install,export: Maybe transform OBJECT libraries to INTERFACE libraries

Teach the `install` and `export` commands to support installing and
exporting `OBJECT` libraries without their object files.  Transform
them to `INTERFACE` libraries in such cases.

For `install(TARGETS)`, activate this when no destination for the object
files is specified.  For `export`, activate this only under Xcode with
multiple architectures when we have no well-defined object file
locations to give to clients.

1 files changed, 18 insertions, 4 deletions

diff --git a/Source/cmExportInstallFileGenerator.cxx b/Source/cmExportInstallFileGenerator.cxx
index 954b561..93ba2ce 100644
--- a/Source/cmExportInstallFileGenerator.cxx
+++ b/Source/cmExportInstallFileGenerator.cxx
@@ -75,11 +75,12 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
   // Create all the imported targets.
   for (cmTargetExport* te : allTargets) {
     cmGeneratorTarget* gt = te->Target;
+    cmStateEnums::TargetType targetType = this->GetExportTargetType(te);
 
     requiresConfigFiles =
-      requiresConfigFiles || gt->GetType() != cmStateEnums::INTERFACE_LIBRARY;
+      requiresConfigFiles || targetType != cmStateEnums::INTERFACE_LIBRARY;
 
-    this->GenerateImportTargetCode(os, gt);
+    this->GenerateImportTargetCode(os, gt, targetType);
 
     ImportPropertyMap properties;
 
@@ -114,7 +115,7 @@ bool cmExportInstallFileGenerator::GenerateMainFile(std::ostream& os)
         require2_8_12 = true;
       }
     }
-    if (gt->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
+    if (targetType == cmStateEnums::INTERFACE_LIBRARY) {
       require3_0_0 = true;
     }
     if (gt->GetProperty("INTERFACE_SOURCES")) {
@@ -308,7 +309,7 @@ void cmExportInstallFileGenerator::GenerateImportTargetsConfig(
   // Add each target in the set to the export.
   for (cmTargetExport* te : *this->IEGen->GetExportSet()->GetTargetExports()) {
     // Collect import properties for this target.
-    if (te->Target->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
+    if (this->GetExportTargetType(te) == cmStateEnums::INTERFACE_LIBRARY) {
       continue;
     }
 
@@ -426,6 +427,19 @@ void cmExportInstallFileGenerator::SetImportLocationProperty(
   }
 }
 
+cmStateEnums::TargetType cmExportInstallFileGenerator::GetExportTargetType(
+  cmTargetExport const* targetExport) const
+{
+  cmStateEnums::TargetType targetType = targetExport->Target->GetType();
+  // An OBJECT library installed with no OBJECTS DESTINATION
+  // is transformed to an INTERFACE library.
+  if (targetType == cmStateEnums::OBJECT_LIBRARY &&
+      targetExport->ObjectsGenerator == nullptr) {
+    targetType = cmStateEnums::INTERFACE_LIBRARY;
+  }
+  return targetType;
+}
+
 void cmExportInstallFileGenerator::HandleMissingTarget(
   std::string& link_libs, std::vector<std::string>& missingTargets,
   cmGeneratorTarget* depender, cmGeneratorTarget* dependee)