Fortran: Restore support for TARGET_OBJECTS providing modules

Continue b665966933 (cmComputeLinkInformation: track OBJECT library
dependencies, 2023-07-22) which added explicitly listed `OBJECT`
libraries to the list of targets which the collator needs to consider.
Now also consider targets which provide objects directly to the target
via a `$<TARGET_OBJECT>` source lists.

Also add tests which use target objects directly and through an
`INTERFACE` library with target objects in its own sources.

Fixes: #25365

Source/cmComputeLinkDepends.cxx

@@ -26,6 +26,7 @@
 #include "cmMakefile.h"
 #include "cmMessageType.h"
 #include "cmRange.h"
+#include "cmSourceFile.h"
 #include "cmStateTypes.h"
 #include "cmStringAlgorithms.h"
 #include "cmTarget.h"
@@ -319,6 +320,9 @@ cmComputeLinkDepends::Compute()
   // Follow the link dependencies of the target to be linked.
   this->AddDirectLinkEntries();
 
+  // Add dependencies on targets named by $<TARGET_OBJECTS:...> sources.
+  this->AddTargetObjectEntries();
+
   // Complete the breadth-first search of dependencies.
   while (!this->BFSQueue.empty()) {
     // Get the next entry.
@@ -701,6 +705,21 @@ void cmComputeLinkDepends::AddDirectLinkEntries()
   }
 }
 
+void cmComputeLinkDepends::AddTargetObjectEntries()
+{
+  std::vector<cmSourceFile const*> externalObjects;
+  this->Target->GetExternalObjects(externalObjects, this->Config);
+  for (auto const* externalObject : externalObjects) {
+    std::string const& objLib = externalObject->GetObjectLibrary();
+    if (objLib.empty()) {
+      continue;
+    }
+    cmLinkItem const& objItem =
+      this->Target->ResolveLinkItem(BT<std::string>(objLib));
+    this->AddLinkObject(objItem);
+  }
+}
+
 template <typename T>
 void cmComputeLinkDepends::AddLinkEntries(size_t depender_index,
                                           std::vector<T> const& libs)

Source/cmComputeLinkDepends.h

@@ -100,6 +100,7 @@ private:
   void AddLinkObject(cmLinkItem const& item);
   void AddVarLinkEntries(size_t depender_index, const char* value);
   void AddDirectLinkEntries();
+  void AddTargetObjectEntries();
   template <typename T>
   void AddLinkEntries(size_t depender_index, std::vector<T> const& libs);
   void AddLinkObjects(std::vector<cmLinkItem> const& objs);

Tests/FortranModules/CMakeLists.txt

@@ -134,3 +134,6 @@ if( # Intel Fortran VS Integration breaks on custom targets with Fortran sources
   add_subdirectory(Issue25252-iface-target)
 endif()
 add_subdirectory(Issue25252-iface-sources)
+
+add_subdirectory(Issue25365-target-objects)
+add_subdirectory(Issue25365-target-objects-iface)

Tests/FortranModules/Issue25365-target-objects-iface/CMakeLists.txt

@@ -0,0 +1,11 @@
+enable_language(C)
+
+add_library(fortran_target_objects_sources_iface STATIC "${CMAKE_CURRENT_SOURCE_DIR}/iface.f90")
+
+add_library(fortran_target_objects_sources_iface_bridge INTERFACE)
+target_sources(fortran_target_objects_sources_iface_bridge
+  INTERFACE
+    "$<TARGET_OBJECTS:fortran_target_objects_sources_iface>")
+
+add_library(lib25365-target-objects-iface lib.f90)
+target_link_libraries(lib25365-target-objects-iface PRIVATE fortran_target_objects_sources_iface_bridge)

Tests/FortranModules/Issue25365-target-objects-iface/iface.f90

@@ -0,0 +1,11 @@
+module m1
+
+implicit none
+
+contains
+
+pure real function pi()
+pi = 4*atan(1.)
+end function
+
+end module m1

Tests/FortranModules/Issue25365-target-objects-iface/lib.f90

@@ -0,0 +1,13 @@
+module lib
+
+use m1, only : pi
+
+implicit none
+
+contains
+
+pure real function func()
+func = pi()
+end function
+
+end module

Tests/FortranModules/Issue25365-target-objects/CMakeLists.txt

@@ -0,0 +1,5 @@
+enable_language(C)
+
+add_library(fortran_target_objects_sources STATIC "${CMAKE_CURRENT_SOURCE_DIR}/iface.f90")
+
+add_library(lib25365-target-objects lib.f90 "$<TARGET_OBJECTS:fortran_target_objects_sources>")

Tests/FortranModules/Issue25365-target-objects/iface.f90

@@ -0,0 +1,11 @@
+module m1
+
+implicit none
+
+contains
+
+pure real function pi()
+pi = 4*atan(1.)
+end function
+
+end module m1

Tests/FortranModules/Issue25365-target-objects/lib.f90

@@ -0,0 +1,13 @@
+module lib
+
+use m1, only : pi
+
+implicit none
+
+contains
+
+pure real function func()
+func = pi()
+end function
+
+end module