[core] Do not clear custom layers upon style switch

2 files changed, 7 insertions, 1 deletions

diff --git a/src/mbgl/style/style.cpp b/src/mbgl/style/style.cpp
index 010f0aeafd..b239ac20dc 100644
--- a/src/mbgl/style/style.cpp
+++ b/src/mbgl/style/style.cpp
@@ -70,7 +70,9 @@ Style::Style(FileSource& fileSource_, float pixelRatio)
 
 void Style::setJSON(const std::string& json, const std::string&) {
     sources.clear();
-    layers.clear();
+    layers.erase(std::remove_if(layers.begin(), layers.end(), [](const auto& layer) {
+            return !layer->template is<CustomLayer>();
+        }), layers.end());
     classes.clear();
 
     StyleParser parser;
diff --git a/test/api/custom_layer.cpp b/test/api/custom_layer.cpp
index 4ad25bbfd5..beffa749d1 100644
--- a/test/api/custom_layer.cpp
+++ b/test/api/custom_layer.cpp
@@ -90,4 +90,8 @@ TEST(CustomLayer, Basic) {
         }, new TestLayer());
 
     test::checkImage("test/fixtures/custom_layer/basic", test::render(map));
+
+    // Custom layer should be preserved when switching styles
+    map.setStyleJSON(util::read_file("test/fixtures/api/empty.json"), "");
+    test::checkImage("test/fixtures/custom_layer/basic", test::render(map));
 }