Reference PolySharp and replace Substring() calls by the range syntax

Directory.Build.props

@@ -64,6 +64,15 @@
     <Serviceable>false</Serviceable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <!--
+      Note: OpenIddict uses PolySharp to dynamically generate polyfills for types that are not available on
+      some of the targeted TFMs (e.g Index, Range or nullable attributes on .NET Framework/.NET Standard).
+    -->
+    <PackageReference Include="PolySharp" Version="1.3.0" IsImplicitlyDefined="true"
+                      PrivateAssets="all" Condition=" '$(DisablePolySharp)' != 'true' " />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectCapability Include="DynamicDependentFile" />
     <ProjectCapability Include="DynamicFileNesting" />

gen/OpenIddict.Client.WebIntegration.Generators/OpenIddictClientWebIntegrationGenerator.cs

@@ -346,7 +346,7 @@ public partial class OpenIddictClientWebIntegrationBuilder
 
                                 Collection = (bool?) setting.Attribute("Collection") ?? false,
                                 Description = (string) setting.Attribute("Description") is string description ?
-                                    char.ToLower(description[0], CultureInfo.GetCultureInfo("en-US")) + description.Substring(1) : null,
+                                    char.ToLower(description[0], CultureInfo.GetCultureInfo("en-US")) + description[1..] : null,
                                 ClrType = (string) setting.Attribute("Type") switch
                                 {
                                     "EncryptionKey" when (string) setting.Element("EncryptionAlgorithm").Attribute("Value")
@@ -875,7 +875,7 @@ public partial class OpenIddictClientWebIntegrationOptions
 
                                 Collection = (bool?) setting.Attribute("Collection") ?? false,
                                 Description = (string) setting.Attribute("Description") is string description ?
-                                    char.ToLower(description[0], CultureInfo.GetCultureInfo("en-US")) + description.Substring(1) : null,
+                                    char.ToLower(description[0], CultureInfo.GetCultureInfo("en-US")) + description[1..] : null,
                                 ClrType = (string) setting.Attribute("Type") switch
                                 {
                                     "EncryptionKey" when (string) setting.Element("EncryptionAlgorithm").Attribute("Value")

sandbox/OpenIddict.Sandbox.AspNet.Client/OpenIddict.Sandbox.AspNet.Client.csproj

@@ -8,6 +8,7 @@
     <MvcBuildViews>false</MvcBuildViews>
     <ImplicitUsings>disable</ImplicitUsings>
     <NoWarn>CA3147</NoWarn>
+    <DisablePolySharp>true</DisablePolySharp>
   </PropertyGroup>
 
   <ItemGroup>

sandbox/OpenIddict.Sandbox.AspNet.Server/OpenIddict.Sandbox.AspNet.Server.csproj

@@ -8,6 +8,7 @@
     <MvcBuildViews>false</MvcBuildViews>
     <ImplicitUsings>disable</ImplicitUsings>
     <NoWarn>CA3147</NoWarn>
+    <DisablePolySharp>true</DisablePolySharp>
   </PropertyGroup>
 
   <ItemGroup>

src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.cs

@@ -506,22 +506,22 @@ public static partial class OpenIddictClientOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default
@@ -706,22 +706,22 @@ public static partial class OpenIddictClientOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default

src/OpenIddict.Client/OpenIddictClientConfiguration.cs

@@ -82,8 +82,7 @@ public class OpenIddictClientConfiguration : IPostConfigureOptions<OpenIddictCli
 
                         if (registration.MetadataAddress.OriginalString.StartsWith("/", StringComparison.Ordinal))
                         {
-                            registration.MetadataAddress = new Uri(registration.MetadataAddress.OriginalString.Substring(
+                            registration.MetadataAddress = new Uri(registration.MetadataAddress.OriginalString[1..], UriKind.Relative);
-                                1, registration.MetadataAddress.OriginalString.Length - 1), UriKind.Relative);
                         }
 
                         registration.MetadataAddress = new Uri(issuer, registration.MetadataAddress);
@@ -196,7 +195,7 @@ public class OpenIddictClientConfiguration : IPostConfigureOptions<OpenIddictCli
 
                 // Only use the 40 first chars of the base64url-encoded modulus.
                 var identifier = Base64UrlEncoder.Encode(parameters.Modulus);
-                return identifier.Substring(0, Math.Min(identifier.Length, 40)).ToUpperInvariant();
+                return identifier[..Math.Min(identifier.Length, 40)].ToUpperInvariant();
             }
 
 #if SUPPORTS_ECDSA
@@ -209,7 +208,7 @@ public class OpenIddictClientConfiguration : IPostConfigureOptions<OpenIddictCli
 
                 // Only use the 40 first chars of the base64url-encoded X coordinate.
                 var identifier = Base64UrlEncoder.Encode(parameters.Q.X);
-                return identifier.Substring(0, Math.Min(identifier.Length, 40)).ToUpperInvariant();
+                return identifier[..Math.Min(identifier.Length, 40)].ToUpperInvariant();
             }
 #endif
 

src/OpenIddict.Client/OpenIddictClientHandlers.Protection.cs

@@ -119,7 +119,7 @@ public static partial class OpenIddictClientHandlers
                         { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } issuer => new[]
                         {
                             issuer.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
-                            issuer.AbsoluteUri.Substring(0, issuer.AbsoluteUri.Length - 1)
+                            issuer.AbsoluteUri[..^1]
                         },
 
                         Uri issuer => new[] { issuer.AbsoluteUri }

src/OpenIddict.Core/Managers/OpenIddictApplicationManager.cs

@@ -1433,10 +1433,10 @@ public class OpenIddictApplicationManager<TApplication> : IOpenIddictApplication
             BinaryPrimitives.WriteUInt32BigEndian(payload.Slice(9, 12), (uint) salt.Length);
 
             // Write the salt.
-            salt.CopyTo(payload.Slice(13));
+            salt.CopyTo(payload[13..]);
 
             // Write the subkey.
-            key.CopyTo(payload.Slice(13 + salt.Length));
+            key.CopyTo(payload[(13 + salt.Length)..]);
 
             return payload;
         }

src/OpenIddict.EntityFramework.Models/OpenIddict.EntityFramework.Models.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net461;netstandard2.0</TargetFrameworks>
+    <DisablePolySharp>true</DisablePolySharp>
   </PropertyGroup>
 
   <PropertyGroup>

src/OpenIddict.EntityFrameworkCore.Models/OpenIddict.EntityFrameworkCore.Models.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net461;netstandard2.0</TargetFrameworks>
+    <DisablePolySharp>true</DisablePolySharp>
   </PropertyGroup>
 
   <PropertyGroup>

src/OpenIddict.MongoDb.Models/OpenIddict.MongoDb.Models.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net461;netstandard2.0</TargetFrameworks>
+    <DisablePolySharp>true</DisablePolySharp>
     <SignAssembly>false</SignAssembly>
     <PublicSign>false</PublicSign>
   </PropertyGroup>

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.cs

@@ -760,7 +760,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             try
             {
-                var value = header.Substring("Basic ".Length).Trim();
+                var value = header["Basic ".Length..].Trim();
                 var data = Encoding.ASCII.GetString(Convert.FromBase64String(value));
 
                 var index = data.IndexOf(':');
@@ -775,8 +775,8 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
 
                 // Attach the basic authentication credentials to the request message.
-                context.Transaction.Request.ClientId = UnescapeDataString(data.Substring(0, index));
+                context.Transaction.Request.ClientId = UnescapeDataString(data[..index]);
-                context.Transaction.Request.ClientSecret = UnescapeDataString(data.Substring(index + 1));
+                context.Transaction.Request.ClientSecret = UnescapeDataString(data[(index + 1)..]);
 
                 return default;
             }
@@ -843,7 +843,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             }
 
             // Attach the access token to the request message.
-            context.Transaction.Request.AccessToken = header.Substring("Bearer ".Length);
+            context.Transaction.Request.AccessToken = header["Bearer ".Length..];
 
             return default;
         }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs

@@ -318,22 +318,22 @@ public static partial class OpenIddictServerOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default
@@ -438,22 +438,22 @@ public static partial class OpenIddictServerOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default
@@ -517,22 +517,22 @@ public static partial class OpenIddictServerOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default
@@ -815,7 +815,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             try
             {
-                var value = header.Substring("Basic ".Length).Trim();
+                var value = header["Basic ".Length..].Trim();
                 var data = Encoding.ASCII.GetString(Convert.FromBase64String(value));
 
                 var index = data.IndexOf(':');
@@ -830,8 +830,8 @@ public static partial class OpenIddictServerOwinHandlers
                 }
 
                 // Attach the basic authentication credentials to the request message.
-                context.Transaction.Request.ClientId = UnescapeDataString(data.Substring(0, index));
+                context.Transaction.Request.ClientId = UnescapeDataString(data[..index]);
-                context.Transaction.Request.ClientSecret = UnescapeDataString(data.Substring(index + 1));
+                context.Transaction.Request.ClientSecret = UnescapeDataString(data[(index + 1)..]);
 
                 return default;
             }
@@ -898,7 +898,7 @@ public static partial class OpenIddictServerOwinHandlers
             }
 
             // Attach the access token to the request message.
-            context.Transaction.Request.AccessToken = header.Substring("Bearer ".Length);
+            context.Transaction.Request.AccessToken = header["Bearer ".Length..];
 
             return default;
         }

src/OpenIddict.Server/OpenIddictServerConfiguration.cs

@@ -318,7 +318,7 @@ public class OpenIddictServerConfiguration : IPostConfigureOptions<OpenIddictSer
 
                 // Only use the 40 first chars of the base64url-encoded modulus.
                 var identifier = Base64UrlEncoder.Encode(parameters.Modulus);
-                return identifier.Substring(0, Math.Min(identifier.Length, 40)).ToUpperInvariant();
+                return identifier[..Math.Min(identifier.Length, 40)].ToUpperInvariant();
             }
 
 #if SUPPORTS_ECDSA
@@ -331,7 +331,7 @@ public class OpenIddictServerConfiguration : IPostConfigureOptions<OpenIddictSer
 
                 // Only use the 40 first chars of the base64url-encoded X coordinate.
                 var identifier = Base64UrlEncoder.Encode(parameters.Q.X);
-                return identifier.Substring(0, Math.Min(identifier.Length, 40)).ToUpperInvariant();
+                return identifier[..Math.Min(identifier.Length, 40)].ToUpperInvariant();
             }
 #endif
 

src/OpenIddict.Server/OpenIddictServerHandlers.Authentication.cs

@@ -1487,9 +1487,7 @@ public static partial class OpenIddictServerHandlers
 
                         // Note: response types can be specified in any order. To ensure permissions are correctly
                         // checked even if the order differs from the one specified in the request, a HashSet is used.
-                        var values = permission.Substring(prefix.Length, permission.Length - prefix.Length)
+                        var values = permission[prefix.Length..].Split(Separators.Space, StringSplitOptions.RemoveEmptyEntries);
-                                               .Split(Separators.Space, StringSplitOptions.RemoveEmptyEntries);
-
                         if (values.Length is not 0 && new HashSet<string>(values, StringComparer.Ordinal).SetEquals(types))
                         {
                             return true;

src/OpenIddict.Server/OpenIddictServerHandlers.Discovery.cs

@@ -393,7 +393,7 @@ public static partial class OpenIddictServerHandlers
                     // for Uri's constructor to correctly compute correct absolute URLs.
                     if (endpoint.OriginalString.StartsWith("/", StringComparison.Ordinal))
                     {
-                        endpoint = new Uri(endpoint.OriginalString.Substring(1, endpoint.OriginalString.Length - 1), UriKind.Relative);
+                        endpoint = new Uri(endpoint.OriginalString[1..], UriKind.Relative);
                     }
 
                     return new Uri(issuer, endpoint);

src/OpenIddict.Server/OpenIddictServerHandlers.cs

@@ -3056,7 +3056,7 @@ public static partial class OpenIddictServerHandlers
                 // for Uri's constructor to correctly compute correct absolute URLs.
                 if (endpoint.OriginalString.StartsWith("/", StringComparison.Ordinal))
                 {
-                    endpoint = new Uri(endpoint.OriginalString.Substring(1, endpoint.OriginalString.Length - 1), UriKind.Relative);
+                    endpoint = new Uri(endpoint.OriginalString[1..], UriKind.Relative);
                 }
 
                 return new Uri(issuer, endpoint);

src/OpenIddict.Validation.AspNetCore/OpenIddictValidationAspNetCoreHandlers.cs

@@ -163,7 +163,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             string? header = request.Headers[HeaderNames.Authorization];
             if (!string.IsNullOrEmpty(header) && header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
             {
-                context.AccessToken = header.Substring("Bearer ".Length);
+                context.AccessToken = header["Bearer ".Length..];
 
                 return default;
             }

src/OpenIddict.Validation.Owin/OpenIddictValidationOwinHandlers.cs

@@ -163,7 +163,7 @@ public static partial class OpenIddictValidationOwinHandlers
             string header = request.Headers[Headers.Authorization];
             if (!string.IsNullOrEmpty(header) && header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
             {
-                context.AccessToken = header.Substring("Bearer ".Length);
+                context.AccessToken = header["Bearer ".Length..];
 
                 return default;
             }
@@ -322,22 +322,22 @@ public static partial class OpenIddictValidationOwinHandlers
                 {
                     // If the property ends with #string, represent it as a string parameter.
                     string key when key.EndsWith(PropertyTypes.String, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.String.Length),
+                        Name: key[..^PropertyTypes.String.Length],
                         Value: new OpenIddictParameter(property.Value)),
 
                     // If the property ends with #boolean, return it as a boolean parameter.
                     string key when key.EndsWith(PropertyTypes.Boolean, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Boolean.Length),
+                        Name: key[..^PropertyTypes.Boolean.Length],
                         Value: new OpenIddictParameter(bool.Parse(property.Value))),
 
                     // If the property ends with #integer, return it as an integer parameter.
                     string key when key.EndsWith(PropertyTypes.Integer, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Integer.Length),
+                        Name: key[..^PropertyTypes.Integer.Length],
                         Value: new OpenIddictParameter(long.Parse(property.Value, CultureInfo.InvariantCulture))),
 
                     // If the property ends with #json, return it as a JSON parameter.
                     string key when key.EndsWith(PropertyTypes.Json, StringComparison.OrdinalIgnoreCase) => (
-                        Name: key.Substring(0, key.Length - PropertyTypes.Json.Length),
+                        Name: key[..^PropertyTypes.Json.Length],
                         Value: new OpenIddictParameter(JsonSerializer.Deserialize<JsonElement>(property.Value))),
 
                     _ => default

src/OpenIddict.Validation/OpenIddictValidationConfiguration.cs

@@ -126,8 +126,7 @@ public class OpenIddictValidationConfiguration : IPostConfigureOptions<OpenIddic
 
                     if (options.MetadataAddress.OriginalString.StartsWith("/", StringComparison.Ordinal))
                     {
-                        options.MetadataAddress = new Uri(options.MetadataAddress.OriginalString.Substring(
+                        options.MetadataAddress = new Uri(options.MetadataAddress.OriginalString[1..], UriKind.Relative);
-                            1, options.MetadataAddress.OriginalString.Length - 1), UriKind.Relative);
                     }
 
                     options.MetadataAddress = new Uri(issuer, options.MetadataAddress);

src/OpenIddict.Validation/OpenIddictValidationHandlers.Protection.cs

@@ -73,7 +73,7 @@ public static partial class OpenIddictValidationHandlers
                     { AbsolutePath: "/", Query.Length: 0, Fragment.Length: 0 } issuer => new[]
                     {
                         issuer.AbsoluteUri, // Uri.AbsoluteUri is normalized and always contains a trailing slash.
-                        issuer.AbsoluteUri.Substring(0, issuer.AbsoluteUri.Length - 1)
+                        issuer.AbsoluteUri[..^1]
                     },
 
                     Uri issuer => new[] { issuer.AbsoluteUri }

test/OpenIddict.Server.IntegrationTests/OpenIddictServerIntegrationTestClient.cs

@@ -435,13 +435,13 @@ public class OpenIddictServerIntegrationTestClient : IAsyncDisposable
                     continue;
                 }
 
-                var name = line.Substring(0, index);
+                var name = line[..index];
                 if (string.IsNullOrEmpty(name))
                 {
                     continue;
                 }
 
-                var value = line.Substring(index + 1);
+                var value = line[(index + 1)..];
 
                 parameters.Add(new KeyValuePair<string, string>(name, value));
             }

test/OpenIddict.Validation.IntegrationTests/OpenIddictValidationIntegrationTestClient.cs

@@ -435,13 +435,13 @@ public class OpenIddictValidationIntegrationTestClient : IAsyncDisposable
                     continue;
                 }
 
-                var name = line.Substring(0, index);
+                var name = line[..index];
                 if (string.IsNullOrEmpty(name))
                 {
                     continue;
                 }
 
-                var value = line.Substring(index + 1);
+                var value = line[(index + 1)..];
 
                 parameters.Add(new KeyValuePair<string, string>(name, value));
             }