Obliterate Boost

* While it may be possible to refactor the code in a way that it does
  not use any `optional` types, like in a616312, fb73b81, 138ad67,
  5724a2c, that would be error prone and would require bigger changes.
  Instead replace `boost::optional` with `std::optional`, now that we
  are using C++17.

* Removing `boost::current_exception_diagnostic_information()` - if the
  caught exception is an instance of `std::exception`, use its `what()`
  method. Otherwise don't provide extra diagnostic information. After
  all `boost::current_exception_diagnostic_information()` would return
  "No diagnostic information available." if it is not `std::exception`
  or `boost::exception`.

* Clean up any mentions of Boost from README.md and CMakeLists.txt.

Author: vasild

CMakeLists.txt

@@ -7,7 +7,6 @@ project("Libmultiprocess" CXX)
 include(CMakePushCheckState)
 include(CTest)
 include(CheckCXXSourceCompiles)
-find_package(Boost)
 find_package(CapnProto REQUIRED)
 find_package(Threads REQUIRED)
 
@@ -64,8 +63,7 @@ target_include_directories(multiprocess PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
   $<INSTALL_INTERFACE:include>
-  ${CAPNP_INCLUDE_DIRECTORY}
-  ${Boost_INCLUDE_DIR})
+  ${CAPNP_INCLUDE_DIRECTORY})
 set_target_properties(multiprocess PROPERTIES
     PUBLIC_HEADER "${MP_PUBLIC_HEADERS}"
     CXX_STANDARD 17

README.md

@@ -29,12 +29,12 @@ _libmultiprocess_ is currently compatible with sandboxing but could add platform
 
 ## Installation
 
-Installation currently requires boost[*] and Cap'n Proto:
+Installation currently requires Cap'n Proto:
 
 ```sh
-apt install libboost-dev libcapnp-dev capnproto
-brew install boost capnp
-dnf install boost-devel capnproto
+apt install libcapnp-dev capnproto
+brew install capnp
+dnf install capnproto
 
 Installation steps are:
 
@@ -46,5 +46,3 @@ make
 make all test
 make install
 ```
-
-[*] The boost dependency should be eliminated; it is solely for `boost::optional`.

include/mp/proxy-io.h

@@ -10,13 +10,13 @@
 
 #include <mp/proxy.capnp.h>
 
-#include <boost/exception/diagnostic_information.hpp>
-#include <boost/optional/optional.hpp>
 #include <capnp/rpc-twoparty.h>
 
 #include <assert.h>
 #include <functional>
+#include <map>
 #include <memory>
+#include <sstream>
 #include <string>
 
 namespace mp {

include/mp/proxy-types.h

@@ -6,6 +6,9 @@
 #define MP_PROXY_TYPES_H
 
 #include <mp/proxy-io.h>
+
+#include <exception>
+#include <optional>
 #include <set>
 #include <vector>
 
@@ -178,7 +181,7 @@ class Emplace
     Value& m_value;
 
     template <typename T, typename... Params>
-    static T& call(boost::optional<T>& value, Params&&... params)
+    static T& call(std::optional<T>& value, Params&&... params)
     {
         value.emplace(std::forward<Params>(params)...);
         return *value;
@@ -227,7 +230,7 @@ class Emplace
 };
 
 template <typename LocalType, typename Input, typename DestValue>
-void ReadFieldUpdate(TypeList<boost::optional<LocalType>>,
+void ReadFieldUpdate(TypeList<std::optional<LocalType>>,
     InvokeContext& invoke_context,
     Input&& input,
     DestValue&& value)
@@ -832,7 +835,7 @@ LocalType BuildPrimitive(InvokeContext& invoke_context,
 }
 
 template <typename LocalType, typename Value, typename Output>
-void CustomBuildField(TypeList<boost::optional<LocalType>>,
+void CustomBuildField(TypeList<std::optional<LocalType>>,
     Priority<1>,
     InvokeContext& invoke_context,
     Value&& value,
@@ -1038,7 +1041,7 @@ template <typename Accessor, typename LocalType, typename ServerContext, typenam
 void DefaultPassField(TypeList<LocalType>, ServerContext& server_context, Fn&& fn, Args&&... args)
 {
     InvokeContext& invoke_context = server_context;
-    boost::optional<Decay<LocalType>> param;
+    std::optional<Decay<LocalType>> param;
     const auto& params = server_context.call_context.getParams();
     MaybeReadField(std::integral_constant<bool, Accessor::in>(), TypeList<LocalType>(), invoke_context,
         Make<StructField, Accessor>(params), Emplace<decltype(param)>(param));
@@ -1434,9 +1437,11 @@ kj::Promise<void> serverInvoke(Server& server, CallContext& call_context, Fn fn)
                 server.m_connection.m_loop.log() << "IPC server send response #" << req << " " << TypeName<Results>()
                                                  << " " << LogEscape(call_context.getResults().toString());
             });
+    } catch (const std::exception& e) {
+        server.m_connection.m_loop.log() << "IPC server unhandled exception: " << e.what();
+        throw;
     } catch (...) {
-        server.m_connection.m_loop.log()
-            << "IPC server unhandled exception " << boost::current_exception_diagnostic_information();
+        server.m_connection.m_loop.log() << "IPC server unhandled exception";
         throw;
     }
 }