Subject: [bug#74609] [PATCH 15/21] gnu: Add mono-5.4.0.

From: Efraim Flashner <[email-masked]>
Date: Mon, 16 Dec 2024 19:26:38 +0200

From: unmush <[email-masked]>

* gnu/packages/dotnet.scm
  (mono-5.4.0-external-repo-specs, mono-5.4.0): New variables.
* gnu/packages/patches/corefx-mono-5.4.0-patches.patch: New patch.
* gnu/packages/patches/mono-5.4.0-patches.patch: New patch.
* gnu/local.mk (dist_patch_DATA): Register new patches.

Change-Id: I1510c8ac13db60e5beab8033be3efc483e984ec0
---
 gnu/local.mk                                  |   2 +
 gnu/packages/dotnet.scm                       |  92 ++
 .../patches/corefx-mono-5.4.0-patches.patch   | 915 ++++++++++++++++++
 gnu/packages/patches/mono-5.4.0-patches.patch | 100 ++
 4 files changed, 1109 insertions(+)
 create mode 100644 gnu/packages/patches/corefx-mono-5.4.0-patches.patch
 create mode 100644 gnu/packages/patches/mono-5.4.0-patches.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 5facc66932b..aa129d89d58 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1114,6 +1114,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/converseen-hide-non-free-pointers.patch	\
   %D%/packages/patches/cool-retro-term-wctype.patch		\
   %D%/packages/patches/coq-autosubst-1.8-remove-deprecated-files.patch		\
+  %D%/packages/patches/corefx-mono-5.4.0-patches.patch		\
   %D%/packages/patches/coreutils-gnulib-tests.patch		\
   %D%/packages/patches/cppcheck-disable-char-signedness-test.patch	\
   %D%/packages/patches/cppdap-add-CPPDAP_USE_EXTERNAL_GTEST_PACKAGE.patch\
@@ -1825,6 +1826,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/mono-2.6.4-fixes.patch			\
   %D%/packages/patches/mono-2.11.4-fixes.patch			\
   %D%/packages/patches/mono-4.9.0-fix-runtimemetadataversion.patch		\
+  %D%/packages/patches/mono-5.4.0-patches.patch		\
   %D%/packages/patches/mosaicatcher-unbundle-htslib.patch	\
   %D%/packages/patches/mrrescue-support-love-11.patch		\
   %D%/packages/patches/mtools-mformat-uninitialized.patch	\
diff --git a/gnu/packages/dotnet.scm b/gnu/packages/dotnet.scm
index cf391ed9200..b4355b048e2 100644
--- a/gnu/packages/dotnet.scm
+++ b/gnu/packages/dotnet.scm
@@ -1104,3 +1104,95 @@ (define-public mono-5.2.0
                            #$@prepare-mono-source-0))))
     (native-inputs (modify-inputs (package-native-inputs mono-5.1.0)
                      (replace "mono" mono-5.1.0)))))
+
+(define mono-5.4.0-external-repo-specs
+  '(("aspnetwebstack"              "e77b12e6cc5ed260a98447f609e887337e44e299"
+     "0rks344qr4fmp3fs1264d2qkmm348m8d1kjd7z4l94iiirwn1fq1")
+    ("api-doc-tools"               "d03e819838c6241f92f90655cb448cc47c9e8791"
+     "1riki79f3ig3cxigviss81dz601hn92a1gifglm0mzjbs76sf3fj"
+     #:recursive? #t)
+    ("api-snapshot"                "b09033be33ab25113743151c644c831158c54042"
+     "0z67iqd1brib6ni36pklrp7rlxyhri5nk3px37fm1aacgrnsk7ck")
+    (("reference-assemblies" "binary-reference-assemblies")
+     "142cbeb62ffabf1dd9c1414d8dd76f93bcbed0c2"
+     "1wkd589hgb16m5zvmp9yb57agyyryaa1jj8vhl4w20i2hp22wad9")
+    ("bockbuild"                   "0efdb371e6d79abc54c0e3bb3689fa1646f4394e"
+     "10qr1m2wa3zb2i3j16i0cq49higjm451bhlqhqd4rlisqn0w8nrv")
+    ("boringssl"                   "3e0770e18835714708860ba9fe1af04a932971ff"
+     "139a0gl91a52k2r6na6ialzkqykaj1rk88zjrkaz3sdxx7nmmg6y")
+    ("cecil"                       "c0eb983dac62519d3ae93a689312076aacecb723"
+     "02i3pwpaf6q00pklfmwxhz0lgp83854dyqnvf4c1ys07cs8y1pdk")
+    (("cecil" "cecil-legacy")      "33d50b874fd527118bc361d83de3d494e8bb55e1"
+     "1p4hl1796ib26ykyf5snl6cj0lx0v7mjh0xqhjw6qdh753nsjyhb")
+    ("corefx"                      "9ad53d674e31327abcc60f35c14387700f50cc68"
+     "0ap4g2fj8wsar4xvbc6dkd2l67qalxlcw5laplq3an5nvj2ld65w"
+     #:patches ("corefx-mono-5.4.0-patches.patch"))
+    ("corert"                      "48dba73801e804e89f00311da99d873f9c550278"
+     "1zw47jf4cwqmaixylisxi73xf6cap41bwf9vlmpxanzxaqklzsvk")
+    ("ikdasm"                      "1d7d43603791e0236b56d076578657bee44fef6b"
+     "1kw8ykkad55qhapg6jbvqim7vainqlpz8469flm083lpz7pks3sg")
+    (("ikvm-fork" "ikvm")          "847e05fced5c9a41ff0f24f1f9d40d5a8a5772c1"
+     "1fl9bm3lmzf8iqv3x4iqkz9fc54mwdvrxisxg2nvwwcsi4saffpi")
+    ("linker"                      "99354bf5c13b8055209cb082cddc50c8047ab088"
+     "05zlajnqf83xfvn2whh9nql6j85sq12aw26sqmyqz7zcpml171mj")
+    ("Newtonsoft.Json"             "471c3e0803a9f40a0acc8aeceb31de6ff93a52c4"
+     "0dgngd5hqk6yhlg40kabn6qdnknm32zcx9q6bm2w31csnsk5978s")
+    (("NuGet.BuildTasks" "nuget-buildtasks")
+     "b58ba4282377bcefd48abdc2d62ce6330e079abe"
+     "1say03fnqkjsx97zacany3sa5j4mhfk827hkwp23ib02q18f7lvp")
+    (("NUnitLite" "nunit-lite")    "690603bea98aae69fca9a65130d88591bc6cabee"
+     "1f845ysjzs3yd9gcyww66dnkx484z5fknb8l0xz74sjmxk2mngwc")
+    ;; ("roslyn-binaries"          "1904c7d0682a878e2d25b4d49f3475d12fbb9cc6"
+    ;;  "")
+    ("rx"                          "b29a4b0fda609e0af33ff54ed13652b6ccf0e05e"
+     "1n1jwhmsbkcv2d806immcpzkb72rz04xy98myw355a8w5ah25yiv")
+    ;; ("xunit-binaries"           "d4433b0972f40cb3efaa3fbba52869bde5df8fa8"
+    ;;  "")
+    ))
+
+(define-public mono-5.4.0
+  (package
+    (inherit mono-5.2.0)
+    (version "5.4.0.212")
+    (name "mono")
+    (source (origin
+              (method git-fetch)
+              (uri
+               (git-reference
+                (url "https://gitlab.winehq.org/mono/mono.git")
+                (commit
+                 ;; 5.4.0.135 and before have a bug that makes mono not
+                 ;; self-hosting (fails to compile self, example error:
+                 ;; System.Data.SqlClient/SqlTransaction.cs(39,22): error
+                 ;; CS0738: `System.Data.SqlClient.SqlTransaction' does not
+                 ;; implement interface member
+                 ;; `System.Data.IDbTransaction.Connection.get' and the best
+                 ;; implementing candidate
+                 ;; `System.Data.SqlClient.SqlTransaction.Connection.get'
+                 ;; return type `System.Data.SqlClient.SqlConnection' does not
+                 ;; match interface member return type
+                 ;; `System.Data.IDbConnection'
+
+                 ;; Note: in above example, SqlConnection implements
+                 ;; IDbConnection.  My understanding is that for this to
+                 ;; compile properly, we need covariant return types, which is
+                 ;; a C# 9.0 feature, but somehow the same code has been
+                 ;; compiled just fine by previous versions of mono, and is
+                 ;; compiled fine by this version, but not specific 5.4.0.XXX
+                 ;; versions.
+                 "mono-5.4.0.212")))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "0gx3fxz1wlq5fkj7iphv32vg9m78ia74m9pgn9rab4fyq2k9an2y"))
+              (modules '((guix build utils)
+                         (ice-9 string-fun)))
+              (snippet #~(begin
+                           #$(add-external-repos
+                              mono-5.4.0-external-repo-specs)
+                           #$@prepare-mono-source-0))
+              (patches
+               (search-patches
+                "mono-5.4.0-patches.patch"))))
+    (native-inputs (modify-inputs (package-native-inputs mono-5.2.0)
+                     (replace "mono" mono-5.2.0)))))
diff --git a/gnu/packages/patches/corefx-mono-5.4.0-patches.patch b/gnu/packages/patches/corefx-mono-5.4.0-patches.patch
new file mode 100644
index 00000000000..034d769ebce
--- /dev/null
+++ b/gnu/packages/patches/corefx-mono-5.4.0-patches.patch
@@ -0,0 +1,915 @@
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ExpressionTreeCallRewriter.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ExpressionTreeCallRewriter.cs
+index aa8afa5a1b..3a2518246a 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ExpressionTreeCallRewriter.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ExpressionTreeCallRewriter.cs
+@@ -246,8 +246,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+             ExprArrayInit arrinit;
+ 
+             ExprList list = (ExprList)pExpr.OptionalArguments;
+-            if (list.OptionalNextListNode is ExprList next)
++            if (list.OptionalNextListNode is ExprList)
+             {
++                ExprList next = (ExprList)list.OptionalNextListNode;
+                 methinfo = (ExprMethodInfo)next.OptionalElement;
+                 arrinit = (ExprArrayInit)next.OptionalNextListNode;
+             }
+@@ -382,8 +383,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+             Expr nextNode = list.OptionalNextListNode;
+             ExprPropertyInfo propinfo;
+             ExprArrayInit arguments;
+-            if (nextNode is ExprList nextList)
++            if (nextNode is ExprList)
+             {
++                ExprList nextList = (ExprList)list.OptionalNextListNode;
+                 propinfo = nextList.OptionalElement as ExprPropertyInfo;
+                 arguments = nextList.OptionalNextListNode as ExprArrayInit;
+             }
+@@ -553,8 +555,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+             list = (ExprList)list.OptionalNextListNode;
+             MethodInfo methodInfo;
+             bool bIsLifted = false;
+-            if (list.OptionalNextListNode is ExprList next)
++            if (list.OptionalNextListNode is ExprList)
+             {
++                ExprList next = (ExprList)list.OptionalNextListNode;
+                 ExprConstant isLifted = (ExprConstant)next.OptionalElement;
+                 Debug.Assert(isLifted != null);
+                 bIsLifted = isLifted.Val.Int32Val == 1;
+@@ -677,8 +680,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+ 
+         private Expression GetExpression(Expr pExpr)
+         {
+-            if (pExpr is ExprWrap wrap)
++            if (pExpr is ExprWrap)
+             {
++                ExprWrap wrap = (ExprWrap) pExpr;
+                 return _DictionaryOfParameters[(ExprCall)wrap.OptionalExpression];
+             }
+             else if (pExpr is ExprConstant)
+@@ -875,20 +879,24 @@ namespace Microsoft.CSharp.RuntimeBinder
+         {
+             for (;;)
+             {
+-                if (pExpr is ExprCast cast)
++                if (pExpr is ExprCast)
+                 {
++                    ExprCast cast = (ExprCast) pExpr;
+                     pExpr = cast.Argument;
+                 }
+-                else if (pExpr is ExprTypeOf typeOf)
++                else if (pExpr is ExprTypeOf)
+                 {
++                    ExprTypeOf typeOf = (ExprTypeOf) pExpr;
+                     return typeOf.SourceType.Type.AssociatedSystemType;
+                 }
+-                else if (pExpr is ExprMethodInfo methodInfo)
++                else if (pExpr is ExprMethodInfo)
+                 {
++                    ExprMethodInfo methodInfo = (ExprMethodInfo) pExpr;
+                     return GetMethodInfoFromExpr(methodInfo);
+                 }
+-                else if (pExpr is ExprConstant constant)
++                else if (pExpr is ExprConstant)
+                 {
++                    ExprConstant constant = (ExprConstant) pExpr;
+                     ConstVal val = constant.Val;
+                     CType underlyingType = pExpr.Type;
+                     object objval;
+@@ -954,8 +962,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+ 
+                     return pExpr.Type.isEnumType() ? Enum.ToObject(pExpr.Type.AssociatedSystemType, objval) : objval;
+                 }
+-                else if (pExpr is ExprZeroInit zeroInit)
++                else if (pExpr is ExprZeroInit)
+                 {
++                    ExprZeroInit zeroInit = (ExprZeroInit) pExpr;
+                     if ((pExpr = zeroInit.OptionalArgument) == null)
+                     {
+                         return Activator.CreateInstance(zeroInit.Type.AssociatedSystemType);
+@@ -981,8 +990,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+                 Expr p = list;
+                 while (list != null)
+                 {
+-                    if (list is ExprList pList)
++                    if (list is ExprList)
+                     {
++                        ExprList pList = (ExprList) list;
+                         p = pList.OptionalElement;
+                         list = pList.OptionalNextListNode;
+                     }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/RuntimeBinder.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/RuntimeBinder.cs
+index 6dc888c6ef..89f881f668 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/RuntimeBinder.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/RuntimeBinder.cs
+@@ -195,7 +195,8 @@ namespace Microsoft.CSharp.RuntimeBinder
+             LocalVariableSymbol[] locals = PopulateLocalScope(payload, pScope, arguments, parameters);
+ 
+             // (1.5) - Check to see if we need to defer.
+-            if (DeferBinding(payload, arguments, args, locals, out DynamicMetaObject o))
++            DynamicMetaObject o;
++            if (DeferBinding(payload, arguments, args, locals, out o))
+             {
+                 deferredBinding = o;
+                 return null;
+@@ -1053,8 +1054,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+ 
+         private static void CheckForConditionalMethodError(Expr pExpr)
+         {
+-            if (pExpr is ExprCall call)
++            if (pExpr is ExprCall)
+             {
++                ExprCall call = (ExprCall)pExpr;
+                 // This mimics the behavior of the native CompilerSymbolLoader in GetConditionalSymbols. Override
+                 // methods cannot have the conditional attribute, but implicitly acquire it from their slot.
+ 
+@@ -1087,8 +1089,9 @@ namespace Microsoft.CSharp.RuntimeBinder
+             ExprMemberGroup memgroup;
+             TypeArray typeArgs;
+ 
+-            if (pResult is ExprCall call)
++            if (pResult is ExprCall)
+             {
++                ExprCall call = (ExprCall) pResult;
+                 type = call.MethWithInst.Ats;
+                 methprop = call.MethWithInst.Meth();
+                 memgroup = call.MemberGroup;
+@@ -1155,12 +1158,15 @@ namespace Microsoft.CSharp.RuntimeBinder
+ 
+         private Expr StripNamedArgument(Expr pArg)
+         {
+-            if (pArg is ExprNamedArgumentSpecification named)
++            if (pArg is ExprNamedArgumentSpecification)
+             {
++                ExprNamedArgumentSpecification named =
++                    (ExprNamedArgumentSpecification) pArg;
+                 pArg = named.Value;
+             }
+-            else if (pArg is ExprArrayInit init)
++            else if (pArg is ExprArrayInit)
+             {
++                ExprArrayInit init = (ExprArrayInit) pArg;
+                 init.OptionalArguments = StripNamedArguments(init.OptionalArguments);
+             }
+ 
+@@ -1169,14 +1175,16 @@ namespace Microsoft.CSharp.RuntimeBinder
+ 
+         private Expr StripNamedArguments(Expr pArg)
+         {
+-            if (pArg is ExprList list)
++            if (pArg is ExprList)
+             {
++                ExprList list = (ExprList) pArg;
+                 for(;;)
+                 {
+                     list.OptionalElement = StripNamedArgument(list.OptionalElement);
+ 
+-                    if (list.OptionalNextListNode is ExprList next)
++                    if (list.OptionalNextListNode is ExprList)
+                     {
++                        ExprList next = (ExprList)list.OptionalNextListNode;
+                         list = next;
+                     }
+                     else
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/Better.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/Better.cs
+index cebfcd94e1..179ac21620 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/Better.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/Better.cs
+@@ -157,8 +157,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             // We then go over the specified arguments and put the type for any named argument in the right position in the array.
+             for (int iParam = 0; iParam < args.carg; iParam++)
+             {
+-                if (prgexpr[iParam] is ExprNamedArgumentSpecification named)
++                if (prgexpr[iParam] is ExprNamedArgumentSpecification)
+                 {
++                    ExprNamedArgumentSpecification named = (ExprNamedArgumentSpecification)prgexpr[iParam];
+                     // We find the index of the type of the argument in the method parameter list and store that in a temp
+                     int index = FindName(methProp.ParameterNames, named.Name);
+                     CType tempType = pta[index];
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/ErrorReporting.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/ErrorReporting.cs
+index c406af43de..0ea81ef21c 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/ErrorReporting.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Binding/ErrorReporting.cs
+@@ -76,22 +76,25 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             {
+                 Debug.Assert(expr != null);
+ 
+-                if (expr is ExprLocal local && local.IsOK)
++                if (expr is ExprLocal && ((ExprLocal)expr).IsOK)
+                 {
++                    ExprLocal local = (ExprLocal)expr;
+                     ReportLocalError(local.Local, kind, isNested);
+                     return true;
+                 }
+ 
+                 Expr pObject = null;
+ 
+-                if (expr is ExprProperty prop)
++                if (expr is ExprProperty)
+                 {
++                    ExprProperty prop = (ExprProperty)expr;
+                     // We've already reported read-only-property errors.
+                     Debug.Assert(prop.MethWithTypeSet != null);
+                     pObject = prop.MemberGroup.OptionalObject;
+                 }
+-                else if (expr is ExprField field)
++                else if (expr is ExprField)
+                 {
++                    ExprField field = (ExprField)expr;
+                     if (field.FieldWithType.Field().isReadOnly)
+                     {
+                         ReportReadOnlyError(field, kind, isNested);
+@@ -105,8 +108,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+                 if (pObject != null && pObject.Type.isStructOrEnum())
+                 {
+-                    if (pObject is IExprWithArgs withArgs)
++                    if (pObject is IExprWithArgs)
+                     {
++                        IExprWithArgs withArgs = (IExprWithArgs)pObject;
+                         // assigning to RHS of method or property getter returning a value-type on the stack or
+                         // passing RHS of method or property getter returning a value-type on the stack, as ref or out
+                         ErrorContext.Error(ErrorCode.ERR_ReturnNotLValue, withArgs.GetSymWithType());
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Conversion.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Conversion.cs
+index bb62a926b5..873feff72f 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Conversion.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Conversion.cs
+@@ -391,9 +391,10 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 FUNDTYPE ftSrc = expr.Type.fundType();
+                 FUNDTYPE ftDest = dest.fundType();
+ 
+-                if (expr is ExprConstant constant && constant.IsOK &&
++                if (expr is ExprConstant && ((ExprConstant)expr).IsOK &&
+                     expr.Type.isSimpleType() && dest.isSimpleType())
+                 {
++                    ExprConstant constant = (ExprConstant) expr;
+                     if ((ftSrc == FUNDTYPE.FT_I4 && (ftDest <= FUNDTYPE.FT_LASTNONLONG || ftDest == FUNDTYPE.FT_U8)) ||
+                         (ftSrc == FUNDTYPE.FT_I8 && ftDest == FUNDTYPE.FT_U8))
+                     {
+@@ -421,8 +422,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                     ErrorContext.Error(dest is TypeParameterType ? ErrorCode.ERR_TypeVarCantBeNull : ErrorCode.ERR_ValueCantBeNull, dest);
+                 }
+ 
+-                else if (expr is ExprMemberGroup memGrp)
++                else if (expr is ExprMemberGroup)
+                 {
++                    ExprMemberGroup memGrp = (ExprMemberGroup) expr;
+                     BindGrpConversion(memGrp, dest, true);
+                 }
+                 else if (!TypeManager.TypeContainsAnonymousTypes(dest) && canCast(expr.Type, dest, flags))
+@@ -555,8 +557,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                     {
+                         ErrorContext.Error(ErrorCode.ERR_ValueCantBeNull, dest);
+                     }
+-                    else if (expr is ExprMemberGroup memGrp)
++                    else if (expr is ExprMemberGroup)
+                     {
++                        ExprMemberGroup memGrp = (ExprMemberGroup)expr;
+                         BindGrpConversion(memGrp, dest, true);
+                     }
+                     else
+@@ -1396,8 +1399,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             for (;;)
+             {
+                 Debug.Assert(pExpr != null);
+-                if (pExpr is ExprCall call)
++                if (pExpr is ExprCall)
+                 {
++                    ExprCall call = (ExprCall)pExpr;
+                     switch (call.NullableCallLiftKind)
+                     {
+                         case NullableCallLiftKind.NotLifted:
+@@ -1411,8 +1415,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                             continue;
+                     }
+                 }
+-                else if (pExpr is ExprUserDefinedConversion udc)
++                else if (pExpr is ExprUserDefinedConversion)
+                 {
++                    ExprUserDefinedConversion udc = (ExprUserDefinedConversion)pExpr;
+                     pExpr = udc.UserDefinedCall;
+                     continue;
+                 }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/EXPRExtensions.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/EXPRExtensions.cs
+index 075ed23a11..6408df4c36 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/EXPRExtensions.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/EXPRExtensions.cs
+@@ -33,8 +33,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             Expr exprCur = expr;
+             while (exprCur != null)
+             {
+-                if (exprCur is ExprList list)
++                if (exprCur is ExprList)
+                 {
++                    ExprList list = (ExprList)exprCur;
+                     yield return list.OptionalElement;
+                     exprCur = list.OptionalNextListNode;
+                 }
+@@ -61,12 +62,12 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+         }
+         public static bool isNull(this Expr expr)
+         {
+-            return expr is ExprConstant constant && constant.IsOK && (expr.Type.fundType() == FUNDTYPE.FT_REF) && constant.Val.IsNullRef;
++            return expr is ExprConstant && ((ExprConstant)expr).IsOK && (expr.Type.fundType() == FUNDTYPE.FT_REF) && ((ExprConstant)expr).Val.IsNullRef;
+         }
+ 
+         public static bool IsZero(this Expr expr)
+         {
+-            return expr is ExprConstant constant && constant.IsOK && constant.IsZero;
++            return expr is ExprConstant && ((ExprConstant)expr).IsOK && ((ExprConstant)expr).IsZero;
+         }
+ 
+         private static Expr GetSeqVal(this Expr expr)
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExplicitConversion.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExplicitConversion.cs
+index 6ea8879c40..137e950e76 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExplicitConversion.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExplicitConversion.cs
+@@ -207,8 +207,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                             VSFAIL("BindExplicitConversion failed unexpectedly");
+                             return false;
+                         }
+-                        if (_exprDest is ExprUserDefinedConversion udc)
++                        if (_exprDest is ExprUserDefinedConversion)
+                         {
++                            ExprUserDefinedConversion udc = (ExprUserDefinedConversion)_exprDest;
+                             udc.Argument = _exprSrc;
+                         }
+                     }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExprFactory.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExprFactory.cs
+index 99ee57626a..ec0d29d6f3 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExprFactory.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExprFactory.cs
+@@ -265,8 +265,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             ExprUserLogicalOp rval = new ExprUserLogicalOp(pType);
+             Expr leftChild = ((ExprList)pCallOp.OptionalArguments).OptionalElement;
+             Debug.Assert(leftChild != null);
+-            if (leftChild is ExprWrap wrap)
++            if (leftChild is ExprWrap)
+             {
++                ExprWrap wrap = (ExprWrap)leftChild;
+                 // In the EE case, we don't create WRAPEXPRs.
+                 leftChild = wrap.OptionalExpression;
+                 Debug.Assert(leftChild != null);
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExpressionBinder.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExpressionBinder.cs
+index 60a1661eac..dc04fa1657 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExpressionBinder.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ExpressionBinder.cs
+@@ -601,10 +601,11 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             // Check if we have a compile time constant. If we do, create a constant for it and set the
+             // original tree to the cast.
+ 
+-            if (exprConst is ExprConstant constant && exprFlags == 0 &&
++            if (exprConst is ExprConstant && exprFlags == 0 &&
+                 exprSrc.Type.fundType() == typeDest.fundType() &&
+-                (!exprSrc.Type.isPredefType(PredefinedType.PT_STRING) || constant.Val.IsNullRef))
++                (!exprSrc.Type.isPredefType(PredefinedType.PT_STRING) || ((ExprConstant)exprConst).Val.IsNullRef))
+             {
++                ExprConstant constant = (ExprConstant)exprConst;
+                 ExprConstant expr = GetExprFactory().CreateConstant(typeDest, constant.Val);
+                 pexprDest = expr;
+                 return;
+@@ -1191,8 +1192,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             while (list != null)
+             {
+                 Expr arg;
+-                if (list is ExprList next)
++                if (list is ExprList)
+                 {
++                    ExprList next = (ExprList)list;
+                     arg = next.OptionalElement;
+                     list = next.OptionalNextListNode;
+                 }
+@@ -1265,8 +1267,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+         private Expr UnwrapExpression(Expr pExpression)
+         {
+-            while (pExpression is ExprWrap wrap)
++            while (pExpression is ExprWrap)
+             {
++                ExprWrap wrap = (ExprWrap)pExpression;
+                 Expr wrapped = wrap.OptionalExpression;
+                 if (wrapped == null)
+                 {
+@@ -1344,8 +1347,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 return false;
+             if (expr.isLvalue())
+             {
+-                if (expr is ExprProperty prop)
++                if (expr is ExprProperty)
+                 {
++                    ExprProperty prop = (ExprProperty)expr;
+                     CheckLvalueProp(prop);
+                 }
+                 markFieldAssigned(expr);
+@@ -1571,9 +1575,10 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+                 // If we're invoking code on a struct-valued field, mark the struct as assigned (to
+                 // avoid warning CS0649).
+-                if (pObject is ExprField field && !field.FieldWithType.Field().isAssigned && !swt.Sym.IsFieldSymbol() &&
++                if (pObject is ExprField && !((ExprField)pObject).FieldWithType.Field().isAssigned && !swt.Sym.IsFieldSymbol() &&
+                     typeObj.isStructType() && !typeObj.isPredefined())
+                 {
++                    ExprField field = (ExprField) pObject;
+                     field.FieldWithType.Field().isAssigned = true;
+                 }
+ 
+@@ -1786,8 +1791,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+                     Expr argument = indir;
+                     Expr rval;
+-                    if (argument is ExprNamedArgumentSpecification named)
++                    if (argument is ExprNamedArgumentSpecification)
+                     {
++                        ExprNamedArgumentSpecification named = (ExprNamedArgumentSpecification)argument;
+                         int index = 0;
+                         // If we're named, look for the type of the matching name.
+                         foreach (Name i in mostDerivedMethod.ParameterNames)
+@@ -1928,8 +1934,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                     Expr expr = it.Current();
+                     count++;
+ 
+-                    if (expr is ExprNamedArgumentSpecification named)
++                    if (expr is ExprNamedArgumentSpecification)
+                     {
++                        ExprNamedArgumentSpecification named = (ExprNamedArgumentSpecification)expr;
+                         named.Value = tryConvert(named.Value, elementType);
+                     }
+                     else
+@@ -1951,8 +1958,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+         private void markFieldAssigned(Expr expr)
+         {
+-            if (0 != (expr.Flags & EXPRFLAG.EXF_LVALUE) && expr is ExprField field)
++            if (0 != (expr.Flags & EXPRFLAG.EXF_LVALUE) && expr is ExprField)
+             {
++                ExprField field = (ExprField) expr;
+                 FieldSymbol symbol;
+                 do
+                 {
+@@ -2019,8 +2027,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             for (Expr list = args; list != null; iarg++)
+             {
+                 Expr arg;
+-                if (list is ExprList next)
++                if (list is ExprList)
+                 {
++                    ExprList next = (ExprList)list;
+                     arg = next.OptionalElement;
+                     list = next.OptionalNextListNode;
+                 }
+@@ -2374,8 +2383,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             {
+                 Expr arg;
+ 
+-                if (list is ExprList next)
++                if (list is ExprList)
+                 {
++                    ExprList next = (ExprList)list;
+                     arg = next.OptionalElement;
+                     list = next.OptionalNextListNode;
+                 }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/GroupToArgsBinder.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/GroupToArgsBinder.cs
+index 7708f197ae..b75ac340be 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/GroupToArgsBinder.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/GroupToArgsBinder.cs
+@@ -510,7 +510,7 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                     // then let us through.
+                     if (methprop.isParamArray &&
+                         index < pArguments.carg &&
+-                        pArguments.prgexpr[index] is ExprArrayInit arrayInit && arrayInit.GeneratedForParamArray)
++                        pArguments.prgexpr[index] is ExprArrayInit && ((ExprArrayInit)pArguments.prgexpr[index]).GeneratedForParamArray)
+                     {
+                         paramArrayArgument = pArguments.prgexpr[index];
+                     }
+@@ -518,7 +518,7 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                     // Positional.
+                     if (index < pArguments.carg &&
+                         !(pArguments.prgexpr[index] is ExprNamedArgumentSpecification) &&
+-                        !(pArguments.prgexpr[index] is ExprArrayInit arrayInitPos && arrayInitPos.GeneratedForParamArray))
++                        !(pArguments.prgexpr[index] is ExprArrayInit && ((ExprArrayInit)pArguments.prgexpr[index]).GeneratedForParamArray))
+                     {
+                         pExprArguments[index] = pArguments.prgexpr[index++];
+                         continue;
+@@ -839,7 +839,7 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 for (int i = 0; i < pArguments.carg; i++)
+                 {
+                     Expr expr = prgexpr[i];
+-                    if (expr is ExprNamedArgumentSpecification named && named.Name == pName)
++                    if (expr is ExprNamedArgumentSpecification && ((ExprNamedArgumentSpecification)expr).Name == pName)
+                     {
+                         return expr;
+                     }
+@@ -861,7 +861,8 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 HashSet<Name> names = new HashSet<Name>();
+                 for (int i = 0; i < _pArguments.carg; i++)
+                 {
+-                    if (!(_pArguments.prgexpr[i] is ExprNamedArgumentSpecification named))
++                    ExprNamedArgumentSpecification named;
++                    if (!(_pArguments.prgexpr[i] is ExprNamedArgumentSpecification))
+                     {
+                         if (!currentPosition.IsEmpty())
+                         {
+@@ -869,6 +870,7 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                         }
+                         continue;
+                     }
++                    named = (ExprNamedArgumentSpecification) _pArguments.prgexpr[i];
+ 
+                     Name name = named.Name;
+                     if (!methprop.ParameterNames.Contains(name))
+@@ -1080,8 +1082,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                             Expr pArgument = _pArguments.prgexpr[ivar];
+ 
+                             // If we have a named argument, strip it to do the conversion.
+-                            if (pArgument is ExprNamedArgumentSpecification named)
++                            if (pArgument is ExprNamedArgumentSpecification)
+                             {
++                                ExprNamedArgumentSpecification named = (ExprNamedArgumentSpecification)pArgument;
+                                 pArgument = named.Value;
+                             }
+ 
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ImplicitConversion.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ImplicitConversion.cs
+index f1a0159e53..fdbd1dd426 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ImplicitConversion.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/ImplicitConversion.cs
+@@ -172,8 +172,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                         VSFAIL("Bad type symbol kind");
+                         break;
+                     case TypeKind.TK_MethodGroupType:
+-                        if (_exprSrc is ExprMemberGroup memGrp)
++                        if (_exprSrc is ExprMemberGroup)
+                         {
++                            ExprMemberGroup memGrp = (ExprMemberGroup)_exprSrc;
+                             ExprCall outExpr;
+                             bool retVal = _binder.BindGrpConversion(memGrp, _typeDest, _needsExprDest, out outExpr, false);
+                             _exprDest = outExpr;
+@@ -744,10 +745,10 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 // *   A constant-expression of type long can be converted to type ulong, provided the value of
+                 //     the constant-expression is not negative.
+                 // Note: Don't use GetConst here since the conversion only applies to bona-fide compile time constants.
+-                if (_exprSrc is ExprConstant constant && _exprSrc.IsOK &&
++                if (_exprSrc is ExprConstant && _exprSrc.IsOK &&
+                     ((ptSrc == PredefinedType.PT_INT && ptDest != PredefinedType.PT_BOOL && ptDest != PredefinedType.PT_CHAR) ||
+                     (ptSrc == PredefinedType.PT_LONG && ptDest == PredefinedType.PT_ULONG)) &&
+-                    isConstantInRange(constant, _typeDest))
++                    isConstantInRange(((ExprConstant)_exprSrc), _typeDest))
+                 {
+                     // Special case (CLR 6.1.6): if integral constant is in range, the conversion is a legal implicit conversion.
+                     convertKind = ConvKind.Implicit;
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/MethodTypeInferrer.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/MethodTypeInferrer.cs
+index 589b9c96d0..2559ca5c85 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/MethodTypeInferrer.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/MethodTypeInferrer.cs
+@@ -1064,10 +1064,11 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             // SPEC:   yields a single method with return CType U then a lower-bound
+             // SPEC:   inference is made from U to Tb.
+ 
+-            if (!(pSource is ExprMemberGroup memGrp))
++            if (!(pSource is ExprMemberGroup))
+             {
+                 return false;
+             }
++            ExprMemberGroup memGrp = (ExprMemberGroup)pSource;
+             pType = pType.GetDelegateTypeOfPossibleExpression();
+             if (!pType.isDelegateType())
+             {
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Nullable.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Nullable.cs
+index 19dbea7e2f..1d258f2d67 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Nullable.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Nullable.cs
+@@ -29,8 +29,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+         {
+             Debug.Assert(expr != null);
+ 
+-            if (expr is ExprCall pCall && pCall.MemberGroup.OptionalObject == null)
++            if (expr is ExprCall && ((ExprCall)expr).MemberGroup.OptionalObject == null)
+             {
++                ExprCall pCall = (ExprCall)expr;
+                 MethodSymbol meth = pCall.MethWithInst.Meth();
+                 if (meth != null && meth.IsNullableConstructor())
+                 {
+@@ -45,7 +46,8 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+ 
+         public static Expr StripNullableConstructor(Expr pExpr)
+         {
+-            while (IsNullableConstructor(pExpr, out ExprCall call))
++            ExprCall call;
++            while (IsNullableConstructor(pExpr, out call))
+             {
+                 pExpr = call.OptionalArguments;
+                 Debug.Assert(pExpr != null && !(pExpr is ExprList));
+@@ -60,7 +62,8 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             Debug.Assert(exprSrc != null && exprSrc.Type.IsNullableType());
+ 
+             // For new T?(x), the answer is x.
+-            if (IsNullableConstructor(exprSrc, out ExprCall call))
++            ExprCall call;
++            if (IsNullableConstructor(exprSrc, out call))
+             {
+                 var args = call.OptionalArguments;
+                 Debug.Assert(args != null && !(args is ExprList));
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/ExpressionIterator.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/ExpressionIterator.cs
+index 96ee032422..9397543de6 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/ExpressionIterator.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/ExpressionIterator.cs
+@@ -83,8 +83,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 _pList = null;
+                 _pCurrent = null;
+             }
+-            else if (pExpr is ExprList pList)
++            else if (pExpr is ExprList)
+             {
++                ExprList pList = (ExprList)pExpr;
+                 _pList = pList;
+                 _pCurrent = pList.OptionalElement;
+             }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExprVisitorBase.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExprVisitorBase.cs
+index e2ce8e88f5..ded4d0b216 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExprVisitorBase.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExprVisitorBase.cs
+@@ -21,8 +21,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 return pResult;
+             }
+ 
+-            if (pExpr is ExprStatement statement)
++            if (pExpr is ExprStatement)
+             {
++                ExprStatement statement = (ExprStatement)pExpr;
+                 return CacheExprMapping(pExpr, DispatchStatementList(statement));
+             }
+ 
+@@ -279,11 +280,13 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                             return;
+                         }
+ 
+-                        if (!(nextNode is ExprList next))
++                        ExprList next;
++                        if (!(nextNode is ExprList))
+                         {
+                             list.OptionalNextListNode = Visit(nextNode);
+                             return;
+                         }
++                        next = (ExprList)nextNode;
+ 
+                         list = next;
+                     }
+diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExpressionTreeRewriter.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExpressionTreeRewriter.cs
+index 8a841ee5d9..cb40a59f6d 100644
+--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExpressionTreeRewriter.cs
++++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Tree/Visitors/ExpressionTreeRewriter.cs
+@@ -54,8 +54,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             // For assignments, we either have a member assignment or an indexed assignment.
+             //Debug.Assert(assignment.GetLHS().isPROP() || assignment.GetLHS().isFIELD() || assignment.GetLHS().isARRAYINDEX() || assignment.GetLHS().isLOCAL());
+             Expr lhs;
+-            if (assignment.LHS is ExprProperty prop)
++            if (assignment.LHS is ExprProperty)
+             {
++                ExprProperty prop = (ExprProperty)assignment.LHS;
+                 if (prop.OptionalArguments== null)
+                 {
+                     // Regular property.
+@@ -318,8 +319,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 // can handle in the general case all implicit boxing conversions. Right now it 
+                 // requires that all arguments to a call that need to be boxed be explicitly boxed.
+ 
+-                if (pObject != null && pObject is ExprCast cast && cast.IsBoxingCast)
++                if (pObject != null && pObject is ExprCast && ((ExprCast)pObject).IsBoxingCast)
+                 {
++                    ExprCast cast = (ExprCast) pObject;
+                     pObject = cast.Argument;
+                 }
+                 pObject = Visit(pObject);
+@@ -597,8 +599,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             if (udcall != null)
+             {
+                 Debug.Assert(udcall.Kind == ExpressionKind.Call || udcall.Kind == ExpressionKind.UserLogicalOp);
+-                if (udcall is ExprCall ascall)
++                if (udcall is ExprCall)
+                 {
++                    ExprCall ascall = (ExprCall)udcall;
+                     ExprList args = (ExprList)ascall.OptionalArguments;
+                     Debug.Assert(args.OptionalNextListNode.Kind != ExpressionKind.List);
+                     p1 = args.OptionalElement;
+@@ -731,8 +734,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+             ExprBlock body = anonmeth.OptionalBody;
+ 
+             // The most likely case:
+-            if (body.OptionalStatements is ExprReturn ret)
++            if (body.OptionalStatements is ExprReturn)
+             {
++                ExprReturn ret = (ExprReturn)body.OptionalStatements;
+                 Debug.Assert(ret.OptionalObject != null);
+                 return Visit(ret.OptionalObject);
+             }
+@@ -854,8 +858,9 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+                 Expr pUDConversion = call?.PConversions;
+                 if (pUDConversion != null)
+                 {
+-                    if (pUDConversion is ExprCall convCall)
++                    if (pUDConversion is ExprCall)
+                     {
++                        ExprCall convCall = (ExprCall)pUDConversion;
+                         Expr pUDConversionArgument = convCall.OptionalArguments;
+                         if (IsNullableValueAccess(pUDConversionArgument, pArgument))
+                         {
+@@ -1238,23 +1243,25 @@ namespace Microsoft.CSharp.RuntimeBinder.Semantics
+         private bool IsNullableValueAccess(Expr pExpr, Expr pObject)
+         {
+             Debug.Assert(pExpr != null);
+-            return pExpr is ExprProperty prop && prop.MemberGroup.OptionalObject == pObject && pObject.Type.IsNullableType();
++            return pExpr is ExprProperty && ((ExprProperty)pExpr).MemberGroup.OptionalObject == pObject && pObject.Type.IsNullableType();
+         }
+ 
+         private bool IsDelegateConstructorCall(Expr pExpr)
+         {
+             Debug.Assert(pExpr != null);
+-            if (!(pExpr is ExprCall pCall))
++            ExprCall pCall;
++            if (!(pExpr is ExprCall))
+             {
+                 return false;
+             }
++            pCall = (ExprCall)pExpr;
+ 
+             return pCall.MethWithInst.Meth() != null &&
+                 pCall.MethWithInst.Meth().IsConstructor() &&
+                 pCall.Type.isDelegateType() &&
+                 pCall.OptionalArguments != null &&
+-                pCall.OptionalArguments is ExprList list &&
+-                list.OptionalNextListNode.Kind == ExpressionKind.FunctionPointer;
++                (pCall.OptionalArguments is ExprList) &&
++                ((ExprList)pCall.OptionalArguments).OptionalNextListNode.Kind == ExpressionKind.FunctionPointer;
+         }
+         private static bool isEnumToDecimalConversion(CType argtype, CType desttype)
+         {
+diff --git a/src/System.Collections/src/System/Collections/Generic/SortedSet.TreeSubSet.cs b/src/System.Collections/src/System/Collections/Generic/SortedSet.TreeSubSet.cs
+index 4eb817c0af..671636f428 100644
+--- a/src/System.Collections/src/System/Collections/Generic/SortedSet.TreeSubSet.cs
++++ b/src/System.Collections/src/System/Collections/Generic/SortedSet.TreeSubSet.cs
+@@ -352,7 +352,10 @@ namespace System.Collections.Generic
+                 throw new PlatformNotSupportedException();
+             }
+ 
+-            protected override void OnDeserialization(Object sender) => throw new PlatformNotSupportedException();
++            protected override void OnDeserialization(Object sender)
++            {
++                throw new PlatformNotSupportedException();
++            }
+         }
+     }
+ }
+diff --git a/src/System.Linq.Expressions/src/System/Dynamic/Utils/TypeExtensions.cs b/src/System.Linq.Expressions/src/System/Dynamic/Utils/TypeExtensions.cs
+index c45caba093..ef9a25203d 100644
+--- a/src/System.Linq.Expressions/src/System/Dynamic/Utils/TypeExtensions.cs
++++ b/src/System.Linq.Expressions/src/System/Dynamic/Utils/TypeExtensions.cs
+@@ -65,7 +65,8 @@ namespace System.Dynamic.Utils
+         internal static ParameterInfo[] GetParametersCached(this MethodBase method)
+         {
+             CacheDict<MethodBase, ParameterInfo[]> pic = s_paramInfoCache;
+-            if (!pic.TryGetValue(method, out ParameterInfo[] pis))
++            ParameterInfo[] pis;
++            if (!pic.TryGetValue(method, out pis))
+             {
+                 pis = method.GetParameters();
+ 
+diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/LambdaCompiler.Expressions.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/LambdaCompiler.Expressions.cs
+index d8b1c61f74..8cefbd4f19 100644
+--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/LambdaCompiler.Expressions.cs
++++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/LambdaCompiler.Expressions.cs
+@@ -952,8 +952,9 @@ namespace System.Linq.Expressions.Compiler
+         private void EmitMemberAssignment(MemberAssignment binding, Type objectType)
+         {
+             EmitExpression(binding.Expression);
+-            if (binding.Member is FieldInfo fi)
++            if (binding.Member is FieldInfo)
+             {
++                FieldInfo fi = (FieldInfo)binding.Member;
+                 _ilg.Emit(OpCodes.Stfld, fi);
+             }
+             else
+@@ -1097,7 +1098,7 @@ namespace System.Linq.Expressions.Compiler
+         private static Type GetMemberType(MemberInfo member)
+         {
+             Debug.Assert(member is FieldInfo || member is PropertyInfo);
+-            return member is FieldInfo fi ? fi.FieldType : (member as PropertyInfo).PropertyType;
++            return member is FieldInfo ? ((FieldInfo)member).FieldType : (member as PropertyInfo).PropertyType;
+         }
+ 
+         #endregion
+diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberAssignment.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberAssignment.cs
+index 475a6c63cc..0787b10186 100644
+--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberAssignment.cs
++++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberAssignment.cs
+@@ -93,23 +93,23 @@ namespace System.Linq.Expressions
+ 
+             // Null paramName as there are two paths here with different parameter names at the API
+             TypeUtils.ValidateType(decType, null);
+-            switch (member)
++            if (member is PropertyInfo)
+             {
+-                case PropertyInfo pi:
+-                    if (!pi.CanWrite)
+-                    {
+-                        throw Error.PropertyDoesNotHaveSetter(pi, nameof(member));
+-                    }
+-
+-                    memberType = pi.PropertyType;
+-                    break;
+-
+-                case FieldInfo fi:
+-                    memberType = fi.FieldType;
+-                    break;
+-
+-                default:
+-                    throw Error.ArgumentMustBeFieldInfoOrPropertyInfo(nameof(member));
++                PropertyInfo pi = (PropertyInfo) member;
++                if (!pi.CanWrite)
++                {
++                    throw Error.PropertyDoesNotHaveSetter(pi, nameof(member));
++                }
++                memberType = pi.PropertyType;
++            }
++            else if (member is FieldInfo)
++            {
++                FieldInfo fi = (FieldInfo) member;
++                memberType = fi.FieldType;
++            }
++            else
++            {
++                throw Error.ArgumentMustBeFieldInfoOrPropertyInfo(nameof(member));
+             }
+         }
+     }
+diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberBinding.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberBinding.cs
+index c1c5884618..43c0698f90 100644
+--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberBinding.cs
++++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberBinding.cs
+@@ -61,6 +61,9 @@ namespace System.Linq.Expressions
+             return ExpressionStringBuilder.MemberBindingToString(this);
+         }
+ 
+-        internal virtual void ValidateAsDefinedHere(int index) => throw Error.UnknownBindingType(index);
++        internal virtual void ValidateAsDefinedHere(int index)
++        {
++            throw Error.UnknownBindingType(index);
++        }
+     }
+ }
+diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberMemberBinding.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberMemberBinding.cs
+index f3981a2b1f..75dd7141da 100644
+--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberMemberBinding.cs
++++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/MemberMemberBinding.cs
+@@ -127,23 +127,24 @@ namespace System.Linq.Expressions
+ 
+             // Null paramName as there are several paths here with different parameter names at the API
+             TypeUtils.ValidateType(decType, null, allowByRef: true, allowPointer: true);
+-            switch (member)
++            if (member is PropertyInfo)
+             {
+-                case PropertyInfo pi:
+-                    if (!pi.CanRead)
+-                    {
+-                        throw Error.PropertyDoesNotHaveGetter(pi, nameof(member));
+-                    }
+-
+-                    memberType = pi.PropertyType;
+-                    break;
+-
+-                case FieldInfo fi:
+-                    memberType = fi.FieldType;
+-                    break;
++                PropertyInfo pi = (PropertyInfo)member;
++                if (!pi.CanRead)
++                {
++                    throw Error.PropertyDoesNotHaveGetter(pi, nameof(member));
++                }
+ 
+-                default:
+-                    throw Error.ArgumentMustBeFieldInfoOrPropertyInfo(nameof(member));
++                memberType = pi.PropertyType;
++            }
++            else if (member is FieldInfo)
++            {
++                FieldInfo fi = (FieldInfo)member;
++                memberType = fi.FieldType;
++            }
++            else
++            {
++                throw Error.ArgumentMustBeFieldInfoOrPropertyInfo(nameof(member));
+             }
+         }
+ 
+diff --git a/src/System.Net.HttpListener/src/System/Net/WebSockets/HttpListenerWebSocketContext.cs b/src/System.Net.HttpListener/src/System/Net/WebSockets/HttpListenerWebSocketContext.cs
+index 5321578946..ff54677027 100644
+--- a/src/System.Net.HttpListener/src/System/Net/WebSockets/HttpListenerWebSocketContext.cs
++++ b/src/System.Net.HttpListener/src/System/Net/WebSockets/HttpListenerWebSocketContext.cs
+@@ -94,8 +94,9 @@ namespace System.Net.WebSockets
+                 if (!(user is WindowsPrincipal))
+                 {
+                     // AuthenticationSchemes.Basic.
+-                    if (user.Identity is HttpListenerBasicIdentity basicIdentity)
++                    if (user.Identity is HttpListenerBasicIdentity)
+                     {
++                        HttpListenerBasicIdentity basicIdentity = (HttpListenerBasicIdentity)user.Identity;
+                         return new GenericPrincipal(new HttpListenerBasicIdentity(basicIdentity.Name, basicIdentity.Password), null);
+                     }
+                 }
diff --git a/gnu/packages/patches/mono-5.4.0-patches.patch b/gnu/packages/patches/mono-5.4.0-patches.patch
new file mode 100644
index 00000000000..007a6b847c6
--- /dev/null
+++ b/gnu/packages/patches/mono-5.4.0-patches.patch
@@ -0,0 +1,100 @@
+diff --git a/mcs/class/System/Mono.Net.Security/AsyncProtocolRequest.cs b/mcs/class/System/Mono.Net.Security/AsyncProtocolRequest.cs
+index 3c537a7e427..59beb19255f 100644
+--- a/mcs/class/System/Mono.Net.Security/AsyncProtocolRequest.cs
++++ b/mcs/class/System/Mono.Net.Security/AsyncProtocolRequest.cs
+@@ -316,7 +316,9 @@ namespace Mono.Net.Security
+ 		{
+ 			Debug ("ProcessRead - read user: {0} {1}", this, status);
+ 
+-			var (ret, wantMore) = Parent.ProcessRead (UserBuffer);
++            System.ValueTuple<int, bool> t0 = Parent.ProcessRead (UserBuffer);
++            var ret = t0.Item1;
++            var wantMore = t0.Item2;
+ 
+ 			Debug ("ProcessRead - read user done: {0} - {1} {2}", this, ret, wantMore);
+ 
+@@ -355,7 +357,9 @@ namespace Mono.Net.Security
+ 				return AsyncOperationStatus.Complete;
+ 			}
+ 
+-			var (ret, wantMore) = Parent.ProcessWrite (UserBuffer);
++            System.ValueTuple<int, bool> t0 = Parent.ProcessWrite (UserBuffer);
++            var ret = t0.Item1;
++            var wantMore = t0.Item2;
+ 
+ 			Debug ("ProcessWrite - write user done: {0} - {1} {2}", this, ret, wantMore);
+ 
+diff --git a/mcs/class/System/Mono.Net.Security/MobileAuthenticatedStream.cs b/mcs/class/System/Mono.Net.Security/MobileAuthenticatedStream.cs
+index 2b380a1ae6c..66e45bc1f1d 100644
+--- a/mcs/class/System/Mono.Net.Security/MobileAuthenticatedStream.cs
++++ b/mcs/class/System/Mono.Net.Security/MobileAuthenticatedStream.cs
+@@ -403,8 +403,10 @@ namespace Mono.Net.Security
+ 				       asyncReadRequest != null ? "async" : "",
+ 				       readBuffer != null ? readBuffer.ToString () : "");
+ 				var asyncRequest = asyncHandshakeRequest ?? asyncReadRequest;
+-				var (ret, wantMore) = InternalRead (asyncRequest, readBuffer, buffer, offset, size);
+-				outWantMore = wantMore;
++                System.ValueTuple<int, bool> t0 = InternalRead (asyncRequest, readBuffer, buffer, offset, size);
++                var ret = t0.Item1;
++                var wantMore = t0.Item2;
++                outWantMore = wantMore;
+ 				return ret;
+ 			} catch (Exception ex) {
+ 				Debug ("InternalRead failed: {0}", ex);
+@@ -414,7 +416,7 @@ namespace Mono.Net.Security
+ 			}
+ 		}
+ 
+-		(int, bool) InternalRead (AsyncProtocolRequest asyncRequest, BufferOffsetSize internalBuffer, byte[] buffer, int offset, int size)
++		System.ValueTuple<int, bool> InternalRead (AsyncProtocolRequest asyncRequest, BufferOffsetSize internalBuffer, byte[] buffer, int offset, int size)
+ 		{
+ 			if (asyncRequest == null)
+ 				throw new InvalidOperationException ();
+@@ -436,7 +438,7 @@ namespace Mono.Net.Security
+ 				Debug ("InternalRead #1: {0} {1} {2}", internalBuffer.Offset, internalBuffer.TotalBytes, size);
+ 				internalBuffer.Offset = internalBuffer.Size = 0;
+ 				asyncRequest.RequestRead (size);
+-				return (0, true);
++				return new ValueTuple<int, bool>(0, true);
+ 			}
+ 
+ 			/*
+@@ -451,7 +453,7 @@ namespace Mono.Net.Security
+ 			Buffer.BlockCopy (internalBuffer.Buffer, internalBuffer.Offset, buffer, offset, len);
+ 			internalBuffer.Offset += len;
+ 			internalBuffer.Size -= len;
+-			return (len, !internalBuffer.Complete && len < size);
++			return new ValueTuple<int, bool>(len, !internalBuffer.Complete && len < size);
+ 		}
+ 
+ 		/*
+@@ -620,21 +622,23 @@ namespace Mono.Net.Security
+ 			}
+ 		}
+ 
+-		internal (int, bool) ProcessRead (BufferOffsetSize userBuffer)
++		internal System.ValueTuple<int, bool> ProcessRead (BufferOffsetSize userBuffer)
+ 		{
+ 			lock (ioLock) {
+ 				// This operates on the internal buffer and will never block.
+-				var ret = xobileTlsContext.Read (userBuffer.Buffer, userBuffer.Offset, userBuffer.Size, out bool wantMore);
+-				return (ret, wantMore);
++                bool wantMore;
++				var ret = xobileTlsContext.Read (userBuffer.Buffer, userBuffer.Offset, userBuffer.Size, out wantMore);
++				return new System.ValueTuple<int, bool>(ret, wantMore);
+ 			}
+ 		}
+ 
+-		internal (int, bool) ProcessWrite (BufferOffsetSize userBuffer)
++		internal System.ValueTuple<int, bool> ProcessWrite (BufferOffsetSize userBuffer)
+ 		{
+ 			lock (ioLock) {
+ 				// This operates on the internal buffer and will never block.
+-				var ret = xobileTlsContext.Write (userBuffer.Buffer, userBuffer.Offset, userBuffer.Size, out bool wantMore);
+-				return (ret, wantMore);
++                bool wantMore;
++				var ret = xobileTlsContext.Write (userBuffer.Buffer, userBuffer.Offset, userBuffer.Size, out wantMore);
++				return new System.ValueTuple<int, bool>(ret, wantMore);
+ 			}
+ 		}
+ 
-- 
Efraim Flashner   <[email-masked]>   אפרים פלשנר
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