MSVC warnings by JurgenLB · Pull Request #422 · Thalhammer/jwt-cpp

JurgenLB · 2026-03-08T16:35:14Z

My previous Attemp seems to focused on other conversions (BN_num_bytes, HMAC, EVP_PKEY_size, EVP_VerifyFinal).
Now I revert #405 and #408 except;
jwt.h:2635
as_date() passes double to std::chrono::seconds(), narrowed to __time64_t
return date(std::chrono::seconds(static_cast<int64_t>(std::llround(as_number()))));

traits/open-source-parsers-jsoncpp/traits.h:90
as_integer() returns val.asInt64() (Int64) implicitly narrowed to integer_type (int)
return static_cast<integer_type>(val.asInt64());

My problem was the order off import, The Windows Libraries bundle version of jwt-cpp used a older version where these fixes haven't been applied yet.
But by changing the include order I found the core problem.

Kind Regards

prince-chrismc · 2026-03-08T18:31:17Z

Can you please share the compiler flags so we can verify the changes?

We typically dont make changes to picojson as its a bundled dependencies and the goal is to keep it in sync.

I believe int64 is a better type for JSON values so intger_type shoube that rather than a cast? Need to double check what all the other traits are.

JurgenLB · 2026-03-08T19:56:16Z

I did use Copilot for finding a solution.
I try without changing picojson.

Submodule 'extern/jwtcpp' (https://github.com/Thalhammer/jwt-cpp) registered for path 'extern/jwtcpp'
Cloning into 'C:/projects/domoticz/extern/jwtcpp'...
Submodule path 'extern/jwtcpp': checked out 'b12ab284d335fb9c4ace61c215f9e0a5d43e0922'

C:\projects\domoticz\extern\jwtcpp\include\jwt-cpp\traits\open-source-parsers-jsoncpp\traits.h(90,44): warning C4244: 'return': conversion from 'Json::Value::Int64' to 'jwt::traits::open_source_parsers_jsoncpp::integer_type', possible loss of data [C:\projects\domoticz\extern\libwebem\webem.vcxproj]
  (compiling source file '/src/cWebem.cpp')

The original warnings;

NotificationFCM.cpp

C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/notifications/NotificationFCM.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\traits\kazuho-picojson\defaults.h(19,58):
          see reference to class template instantiation 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3706,57):
          see reference to class template instantiation 'jwt::basic_claim<jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2565,49):
          see reference to class template instantiation 'jwt::details::is_valid_json_types<jwt::traits::kazuho_picojson::value_type,jwt::traits::kazuho_picojson::object_type,jwt::traits::kazuho_picojson::array_type,jwt::traits::kazuho_picojson::string_type,jwt::traits::kazuho_picojson::number_type,jwt::traits::kazuho_picojson::integer_type,jwt::traits::kazuho_picojson::boolean_type>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2534,74):
          see reference to class template instantiation 'jwt::details::is_valid_json_string<value_type,string_type,integer_type>' being compiled
          with
          [
              value_type=jwt::traits::kazuho_picojson::value_type,
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2489,35):
          see reference to alias template instantiation 'jwt::details::is_substr_start_end_index_signature<string_type,integer_type>' being compiled
          with
          [
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/notifications/NotificationFCM.cpp')
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/notifications/NotificationFCM.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2490,14):
          see reference to alias template instantiation 'jwt::details::is_substr_start_index_signature<string_type,integer_type>' being compiled
          with
          [
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2635,85): warning C4244: 'argument': conversion from 'double' to '__time64_t', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/notifications/NotificationFCM.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2635,85):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\traits\kazuho-picojson\defaults.h(19,58):
          see reference to class template instantiation 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3706,57):
          see reference to class template instantiation 'jwt::basic_claim<jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2633,8):
          while compiling class template member function 'jwt::date jwt::basic_claim<jwt::traits::kazuho_picojson>::as_date(void) const'
              C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2849,32):
              see the first reference to 'jwt::basic_claim<jwt::traits::kazuho_picojson>::as_date' in 'jwt::payload<json_traits>::get_issued_at'
          with
          [
              json_traits=jwt::traits::kazuho_picojson
          ]
              C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3612,24):
              see the first reference to 'jwt::payload<json_traits>::get_issued_at' in 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>::{ctor}::<lambda_3d1cddfef0305f90113ebc4bb7c85a28>::operator ()'
          with
          [
              json_traits=jwt::traits::kazuho_picojson
          ]

for the NotificationFCM.cpp there is a change in de domoticz repo;

	{
	const std::chrono::system_clock::time_point now = std::chrono::system_clock::now();
	auto JWT = jwt::create()
		.set_type("JWT")
		.set_issuer(FCMissuer)
		.set_audience(GAPI_OAUTH2_TOKEN_URL)
		.set_issued_at(now)
		.set_expires_at(now + std::chrono::seconds{600})
		.set_payload_claim("scope", jwt::claim(std::string{GAPI_FCM_SCOPE}));
		sFCMjwt = JWT.sign(jwt::algorithm::rs256{"", m_GAPI_FCM_privkey, "", ""}, &base64url_encode);
	}

instead off;

	{
	auto JWT = jwt::create()
		.set_type("JWT")
		.set_issuer(FCMissuer)
		.set_audience(GAPI_OAUTH2_TOKEN_URL)
		.set_issued_at(std::chrono::system_clock::now())
		.set_expires_at(std::chrono::system_clock::now() + std::chrono::seconds{600})
		.set_payload_claim("scope", jwt::claim(std::string{GAPI_FCM_SCOPE}));
		sFCMjwt = JWT.sign(jwt::algorithm::rs256{"", m_GAPI_FCM_privkey, "", ""}, &base64url_encode);
	}

cWebem.cpp

C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/webserver/cWebem.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2474,48):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\traits\kazuho-picojson\defaults.h(19,58):
          see reference to class template instantiation 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3706,57):
          see reference to class template instantiation 'jwt::basic_claim<jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2565,49):
          see reference to class template instantiation 'jwt::details::is_valid_json_types<jwt::traits::kazuho_picojson::value_type,jwt::traits::kazuho_picojson::object_type,jwt::traits::kazuho_picojson::array_type,jwt::traits::kazuho_picojson::string_type,jwt::traits::kazuho_picojson::number_type,jwt::traits::kazuho_picojson::integer_type,jwt::traits::kazuho_picojson::boolean_type>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2534,74):
          see reference to class template instantiation 'jwt::details::is_valid_json_string<value_type,string_type,integer_type>' being compiled
          with
          [
              value_type=jwt::traits::kazuho_picojson::value_type,
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2489,35):
          see reference to alias template instantiation 'jwt::details::is_substr_start_end_index_signature<string_type,integer_type>' being compiled
          with
          [
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2473,96): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/webserver/cWebem.cpp')
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244: 'argument': conversion from '_Ty1' to 'const unsigned int', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         with [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         [ [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:             _Ty1=__int64 [C:\projects\domoticz\msbuild\domoticz.vcxproj]
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96): warning C4244:         ] [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/webserver/cWebem.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2479,96):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2490,14):
          see reference to alias template instantiation 'jwt::details::is_substr_start_index_signature<string_type,integer_type>' being compiled
          with
          [
              string_type=jwt::traits::kazuho_picojson::string_type,
              integer_type=jwt::traits::kazuho_picojson::integer_type
          ]
  
C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2635,85): warning C4244: 'argument': conversion from 'double' to '__time64_t', possible loss of data [C:\projects\domoticz\msbuild\domoticz.vcxproj]
  (compiling source file '/webserver/cWebem.cpp')
      C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2635,85):
      the template instantiation context (the oldest one first) is
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\traits\kazuho-picojson\defaults.h(19,58):
          see reference to class template instantiation 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3706,57):
          see reference to class template instantiation 'jwt::basic_claim<jwt::traits::kazuho_picojson>' being compiled
          C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2633,8):
          while compiling class template member function 'jwt::date jwt::basic_claim<jwt::traits::kazuho_picojson>::as_date(void) const'
              C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(2849,32):
              see the first reference to 'jwt::basic_claim<jwt::traits::kazuho_picojson>::as_date' in 'jwt::payload<json_traits>::get_issued_at'
          with
          [
              json_traits=jwt::traits::kazuho_picojson
          ]
              C:\projects\domoticz\msbuild\Windows Libraries\include\jwt-cpp\jwt.h(3612,24):
              see the first reference to 'jwt::payload<json_traits>::get_issued_at' in 'jwt::verifier<jwt::default_clock,jwt::traits::kazuho_picojson>::{ctor}::<lambda_3d1cddfef0305f90113ebc4bb7c85a28>::operator ()'
          with
          [
              json_traits=jwt::traits::kazuho_picojson
          ]

JurgenLB · 2026-03-08T21:19:05Z

// Before (triggered MSVC C4244: implicit int64_t → unsigned int)

using is_substr_start_end_index_signature =
    typename std::is_same<decltype(std::declval<string_type>().substr(
                              std::declval<integer_type>(),
                              std::declval<integer_type>())),
                          string_type>;

// After (explicit cast — no warning, no suppression)

using is_substr_start_end_index_signature =
    typename std::is_same<decltype(std::declval<string_type>().substr(
                              static_cast<std::size_t>(std::declval<integer_type>()),
                              static_cast<std::size_t>(std::declval<integer_type>()))),
                          string_type>;

Same change applied to is_substr_start_index_signature.

// BEFORE: integer_type is Json::Value::Int (32-bit int), but asInt64() returns Int64 (64-bit)
using integer_type = Json::Value::Int;
// ...
case Json::intValue: return val.asInt64(); // C4244: Int64 → Int (data loss)

case Json::intValue: return static_cast<integer_type>(val.asInt64());
or u want
case Json::Value::Int64: return val.asInt64();

// BEFORE: std::round() returns double, from_time_t() expects __time64_t (long long)
return system_clock::from_time_t(std::round(as_number())); // C4244: double → __time64_t

return system_clock::from_time_t(static_cast<std::time_t>(std::round(as_number())));

JurgenLB added 3 commits March 8, 2026 13:55

undo unwanted changes from Thalhammer#405 and Thalhammer#408

5a24f32

Cast asInt64 result to integer_type

5119b79

Fix double type handling for int64_type

9b9c351

unwanted change

eada5ff

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

MSVC warnings#422

MSVC warnings#422
JurgenLB wants to merge 4 commits intoThalhammer:masterfrom
JurgenLB:master

JurgenLB commented Mar 8, 2026

Uh oh!

prince-chrismc commented Mar 8, 2026

Uh oh!

JurgenLB commented Mar 8, 2026

Uh oh!

JurgenLB commented Mar 8, 2026 •

edited

Loading

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Uh oh!

Conversation

JurgenLB commented Mar 8, 2026

Uh oh!

prince-chrismc commented Mar 8, 2026

Uh oh!

JurgenLB commented Mar 8, 2026

Uh oh!

JurgenLB commented Mar 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

JurgenLB commented Mar 8, 2026 •

edited

Loading