Convert TORCH_LIBRARIES into abacus::torch target

Author: Growl1234

source/CMakeLists.txt

@@ -136,6 +136,17 @@ add_library(abacus::feature_libs ALIAS abacus_feature_libs)
 add_library(abacus_link_libs INTERFACE)
 add_library(abacus::link_libs ALIAS abacus_link_libs)
 
+if(ENABLE_MLALGO OR DEFINED Torch_DIR)
+  # TorchConfig.cmake exposes its complete link closure through
+  # TORCH_LIBRARIES rather than a stable namespaced target. Keep that
+  # provider-specific representation behind an imported adapter so the
+  # installed ABACUS package can recreate it after find_dependency(Torch).
+  add_library(abacus::torch INTERFACE IMPORTED GLOBAL)
+  target_link_libraries(abacus::torch INTERFACE ${TORCH_LIBRARIES})
+  target_include_directories(abacus::torch INTERFACE ${TORCH_INCLUDE_DIRS})
+  target_compile_options(abacus::torch INTERFACE ${ABACUS_TORCH_CXX_FLAGS})
+endif()
+
 target_link_libraries(abacus_link_libs INTERFACE
   abacus::feature_libs
   abacus::linalg_libs)
@@ -263,8 +274,7 @@ if(ENABLE_MLALGO)
 endif()
 
 if(ENABLE_MLALGO OR DEFINED Torch_DIR)
-  list(APPEND _abacus_feature_include_dirs ${TORCH_INCLUDE_DIRS})
-  list(APPEND _abacus_feature_compile_options ${ABACUS_TORCH_CXX_FLAGS})
+  list(APPEND _abacus_feature_libs abacus::torch)
 endif()
 
 if(ENABLE_CNPY)
@@ -372,6 +382,7 @@ foreach(_abacus_feature_target IN ITEMS
     DeePMD::deepmd_cc
     NEP::nep
     TensorFlow::tensorflow_cc
+    abacus::torch
     ZLIB::ZLIB
     PEXSI::PEXSI
     NCCL::NCCL