Fix json rendering of large osm ids

CHANGELOG.md

@@ -80,6 +80,7 @@
       - FIXED: Ensure required file check in osrm-routed is correctly enforced. [#6655](https://github.com/Project-OSRM/osrm-backend/pull/6655)
       - FIXED: Correct HTTP docs to reflect summary output dependency on steps parameter. [#6655](https://github.com/Project-OSRM/osrm-backend/pull/6655)
       - ADDED: Extract prerelease/build information from package semver [#6839](https://github.com/Project-OSRM/osrm-backend/pull/6839)
+      - FIXED: Fix json rendering problem for large osm ids [#7096](https://github.com/Project-OSRM/osrm-backend/pull/7096)
       - FIXED: Segfault in `UnresolvedManeuverOverride::Turns()` on Australia extracts [#7112](https://github.com/Project-OSRM/osrm-backend/pull/7112)
       - CHANGED: Replaced PL:trunk with PL:expressway to match the latest changes in Polish tagging [#7079](https://github.com/Project-OSRM/osrm-backend/pull/7079)
       - FIXED: Remove unused C++ headers [#7105](https://github.com/Project-OSRM/osrm-backend/pull/7105)

include/util/json_renderer.hpp

@@ -53,7 +53,12 @@ template <typename Out> struct Renderer
         // `fmt::memory_buffer` stores first 500 bytes in the object itself(i.e. on stack in this
         // case) and then grows using heap if needed
         fmt::memory_buffer buffer;
-        fmt::format_to(std::back_inserter(buffer), FMT_COMPILE("{:.10g}"), number.value);
+        if (static_cast<std::uint64_t>(number.value) == number.value)
+            fmt::format_to(std::back_inserter(buffer),
+                           FMT_COMPILE("{}"),
+                           static_cast<std::uint64_t>(number.value));
+        else
+            fmt::format_to(std::back_inserter(buffer), FMT_COMPILE("{:.10g}"), number.value);
 
         write(buffer.data(), buffer.size());
     }

unit_tests/util/json_render.cpp

@@ -85,8 +85,13 @@ BOOST_AUTO_TEST_CASE(test_json_issue_6531)
     BOOST_CHECK_EQUAL(output, "0.1234567892");
 
     output.clear();
-    renderer(123456789123456789.);
-    BOOST_CHECK_EQUAL(output, "1.234567891e+17");
+    renderer(12345678912345678.);
+    BOOST_CHECK_EQUAL(output, "12345678912345678");
+
+    // handle large osm ids
+    output.clear();
+    renderer(1000396615812);
+    BOOST_CHECK_EQUAL(output, "1000396615812");
 }
 
 BOOST_AUTO_TEST_SUITE_END()