server-mode: Query global configuration of cmake via a command

Add "globalSettings" command that returns:
* Return capability information
* Return currently used generator/extra generator
* Return a range of flags for debug/trace/etc.

Source/cmServerDictionary.h

@@ -17,6 +17,7 @@
 // Vocabulary:
 
 static const std::string kERROR_TYPE = "error";
+static const std::string kGLOBAL_SETTINGS_TYPE = "globalSettings";
 static const std::string kHANDSHAKE_TYPE = "handshake";
 static const std::string kMESSAGE_TYPE = "message";
 static const std::string kPROGRESS_TYPE = "progress";
@@ -24,7 +25,10 @@ static const std::string kREPLY_TYPE = "reply";
 static const std::string kSIGNAL_TYPE = "signal";
 
 static const std::string kBUILD_DIRECTORY_KEY = "buildDirectory";
+static const std::string kCAPABILITIES_KEY = "capabilities";
+static const std::string kCHECK_SYSTEM_VARS_KEY = "checkSystemVars";
 static const std::string kCOOKIE_KEY = "cookie";
+static const std::string kDEBUG_OUTPUT_KEY = "debugOutput";
 static const std::string kERROR_MESSAGE_KEY = "errorMessage";
 static const std::string kEXTRA_GENERATOR_KEY = "extraGenerator";
 static const std::string kGENERATOR_KEY = "generator";
@@ -43,7 +47,12 @@ static const std::string kSOURCE_DIRECTORY_KEY = "sourceDirectory";
 static const std::string kSUPPORTED_PROTOCOL_VERSIONS =
   "supportedProtocolVersions";
 static const std::string kTITLE_KEY = "title";
+static const std::string kTRACE_EXPAND_KEY = "traceExpand";
+static const std::string kTRACE_KEY = "trace";
 static const std::string kTYPE_KEY = "type";
+static const std::string kWARN_UNINITIALIZED_KEY = "warnUninitialized";
+static const std::string kWARN_UNUSED_CLI_KEY = "warnUnusedCli";
+static const std::string kWARN_UNUSED_KEY = "warnUnused";
 
 static const std::string kSTART_MAGIC = "[== CMake Server ==[";
 static const std::string kEND_MAGIC = "]== CMake Server ==]";

Source/cmServerProtocol.cxx

@@ -13,6 +13,7 @@
 #include "cmServerProtocol.h"
 
 #include "cmExternalMakefileProjectGenerator.h"
+#include "cmGlobalGenerator.h"
 #include "cmServer.h"
 #include "cmServerDictionary.h"
 #include "cmSystemTools.h"
@@ -279,6 +280,10 @@ const cmServerResponse cmServerProtocol1_0::Process(
 {
   assert(this->m_State >= STATE_ACTIVE);
 
+  if (request.Type == kGLOBAL_SETTINGS_TYPE) {
+    return this->ProcessGlobalSettings(request);
+  }
+
   return request.ReportError("Unknown command!");
 }
 
@@ -286,3 +291,32 @@ bool cmServerProtocol1_0::IsExperimental() const
 {
   return true;
 }
+
+cmServerResponse cmServerProtocol1_0::ProcessGlobalSettings(
+  const cmServerRequest& request)
+{
+  cmake* cm = this->CMakeInstance();
+  Json::Value obj = Json::objectValue;
+
+  // Capabilities information:
+  obj[kCAPABILITIES_KEY] = cm->ReportCapabilitiesJson(true);
+
+  obj[kDEBUG_OUTPUT_KEY] = cm->GetDebugOutput();
+  obj[kTRACE_KEY] = cm->GetTrace();
+  obj[kTRACE_EXPAND_KEY] = cm->GetTraceExpand();
+  obj[kWARN_UNINITIALIZED_KEY] = cm->GetWarnUninitialized();
+  obj[kWARN_UNUSED_KEY] = cm->GetWarnUnused();
+  obj[kWARN_UNUSED_CLI_KEY] = cm->GetWarnUnusedCli();
+  obj[kCHECK_SYSTEM_VARS_KEY] = cm->GetCheckSystemVars();
+
+  obj[kSOURCE_DIRECTORY_KEY] = cm->GetHomeDirectory();
+  obj[kBUILD_DIRECTORY_KEY] = cm->GetHomeOutputDirectory();
+
+  // Currently used generator:
+  cmGlobalGenerator* gen = cm->GetGlobalGenerator();
+  obj[kGENERATOR_KEY] = gen ? gen->GetName() : std::string();
+  obj[kEXTRA_GENERATOR_KEY] =
+    gen ? gen->GetExtraGeneratorName() : std::string();
+
+  return request.Reply(obj);
+}

Source/cmServerProtocol.h

@@ -13,6 +13,7 @@
 #pragma once
 
 #include "cmListFileCache.h"
+#include "cmake.h"
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cm_jsoncpp_writer.h"
@@ -116,6 +117,9 @@ private:
   bool DoActivate(const cmServerRequest& request,
                   std::string* errorMessage) override;
 
+  // Handle requests:
+  cmServerResponse ProcessGlobalSettings(const cmServerRequest& request);
+
   enum State
   {
     STATE_INACTIVE,