINK_LIBRARIES",
+        target.GetDebugGeneratorExpressions(libraryName, libType).c_str());
+    }
   }
 }
 
@@ -2074,19 +2080,32 @@ void cmMakefile::ExpandVariablesCMP0019()
       }
     }
   }
-  for (cmTarget::LinkLibraryVectorType::iterator l =
-         this->LinkLibraries.begin();
-       l != this->LinkLibraries.end(); ++l) {
-    if (mightExpandVariablesCMP0019(l->first.c_str())) {
-      std::string orig = l->first;
-      this->ExpandVariablesInString(l->first, true, true);
-      if (pol == cmPolicies::WARN && l->first != orig) {
-        /* clang-format off */
+
+  if (const char* linkLibsProp = this->GetProperty("LINK_LIBRARIES")) {
+    std::vector<std::string> linkLibs;
+    cmSystemTools::ExpandListArgument(linkLibsProp, linkLibs);
+
+    for (std::vector<std::string>::iterator l = linkLibs.begin();
+         l != linkLibs.end(); ++l) {
+      std::string libName = *l;
+      if (libName == "optimized") {
+        ++l;
+        libName = *l;
+      } else if (libName == "debug") {
+        ++l;
+        libName = *l;
+      }
+      if (mightExpandVariablesCMP0019(libName.c_str())) {
+        std::string orig = libName;
+        this->ExpandVariablesInString(libName, true, true);
+        if (pol == cmPolicies::WARN && libName != orig) {
+          /* clang-format off */
         w << "Evaluated link library\n"
           << "  " << orig << "\n"
           << "as\n"
-          << "  " << l->first << "\n";
-        /* clang-format on */
+          << "  " << libName << "\n";
+          /* clang-format on */
+        }
       }
     }
   }

Source/cmMakefile.h

@@ -196,11 +196,6 @@ public:
     const cmCustomCommandLines& commandLines, bool escapeOldStyle = true,
     const char* comment = CM_NULLPTR, bool uses_terminal = false);
 
-  /**
-   * Add a link library to the build.
-   */
-  void AddLinkLibrary(const std::string&, cmTargetLinkLibraryType type);
-
   /**
    * Add a subdirectory to the build.
    */
@@ -808,8 +803,6 @@ protected:
   std::vector<std::string> ListFiles;
   std::vector<std::string> OutputFiles;
 
-  cmTarget::LinkLibraryVectorType LinkLibraries;
-
   std::vector<cmInstallGenerator*> InstallGenerators;
   std::vector<cmTestGenerator*> TestGenerators;