target_link_libraries: Place $<TARGET_OBJECTS> before libraries

Linkers always use object files explicitly specified on the command line
regardless of where they appear.  Move them to the front of the list of
linked libraries in so that symbols required by the object files can be
resolved by any library.

Issue: #22149

1 files changed, 33 insertions, 5 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 51742cf..5deb2df 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -6275,8 +6275,8 @@ cm::optional<cmLinkItem> cmGeneratorTarget::LookupLinkItem(
 void cmGeneratorTarget::ExpandLinkItems(
   std::string const& prop, std::string const& value, std::string const& config,
   cmGeneratorTarget const* headTarget, bool usage_requirements_only,
-  std::vector<cmLinkItem>& items, bool& hadHeadSensitiveCondition,
-  bool& hadContextSensitiveCondition,
+  std::vector<cmLinkItem>& items, std::vector<cmLinkItem>& objects,
+  bool& hadHeadSensitiveCondition, bool& hadContextSensitiveCondition,
   bool& hadLinkLanguageSensitiveCondition) const
 {
   // Keep this logic in sync with ComputeLinkImplementationLibraries.
@@ -6294,9 +6294,22 @@ void cmGeneratorTarget::ExpandLinkItems(
   cmExpandList(cge->Evaluate(this->LocalGenerator, config, headTarget,
                              &dagChecker, this, headTarget->LinkerLanguage),
                libs);
+  cmMakefile const* mf = this->LocalGenerator->GetMakefile();
   for (std::string const& lib : libs) {
     if (cm::optional<cmLinkItem> maybeItem =
           this->LookupLinkItem(lib, cge->GetBacktrace())) {
+      if (!maybeItem->Target) {
+        // Report explicitly linked object files separately.
+        std::string const& maybeObj = maybeItem->AsStr();
+        if (cmSystemTools::FileIsFullPath(maybeObj)) {
+          cmSourceFile const* sf =
+            mf->GetSource(maybeObj, cmSourceFileLocationKind::Known);
+          if (sf && sf->GetPropertyAsBool("EXTERNAL_OBJECT")) {
+            objects.emplace_back(std::move(*maybeItem));
+            continue;
+          }
+        }
+      }
       items.emplace_back(std::move(*maybeItem));
     }
   }
@@ -6804,7 +6817,7 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
     // The interface libraries have been explicitly set.
     this->ExpandLinkItems(linkIfaceProp, *explicitLibraries, config,
                           headTarget, usage_requirements_only, iface.Libraries,
-                          iface.HadHeadSensitiveCondition,
+                          iface.Objects, iface.HadHeadSensitiveCondition,
                           iface.HadContextSensitiveCondition,
                           iface.HadLinkLanguageSensitiveCondition);
     return;
@@ -6828,6 +6841,7 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
       // Compare the link implementation fallback link interface to the
       // preferred new link interface property and warn if different.
       std::vector<cmLinkItem> ifaceLibs;
+      std::vector<cmLinkItem> ifaceObjects;
       static const std::string newProp = "INTERFACE_LINK_LIBRARIES";
       if (cmProp newExplicitLibraries = this->GetProperty(newProp)) {
         bool hadHeadSensitiveConditionDummy = false;
@@ -6835,7 +6849,7 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
         bool hadLinkLanguageSensitiveConditionDummy = false;
         this->ExpandLinkItems(newProp, *newExplicitLibraries, config,
                               headTarget, usage_requirements_only, ifaceLibs,
-                              hadHeadSensitiveConditionDummy,
+                              ifaceObjects, hadHeadSensitiveConditionDummy,
                               hadContextSensitiveConditionDummy,
                               hadLinkLanguageSensitiveConditionDummy);
       }
@@ -6903,7 +6917,7 @@ const cmLinkInterface* cmGeneratorTarget::GetImportLinkInterface(
     cmExpandList(info->Languages, iface.Languages);
     this->ExpandLinkItems(info->LibrariesProp, info->Libraries, config,
                           headTarget, usage_requirements_only, iface.Libraries,
-                          iface.HadHeadSensitiveCondition,
+                          iface.Objects, iface.HadHeadSensitiveCondition,
                           iface.HadContextSensitiveCondition,
                           iface.HadLinkLanguageSensitiveCondition);
     std::vector<std::string> deps = cmExpandedList(info->SharedDeps);
@@ -7425,6 +7439,7 @@ void cmGeneratorTarget::ComputeLinkImplementationLibraries(
   cmGeneratorTarget const* head) const
 {
   cmLocalGenerator const* lg = this->LocalGenerator;
+  cmMakefile const* mf = lg->GetMakefile();
   cmStringRange entryRange = this->Target->GetLinkImplementationEntries();
   cmBacktraceRange btRange = this->Target->GetLinkImplementationBacktraces();
   cmBacktraceRange::const_iterator btIt = btRange.begin();
@@ -7500,6 +7515,19 @@ void cmGeneratorTarget::ComputeLinkImplementationLibraries(
 
       // The entry is meant for this configuration.
       cmLinkItem item = this->ResolveLinkItem(name, *btIt, lg);
+      if (!item.Target) {
+        // Report explicitly linked object files separately.
+        std::string const& maybeObj = item.AsStr();
+        if (cmSystemTools::FileIsFullPath(maybeObj)) {
+          cmSourceFile const* sf =
+            mf->GetSource(maybeObj, cmSourceFileLocationKind::Known);
+          if (sf && sf->GetPropertyAsBool("EXTERNAL_OBJECT")) {
+            impl.Objects.emplace_back(std::move(item));
+            continue;
+          }
+        }
+      }
+
       impl.Libraries.emplace_back(std::move(item), evaluated != *le);
     }