Xcode: Fix object library references in multi-project trees (#13452)

In cmGlobalXCodeGenerator::Generate we generate a .xcodeproj for each
directory in the tree containing a project() command.  First we
iteratively use SetGenerationRoot to add "ALL_BUILD" and other targets
to each project.  This leaves "CurrentProject" set to the last project
when we invoke cmGlobalGenerator::Generate, which is not the same as the
top-level project if any subdirectories invoke the project() command.

When cmGlobalGenerator::Generate reaches CreateGeneratorTargets it
constructs cmGeneratorTarget and calls ComputeTargetObjects exactly once
per target.  In this context the value of CurrentProject is undefined so
we cannot pass it to GetObjectsNormalDirectory.  Use "$(PROJECT_NAME)"
instead so it will adapt automatically to each project.

Also teach Tests/ObjectLibrary to cover this case.

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index 938977b..c366bcb 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -3739,7 +3739,7 @@ cmGlobalXCodeGenerator
 
   const char* configName = this->GetCMakeCFGIntDir();
   std::string dir = this->GetObjectsNormalDirectory(
-    this->CurrentProject, configName, gt->Target);
+    "$(PROJECT_NAME)", configName, gt->Target);
   if(this->XcodeVersion >= 21)
     {
     dir += "$(CURRENT_ARCH)/";