Report missing nodes in the input

src/output-flex.cpp

@@ -499,10 +499,39 @@ void output_flex_t::way_cache_t::init(osmium::Way *way)
     m_way = way;
 }
 
+static std::size_t get_nodes(middle_query_t const &middle, osmium::Way *way)
+{
+    constexpr std::size_t const max_missing_nodes = 100;
+    static std::size_t count_missing_nodes = 0;
+
+    auto const count = middle.nodes_get_list(&way->nodes());
+
+    if (count_missing_nodes <= max_missing_nodes &&
+        count != way->nodes().size()) {
+        util::string_joiner_t id_list{','};
+        for (auto const &nr : way->nodes()) {
+            if (!nr.location().valid()) {
+                id_list.add(fmt::to_string(nr.ref()));
+                ++count_missing_nodes;
+            }
+        }
+
+        log_debug("Missing nodes in way {}: {}", way->id(), id_list());
+
+        if (count_missing_nodes > max_missing_nodes) {
+            log_debug("Reported more than {} missing nodes, no further missing "
+                      "nodes will be reported!",
+                      max_missing_nodes);
+        }
+    }
+
+    return count;
+}
+
 std::size_t output_flex_t::way_cache_t::add_nodes(middle_query_t const &middle)
 {
     if (m_num_way_nodes == std::numeric_limits<std::size_t>::max()) {
-        m_num_way_nodes = middle.nodes_get_list(&m_way->nodes());
+        m_num_way_nodes = get_nodes(middle, m_way);
     }
 
     return m_num_way_nodes;
@@ -547,7 +576,7 @@ bool output_flex_t::relation_cache_t::add_members(middle_query_t const &middle)
         }
 
         for (auto &way : m_members_buffer.select<osmium::Way>()) {
-            middle.nodes_get_list(&(way.nodes()));
+            get_nodes(middle, &way);
         }
     }
 

tests/bdd/flex/missing-nodes.feature

@@ -0,0 +1,39 @@
+Feature: Test handling of missing nodes
+
+    Background:
+        Given the lua style
+            """
+            local tables = {}
+
+            tables.line = osm2pgsql.define_table{
+                name = 'osm2pgsql_test_lines',
+                ids = { type = 'way', id_column = 'osm_id' },
+                columns = {
+                    { column = 'geom', type = 'linestring', projection = 4326 },
+                }
+            }
+
+            function osm2pgsql.process_way(object)
+                tables.line:insert({
+                    geom = object:as_linestring()
+                })
+            end
+            """
+
+    Scenario: Missing node is reported
+        Given the OSM data
+            """
+            n10 v1 dV x10.0 y10.0
+            n11 v1 dV x10.0 y11.0
+            w20 v1 dV Thighway=primary Nn10,n11,n12,n13
+            """
+        When running osm2pgsql flex with parameters
+            | --log-level=debug |
+
+        Then table osm2pgsql_test_lines has 1 rows
+
+        And the error output contains
+            """
+            Missing nodes in way 20: 12,13
+            """
+