Make `zstd::libzstd` an imported interface target.

It cannot be an alias, because it would lock the package to use either static or shared libraries at its build time. We want to decide this at the time `find_package` is called.

diff --git a/build/cmake/zstdConfig.cmake.in b/build/cmake/zstdConfig.cmake.in
index 752f3ab11ce79a5e5a9f3566ec1a340a750e5693..0a7f773d75fab49fc0fda74b5cccbf71796de10a 100644 (file)
--- a/build/cmake/zstdConfig.cmake.in
+++ b/build/cmake/zstdConfig.cmake.in
@@ -7,10 +7,18 @@ endif()
 
 include("${CMAKE_CURRENT_LIST_DIR}/zstdTargets.cmake")
 
-if(@ZSTD_BUILD_SHARED@ AND NOT @ZSTD_BUILD_STATIC@)
-  add_library(zstd::libzstd ALIAS zstd::libzstd_shared)
-elseif(NOT @ZSTD_BUILD_SHARED@ AND @ZSTD_BUILD_STATIC@)
-  add_library(zstd::libzstd ALIAS zstd::libzstd_static)
+if(NOT TARGET zstd::libzstd)
+  if(@ZSTD_BUILD_SHARED@ AND NOT @ZSTD_BUILD_STATIC@)
+    add_library(zstd::libzstd INTERFACE IMPORTED)
+    set_target_properties(zstd::libzstd PROPERTIES
+      INTERFACE_LINK_LIBRARIES "zstd::libzstd_shared"
+    )
+  elseif(NOT @ZSTD_BUILD_SHARED@ AND @ZSTD_BUILD_STATIC@)
+    add_library(zstd::libzstd INTERFACE IMPORTED)
+    set_target_properties(zstd::libzstd PROPERTIES
+      INTERFACE_LINK_LIBRARIES "zstd::libzstd_static"
+    )
+  endif()
 endif()
 
 check_required_components("zstd")