Bug 16898 - GetAssembly returns null CustomAttributes on Android and iOS when it should be returning information. Expecting to find DebuggableAttribute.
Summary: GetAssembly returns null CustomAttributes on Android and iOS when it should b...
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: master
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on: 16924
  Show dependency tree
Reported: 2013-12-19 12:45 UTC by Stephen Rawlins
Modified: 2014-01-06 12:47 UTC (History)
5 users (show)

Tags: mscorlib,pcl,getassembly
Is this bug a regression?: ---
Last known good build:

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Description Stephen Rawlins 2013-12-19 12:45:28 UTC
We are trying to determine if an assembly is Debug or Production using Assembly.GetAssembly(typeof(iApp));

The code works on Microsoft Windows, but not on Xamarin's mscorlib 

On Xamarin/iOS mscorblib, GetAssembly returns 11 null CustomAttributes
On Xamarin/Android mscorlib, same call returns 13 null CustomAttributes

On Windows, the same call returns 13 non-null CustomAttributes, including the Debugging Attribute we depend upon to determine whether or not the target assembly is Debug-build.

      public static bool IsReleaseBuild()  
            Assembly assm = Assembly.GetAssembly(typeof(iApp));  //  iApp is in the Assembly in question
            object[] attributes = assm.GetCustomAttributes(typeof(DebuggableAttribute), false);

            // The Assembly is assumed to be a Release Build (vs. Debug) if there are no attributes at all, or if the
            // attributes carry no debug
            bool isRelease = true;
            if (attributes.Length > 0)
                foreach (Attribute attr in attributes)
                    if (isRelease && attr is DebuggableAttribute)
                        DebuggableAttribute d = attr as DebuggableAttribute;
                           String.Format("Run time Optimizer is enabled : {0}", !d.IsJITOptimizerDisabled));
                            String.Format("Run time Tracking is enabled : {0}", d.IsJITTrackingEnabled));
                        if (d.IsJITOptimizerDisabled == true)  // If Optimization turned off, call it a Debug build and quit.
                            System.Diagnostics.Debug.WriteLine(String.Format("{0} is a DEBUG Build....", assm.FullName));
                            isRelease = false;
                        else   // if Optimized code, then keep looping, but still assume it's a Relase build
                            System.Diagnostics.Debug.WriteLine(String.Format("{0} is a RELEASE Build....", assm.FullName));
            return isRelease;
Comment 1 Stephen Rawlins 2013-12-19 13:54:07 UTC
Here is debug from Xamarin Studio, showing the CustomAttributes (Count=11).  All 11 were null.

{iFactr.UI, Version=, Culture=neutral, PublicKeyToken=null}
	CodeBase: "file:///Users/ifactr/Library/Application Support/iPhone Simulator/7.0.3/Applications/FCF74405-7943-4F06-9E8E-723870FA7141/TestRunnerTouch.app/iFactr.UI.dll"
	CustomAttributes: Count=11
	DefinedTypes: {System.Reflection.Assembly}
	EntryPoint: (null)
	EscapedCodeBase: "file:///Users/ifactr/Library/Application%20Support/iPhone%20Simulator/7.0.3/Applications/FCF74405-7943-4F06-9E8E-723870FA7141/TestRunnerTouch.app/iFactr.UI.dll"
	Evidence: (null)
	ExportedTypes: {System.MonoType[136]}
	FullName: "iFactr.UI, Version=, Culture=neutral, PublicKeyToken=null"
	GlobalAssemblyCache (System.Reflection.MonoAssembly): false
	System.NotImplementedException: Derived classes must implement it
	HostContext: 0
	ImageRuntimeVersion: "v4.0.30319"
	IsDynamic: false
	IsFullyTrusted: true
	Location: "/Users/ifactr/Library/Application Support/iPhone Simulator/7.0.3/Applications/FCF74405-7943-4F06-9E8E-723870FA7141/TestRunnerTouch.app/iFactr.UI.dll"
	ManifestModule (System.Reflection.MonoAssembly): {iFactr.UI.dll}
	System.NotImplementedException: Derived classes must implement it
	Modules: {System.Reflection.Module[1]}
	ReflectionOnly: false
	Non-public members:
Comment 2 Stephen Rawlins 2013-12-19 14:02:39 UTC
MSWindows, in contrast, returns the following from GetAssembly:

{iFactr.UI, Version=, Culture=neutral, PublicKeyToken=null}
    [System.Reflection.RuntimeAssembly]: {iFactr.UI, Version=, Culture=neutral, PublicKeyToken=null}
    CodeBase: "file:///Z:/Projects/iFactr_Trunk_Repo/QA/Core.UnitTests/bin/Debug/iFactr.UI.DLL"
    CustomAttributes: Count = 13
    DefinedTypes: {System.RuntimeType[157]}
    EntryPoint: null
    EscapedCodeBase: "file:///Z:/Projects/iFactr_Trunk_Repo/QA/Core.UnitTests/bin/Debug/iFactr.UI.DLL"
    Evidence: {System.Security.Policy.Evidence}
    ExportedTypes: {System.Type[136]}
    FullName: "iFactr.UI, Version=, Culture=neutral, PublicKeyToken=null"
    GlobalAssemblyCache: false
    HostContext: 0
    ImageRuntimeVersion: "v4.0.30319"
    IsDynamic: false
    IsFullyTrusted: true
    Location: "Z:\\Projects\\iFactr_Trunk_Repo\\QA\\Core.UnitTests\\bin\\Debug\\iFactr.UI.dll"
    ManifestModule: {iFactr.UI.dll}
    Modules: {System.Reflection.RuntimeModule[1]}
    PermissionSet: {<PermissionSet class="System.Security.PermissionSet"
    ReflectionOnly: false
    SecurityRuleSet: Level2

Here is the DebuggableAttribute (for example), showing its actionable content:

    [0]: {System.Diagnostics.DebuggableAttribute}
    base: {System.Diagnostics.DebuggableAttribute}
    DebuggingFlags: Default | DisableOptimizations | IgnoreSymbolStoreSequencePoints | EnableEditAndContinue
    IsJITOptimizerDisabled: true
    IsJITTrackingEnabled: true
Comment 3 Jonathan Pryor 2013-12-20 09:36:59 UTC
What link mode do you have enabled, Link SDK Assemblies or Link All Assemblies?

The linker always removes the following attributes from linked assemblies:


The linker will remove the following attributes from linked assemblies in Release builds, but preserve them for Debug builds:


I would expect these attributes to be preserved in your application assemblies if you're using Link SDK Assemblies. If you're using Link All Assemblies, I would expect these attributes to be removed in Release builds.
Comment 4 Stephen Rawlins 2013-12-20 10:37:34 UTC
For the main programmer on our iOS/Touch app (TestRunner.Touch) the Options/iOS Build/Linker Options
/Linker Behavior is "Don't Link"
Comment 5 Rolf Bjarne Kvinge [MSFT] 2013-12-20 18:39:33 UTC
The problem seems to be that mcs does not add DebuggableAttribute to any assemblies.
Comment 6 Rolf Bjarne Kvinge [MSFT] 2014-01-06 11:51:23 UTC
mcs has now been fixed, so this should work once Mono 3.2.7 is released (note in particular that 3.2.6 will not have this fix).
Comment 7 Stephen Rawlins 2014-01-06 12:47:52 UTC
Thank you very much for your quick attention to this issue. I appreciate it.