split <2.34 code in cmake

CMakeLists.txt

@@ -8,4 +8,9 @@ add_library(nix-scope-plugin MODULE scope.cc)
 target_link_libraries(nix-scope-plugin PkgConfig::NIX_EXPR)
 set_target_properties(nix-scope-plugin PROPERTIES PREFIX "lib")
 
+if(NIX_EXPR_VERSION VERSION_LESS "2.34")
+    target_compile_definitions(nix-scope-plugin PRIVATE NIX_PRE_234)
+endif()
+message(STATUS "Building nix-scope-plugin against nix-expr ${NIX_EXPR_VERSION}")
+
 install(TARGETS nix-scope-plugin DESTINATION lib/nix/plugins)

scope.cc

@@ -40,13 +40,22 @@ static void prim_scope(EvalState & state, const PosIdx pos, Value ** args, Value
     v = *inner;
 }
 
-static RegisterPrimOp rp(PrimOp{
-    .name = "scope",
-    .args = {"path", "value"},
-    .doc = R"(
-      Construct a nested attribute set from a dotted string path and a value.
+static RegisterPrimOp rp(
+#ifndef NIX_PRE_234
+    PrimOp
+#endif
+    {
+        .name = "scope",
+        .args = {"path", "value"},
+        .doc = R"(
+          Construct a nested attribute set from a dotted string path and a value.
 
-      Example: `scope "a.b.c" 42` evaluates to `{ a = { b = { c = 42; }; }; }`.
-    )",
-    .impl = prim_scope,
-});
+          Example: `scope "a.b.c" 42` evaluates to `{ a = { b = { c = 42; }; }; }`.
+        )",
+#ifdef NIX_PRE_234
+        .fun = prim_scope,
+#else
+        .impl = prim_scope,
+#endif
+    }
+);