Unable to build hello-world on local install

[wbmartin]

First, wanted to thank you for offering this tool to the community. I've been interested since I saw it win the TechEmpower Benchmark (Congratulations!). I am admittedly a bit rusty with my C++, so I may be missing something obvious. I ran the CLI/docker install and it worked great the first time, but complained about the port being already in use on subsequent runs. I can go back to that method if you suggest. I decided to try the local install on a new debian buster install.

I stumbled on the prerequisites needed, but I think I got past that with this:

apt-get install libcurl4-openssl-dev
apt-get install libboost-all-dev

I also had to modify the install.sh g++ command, adding " -lstdc++fs" in two places to get it to build, guessing it is a debian quirk related to the filesystem library.

g++ -O3 -DNDEBUG -lstdc++fs -std=c++17 $DIR/libraries/symbol/symbol/symbol_generator.cc -o $PREFIX/bin/li_symbol_generator -lstdc++fs

Then I tried a fresh project with a copy of the hello_world script in my_api.cc (to follow the cmake_project_template):

#include "lithium_http_server.hh"

int main() {

  // Define an api with one HTTP GET route.
  li::http_api api;
  api.get("/hello_world") = [&](li::http_request& request, li::http_response& response) {
    response.write("hello world.");
  };

  // Start a http server.
  li::http_serve(api, 12345);

}

and the CMakeLists.txt from the cmake_project_template, removing the mysql and sqllite

cmake_minimum_required(VERSION 2.8)
set(CMAKE_CXX_STANDARD 17)

find_package(CURL REQUIRED)
find_package(Threads REQUIRED)
find_package(PostgreSQL REQUIRED)
find_package(OpenSSL REQUIRED)
find_package(Boost REQUIRED context)

include_directories(${CURL_INCLUDE_DIRS} ${OPENSSL_INCLUDE_DIR} ${PostgreSQL_INCLUDE_DIRS})

set(LIBS ${CURL_LIBRARIES} 
          ${Boost_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT}
          ${PostgreSQL_LIBRARIES} ${OPENSSL_LIBRARIES})

# Directory where lithium headers are located if not in the default include path.
include_directories($ENV{HOME}/local/include)

add_custom_target(symbols_generation COMMAND li_symbol_generator ${CMAKE_CURRENT_SOURCE_DIR})

add_executable(my_api my_api.cc)
add_dependencies(my_api symbols_generation)
target_link_libraries(my_api ${LIBS})

Then ran

mkdir build
cd build
cmake ..
make

but unfortunately I receive this error message:

[  0%] Built target symbols_generation
[ 50%] Building CXX object CMakeFiles/my_api.dir/my_api.cc.o
In file included from /home/brandon/proj/li-test-proj/my_api.cc:1:
/usr/local/include/lithium_http_server.hh: In instantiation of ‘auto li::http_serve(li::api<li::http_request, li::http_response>, int, O ...) [with O = {}]’:
/home/brandon/proj/li-test-proj/my_api.cc:12:28:   required from here
/usr/local/include/lithium_http_server.hh:6753:5: error: ‘this’ is not a constant expression
     if constexpr (has_key(options, s::ssl_key))
     ^~
/usr/local/include/lithium_http_server.hh:6755:28: error: non-constant condition for static assertion
       static_assert(has_key(options, s::ssl_certificate), "You need to provide both the ssl_certificate option and the ssl_key option.");
                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/lithium_http_server.hh:6755:28: error: ‘this’ is not a constant expression
/usr/local/include/lithium_http_server.hh:6756:37: error: ‘const struct li::metamap<>’ has no member named ‘ssl_key’
       std::string ssl_key = options.ssl_key;
                             ~~~~~~~~^~~~~~~
/usr/local/include/lithium_http_server.hh:6757:38: error: ‘const struct li::metamap<>’ has no member named ‘ssl_certificate’
       std::string ssl_cert = options.ssl_certificate;
                              ~~~~~~~~^~~~~~~~~~~~~~~
/usr/local/include/lithium_http_server.hh:6759:7: error: ‘this’ is not a constant expression
       if constexpr (has_key(options, s::ssl_ciphers))
       ^~
/usr/local/include/lithium_http_server.hh:6761:31: error: ‘const struct li::metamap<>’ has no member named ‘ssl_ciphers’
         ssl_ciphers = options.ssl_ciphers;
                       ~~~~~~~~^~~~~~~~~~~
make[2]: *** [CMakeFiles/my_api.dir/build.make:63: CMakeFiles/my_api.dir/my_api.cc.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:105: CMakeFiles/my_api.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

I wanted to see if you could offer any suggestions as to what I did wrong?

[matt-42]

Hi @wbmartin,
Thanks for the feedback, which version of g++ are you using ?

[wbmartin]

Thanks for the quick response @matt-42. g++ -v yields "gcc version 8.3.0 (Debian 8.3.0-6)

[matt-42]

gcc 8.3 is not supported, can you upgrade to g++ 9.3 or a more recent version ? It should work with this version.

[wbmartin]

@matt-42 that fixed it nicely. Thanks for the great support.