If I run the failing step by hand without /verbosity:quiet I get $ cd src; /usr/bin/xbuild dbus-sharp.csproj
Build started 7/31/2015 2:18:09 PM. __________________________________________________ Project "/raid/build/work/dbus-sharp-0.8.1/src/dbus-sharp.csproj" (default target(s)): Target PrepareForBuild: Configuration: Debug Platform: AnyCPU Target GenerateSatelliteAssemblies: No input files were specified for target GenerateSatelliteAssemblies, skipping. Target GenerateTargetFrameworkMonikerAttribute: Skipping target "GenerateTargetFrameworkMonikerAttribute" because its outputs are up-to-date. Target CoreCompile: Tool /usr/lib/mono/4.5/mcs.exe execution started with arguments: /noconfig /debug:full /debug+ /keyfile:../dbus-sharp.snk /optimize- /out:obj/Debug/dbus-sharp.dll Address.cs Authentication.cs Bus.cs BusObject.cs Connection.cs DBus.cs DProxy.cs ExportObject.cs Introspection.cs Mapper.cs OSHelpers.cs TypeImplementer.cs ArgDirection.cs ObjectPath.cs BusException.cs AddressEntry.cs Protocol/DBusStruct.cs Protocol/DType.cs Protocol/DValue.cs Protocol/EndianFlag.cs Protocol/FieldCode.cs Protocol/Header.cs Protocol/HeaderFlag.cs Protocol/MatchRule.cs Protocol/Message.cs Protocol/MessageContainer.cs Protocol/MessageDumper.cs Protocol/MessageFilter.cs Protocol/MessageReader.cs Protocol/MessageType.cs Protocol/MessageWriter.cs Protocol/PendingCall.cs Protocol/ProtocolInformation.cs Protocol/Signature.cs Protocol/SocketTransport.cs Protocol/Transport.cs Transports/UnixNativeTransport.cs Transports/UnixTransport.cs Unix/UnixStream.cs Unix/UnixError.cs Unix/UnixSocket.cs AssemblyInfo.cs /target:library /unsafe+ /define:"DEBUG;TRACE;STRONG_NAME;NET35" /nostdlib /reference:/usr/lib/mono/gac/System/4.0.0.0__b77a5c561934e089/System.dll /reference:/usr/lib/mono/gac/System.Xml/4.0.0.0__b77a5c561934e089/System.Xml.dll /reference:/usr/lib/mono/gac/Mono.Posix/4.0.0.0__0738eb9f132ed756/Mono.Posix.dll /reference:/usr/lib/mono/gac/System.Core/4.0.0.0__b77a5c561934e089/System.Core.dll /warn:4 CSC: error CS0518: The predefined type `System.Object' is not defined or imported CSC: error CS0518: The predefined type `System.ValueType' is not defined or imported CSC: error CS0518: The predefined type `System.Attribute' is not defined or imported ... Note "/nostdlib" in the arguments for mcs.exe. This contradicts the line <NoStandardLibraries>false</NoStandardLibraries> in src/dbus-sharp.csproj. Looks like mono-xbuild (4.0.2.5+dfsg-2) doesn't honor this setting anymore. There's a suspicious change in /usr/lib/mono/4.5/Microsoft.CSharp.targets from 3.2.8+dfsg-10 to 4.0.2.5+dfsg-2: @@ -50,7 +81,7 @@ ModuleAssemblyName="$(ModuleAssemblyName)" NoConfig="true" NoLogo="$(NoLogo)" - NoStandardLib="$(NoStdLib)" + NoStandardLib="$(NoCompilerStandardLib)" Optimize="$(Optimize)" OutputAssembly="@(IntermediateAssembly)" PdbFile="$(PdbFile)" If I revert that change, "/nostdlib" is gone and dbus-sharp builds again. Cheers, Roderich