install,export: Do not treat language names as target names

When generating `IMPORTED_LINK_INTERFACE_LANGUAGES`, do not treat the
entries as target names.

Fixes: #19846

Source/cmExportFileGenerator.cxx

@@ -752,9 +752,9 @@ void cmExportFileGenerator::SetImportLinkInterface(
 
   if (iface->ImplementationIsInterface) {
     // Policy CMP0022 must not be NEW.
-    this->SetImportLinkProperty(suffix, target,
-                                "IMPORTED_LINK_INTERFACE_LIBRARIES",
-                                iface->Libraries, properties, missingTargets);
+    this->SetImportLinkProperty(
+      suffix, target, "IMPORTED_LINK_INTERFACE_LIBRARIES", iface->Libraries,
+      properties, missingTargets, ImportLinkPropertyTargetNames::Yes);
     return;
   }
 
@@ -832,14 +832,14 @@ void cmExportFileGenerator::SetImportDetailProperties(
   // Add the transitive link dependencies for this configuration.
   if (cmLinkInterface const* iface =
         target->GetLinkInterface(config, target)) {
-    this->SetImportLinkProperty(suffix, target,
-                                "IMPORTED_LINK_INTERFACE_LANGUAGES",
-                                iface->Languages, properties, missingTargets);
+    this->SetImportLinkProperty(
+      suffix, target, "IMPORTED_LINK_INTERFACE_LANGUAGES", iface->Languages,
+      properties, missingTargets, ImportLinkPropertyTargetNames::No);
 
     std::vector<std::string> dummy;
-    this->SetImportLinkProperty(suffix, target,
-                                "IMPORTED_LINK_DEPENDENT_LIBRARIES",
-                                iface->SharedDeps, properties, dummy);
+    this->SetImportLinkProperty(
+      suffix, target, "IMPORTED_LINK_DEPENDENT_LIBRARIES", iface->SharedDeps,
+      properties, dummy, ImportLinkPropertyTargetNames::Yes);
     if (iface->Multiplicity > 0) {
       std::string prop =
         cmStrCat("IMPORTED_LINK_INTERFACE_MULTIPLICITY", suffix);
@@ -880,7 +880,8 @@ template <typename T>
 void cmExportFileGenerator::SetImportLinkProperty(
   std::string const& suffix, cmGeneratorTarget* target,
   const std::string& propName, std::vector<T> const& entries,
-  ImportPropertyMap& properties, std::vector<std::string>& missingTargets)
+  ImportPropertyMap& properties, std::vector<std::string>& missingTargets,
+  ImportLinkPropertyTargetNames targetNames)
 {
   // Skip the property if there are no entries.
   if (entries.empty()) {
@@ -895,9 +896,13 @@ void cmExportFileGenerator::SetImportLinkProperty(
     link_entries += sep;
     sep = ";";
 
-    std::string temp = asString(l);
-    this->AddTargetNamespace(temp, target, missingTargets);
-    link_entries += temp;
+    if (targetNames == ImportLinkPropertyTargetNames::Yes) {
+      std::string temp = asString(l);
+      this->AddTargetNamespace(temp, target, missingTargets);
+      link_entries += temp;
+    } else {
+      link_entries += asString(l);
+    }
   }
 
   // Store the property.

Source/cmExportFileGenerator.h

@@ -102,13 +102,19 @@ protected:
                                  ImportPropertyMap& properties,
                                  std::vector<std::string>& missingTargets);
 
+  enum class ImportLinkPropertyTargetNames
+  {
+    Yes,
+    No,
+  };
   template <typename T>
   void SetImportLinkProperty(std::string const& suffix,
                              cmGeneratorTarget* target,
                              const std::string& propName,
                              std::vector<T> const& entries,
                              ImportPropertyMap& properties,
-                             std::vector<std::string>& missingTargets);
+                             std::vector<std::string>& missingTargets,
+                             ImportLinkPropertyTargetNames targetNames);
 
   /** Each subclass knows how to generate its kind of export file.  */
   virtual bool GenerateMainFile(std::ostream& os) = 0;

Tests/ExportImport/Export/CMakeLists.txt

@@ -645,3 +645,8 @@ if(CMAKE_GENERATOR MATCHES "Make|Ninja")
     EXPORT RequiredExp DESTINATION lib)
   export(TARGETS testLinkDepends NAMESPACE bld_ APPEND FILE ExportBuildTree.cmake)
 endif()
+
+# Test the presence of targets named the same as languages.
+# IMPORTED_LINK_INTERFACE_LANGUAGES entries should not be targets.
+add_library(C INTERFACE)
+add_library(CXX INTERFACE)