Use SDK 8.0 recommended analyzers

Directory.Build.props

@@ -35,13 +35,13 @@
     <SignAssembly>false</SignAssembly>
     <Deterministic>true</Deterministic>
 
-    <!-- Enable analyzers; treat all warnings as errors; disable 'using directive is unnecessary' and XML comment warnings -->
+    <!-- Enable analyzers; treat all warnings as errors; disable 'using directive is unnecessary' and throw helper warnings -->
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <EnforceCodeStyleInBuild>True</EnforceCodeStyleInBuild>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
-    <NoWarn>$(NoWarn);IDE0005</NoWarn>
+    <NoWarn>$(NoWarn);IDE0005;CA1510</NoWarn>
     <EnableNETAnalyzers>True</EnableNETAnalyzers>
-    <AnalysisMode>Recommended</AnalysisMode>
+    <AnalysisLevel>8-recommended</AnalysisLevel>
   </PropertyGroup>
 
   <!-- Include README for packable projects -->

QRCoder/Extensions/StringExtensions.cs

@@ -30,6 +30,17 @@ public static bool IsNullOrWhiteSpace(
 #endif
     }
 
+#if !NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+    /// <summary>
+    /// Determines whether the beginning of this string instance matches the specified character.
+    /// </summary>
+    /// <param name="value">The string to check.</param>
+    /// <param name="c">The character to compare.</param>
+    /// <returns>true if value starts with c; otherwise, false.</returns>
+    internal static bool StartsWith(this string value, char c)
+        => value.Length > 0 && value[0] == c;
+#endif
+
     /// <summary>
     /// Converts a hex color string to a byte array.
     /// </summary>
@@ -38,7 +49,7 @@ public static bool IsNullOrWhiteSpace(
     internal static byte[] HexColorToByteArray(this string colorString)
     {
         var offset = 0;
-        if (colorString.StartsWith("#", StringComparison.Ordinal))
+        if (colorString.StartsWith('#'))
             offset = 1;
         byte[] byteColor = new byte[(colorString.Length - offset) / 2];
         for (int i = 0; i < byteColor.Length; i++)

QRCoder/PayloadGenerator.cs

@@ -33,7 +33,7 @@ private static bool IsValidIban(string iban)
 #if NET5_0_OR_GREATER
             var n = string.Concat(i == 0 ? "" : m.ToString(CultureInfo.InvariantCulture), sum.AsSpan(start, Math.Min(9 - offset, sum.Length - start)));
 #else
-            var n = (i == 0 ? "" : m.ToString()) + sum.Substring(start, Math.Min(9 - offset, sum.Length - start));
+            var n = (i == 0 ? "" : m.ToString(CultureInfo.InvariantCulture)) + sum.Substring(start, Math.Min(9 - offset, sum.Length - start));
 #endif
             if (!int.TryParse(n, NumberStyles.Any, CultureInfo.InvariantCulture, out m))
                 break;

QRCoder/PayloadGenerator/BezahlCode.cs

@@ -225,7 +225,7 @@ public BezahlCode(AuthorityType authority, string name, string account, string b
                 if (authority == AuthorityType.periodicsinglepayment || authority == AuthorityType.periodicsinglepaymentsepa)
 #pragma warning restore CS0618
                 {
-                    if (periodicTimeunit.ToUpperInvariant() != "M" && periodicTimeunit.ToUpperInvariant() != "W")
+                    if (!periodicTimeunit.Equals("M", StringComparison.OrdinalIgnoreCase) && !periodicTimeunit.Equals("W", StringComparison.OrdinalIgnoreCase))
                         throw new BezahlCodeException("The periodicTimeunit must be either 'M' (monthly) or 'W' (weekly).");
                     _periodicTimeunit = periodicTimeunit;
                     if (periodicTimeunitRotation < 1 || periodicTimeunitRotation > 52)

QRCoder/PayloadGenerator/ContactData.cs

@@ -7,6 +7,7 @@ public static partial class PayloadGenerator
     /// </summary>
     public class ContactData : Payload
     {
+        private static readonly char[] _trimChars = { '\r', '\n' };
         private readonly string _firstname;
         private readonly string _lastname;
         private readonly string? _nickname;
@@ -152,7 +153,7 @@ public override string ToString()
                     payload += $"URL:{_website}\r\n";
                 if (!string.IsNullOrEmpty(_nickname))
                     payload += $"NICKNAME:{_nickname}\r\n";
-                payload = payload.Trim(new char[] { '\r', '\n' });
+                payload = payload.Trim(_trimChars);
             }
             else
             {

QRCoder/PayloadGenerator/Mail.cs

@@ -40,7 +40,7 @@ public override string ToString()
                         parts.Add("subject=" + Uri.EscapeDataString(_subject));
                     if (!string.IsNullOrEmpty(_message))
                         parts.Add("body=" + Uri.EscapeDataString(_message));
-                    var queryString = parts.Any() ? $"?{string.Join("&", parts.ToArray())}" : "";
+                    var queryString = parts.Count > 0 ? $"?{string.Join("&", parts.ToArray())}" : "";
                     return $"mailto:{_mailReceiver}{queryString}";
                 case MailEncoding.MATMSG:
                     return $"MATMSG:TO:{_mailReceiver};SUB:{EscapeInput(_subject ?? "")};BODY:{EscapeInput(_message ?? "")};;";

QRCoder/PayloadGenerator/RussiaPaymentOrder.cs

@@ -146,7 +146,7 @@ private List<string> GetOptionalFieldsAsList()
                     .Select(field =>
                     {
                         var objValue = field.GetValue(_oFields, null);
-                        var value = field.PropertyType.Equals(typeof(DateTime?)) ? ((DateTime)objValue).ToString("dd.MM.yyyy") : objValue.ToString();
+                        var value = field.PropertyType.Equals(typeof(DateTime?)) ? ((DateTime)objValue).ToString("dd.MM.yyyy", CultureInfo.InvariantCulture) : objValue.ToString();
                         return $"{field.Name}={value}";
                     })
                     .ToList();
@@ -176,7 +176,7 @@ private List<string> GetMandatoryFieldsAsList()
                     .Select(field =>
                     {
                         var objValue = field.GetValue(_mFields);
-                        var value = field.FieldType.Equals(typeof(DateTime?)) ? ((DateTime)objValue).ToString("dd.MM.yyyy") : objValue.ToString();
+                        var value = field.FieldType.Equals(typeof(DateTime?)) ? ((DateTime)objValue).ToString("dd.MM.yyyy", CultureInfo.InvariantCulture) : objValue.ToString();
                         return $"{field.Name}={value}";
                     })
                     .ToList();
@@ -224,7 +224,7 @@ private static string ValidateInput(string input, string fieldname, string[] pat
             return input;
         }
 
-        private class MandatoryFields
+        private sealed class MandatoryFields
         {
             public string Name = null!;
             public string PersonalAcc = null!;

QRCoder/QRCodeGenerator.cs

@@ -1231,9 +1231,13 @@ static int[] GetNotUniqueExponents(Polynom list)
             var dic = new Dictionary<int, bool>(list.Count);
             foreach (var row in list)
             {
+#if NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+                if (!dic.TryAdd(row.Exponent, false))
+#else
                 if (!dic.ContainsKey(row.Exponent))
                     dic.Add(row.Exponent, false);
                 else
+#endif
                     dic[row.Exponent] = true;
             }
 

QRCoder/SvgQRCode.cs

@@ -324,7 +324,7 @@ private static int GetTransparency(string colorHex)
             return 0; // Fully transparent
 
         // Check for hex color with alpha channel
-        if (colorHex.StartsWith("#", StringComparison.Ordinal))
+        if (colorHex.StartsWith('#'))
         {
             // #RRGGBBAA format (9 characters)
             if (colorHex.Length == 9)

QRCoderConsole/Program.cs

@@ -10,7 +10,7 @@ namespace QRCoderConsole;
 #if NET6_0 && WINDOWS
 [System.Runtime.Versioning.SupportedOSPlatform("windows")]
 #endif
-internal class MainClass
+internal sealed class MainClass
 {
     public static void Main(string[] args)
     {

QRCoderTests/Helpers/ShouldMatchApprovedBinaryExtensions.cs

@@ -45,7 +45,7 @@ public static void ShouldMatchApproved(this byte[] actual, string fileExtension,
             var declaringType = currentMethod?.DeclaringType;
 
             // Check if the declaring type has the ShouldlyMethods attribute
-            var hasShouldlyAttribute = declaringType?.GetCustomAttributes(typeof(ShouldlyMethodsAttribute), false).Any() ?? false;
+            var hasShouldlyAttribute = declaringType?.GetCustomAttributes(typeof(ShouldlyMethodsAttribute), false).Length > 0;
 
             // If this method is NOT in a ShouldlyMethods class, use it
             if (!hasShouldlyAttribute)

QRCoderTests/QRCoderTests.csproj

@@ -7,7 +7,7 @@
     <DefineConstants Condition="'$(TargetFramework)' == 'net462' or '$(TargetFramework)' == 'net5.0-windows' or '$(TargetFramework)' == 'net6.0-windows'">$(DefineConstants);TEST_XAML</DefineConstants>
     <SuppressTfmSupportBuildErrors>true</SuppressTfmSupportBuildErrors>
     <RuntimeFrameworkVersion Condition="'$(TargetFramework)' == 'netcoreapp2.1'">2.1.30</RuntimeFrameworkVersion>
-    <NoWarn>$(NoWarn);CA1707;CA1416</NoWarn>
+    <NoWarn>$(NoWarn);CA1707;CA1416;CA1850</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

QRCoderTests/QRGeneratorTests.cs

@@ -602,7 +602,7 @@ void Verify(QRCodeGenerator.ECCLevel eccLevel, string expected)
         string Encode(QRCodeData qrData) => string.Join("", qrData.ModuleMatrix.Select(x => x.ToBitString()).ToArray());
     }
 
-    private class SamplePayload : PayloadGenerator.Payload
+    private sealed class SamplePayload : PayloadGenerator.Payload
     {
         private readonly string _data;
         private readonly QRCodeGenerator.ECCLevel _eccLevel;