Change private->public spec for error checking in mjCSkin recompilation.

Fixes #2485.

PiperOrigin-RevId: 735323174
Change-Id: Ifcc2055f6a74afaa18ad5228633f36f760adcffd

src/user/user_mesh.cc

@@ -2526,16 +2526,15 @@ void mjCSkin::Compile(const mjVFS* vfs) {
   // load file
   if (!file_.empty()) {
     // make sure data is not present
-    if (!vert_.empty() ||
+    if (!spec_vert_.empty() ||
-        !texcoord_.empty() ||
+        !spec_texcoord_.empty() ||
-        !face_.empty() ||
+        !spec_face_.empty() ||
-        !bodyname_.empty() ||
+        !spec_bodyname_.empty() ||
-        !bindpos_.empty() ||
+        !spec_bindpos_.empty() ||
-        !bindquat_.empty() ||
+        !spec_bindquat_.empty() ||
-        !vertid_.empty() ||
+        !spec_vertid_.empty() ||
-        !vertweight_.empty() ||
+        !spec_vertweight_.empty()) {
-        !bodyid.empty()) {
+      throw mjCError(this, "Both skin data and file were specified: %s", file_.c_str());
-      throw mjCError(this, "Data already exists, trying to load from skin file: %s", file_.c_str());
     }
 
     // remove path from file if necessary

test/user/testdata/cube_skin.xml

@@ -0,0 +1,13 @@
+<mujoco>
+    <asset>
+      <mesh name="cube" file="cube.stl" scale=".05 .05 .05"/>
+      <skin name="skin" file="cube.skn"/>
+    </asset>
+
+    <worldbody>
+      <body name="box">
+        <geom type="box" mesh="cube"/>
+      </body>
+
+    </worldbody>
+</mujoco>

test/user/user_mesh_test.cc

@@ -66,6 +66,8 @@ static const char* const kDuplicateOBJPath =
     "user/testdata/duplicate.xml";
 static const char* const kMalformedFaceOBJPath =
     "user/testdata/malformed_face.xml";
+static const char* const kCubeSkinPath =
+    "user/testdata/cube_skin.xml";
 
 using ::testing::ElementsAre;
 using ::testing::HasSubstr;
@@ -1184,6 +1186,19 @@ TEST_F(MjCMeshTest, InvalidIndexInFace) {
   mj_deleteModel(model);
 }
 
+TEST_F(MjCMeshTest, LoadSkin) {
+  const std::string xml_path = GetTestDataFilePath(kCubeSkinPath);
+  std::array<char, 1024> error;
+  mjSpec* spec = mj_parseXML(xml_path.c_str(), 0, error.data(), error.size());
+  EXPECT_THAT(spec, NotNull()) << error.data();
+  mjModel* m1 = mj_compile(spec, 0);
+  EXPECT_THAT(m1, NotNull());
+  mj_deleteModel(m1);
+  mjModel* m2 = mj_compile(spec, 0);
+  EXPECT_THAT(m2, NotNull());
+  mj_deleteModel(m2);
+  mj_deleteSpec(spec);
+}
 
 
 }  // namespace