Merge branch 'upstream'

Former-commit-id: ea8fd7dc0d8d4b489e79368618e35d4745db1d46

configure.REMOVED.git-id

@@ -1 +1 @@
-f3cdec28bfd3d14c4e51f3f8697b1c542f26bcfa
+dad97840452a2f832fc1323d67be2b04d45fc712

configure.ac.REMOVED.git-id

@@ -1 +1 @@
-34b930d40a1798a2e6cf86e9dc5b5aef795412f2
+1b855480ca426b8d704fef63adf86f09b2b33da2

mcs/build/common/Consts.cs

@@ -34,7 +34,7 @@ static class Consts
 	// Use these assembly version constants to make code more maintainable.
 	//
 
-	public const string MonoVersion = "5.10.0.71";
+	public const string MonoVersion = "5.10.0.78";
 	public const string MonoCompany = "Mono development team";
 	public const string MonoProduct = "Mono Common Language Infrastructure";
 	public const string MonoCopyright = "(c) Various Mono authors";

mcs/class/lib/monolite-darwin/1051000001/Mono.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-f46637fe7b50026e71c6ce268ea9f06072f1427c
+cf7fd8b1f52fa69a3f0c94971b492a2e3ad201bd

mcs/class/lib/monolite-darwin/1051000001/System.Configuration.dll.REMOVED.git-id

@@ -1 +1 @@
-09a0bbd139544d6660f459487cd7b64444fa0110
+622d2ec0823ad7bd945fc203628e4a1290ba8528

mcs/class/lib/monolite-darwin/1051000001/System.Numerics.dll.REMOVED.git-id

@@ -1 +1 @@
-9dbd62725d59ac2b05fb7b233c7392fc2701c97c
+bd7bcec7d9505215a55dda1ebc8154522a62f70d

mcs/class/lib/monolite-darwin/1051000001/System.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-155d65127d43b1f2e787e1c95de7098297585a65
+e87333586392ab866201d6ba269f3d8855e6d0a9

mcs/class/lib/monolite-darwin/1051000001/System.Xml.dll.REMOVED.git-id

@@ -1 +1 @@
-7934a0f5c354efc029c3deca559be7d379278ae7
+d718c10f264ce127870f830fde9359d0d2106b88

mcs/class/lib/monolite-darwin/1051000001/mcs.exe.REMOVED.git-id

@@ -1 +1 @@
-a2d6f567f1c826b06f814cdc88138a155050fb50
+11fa18ea6714274085a830b743543b03862fed53

mcs/class/lib/monolite-darwin/1051000001/mscorlib.dll.REMOVED.git-id

@@ -1 +1 @@
-e66da28062c88338d362b64caa5b9844cceac6c6
+29c3b6cb6acbee9ec9a2bcf01e8dcc796eaa4696

mcs/class/lib/monolite-linux/1051000001/Mono.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-f46637fe7b50026e71c6ce268ea9f06072f1427c
+cf7fd8b1f52fa69a3f0c94971b492a2e3ad201bd

mcs/class/lib/monolite-linux/1051000001/System.Configuration.dll.REMOVED.git-id

@@ -1 +1 @@
-09a0bbd139544d6660f459487cd7b64444fa0110
+622d2ec0823ad7bd945fc203628e4a1290ba8528

mcs/class/lib/monolite-linux/1051000001/System.Numerics.dll.REMOVED.git-id

@@ -1 +1 @@
-9dbd62725d59ac2b05fb7b233c7392fc2701c97c
+bd7bcec7d9505215a55dda1ebc8154522a62f70d

mcs/class/lib/monolite-linux/1051000001/System.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-155d65127d43b1f2e787e1c95de7098297585a65
+e87333586392ab866201d6ba269f3d8855e6d0a9

mcs/class/lib/monolite-linux/1051000001/System.Xml.dll.REMOVED.git-id

@@ -1 +1 @@
-7934a0f5c354efc029c3deca559be7d379278ae7
+d718c10f264ce127870f830fde9359d0d2106b88

mcs/class/lib/monolite-linux/1051000001/mcs.exe.REMOVED.git-id

@@ -1 +1 @@
-a2d6f567f1c826b06f814cdc88138a155050fb50
+11fa18ea6714274085a830b743543b03862fed53

mcs/class/lib/monolite-linux/1051000001/mscorlib.dll.REMOVED.git-id

@@ -1 +1 @@
-e66da28062c88338d362b64caa5b9844cceac6c6
+29c3b6cb6acbee9ec9a2bcf01e8dcc796eaa4696

mcs/class/lib/monolite-win32/1051000001/Mono.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-f46637fe7b50026e71c6ce268ea9f06072f1427c
+cf7fd8b1f52fa69a3f0c94971b492a2e3ad201bd

mcs/class/lib/monolite-win32/1051000001/System.Configuration.dll.REMOVED.git-id

@@ -1 +1 @@
-09a0bbd139544d6660f459487cd7b64444fa0110
+622d2ec0823ad7bd945fc203628e4a1290ba8528

mcs/class/lib/monolite-win32/1051000001/System.Numerics.dll.REMOVED.git-id

@@ -1 +1 @@
-9dbd62725d59ac2b05fb7b233c7392fc2701c97c
+bd7bcec7d9505215a55dda1ebc8154522a62f70d

mcs/class/lib/monolite-win32/1051000001/System.Security.dll.REMOVED.git-id

@@ -1 +1 @@
-155d65127d43b1f2e787e1c95de7098297585a65
+e87333586392ab866201d6ba269f3d8855e6d0a9

mcs/class/lib/monolite-win32/1051000001/System.Xml.dll.REMOVED.git-id

@@ -1 +1 @@
-7934a0f5c354efc029c3deca559be7d379278ae7
+d718c10f264ce127870f830fde9359d0d2106b88

mcs/class/lib/monolite-win32/1051000001/mcs.exe.REMOVED.git-id

@@ -1 +1 @@
-a2d6f567f1c826b06f814cdc88138a155050fb50
+11fa18ea6714274085a830b743543b03862fed53

mcs/class/lib/monolite-win32/1051000001/mscorlib.dll.REMOVED.git-id

@@ -1 +1 @@
-e66da28062c88338d362b64caa5b9844cceac6c6
+29c3b6cb6acbee9ec9a2bcf01e8dcc796eaa4696

mcs/errors/cs1983.cs

@@ -1,4 +1,4 @@
-// CS1983: The return type of an async method must be void, Task, or Task<T>
+// CS1983: The return type of an async method must be void or task type
 // Line: 6
 
 class C

mcs/errors/cs8346.cs

@@ -0,0 +1,13 @@
+// CS8346: Cannot convert a stackalloc expression of type `byte' to type `System.Span<int>'
+// Line: 11
+// Compiler options: -langversion:7.2
+
+using System;
+
+class X
+{
+	public static void Main ()
+	{
+		Span<int> stackSpan = stackalloc byte[1];
+	}
+}

mcs/mcs/assign.cs

@@ -391,9 +391,21 @@ namespace Mono.CSharp {
 			return System.Linq.Expressions.Expression.Assign (target_object, source_object);
 		}
 
-		protected virtual Expression ResolveConversions (ResolveContext ec)
+		protected virtual Expression ResolveConversions (ResolveContext rc)
 		{
-			source = Convert.ImplicitConversionRequired (ec, source, target.Type, source.Location);
+			var ttype = target.Type;
+			var stackAlloc = source as StackAlloc;
+			if (stackAlloc != null && ttype.Arity == 1 && ttype.GetDefinition () == rc.Module.PredefinedTypes.SpanGeneric.TypeSpec &&
+			    rc.Module.Compiler.Settings.Version >= LanguageVersion.V_7_2) {
+
+				var etype = ttype.TypeArguments [0];
+				var stype = ((PointerContainer)source.Type).Element;
+				if (etype == stype && stackAlloc.ResolveSpanConversion (rc, ttype)) {
+					return this;
+				}
+			}
+
+			source = Convert.ImplicitConversionRequired (rc, source, ttype, source.Location);
 			if (source == null)
 				return null;
 

mcs/mcs/async.cs

@@ -628,59 +628,113 @@ namespace Mono.CSharp
 
 		protected override bool DoDefineMembers ()
 		{
-			PredefinedType builder_type;
+			TypeSpec bt;
-			PredefinedMember<MethodSpec> bf;
-			PredefinedMember<MethodSpec> bs;
-			PredefinedMember<MethodSpec> sr;
-			PredefinedMember<MethodSpec> se;
-			PredefinedMember<MethodSpec> sm;
 			bool has_task_return_type = false;
-			var pred_members = Module.PredefinedMembers;
-
-			if (return_type.Kind == MemberKind.Void) {
-				builder_type = Module.PredefinedTypes.AsyncVoidMethodBuilder;
-				bf = pred_members.AsyncVoidMethodBuilderCreate;
-				bs = pred_members.AsyncVoidMethodBuilderStart;
-				sr = pred_members.AsyncVoidMethodBuilderSetResult;
-				se = pred_members.AsyncVoidMethodBuilderSetException;
-				sm = pred_members.AsyncVoidMethodBuilderSetStateMachine;
-			} else if (return_type == Module.PredefinedTypes.Task.TypeSpec) {
-				builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilder;
-				bf = pred_members.AsyncTaskMethodBuilderCreate;
-				bs = pred_members.AsyncTaskMethodBuilderStart;
-				sr = pred_members.AsyncTaskMethodBuilderSetResult;
-				se = pred_members.AsyncTaskMethodBuilderSetException;
-				sm = pred_members.AsyncTaskMethodBuilderSetStateMachine;
-				task = pred_members.AsyncTaskMethodBuilderTask.Get ();
-			} else {
-				builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilderGeneric;
-				bf = pred_members.AsyncTaskMethodBuilderGenericCreate;
-				bs = pred_members.AsyncTaskMethodBuilderGenericStart;
-				sr = pred_members.AsyncTaskMethodBuilderGenericSetResult;
-				se = pred_members.AsyncTaskMethodBuilderGenericSetException;
-				sm = pred_members.AsyncTaskMethodBuilderGenericSetStateMachine;
-				task = pred_members.AsyncTaskMethodBuilderGenericTask.Get ();
-				has_task_return_type = true;
-			}
-
-			set_result = sr.Get ();
-			set_exception = se.Get ();
-			builder_factory = bf.Get ();
-			builder_start = bs.Get ();
-
 			var istate_machine = Module.PredefinedTypes.IAsyncStateMachine;
-			var set_statemachine = sm.Get ();
+			MethodSpec set_statemachine;
 
-			if (!builder_type.Define () || !istate_machine.Define () || set_result == null || builder_factory == null ||
+			if (return_type.IsCustomTaskType ()) {
-				set_exception == null || set_statemachine == null || builder_start == null ||
+				//
-				!Module.PredefinedTypes.INotifyCompletion.Define ()) {
+				// TODO: Would be nice to cache all this on per-type basis
-				Report.Error (1993, Location,
+				//
-					"Cannot find compiler required types for asynchronous functions support. Are you targeting the wrong framework version?");
+				var btypes = Compiler.BuiltinTypes;
-				return base.DoDefineMembers ();
+				bt = return_type.MemberDefinition.GetAsyncMethodBuilder ();
+				TypeSpec bt_inflated;
+				if (return_type.IsGeneric) {
+					bt_inflated = bt.MakeGenericType (Module, bt.MemberDefinition.TypeParameters);
+				} else {
+					bt_inflated = bt;
+				}
+
+				var set_result_sign = MemberFilter.Method ("SetResult", 0, ParametersCompiled.CreateFullyResolved (bt.MemberDefinition.TypeParameters), btypes.Void);
+				set_result = new PredefinedMember<MethodSpec> (Module, bt, set_result_sign).Resolve (Location);
+
+				var set_exception_sign = MemberFilter.Method ("SetException", 0, ParametersCompiled.CreateFullyResolved (btypes.Exception), btypes.Void);
+				set_exception = new PredefinedMember<MethodSpec> (Module, bt, set_exception_sign).Resolve (Location);
+
+				var builder_factory_sign = MemberFilter.Method ("Create", 0, ParametersCompiled.EmptyReadOnlyParameters, bt_inflated);
+				builder_factory = new PredefinedMember<MethodSpec> (Module, bt, builder_factory_sign).Resolve (Location);
+				if (builder_factory?.IsStatic == false)
+					throw new NotImplementedException ("report better error message");
+
+				var builder_start_sign = MemberFilter.Method ("Start", 1, new ParametersImported (
+						new [] {
+								new ParameterData (null, Parameter.Modifier.REF),
+							},
+						new [] {
+								new TypeParameterSpec (0, null, SpecialConstraint.None, Variance.None, null),
+							}, false),
+					btypes.Void);
+				builder_start = new PredefinedMember<MethodSpec> (Module, bt, builder_start_sign).Resolve (Location);
+
+				if (!istate_machine.Define ())
+					return false;
+
+				var set_statemachine_sign = MemberFilter.Method ("SetStateMachine", 0, ParametersCompiled.CreateFullyResolved (istate_machine.TypeSpec), btypes.Void);
+				set_statemachine = new PredefinedMember<MethodSpec> (Module, bt, set_statemachine_sign).Resolve (Location); ;
+
+				var task_sign = MemberFilter.Property ("Task", return_type.MemberDefinition as TypeSpec);
+				task = new PredefinedMember<PropertySpec> (Module, bt, task_sign).Resolve (Location);
+
+				if (set_result == null || set_exception == null || builder_factory == null || builder_start == null || set_statemachine == null || task == null ||
+					!Module.PredefinedTypes.INotifyCompletion.Define ()) {
+					return false;
+				}
+
+				has_task_return_type = return_type.IsGeneric;
+			} else {
+				PredefinedType builder_type;
+				PredefinedMember<MethodSpec> bf;
+				PredefinedMember<MethodSpec> bs;
+				PredefinedMember<MethodSpec> sr;
+				PredefinedMember<MethodSpec> se;
+				PredefinedMember<MethodSpec> sm;
+				var pred_members = Module.PredefinedMembers;
+
+				if (return_type.Kind == MemberKind.Void) {
+					builder_type = Module.PredefinedTypes.AsyncVoidMethodBuilder;
+					bf = pred_members.AsyncVoidMethodBuilderCreate;
+					bs = pred_members.AsyncVoidMethodBuilderStart;
+					sr = pred_members.AsyncVoidMethodBuilderSetResult;
+					se = pred_members.AsyncVoidMethodBuilderSetException;
+					sm = pred_members.AsyncVoidMethodBuilderSetStateMachine;
+				} else if (return_type == Module.PredefinedTypes.Task.TypeSpec) {
+					builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilder;
+					bf = pred_members.AsyncTaskMethodBuilderCreate;
+					bs = pred_members.AsyncTaskMethodBuilderStart;
+					sr = pred_members.AsyncTaskMethodBuilderSetResult;
+					se = pred_members.AsyncTaskMethodBuilderSetException;
+					sm = pred_members.AsyncTaskMethodBuilderSetStateMachine;
+					task = pred_members.AsyncTaskMethodBuilderTask.Get ();
+				} else {
+					builder_type = Module.PredefinedTypes.AsyncTaskMethodBuilderGeneric;
+					bf = pred_members.AsyncTaskMethodBuilderGenericCreate;
+					bs = pred_members.AsyncTaskMethodBuilderGenericStart;
+					sr = pred_members.AsyncTaskMethodBuilderGenericSetResult;
+					se = pred_members.AsyncTaskMethodBuilderGenericSetException;
+					sm = pred_members.AsyncTaskMethodBuilderGenericSetStateMachine;
+					task = pred_members.AsyncTaskMethodBuilderGenericTask.Get ();
+					has_task_return_type = true;
+				}
+
+				set_result = sr.Get ();
+				set_exception = se.Get ();
+				builder_factory = bf.Get ();
+				builder_start = bs.Get ();
+
+				set_statemachine = sm.Get ();
+
+				if (!builder_type.Define () || !istate_machine.Define () || set_result == null || builder_factory == null ||
+					set_exception == null || set_statemachine == null || builder_start == null ||
+					!Module.PredefinedTypes.INotifyCompletion.Define ()) {
+					Report.Error (1993, Location,
+						"Cannot find compiler required types for asynchronous functions support. Are you targeting the wrong framework version?");
+					return base.DoDefineMembers ();
+				}
+
+				bt = builder_type.TypeSpec;
 			}
 
-			var bt = builder_type.TypeSpec;
-
 			//
 			// Inflate generic Task types
 			//
@@ -825,9 +879,26 @@ namespace Mono.CSharp
 				predefined = unsafeVersion ? pm.AsyncVoidMethodBuilderOnCompletedUnsafe : pm.AsyncVoidMethodBuilderOnCompleted;
 			} else if (return_type == Module.PredefinedTypes.Task.TypeSpec) {
 				predefined = unsafeVersion ? pm.AsyncTaskMethodBuilderOnCompletedUnsafe : pm.AsyncTaskMethodBuilderOnCompleted;
-			} else {
+			} else if (return_type.IsGenericTask) {
 				predefined = unsafeVersion ? pm.AsyncTaskMethodBuilderGenericOnCompletedUnsafe : pm.AsyncTaskMethodBuilderGenericOnCompleted;
 				has_task_return_type = true;
+			} else {
+				var parameters = new ParametersImported (
+					new [] {
+								new ParameterData (null, Parameter.Modifier.REF),
+								new ParameterData (null, Parameter.Modifier.REF)
+						},
+					new [] {
+								new TypeParameterSpec (0, null, SpecialConstraint.None, Variance.None, null),
+								new TypeParameterSpec (1, null, SpecialConstraint.None, Variance.None, null)
+					}, false);
+
+				var on_completed_sign = unsafeVersion ?
+					MemberFilter.Method ("AwaitUnsafeOnCompleted", 2, parameters, Compiler.BuiltinTypes.Void) :
+				    MemberFilter.Method ("AwaitOnCompleted", 2, parameters, Compiler.BuiltinTypes.Void);
+				
+				predefined = new PredefinedMember<MethodSpec> (Module, return_type.MemberDefinition.GetAsyncMethodBuilder (), on_completed_sign);
+				has_task_return_type = return_type.IsGeneric;
 			}
 
 			var on_completed = predefined.Resolve (Location);
@@ -887,11 +958,14 @@ namespace Mono.CSharp
 			// stateMachine.$builder.Start<{storey-type}>(ref stateMachine);
 			//
 			instance.AddressOf (ec, AddressOp.Store);
-			ec.Emit (OpCodes.Ldflda, builder_field);
+
+			bool struct_builder = builder.MemberType.IsStruct;
+
+			ec.Emit (struct_builder ? OpCodes.Ldflda : OpCodes.Ldfld, builder_field);
 			if (Task != null)
 				ec.Emit (OpCodes.Dup);
 			instance.AddressOf (ec, AddressOp.Store);
-			ec.Emit (OpCodes.Call, builder_start.MakeGenericMethod (Module, instance.Type));
+			ec.Emit (struct_builder ? OpCodes.Call : OpCodes.Callvirt, builder_start.MakeGenericMethod (Module, instance.Type));
 
 			//
 			// Emits return stateMachine.$builder.Task;
@@ -1029,4 +1103,20 @@ namespace Mono.CSharp
 			EmitAssign (ec, new NullConstant (type, loc), false, false);
 		}
 	}
+
+	static class TypeSpecAsyncExtensions
+	{
+		public static bool IsCustomTaskType (this TypeSpec type)
+		{
+			// LAMESPEC: Arity is not mentioned
+			if (type.Arity > 1)
+				return false;
+			
+			var amb = type.MemberDefinition.GetAsyncMethodBuilder ();
+			if (amb == null)
+				return false;
+
+			return amb.Arity == type.Arity;
+		}
+	}
 }

mcs/mcs/attribute.cs

@@ -789,6 +789,17 @@ namespace Mono.CSharp {
 			return ((BoolConstant) pos_args[0].Expr).Value;
 		}
 
+		public TypeSpec GetAsyncMethodBuilderValue ()
+		{
+			if (!arg_resolved)
+				Resolve ();
+
+			if (resolve_error)
+				return null;
+
+			return GetArgumentType ();
+		}
+
 		public TypeSpec GetCoClassAttributeValue ()
 		{
 			if (!arg_resolved)
@@ -1754,6 +1765,7 @@ namespace Mono.CSharp {
 
 		// New in .NET 4.7
 		public readonly PredefinedTupleElementNamesAttribute TupleElementNames;
+		public readonly PredefinedAttribute AsyncMethodBuilder;
 
 		// New in .NET 4.7.1
 		public readonly PredefinedAttribute IsReadOnly;
@@ -1838,6 +1850,7 @@ namespace Mono.CSharp {
 			CallerLineNumberAttribute = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CallerLineNumberAttribute");
 			CallerFilePathAttribute = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CallerFilePathAttribute");
 
+			AsyncMethodBuilder = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "AsyncMethodBuilderAttribute");
 			TupleElementNames = new PredefinedTupleElementNamesAttribute (module, "System.Runtime.CompilerServices", "TupleElementNamesAttribute");
 			IsReadOnly = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "IsReadOnlyAttribute");
 			IsByRefLike = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "IsByRefLikeAttribute");

mcs/mcs/class.cs.REMOVED.git-id

@@ -1 +1 @@
-da3ec32d6fb042738c08224ca2367f0262506c27
+6b1adc297a3831c9f1efbe0d0eb0b1af7230f911

mcs/mcs/ecore.cs.REMOVED.git-id

@@ -1 +1 @@
-b6a508cffc61cadc2e4ab73e7cc62af1fc2793d6
+20ee9e73b19c3cf415315fbd67fcaeb787ac8ef6

mcs/mcs/expression.cs.REMOVED.git-id

@@ -1 +1 @@
-51f268737c01310008f6ef3be4705ffc0373b7ed
+518ccc8ef43fb3e1a0902069579690ac6875696a

mcs/mcs/generic.cs

@@ -693,6 +693,11 @@ namespace Mono.CSharp {
 					GetSignatureForError (), mc.GetSignatureForError (), input_variance, gtype_variance, parameters);
 		}
 
+		public TypeSpec GetAsyncMethodBuilder ()
+		{
+			return null;
+		}
+
 		public TypeSpec GetAttributeCoClass ()
 		{
 			return null;

mcs/mcs/import.cs

@@ -1405,6 +1405,7 @@ namespace Mono.CSharp
 			public string DefaultIndexerName;
 			public bool? CLSAttributeValue;
 			public TypeSpec CoClass;
+			public TypeSpec AsyncMethodBuilder;
 
 			static bool HasMissingType (ConstructorInfo ctor)
 			{
@@ -1446,7 +1447,14 @@ namespace Mono.CSharp
 						if (args.Count == 1) {
 							bag.Obsolete = new ObsoleteAttribute ((string) args[0].Value);
 						} else if (args.Count == 2) {
-							bag.Obsolete = new ObsoleteAttribute ((string) args[0].Value, (bool) args[1].Value);
+							const string ByRefLikeMarker = "Types with embedded references are not supported in this version of your compiler.";
+
+							var msg = (string)args[0].Value;
+
+							if (msg == ByRefLikeMarker)
+								continue;
+
+							bag.Obsolete = new ObsoleteAttribute (msg, (bool) args[1].Value);
 						} else {
 							bag.Obsolete = new ObsoleteAttribute ();
 						}
@@ -1526,6 +1534,20 @@ namespace Mono.CSharp
 							bag.CoClass = importer.ImportType ((MetaType) a.ConstructorArguments[0].Value);
 							continue;
 						}
+
+						if (name == "AsyncMethodBuilderAttribute") {
+							if (dt.Namespace != "System.Runtime.CompilerServices")
+								continue;
+
+							if (HasMissingType (a.Constructor))
+								continue;
+
+							if (bag == null)
+								bag = new AttributesBag ();
+
+							bag.AsyncMethodBuilder = importer.ImportType ((MetaType)a.ConstructorArguments [0].Value);
+							continue;
+						}
 					}
 				}
 
@@ -2133,6 +2155,14 @@ namespace Mono.CSharp
 			}
 		}
 
+		public TypeSpec GetAsyncMethodBuilder ()
+		{
+			if (cattrs == null)
+				ReadAttributes ();
+
+			return cattrs.AsyncMethodBuilder;
+		}
+
 		public TypeSpec GetAttributeCoClass ()
 		{
 			if (cattrs == null)
@@ -2449,6 +2479,11 @@ namespace Mono.CSharp
 
 		#endregion
 
+		public TypeSpec GetAsyncMethodBuilder ()
+		{
+			return null;
+		}
+
 		public TypeSpec GetAttributeCoClass ()
 		{
 			return null;

mcs/mcs/method.cs

@@ -1267,8 +1267,9 @@ namespace Mono.CSharp {
 				if ((ModFlags & Modifiers.ASYNC) != 0) {
 					if (ReturnType.Kind != MemberKind.Void &&
 						ReturnType != Module.PredefinedTypes.Task.TypeSpec &&
-						!ReturnType.IsGenericTask) {
+						!ReturnType.IsGenericTask &&
-						Report.Error (1983, Location, "The return type of an async method must be void, Task, or Task<T>");
+					    !ReturnType.IsCustomTaskType ()) {
+						Report.Error (1983, Location, "The return type of an async method must be void or task type");
 					}
 
 					block = (ToplevelBlock) block.ConvertToAsyncTask (this, Parent.PartialContainer, parameters, ReturnType, null, Location);

mcs/mcs/statement.cs.REMOVED.git-id

@@ -1 +1 @@
-6f86db260bf6516fe48fce41e5197b299a5cfc88
+9c51128548f7bf24c42648a23fef1bf5dbc67fa8

mcs/mcs/typemanager.cs

@@ -242,6 +242,7 @@ namespace Mono.CSharp
 
 		// C# 7.0
 		public readonly PredefinedType[] Tuples;
+		public readonly PredefinedType SpanGeneric;
 
 		public PredefinedTypes (ModuleContainer module)
 		{
@@ -301,6 +302,8 @@ namespace Mono.CSharp
 			FormattableString = new PredefinedType (module, MemberKind.Class, "System", "FormattableString");
 			FormattableStringFactory = new PredefinedType (module, MemberKind.Class, "System.Runtime.CompilerServices", "FormattableStringFactory");
 
+			SpanGeneric = new PredefinedType (module, MemberKind.Struct, "System", "Span", 1);
+
 			//
 			// Define types which are used for comparison. It does not matter
 			// if they don't exist as no error report is needed
@@ -348,6 +351,8 @@ namespace Mono.CSharp
 				if (pt.Define ())
 					pt.TypeSpec.IsTupleType = true;
 			}
+
+			SpanGeneric.Define ();
 		}
 	}
 
@@ -430,6 +435,7 @@ namespace Mono.CSharp
 			ArrayEmpty = new PredefinedMember<MethodSpec> (module, types.Array,
 				MemberFilter.Method ("Empty", 1, ParametersCompiled.EmptyReadOnlyParameters, null));
 
+			// TODO: Must me static
 			AsyncTaskMethodBuilderCreate = new PredefinedMember<MethodSpec> (module, types.AsyncTaskMethodBuilder,
 				MemberFilter.Method ("Create", 0, ParametersCompiled.EmptyReadOnlyParameters, types.AsyncTaskMethodBuilder.TypeSpec));
 
@@ -485,6 +491,7 @@ namespace Mono.CSharp
 			AsyncTaskMethodBuilderTask = new PredefinedMember<PropertySpec> (module, types.AsyncTaskMethodBuilder,
 				MemberFilter.Property ("Task", null));
 
+			// TODO: Must me static
 			AsyncTaskMethodBuilderGenericCreate = new PredefinedMember<MethodSpec> (module, types.AsyncTaskMethodBuilderGeneric,
 				MemberFilter.Method ("Create", 0, ParametersCompiled.EmptyReadOnlyParameters, types.AsyncVoidMethodBuilder.TypeSpec));
 
@@ -542,6 +549,7 @@ namespace Mono.CSharp
 			AsyncTaskMethodBuilderGenericTask = new PredefinedMember<PropertySpec> (module, types.AsyncTaskMethodBuilderGeneric,
 				MemberFilter.Property ("Task", null));
 
+			// TODO: Must me static
 			AsyncVoidMethodBuilderCreate = new PredefinedMember<MethodSpec> (module, types.AsyncVoidMethodBuilder,
 				MemberFilter.Method ("Create", 0, ParametersCompiled.EmptyReadOnlyParameters, types.AsyncVoidMethodBuilder.TypeSpec));
 
@@ -1006,9 +1014,6 @@ namespace Mono.CSharp
 
 		public T Resolve (Location loc)
 		{
-			if (member != null)
-				return member;
-
 			if (Get () != null)
 				return member;
 

mcs/mcs/typespec.cs

@@ -1454,6 +1454,7 @@ namespace Mono.CSharp
 		int TypeParametersCount { get; }
 		TypeParameterSpec[] TypeParameters { get; }
 
+		TypeSpec GetAsyncMethodBuilder ();
 		TypeSpec GetAttributeCoClass ();
 		string GetAttributeDefaultMember ();
 		AttributeUsageAttribute GetAttributeUsage (PredefinedAttribute pa);
@@ -1588,6 +1589,11 @@ namespace Mono.CSharp
 
 		#region ITypeDefinition Members
 
+		TypeSpec ITypeDefinition.GetAsyncMethodBuilder ()
+		{
+			return null;
+		}
+
 		TypeSpec ITypeDefinition.GetAttributeCoClass ()
 		{
 			return null;
@@ -1776,6 +1782,11 @@ namespace Mono.CSharp
 			}
 		}
 
+		public TypeSpec GetAsyncMethodBuilder ()
+		{
+			return null;
+		}
+
 		public TypeSpec GetAttributeCoClass ()
 		{
 			return Element.MemberDefinition.GetAttributeCoClass ();

mcs/tests/test-948.cs

@@ -0,0 +1,16 @@
+// Compiler options: -langversion:7.2 -unsafe
+
+using System;
+
+class X
+{
+	public static void Main ()
+	{
+		Span<int> stackSpan = stackalloc int[100];
+	}
+
+	unsafe void Foo ()
+	{
+
+	}
+}

mcs/tests/test-async-94.cs

@@ -0,0 +1,127 @@
+using System;
+using System.Threading.Tasks;
+using System.Runtime.CompilerServices;
+
+[AsyncMethodBuilder (typeof(MyTaskMethodBuilder<>))]
+class MyTask<T>
+{
+}
+
+[AsyncMethodBuilder (typeof(MyTaskMethodBuilder))]
+class MyTask
+{
+}
+
+class MyTaskMethodBuilder
+{
+	public static MyTaskMethodBuilder Create()
+	{
+		return null;
+	}
+
+	public MyTask Task {
+		get {
+			return null;
+		}
+	}
+
+	public void SetException (Exception exception)
+	{
+
+	}
+
+	public void SetResult ()
+	{
+
+	}
+
+	public void AwaitOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void Start<TStateMachine> (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void SetStateMachine (IAsyncStateMachine stateMachine)
+	{
+
+	}	
+}
+
+class MyTaskMethodBuilder<T>
+{
+	public static MyTaskMethodBuilder<T> Create()
+	{
+		return null;
+	}
+
+	public MyTask<T> Task {
+		get {
+			return null;
+		}
+	}
+
+	public void SetException (Exception exception)
+	{
+
+	}
+
+	public void SetResult (T result)
+	{
+
+	}
+
+	public void AwaitOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine> (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void Start<TStateMachine> (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine
+	{
+
+	}
+
+	public void SetStateMachine (IAsyncStateMachine stateMachine)
+	{
+
+	}
+}
+
+class X
+{
+	public async MyTask Test ()
+	{
+		await Task.Delay (1);
+	}
+
+	public async MyTask<int> Test2 ()
+	{
+		await Task.Delay (1);
+		return 2;
+	}
+
+	public async ValueTask<string> Test3 ()
+	{
+		await Task.Delay (1);
+		return "as";
+	}	
+
+	public static void Main ()
+	{
+		var x = new X ();
+		var r1 = x.Test3 ().Result;
+	}
+}

mcs/tests/test-readonly-03.cs

@@ -0,0 +1,16 @@
+// Compiler options: -langversion:latest
+using System;
+
+readonly struct S
+{
+	static S shared = new S ();
+
+	public S (int arg)
+	{
+		this = shared;
+	}
+
+	public static void Main ()
+	{
+	}
+}

mcs/tests/test-ref-10.cs

@@ -0,0 +1,24 @@
+// Compiler options: -langversion:latest
+
+using System;
+
+ref struct ValueStringBuilder
+{
+	public override string ToString ()
+	{
+		return "aaa";
+	}
+}
+
+
+class X
+{
+	public static int Main ()
+	{
+		var s = new ValueStringBuilder ();
+		if (s.ToString () != "aaa")
+			return 1;
+
+		return 0;
+	}
+}

mcs/tests/ver-il-net_4_x.xml.REMOVED.git-id

@@ -1 +1 @@
-4e488c37bc46fed416be09476a01fed86a94ba5e
+4dbc7042a8a8252f26b40788a5460fbf138e5b46

mcs/tools/mkbundle/mkbundle.cs

@@ -821,6 +821,11 @@ typedef struct {
 void          mono_register_bundled_assemblies (const MonoBundledAssembly **assemblies);
 void          mono_register_config_for_assembly (const char* assembly_name, const char* config_xml);
 ");
+
+				// These values are part of the public API, so they are expected not to change
+				tc.WriteLine("#define MONO_AOT_MODE_NORMAL 1");
+				tc.WriteLine("#define MONO_AOT_MODE_FULL 3");
+				tc.WriteLine("#define MONO_AOT_MODE_LLVMONLY 4");
 			} else {
 				tc.WriteLine ("#include <mono/metadata/mono-config.h>");
 				tc.WriteLine ("#include <mono/metadata/assembly.h>\n");

mono/mini/mini-exceptions.c.REMOVED.git-id

@@ -1 +1 @@
-fa050c7d79f62e040d8997246d7e2dc715f9d05b
+d6a633d3b240e5bd794a91bd7e48897acaa7fc64

mono/mini/version.h

@@ -1 +1 @@
-#define FULL_VERSION "explicit/94fa6e5"
+#define FULL_VERSION "explicit/e87f9d7"

po/mcs/de.po.REMOVED.git-id

@@ -1 +1 @@
-bedee19c69662447845648dc66e8e47a43644128
+da8f1364e436f162752907da2e26c20ea9ac161c

po/mcs/es.po.REMOVED.git-id

@@ -1 +1 @@
-7155f3bc3eed5336428e7599a3950cdeece8507f
+c6396bb9a350263cb5f35de2bbf5bcdf7f6a7407

po/mcs/ja.po.REMOVED.git-id

@@ -1 +1 @@
-a7da8cdcf0efaa86d5b0e16899cfc2c52dd06560
+89e4e228d152cb3572b8074df47cbf593ae4b73f

po/mcs/pt_BR.po.REMOVED.git-id

@@ -1 +1 @@
-a40a4e7f3a6f233e6afa13e4a33b434134da328f
+7fdfb7dd15beb1e0153cff685188a25415de0f86