gnu: Add roslyn@3.0.0.

* gnu/packages/patches/roslyn-3.0.0-bootstrap-with-csc-2.8.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add reference to it.
* gnu/packages/dotnet.scm (roslyn-3.0): New variable.

Change-Id: I385b29abff8c0b4672125786b948aafdd69cb014

3 files changed, 496 insertions, 0 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index aca3d6cbef6..0046d700f4c 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -2427,6 +2427,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/roslyn-2.0.0-bootstrap-with-mono.patch   \
   %D%/packages/patches/roslyn-2.3.0-default-literal-for-csc-2.0.patch   \
   %D%/packages/patches/roslyn-2.8.2-csharp-7.2-for-csc-2.3.patch        \
+  %D%/packages/patches/roslyn-3.0.0-bootstrap-with-csc-2.8.patch        \
   %D%/packages/patches/rottlog-direntry.patch                   \
   %D%/packages/patches/ruby-actionpack-remove-browser-tests.patch       \
   %D%/packages/patches/ruby-activesupport-fix-deprecation-warning.patch \
diff --git a/gnu/packages/dotnet.scm b/gnu/packages/dotnet.scm
index 2564dc2f33f..b914d29fe60 100644
--- a/gnu/packages/dotnet.scm
+++ b/gnu/packages/dotnet.scm
@@ -2783,6 +2783,180 @@ namespace Microsoft.DiaSymReader
      "This package provides the Roslyn C# compiler (@command{csc}), built
 from source using @code{roslyn-2.3} as the bootstrap compiler.  It produces
 a C# 7.2 compiler.")))
+
+;;;
+;;; roslyn-3.0: inherits roslyn-2.8, built with csc 2.8
+;;;
+
+(define-public roslyn-3.0
+  (package
+    (inherit roslyn-2.8)
+    (version "3.0.0")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/dotnet/roslyn")
+             (commit (string-append "version-" version))))
+       (file-name (git-file-name "roslyn" version))
+       (sha256
+        (base32
+         "17x9bapqaaapa7jsb2sz9pm20swgj40naxlgci4nc9xh7brahcqw"))
+       (patches
+        (search-patches "roslyn-3.0.0-bootstrap-with-csc-2.8.patch"))))
+    (native-inputs (list roslyn-2.8))
+    (arguments
+     (substitute-keyword-arguments (package-arguments roslyn-2.8)
+       ((#:phases phases '())
+        #~(modify-phases #$phases
+            ;; No compiler-compat or mono-compat fixes needed for 3.0;
+            ;; the patch handles ReadOnlySpan and other changes.
+            ;; KeyValuePair helper was removed in 3.0.
+            (replace 'fix-compiler-compat
+              (lambda _ #t))
+            (replace 'fix-mono-compat
+              (lambda _
+                ;; Only CodePagesEncodingProvider remains.
+                (substitute* "src/Compilers/Core/Portable/EncodedStringText.cs"
+                  (("if \\(CodePagesEncodingProvider\\.Instance != null\\)")
+                   "if (false)")
+                  (("Encoding\\.RegisterProvider\\(CodePagesEncodingProvider\\.Instance\\);")
+                   "// not available in Mono"))))
+
+            ;; 3.0 has more files with PathUtilities ambiguity.
+            (add-after 'fix-srm-inline 'fix-srm-inline-3.0
+              (lambda _
+                (substitute* (list
+                              "src/Compilers/Core/Portable/StrongName/DesktopStrongNameProvider.cs"
+                              "src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerFileReference.cs")
+                  (("\\bPathUtilities\\.")
+                   "Roslyn.Utilities.PathUtilities."))))
+
+            ;; 3.0 has no stale files from 2.x.  Only DiaSymReader COM
+            ;; files need stubbing (inherited from create-diasymreader-stubs).
+            ;; Rename file with trailing space in its name.
+            (replace 'remove-stale-files
+              (lambda _
+                (rename-file
+                 "src/Compilers/Core/Portable/Operations/IConstructorBodyOperation .cs"
+                 "src/Compilers/Core/Portable/Operations/IConstructorBodyOperation.cs")
+                (for-each
+                 (lambda (f) (when (file-exists? f) (delete-file f)))
+                 '("src/Compilers/Core/Portable/DiaSymReader/Utilities/IUnsafeComStream.cs"
+                   "src/Compilers/Core/Portable/DiaSymReader/Utilities/ComMemoryStream.cs"))))
+
+            ;; csc.rsp: C# 7.3 langversion, NET472 define (was NET46 in 2.8).
+            (replace 'create-csc-rsp
+              (lambda _
+                (call-with-output-file "csc.rsp"
+                  (lambda (port)
+                    (display "-langversion:7.3\n-d:NET472\n" port)))))
+
+            ;; Point at roslyn-2.8's csc.
+            (replace 'create-csc-wrapper
+              (lambda* (#:key inputs #:allow-other-keys)
+                (mkdir-p "bootstrap-bin")
+                (call-with-output-file "bootstrap-bin/csc"
+                  (lambda (port)
+                    (format port "#!~a~%exec mono ~a \"$@\"~%"
+                            (which "bash")
+                            (string-append (assoc-ref inputs "roslyn") "/lib/roslyn/csc.exe"))))
+                (chmod "bootstrap-bin/csc" #o755)
+                (setenv "PATH"
+                        (string-append (getcwd) "/bootstrap-bin:"
+                                       (getenv "PATH")))))
+
+            ;; 3.0 csc.exe needs additional shared files.
+            (replace 'compile
+              (lambda* (#:key inputs #:allow-other-keys)
+                (let* ((sci-dll
+                        (search-input-file
+                         inputs "/lib/mono/4.5/System.Collections.Immutable.dll"))
+                       (srm-dir
+                        (if (file-exists? "srm-src-patched")
+                            "srm-src-patched"
+                            #$%srm-source-dir))
+                       (srm-source-files
+                        (filter
+                         (lambda (f)
+                           (not (or (string-contains f "netstandard")
+                                    (string-contains f "netcoreapp")
+                                    (string-contains f "AssemblyInfo")
+                                    (string-suffix? "/SR.cs" f))))
+                         (find-files srm-dir "\\.cs$")))
+                       (deps-dir
+                        (if (file-exists? "src/Dependencies/CodeAnalysis.Metadata")
+                            "src/Dependencies/CodeAnalysis.Metadata"
+                            "src/Dependencies/CodeAnalysis.Debugging")))
+
+                  ;; 1. Microsoft.CodeAnalysis.dll
+                  (apply invoke "csc" "@csc.rsp" "-target:library" "-unsafe"
+                         "-out:Microsoft.CodeAnalysis.dll"
+                         (string-append
+                          "-resource:Microsoft.CodeAnalysis.CodeAnalysisResources.resources"
+                          ",Microsoft.CodeAnalysis.CodeAnalysisResources.resources")
+                         "-r:System.dll" "-r:System.Core.dll"
+                         "-r:System.Xml.dll" "-r:System.Xml.Linq.dll"
+                         "-r:System.Numerics.dll" "-r:System.IO.Compression.dll"
+                         "-r:System.Security.dll"
+                         "-r:System.Runtime.Serialization.dll"
+                         (string-append "-r:" sci-dll)
+                         "-d:COMPILERCORE" "-d:SRM"
+                         "bootstrap-sr.cs" "bootstrap-ivt.cs"
+                         "src/Compilers/Shared/CoreClrShim.cs"
+                         "src/Compilers/Shared/DesktopShim.cs"
+                         (append
+                          (find-files "src/Compilers/Core/Portable" "\\.cs$")
+                          (find-files "src/Compilers/Core/AnalyzerDriver" "\\.cs$")
+                          (find-files deps-dir "\\.cs$")
+                          (find-files "src/Dependencies/PooledObjects" "\\.cs$")
+                          srm-source-files))
+
+                  ;; 2. Microsoft.CodeAnalysis.CSharp.dll
+                  (apply invoke "csc" "@csc.rsp" "-target:library" "-unsafe"
+                         "-out:Microsoft.CodeAnalysis.CSharp.dll"
+                         (string-append
+                          "-resource:Microsoft.CodeAnalysis.CSharp.CSharpResources.resources"
+                          ",Microsoft.CodeAnalysis.CSharp.CSharpResources.resources")
+                         "-r:System.dll" "-r:System.Core.dll"
+                         "-r:System.Xml.dll" "-r:System.Xml.Linq.dll"
+                         "-r:System.Numerics.dll" "-r:System.IO.Compression.dll"
+                         (string-append "-r:" sci-dll)
+                         "-r:Microsoft.CodeAnalysis.dll"
+                         "bootstrap-csharp-ivt.cs"
+                         "src/Compilers/CSharp/CSharpAnalyzerDriver/CSharpDeclarationComputer.cs"
+                         (append
+                          (find-files "src/Compilers/CSharp/Portable" "\\.cs$")
+                          (if (file-exists? "generated")
+                              (find-files "generated" "\\.cs$")
+                              '())))
+
+                  ;; 3. csc.exe - 3.0 added RuntimeHostInfo and NamedPipeUtil.
+                  (invoke "csc" "@csc.rsp" "-out:csc.exe"
+                          "-r:System.dll" "-r:System.Core.dll"
+                          (string-append "-r:" sci-dll)
+                          "-r:Microsoft.CodeAnalysis.dll"
+                          "-r:Microsoft.CodeAnalysis.CSharp.dll"
+                          "src/Compilers/CSharp/csc/Program.cs"
+                          "src/Compilers/Shared/Csc.cs"
+                          "src/Compilers/Shared/BuildClient.cs"
+                          "src/Compilers/Shared/BuildServerConnection.cs"
+                          "src/Compilers/Shared/DesktopBuildClient.cs"
+                          "src/Compilers/Shared/DesktopAnalyzerAssemblyLoader.cs"
+                          "src/Compilers/Shared/ExitingTraceListener.cs"
+                          "src/Compilers/Shared/CoreClrShim.cs"
+                          "src/Compilers/Shared/DesktopShim.cs"
+                          "src/Compilers/Shared/RuntimeHostInfo.cs"
+                          "src/Compilers/Shared/NamedPipeUtil.cs"
+                          "src/Compilers/Core/CommandLine/BuildProtocol.cs"
+                          "src/Compilers/Core/CommandLine/NativeMethods.cs"
+                          "src/Compilers/Core/CommandLine/ConsoleUtil.cs"
+                          "src/Compilers/Core/CommandLine/CompilerServerLogger.cs"))))))))
+    (synopsis "C# 8.0 compiler bootstrapped from source")
+    (description
+     "This package provides the Roslyn C# compiler (@command{csc}), built
+from source using @code{roslyn-2.8} as the bootstrap compiler.  It produces
+a C# 8.0 compiler.")))
 ;; too new version: 15.9.21.664
 ;; too old (no support for mono) version: 14.0
 (define-public msbuild
diff --git a/gnu/packages/patches/roslyn-3.0.0-bootstrap-with-csc-2.8.patch b/gnu/packages/patches/roslyn-3.0.0-bootstrap-with-csc-2.8.patch
new file mode 100644
index 00000000000..dac5687aaf8
--- /dev/null
+++ b/gnu/packages/patches/roslyn-3.0.0-bootstrap-with-csc-2.8.patch
@@ -0,0 +1,321 @@
+Author: Danny Milosavljevic <dannym@friendly-machines.com>
+Date: 2026-04-08
+Subject: Avoid ReadOnlySpan since mono runtime doesn't have it.  Avoid CodePagesEncodingProvider.
+
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/Collections/ImmutableArrayExtensions.cs b/src/Compilers/Core/Portable/Collections/ImmutableArrayExtensions.cs
+--- a/src/Compilers/Core/Portable/Collections/ImmutableArrayExtensions.cs       2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/Collections/ImmutableArrayExtensions.cs       2026-04-08 04:40:30.652729285 +0000
+@@ -508,9 +508,9 @@
+         // TODO(https://github.com/dotnet/corefx/issues/34126): Remove when System.Collections.Immutable
+         // provides a Span API
+         internal static T[] DangerousGetUnderlyingArray<T>(this ImmutableArray<T> array)
+-            => Unsafe.As<ImmutableArray<T>, ImmutableArrayProxy<T>>(ref array).MutableArray;
++            => array.ToArray();
+ 
+-        internal static ReadOnlySpan<T> AsSpan<T>(this ImmutableArray<T> array)
++        internal static T[] AsSpan<T>(this ImmutableArray<T> array)
+             => array.DangerousGetUnderlyingArray();
+ 
+         internal static Dictionary<K, ImmutableArray<T>> ToDictionary<K, T>(this ImmutableArray<T> items, Func<T, K> keySelector, IEqualityComparer<K> comparer = null)
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriter.cs b/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriter.cs
+--- a/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriter.cs     2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriter.cs     2026-04-08 04:40:30.662352748 +0000
+@@ -44,7 +44,7 @@
+         /// <exception cref="ObjectDisposedException">Object has been disposed.</exception>
+         /// <exception cref="InvalidOperationException">Writes are not allowed to the underlying stream.</exception>
+         /// <exception cref="SymUnmanagedWriterException">Error occurred while writing PDB data.</exception>
+-        public abstract int DefineDocument(string name, Guid language, Guid vendor, Guid type, Guid algorithmId, ReadOnlySpan<byte> checksum, ReadOnlySpan<byte> source);
++        public abstract int DefineDocument(string name, Guid language, Guid vendor, Guid type, Guid algorithmId, byte[] checksum, byte[] source);
+ 
+         /// <summary>
+         /// Defines sequence points.
+@@ -127,8 +127,8 @@
+             int moveNextMethodToken,
+             int kickoffMethodToken,
+             int catchHandlerOffset,
+-            ReadOnlySpan<int> yieldOffsets,
+-            ReadOnlySpan<int> resumeOffsets);
++            int[] yieldOffsets,
++            int[] resumeOffsets);
+ 
+         /// <summary>
+         /// Associates custom debug information blob with the current method.
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriterImpl.cs b/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriterImpl.cs
+--- a/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriterImpl.cs 2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/DiaSymReader/Writer/SymUnmanagedWriterImpl.cs 2026-04-08 04:41:40.581693982 +0000
+@@ -137,7 +137,7 @@
+             }
+         }
+ 
+-        public override int DefineDocument(string name, Guid language, Guid vendor, Guid type, Guid algorithmId, ReadOnlySpan<byte> checksum, ReadOnlySpan<byte> source)
++        public override int DefineDocument(string name, Guid language, Guid vendor, Guid type, Guid algorithmId, byte[] checksum, byte[] source)
+         {
+             if (name == null)
+             {
+@@ -468,8 +468,8 @@
+             int moveNextMethodToken,
+             int kickoffMethodToken,
+             int catchHandlerOffset,
+-            ReadOnlySpan<int> yieldOffsets,
+-            ReadOnlySpan<int> resumeOffsets)
++            int[] yieldOffsets,
++            int[] resumeOffsets)
+         {
+             if (yieldOffsets == null) throw new ArgumentNullException(nameof(yieldOffsets));
+             if (resumeOffsets == null) throw new ArgumentNullException(nameof(resumeOffsets));
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/InternalUtilities/Hash.cs b/src/Compilers/Core/Portable/InternalUtilities/Hash.cs
+--- a/src/Compilers/Core/Portable/InternalUtilities/Hash.cs     2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/InternalUtilities/Hash.cs     2026-04-08 04:40:30.590942249 +0000
+@@ -180,7 +180,7 @@
+         /// <param name="data">The sequence of bytes that are likely to be ASCII text.</param>
+         /// <param name="isAscii">True if the sequence contains only characters in the ASCII range.</param>
+         /// <returns>The FNV-1a hash of <paramref name="data"/></returns>
+-        internal static int GetFNVHashCode(ReadOnlySpan<byte> data, out bool isAscii)
++        internal static int GetFNVHashCode(byte[] data, out bool isAscii)
+         {
+             int hashCode = Hash.FnvOffsetBias;
+ 
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/InternalUtilities/LittleEndianReader.cs b/src/Compilers/Core/Portable/InternalUtilities/LittleEndianReader.cs
+--- a/src/Compilers/Core/Portable/InternalUtilities/LittleEndianReader.cs       2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/InternalUtilities/LittleEndianReader.cs       2026-04-08 04:42:30.135720458 +0000
+@@ -1,62 +1,59 @@
+-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+-
++// Bootstrap: rewritten to avoid ReadOnlySpan (csc 2.8 can't use its indexer).
+ using System;
+-using Roslyn.Utilities;
+-using static System.Buffers.Binary.BinaryPrimitives;
+ 
+-namespace Microsoft.CodeAnalysis
++namespace Roslyn.Utilities
+ {
+-    /// <summary>
+-    /// A Span-compatible version of <see cref="System.IO.BinaryReader"/>.
+-    /// </summary>
+-    internal ref struct LittleEndianReader
++    internal struct LittleEndianReader
+     {
+-        private ReadOnlySpan<byte> _span;
++        private readonly byte[] _data;
++        private int _offset;
+ 
+-        public LittleEndianReader(ReadOnlySpan<byte> span)
++        public LittleEndianReader(byte[] data)
+         {
+-            _span = span;
++            _data = data;
++            _offset = 0;
+         }
+ 
+         internal uint ReadUInt32()
+         {
+-            var result = ReadUInt32LittleEndian(_span);
+-            _span = _span.Slice(sizeof(uint));
++            var result = (uint)(_data[_offset] | _data[_offset+1] << 8 |
++                                _data[_offset+2] << 16 | _data[_offset+3] << 24);
++            _offset += sizeof(uint);
+             return result;
+         }
+ 
+         internal byte ReadByte()
+         {
+-            var result = _span[0];
+-            _span = _span.Slice(sizeof(byte));
+-            return result;
++            return _data[_offset++];
+         }
+ 
+         internal ushort ReadUInt16()
+         {
+-            var result = ReadUInt16LittleEndian(_span);
+-            _span = _span.Slice(sizeof(ushort));
++            var result = (ushort)(_data[_offset] | _data[_offset+1] << 8);
++            _offset += sizeof(ushort);
+             return result;
+         }
+ 
+-        internal ReadOnlySpan<byte> ReadBytes(int byteCount)
++        internal byte[] ReadBytes(int byteCount)
+         {
+-            var result = _span.Slice(0, byteCount);
+-            _span = _span.Slice(byteCount);
++            var result = new byte[byteCount];
++            Array.Copy(_data, _offset, result, 0, byteCount);
++            _offset += byteCount;
+             return result;
+         }
+ 
+         internal int ReadInt32()
+         {
+-            var result = ReadInt32LittleEndian(_span);
+-            _span = _span.Slice(sizeof(int));
++            var result = _data[_offset] | _data[_offset+1] << 8 |
++                         _data[_offset+2] << 16 | _data[_offset+3] << 24;
++            _offset += sizeof(int);
+             return result;
+         }
+ 
+-        internal byte[] ReadReversed(int byteCount)
++        internal byte[] ReadReversed(int count)
+         {
+-            var result = ReadBytes(byteCount).ToArray();
+-            result.ReverseContents();
++            var result = ReadBytes(count);
++            Array.Reverse(result);
+             return result;
+         }
+     }
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/InternalUtilities/StringTable.cs b/src/Compilers/Core/Portable/InternalUtilities/StringTable.cs
+--- a/src/Compilers/Core/Portable/InternalUtilities/StringTable.cs      2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/InternalUtilities/StringTable.cs      2026-04-08 04:45:58.668140916 +0000
+@@ -109,7 +109,7 @@
+ 
+         internal string Add(char[] chars, int start, int len)
+         {
+-            var span = chars.AsSpan(start, len);
++            var span = new string(chars, start, len).ToCharArray();
+             var hashCode = Hash.GetFNVHashCode(chars, start, len);
+ 
+             // capture array to avoid extra range checks
+@@ -295,7 +295,7 @@
+ 
+                 if (e != null)
+                 {
+-                    if (hash == hashCode && TextEquals(e, chars.AsSpan(start, len)))
++                    if (hash == hashCode && TextEquals(e, new string(chars, start, len).ToCharArray()))
+                     {
+                         break;
+                     }
+@@ -350,7 +350,7 @@
+             return e;
+         }
+ 
+-        private static string FindSharedEntryASCII(int hashCode, ReadOnlySpan<byte> asciiChars)
++        private static string FindSharedEntryASCII(int hashCode, byte[] asciiChars)
+         {
+             var arr = s_sharedTable;
+             int idx = SharedIdxFromHash(hashCode);
+@@ -581,7 +581,7 @@
+             return text;
+         }
+ 
+-        internal static string AddSharedUTF8(ReadOnlySpan<byte> bytes)
++        internal static string AddSharedUTF8(byte[] bytes)
+         {
+             bool isAscii;
+             int hashCode = Hash.GetFNVHashCode(bytes, out isAscii);
+@@ -598,13 +598,13 @@
+             return AddSharedSlow(hashCode, bytes, isAscii);
+         }
+ 
+-        private static string AddSharedSlow(int hashCode, ReadOnlySpan<byte> utf8Bytes, bool isAscii)
++        private static string AddSharedSlow(int hashCode, byte[] utf8Bytes, bool isAscii)
+         {
+             string text;
+ 
+             unsafe
+             {
+-                fixed (byte* bytes = &utf8Bytes.GetPinnableReference())
++                fixed (byte* bytes = utf8Bytes)
+                 {
+                     text = Encoding.UTF8.GetString(bytes, utf8Bytes.Length);
+                 }
+@@ -711,7 +711,7 @@
+             return true;
+         }
+ 
+-        internal static bool TextEqualsASCII(string text, ReadOnlySpan<byte> ascii)
++        internal static bool TextEqualsASCII(string text, byte[] ascii)
+         {
+ #if DEBUG
+             for (var i = 0; i < ascii.Length; i++)
+@@ -736,7 +736,7 @@
+             return true;
+         }
+ 
+-        internal static bool TextEquals(string array, ReadOnlySpan<char> text)
+-            => text.Equals(array.AsSpan(), StringComparison.Ordinal);
++        internal static bool TextEquals(string array, char[] text)
++            => string.Equals(new string(text), array, StringComparison.Ordinal);
+     }
+ }
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/InternalUtilities/TextKeyedCache.cs b/src/Compilers/Core/Portable/InternalUtilities/TextKeyedCache.cs
+--- a/src/Compilers/Core/Portable/InternalUtilities/TextKeyedCache.cs   2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/InternalUtilities/TextKeyedCache.cs   2026-04-08 04:43:25.581261044 +0000
+@@ -118,7 +118,7 @@
+ 
+             if (text != null && localSlot.HashCode == hashCode)
+             {
+-                if (StringTable.TextEquals(text, chars.AsSpan(start, len)))
++                if (StringTable.TextEquals(text, new string(chars, start, len).ToCharArray()))
+                 {
+                     return localSlot.Item;
+                 }
+@@ -155,7 +155,7 @@
+ 
+                 if (e != null)
+                 {
+-                    if (hash == hashCode && StringTable.TextEquals(e.Text, chars.AsSpan(start, len)))
++                    if (hash == hashCode && StringTable.TextEquals(e.Text, new string(chars, start, len).ToCharArray()))
+                     {
+                         break;
+                     }
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/MetadataReader/PEModule.cs b/src/Compilers/Core/Portable/MetadataReader/PEModule.cs
+--- a/src/Compilers/Core/Portable/MetadataReader/PEModule.cs    2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/MetadataReader/PEModule.cs    2026-04-08 04:40:42.540150457 +0000
+@@ -3151,7 +3151,7 @@
+ 
+             public unsafe override string GetString(byte* bytes, int byteCount)
+             {
+-                return StringTable.AddSharedUTF8(new ReadOnlySpan<byte>(bytes, byteCount));
++                var arr = new byte[byteCount]; System.Runtime.InteropServices.Marshal.Copy((System.IntPtr)bytes, arr, 0, byteCount); return StringTable.AddSharedUTF8(arr);
+             }
+         }
+ 
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs b/src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs
+--- a/src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs  2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs  2026-04-08 04:40:30.630288586 +0000
+@@ -573,8 +573,8 @@
+             }
+ 
+             Guid algorithmId;
+-            ReadOnlySpan<byte> checksum;
+-            ReadOnlySpan<byte> embeddedSource;
++            byte[] checksum;
++            byte[] embeddedSource;
+ 
+             DebugSourceInfo info = document.GetSourceInfo();
+             if (!info.Checksum.IsDefault)
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Core/Portable/StrongName/CryptoBlobParser.cs b/src/Compilers/Core/Portable/StrongName/CryptoBlobParser.cs
+--- a/src/Compilers/Core/Portable/StrongName/CryptoBlobParser.cs        2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Core/Portable/StrongName/CryptoBlobParser.cs        2026-04-08 04:41:40.581488708 +0000
+@@ -153,7 +153,7 @@
+             uint magic,
+             uint bitLen,
+             uint pubExp,
+-            ReadOnlySpan<byte> pubKeyData)
++            byte[] pubKeyData)
+         {
+             var w = new BlobWriter(3 * sizeof(uint) + s_offsetToKeyData + pubKeyData.Length);
+             w.WriteUInt32(AlgorithmId.RsaSign);
+@@ -250,7 +250,7 @@
+         /// Helper for RsaCryptoServiceProvider.ExportParameters()
+         /// Copied from https://github.com/dotnet/corefx/blob/5fe5f9aae7b2987adc7082f90712b265bee5eefc/src/System.Security.Cryptography.Csp/src/System/Security/Cryptography/CapiHelper.Shared.cs
+         /// </summary>
+-        internal static RSAParameters ToRSAParameters(this ReadOnlySpan<byte> cspBlob, bool includePrivateParameters)
++        internal static RSAParameters ToRSAParameters(this byte[] cspBlob, bool includePrivateParameters)
+         {
+             var br = new LittleEndianReader(cspBlob);
+ 
+diff -ruN '--exclude=*.resx' '--exclude=*.xlf' '--exclude=*.xml' '--exclude=*.rsp' '--exclude=srm-src-patched' '--exclude=*.resources' '--exclude=bootstrap-*' '--exclude=*.dll' '--exclude=*.exe' '--exclude=srm-strings.cs' '--exclude=generated' a/src/Compilers/Shared/DesktopBuildClient.cs b/src/Compilers/Shared/DesktopBuildClient.cs
+--- a/src/Compilers/Shared/DesktopBuildClient.cs        2019-03-20 01:30:13.000000000 +0000
++++ b/src/Compilers/Shared/DesktopBuildClient.cs        2026-04-08 04:48:35.412540299 +0000
+@@ -33,7 +33,7 @@
+             {
+                 // Register encodings for console
+                 // https://github.com/dotnet/roslyn/issues/10785
+-                System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);
++                // CodePagesEncodingProvider not available in Mono
+             }
+ 
+             var client = new DesktopBuildClient(language, compileFunc, analyzerAssemblyLoader);