INSTALL_NAME_DIR: Add support for generator expressions

Source/cmExportInstallFileGenerator.cxx

@@ -517,13 +517,14 @@ void cmExportInstallFileGenerator::ComplainAboutMissingTarget(
 }
 
 std::string cmExportInstallFileGenerator::InstallNameDir(
-  cmGeneratorTarget* target, const std::string& /*config*/)
+  cmGeneratorTarget* target, const std::string& config)
 {
   std::string install_name_dir;
 
   cmMakefile* mf = target->Target->GetMakefile();
   if (mf->IsOn("CMAKE_PLATFORM_HAS_INSTALLNAME")) {
-    install_name_dir = target->GetInstallNameDirForInstallTree();
+    install_name_dir =
+      target->GetInstallNameDirForInstallTree(config, "${_IMPORT_PREFIX}");
   }
 
   return install_name_dir;

Source/cmGeneratorTarget.cxx

@@ -2125,7 +2125,9 @@ std::string cmGeneratorTarget::GetInstallNameDirForBuildTree(
     // If building directly for installation then the build tree install_name
     // is the same as the install tree.
     if (this->MacOSXUseInstallNameDir()) {
-      return this->GetInstallNameDirForInstallTree();
+      std::string installPrefix =
+        this->Makefile->GetSafeDefinition("CMAKE_INSTALL_PREFIX");
+      return this->GetInstallNameDirForInstallTree(config, installPrefix);
     }
 
     // Use the build tree directory for the target.
@@ -2143,7 +2145,8 @@ std::string cmGeneratorTarget::GetInstallNameDirForBuildTree(
   return "";
 }
 
-std::string cmGeneratorTarget::GetInstallNameDirForInstallTree() const
+std::string cmGeneratorTarget::GetInstallNameDirForInstallTree(
+  const std::string& config, const std::string& installPrefix) const
 {
   if (this->Makefile->IsOn("CMAKE_PLATFORM_HAS_INSTALLNAME")) {
     std::string dir;
@@ -2151,7 +2154,13 @@ std::string cmGeneratorTarget::GetInstallNameDirForInstallTree() const
 
     if (this->CanGenerateInstallNameDir(INSTALL_NAME_FOR_INSTALL)) {
       if (install_name_dir && *install_name_dir) {
-        dir = cmStrCat(install_name_dir, '/');
+        dir = install_name_dir;
+        cmGeneratorExpression::ReplaceInstallPrefix(dir, installPrefix);
+        dir =
+          cmGeneratorExpression::Evaluate(dir, this->LocalGenerator, config);
+        if (!dir.empty()) {
+          dir = cmStrCat(dir, '/');
+        }
       }
     }
     if (!install_name_dir) {

Source/cmGeneratorTarget.h

@@ -276,7 +276,8 @@ public:
 
   /** Return the install name directory for the target in the
    * install tree.  For example: "\@rpath/" or "\@loader_path/". */
-  std::string GetInstallNameDirForInstallTree() const;
+  std::string GetInstallNameDirForInstallTree(
+    const std::string& config, const std::string& installPrefix) const;
 
   cmListFileBacktrace GetBacktrace() const;
 

Source/cmInstallTargetGenerator.cxx

@@ -554,7 +554,8 @@ void cmInstallTargetGenerator::AddInstallNamePatchRule(
       // components of the install_name field then we need to create a
       // mapping to be applied after installation.
       std::string for_build = tgt->GetInstallNameDirForBuildTree(config);
-      std::string for_install = tgt->GetInstallNameDirForInstallTree();
+      std::string for_install = tgt->GetInstallNameDirForInstallTree(
+        config, "${CMAKE_INSTALL_PREFIX}");
       if (for_build != for_install) {
         // The directory portions differ.  Append the filename to
         // create the mapping.
@@ -577,7 +578,8 @@ void cmInstallTargetGenerator::AddInstallNamePatchRule(
   if (this->Target->GetType() == cmStateEnums::SHARED_LIBRARY) {
     std::string for_build =
       this->Target->GetInstallNameDirForBuildTree(config);
-    std::string for_install = this->Target->GetInstallNameDirForInstallTree();
+    std::string for_install = this->Target->GetInstallNameDirForInstallTree(
+      config, "${CMAKE_INSTALL_PREFIX}");
 
     if (this->Target->IsFrameworkOnApple() && for_install.empty()) {
       // Frameworks seem to have an id corresponding to their own full