Catch errors in attach during replicate.

PiperOrigin-RevId: 651041336
Change-Id: I59986e157b4e22c74f8b8493899cdd4a3d5df839

src/user/user_api.cc

@@ -98,7 +98,11 @@ int mjs_attachBody(mjsFrame* parent, const mjsBody* child,
                    const char* prefix, const char* suffix) {
   mjCFrame* frame_parent = static_cast<mjCFrame*>(parent->element);
   mjCBody* child_body = static_cast<mjCBody*>(child->element);
-  *frame_parent += std::string(prefix) + *child_body + std::string(suffix);
+  try {
+    *frame_parent += std::string(prefix) + *child_body + std::string(suffix);
+  } catch (mjCError& e) {
+    return -1;
+  }
   return 0;
 }
 
@@ -109,7 +113,11 @@ int mjs_attachFrame(mjsBody* parent, const mjsFrame* child,
                     const char* prefix, const char* suffix) {
   mjCBody* body_parent = static_cast<mjCBody*>(parent->element);
   mjCFrame* child_frame = static_cast<mjCFrame*>(child->element);
-  *body_parent += std::string(prefix) + *child_frame + std::string(suffix);
+  try {
+    *body_parent += std::string(prefix) + *child_frame + std::string(suffix);
+  } catch (mjCError& e) {
+    return -1;
+  }
   return 0;
 }
 

src/xml/xml_native_reader.cc

@@ -3437,7 +3437,9 @@ void mjXReader::Body(XMLElement* section, mjsBody* pbody, mjsFrame* frame) {
         Body(elem, subtree, pframe);
 
         // attach to parent
-        mjs_attachFrame(pbody, pframe, /*prefix=*/"", suffix.c_str());
+        if (mjs_attachFrame(pbody, pframe, /*prefix=*/"", suffix.c_str()) < 0) {
+          throw mjXError(elem, "failed to attach frame");
+        }
       }
 
       // delete subtree

test/xml/xml_native_reader_test.cc

@@ -1217,6 +1217,45 @@ TEST_F(XMLReaderTest, ParseReplicateDefaultPropagate) {
   mj_deleteSpec(spec);
 }
 
+TEST_F(XMLReaderTest, ParseReplicateRepeatedName) {
+  static constexpr char xml[] = R"(
+  <mujoco>
+    <compiler>
+      <lengthrange mode="all"/>
+    </compiler>
+
+    <worldbody>
+      <light pos="0 0 10"/>
+
+      <replicate offset="0 .1 0" count="2">
+        <site name="a" size=".02"/>
+        <body pos="1 0 1">
+          <joint axis="0 -1 0" range="0 90"/>
+          <geom type="capsule" size=".02" fromto="0 0 0 0 0 -1"/>
+          <site name="b" pos="0 0 -1"/>
+        </body>
+      </replicate>
+    </worldbody>
+
+    <tendon>
+      <spatial name="b">
+        <site site="a"/>
+        <site site="b"/>
+      </spatial>
+    </tendon>
+
+    <actuator>
+      <position name="b" tendon="b0" ctrlrange="0 3" kp="100" dampratio="1"/>
+      <position name="b" tendon="b1" ctrlrange="0 3" kp="100" dampratio="1"/>
+    </actuator>
+  </mujoco>
+  )";
+  std::array<char, 1024> error;
+  mjSpec* spec = mj_parseXMLString(xml, 0, error.data(), error.size());
+  EXPECT_THAT(spec, IsNull()) << error.data();
+  EXPECT_THAT(error.data(), HasSubstr("failed to attach frame"));
+}
+
 // ----------------------- test camera parsing ---------------------------------
 
 TEST_F(XMLReaderTest, CameraInvalidFovyAndSensorsize) {