Changing the logic for how we deal with RegexOptions.IgnoreCase matching.

src/libraries/System.Private.CoreLib/Tools/GenUnicodeProp/Updating-Unicode-Versions.md

@@ -1,6 +1,7 @@
 # Instructions for updating Unicode version in dotnet/runtime
 
 ## Table of Contents
+
 - [Instructions for updating Unicode version in dotnet/runtime](#instructions-for-updating-unicode-version-in-dotnetruntime)
   - [Table of Contents](#table-of-contents)
   - [Overview](#overview)
@@ -24,8 +25,7 @@ This repository has several places that need to be updated when we are ingesting
     - extracted/DerivedBidiClass.txt
     - extracted/DerivedName.txt
 
-2. Once you have downloaded all those files, create a fork of the repo https://github.com/dotnet/runtime-assets and send a PR which creates a folder at `src/System.Private.Runtime.UnicodeData/<YourUnicodeVersion>` and places all of the downloaded files from step 1 there. You can look at a sample PR that did this for Unicode 14.0.0 here: https://github.com/dotnet/runtime-assets/pull/179
-
+2. Once you have downloaded all those files, create a fork of the repo <https://github.com/dotnet/runtime-assets> and send a PR which creates a folder at `src/System.Private.Runtime.UnicodeData/<YourUnicodeVersion>` and places all of the downloaded files from step 1 there. You can look at a sample PR that did this for Unicode 14.0.0 here: <https://github.com/dotnet/runtime-assets/pull/179>
 
 ## Ingest the created package into dotnet/runtime repo
 
@@ -42,6 +42,6 @@ This should be done automatically by dependency-flow, so in theory there shouldn
    - System.Globalization.Nls.Tests.csproj
    - System.Text.Encodings.Web.Tests.csproj
 4. If the new Unicode data contains casing changes/updates, then we will also need to update `src/coreclr/pal/src/locale/unicodedata.cpp` file. This file is used by most of the reflection stack whenever you specify the `BindingFlags.IgnoreCase`. In order to regenerate the contents of the `unicdedata.cpp` file, you need to run the Program located at `src/coreclr/pal/src/locale/unicodedata.cs` and give a full path to the new UnicodeData.txt as a parameter.
-5. If the new Unicode data made changes on what character class a specific character belongs to, or added new characters, you may need to update the serialized Unicode character classes data in `System.Text.RegularExpressions` for the `NonBacktracking` engine. The telling sign that will show you if you need to do this, is if any tests are failing in the `System.Text.RegularExpressions.Tests` test project. In case some tests do fail (which means you need to update the serialized mappings), you will need to edit the file `src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexExperiment.cs` and set the `Enabled` bool to `true`, and re-run the RegexTests. This will generate a couple of files in your `%temp%` directory: `IgnoreCaseRelation.cs` and `UnicodeCategoryRanges.cs`. These files will need to be copied (and overwrite the existing ones) to the folder `src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Symbolic/Unicode/`
+5. Update the Regex casing equivalence table using the UnicodeData.txt file from the new Unicode version. You can find the instructions on how to do this [here](../../../System.Text.RegularExpressions/tools/Readme.md).
 6. Finally, last step is to update the license for the Unicode data into our [Third party notices](../../../../../THIRD-PARTY-NOTICES.TXT) by copying the contents located in `https://www.unicode.org/license.html` to the section that has the Unicode license in our notices.
 7. That's it, now commit all of the changed files, and send a PR into dotnet/runtime with the updates. If there were any special things you had to do that are not noted on this document, PLEASE UPDATE THESE INSTRUCTIONS to facilitate future updates.

src/libraries/System.Text.RegularExpressions/gen/System.Text.RegularExpressions.Generator.csproj

@@ -33,8 +33,10 @@
     <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\ValueListBuilder.cs" Link="Production\ValueListBuilder.cs" />
     <Compile Include="..\src\System\Collections\Generic\ValueListBuilder.Pop.cs" Link="Production\ValueListBuilder.Pop.cs" />
     <Compile Include="..\src\System\Threading\StackHelper.cs" Link="Production\StackHelper.cs" />
+    <Compile Include="..\src\System\Text\RegularExpressions\RegexCaseEquivalences.Data.cs" Link="Production\RegexCaseEquivalences.Data.cs" />
+    <Compile Include="..\src\System\Text\RegularExpressions\RegexCaseEquivalences.cs" Link="Production\RegexCaseEquivalences.cs" />
+    <Compile Include="..\src\System\Text\RegularExpressions\RegexCaseBehavior.cs" Link="Production\RegexCaseBehavior.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexCharClass.cs" Link="Production\RegexCharClass.cs" />
-    <Compile Include="..\src\System\Text\RegularExpressions\RegexCharClass.MappingTable.cs" Link="Production\RegexCharClass.MappingTable.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexFindOptimizations.cs" Link="Production\RegexFindOptimizations.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexNode.cs" Link="Production\RegexNode.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexNodeKind.cs" Link="Production\RegexNodeKind.cs" />

src/libraries/System.Text.RegularExpressions/src/System.Text.RegularExpressions.csproj

@@ -24,8 +24,10 @@
     <Compile Include="System\Text\RegularExpressions\Regex.Replace.cs" />
     <Compile Include="System\Text\RegularExpressions\Regex.Split.cs" />
     <Compile Include="System\Text\RegularExpressions\Regex.Timeout.cs" />
+    <Compile Include="System\Text\RegularExpressions\RegexCaseBehavior.cs" />
+    <Compile Include="System\Text\RegularExpressions\RegexCaseEquivalences.Data.cs" />
+    <Compile Include="System\Text\RegularExpressions\RegexCaseEquivalences.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCharClass.cs" />
-    <Compile Include="System\Text\RegularExpressions\RegexCharClass.MappingTable.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCompilationInfo.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexFindOptimizations.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexGeneratorAttribute.cs" />
@@ -83,10 +85,6 @@
     <Compile Include="System\Text\RegularExpressions\Symbolic\SymbolicRegexSet.cs" />
     <Compile Include="System\Text\RegularExpressions\Symbolic\TransitionRegex.cs" />
     <Compile Include="System\Text\RegularExpressions\Symbolic\TransitionRegexKind.cs" />
-    <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\GeneratorHelper.cs" />
-    <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\IgnoreCaseRelation.cs" />
-    <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\IgnoreCaseRelationGenerator.cs" />
-    <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\IgnoreCaseTransformer.cs" />
     <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\UnicodeCategoryRanges.cs" />
     <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\UnicodeCategoryRangesGenerator.cs" />
     <Compile Include="System\Text\RegularExpressions\Symbolic\Unicode\UnicodeCategoryTheory.cs" />

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/CompiledRegexRunner.cs

@@ -1,17 +1,22 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Globalization;
+
 namespace System.Text.RegularExpressions
 {
     internal sealed class CompiledRegexRunner : RegexRunner
     {
         private readonly ScanDelegate _scanMethod;
+        /// <summary>This field will only be set if the pattern contains backreferences and has RegexOptions.IgnoreCase</summary>
+        private readonly TextInfo? _textInfo;
 
         internal delegate void ScanDelegate(RegexRunner runner, ReadOnlySpan<char> text);
 
-        public CompiledRegexRunner(ScanDelegate scan)
+        public CompiledRegexRunner(ScanDelegate scan, CultureInfo? culture)
         {
             _scanMethod = scan;
+            _textInfo = culture?.TextInfo;
         }
 
         protected internal override void Scan(ReadOnlySpan<char> text)

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/CompiledRegexRunnerFactory.cs

@@ -1,24 +1,28 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Globalization;
 using System.Reflection.Emit;
 
 namespace System.Text.RegularExpressions
 {
     internal sealed class CompiledRegexRunnerFactory : RegexRunnerFactory
     {
         private readonly DynamicMethod _scanMethod;
+        /// <summary>This field will only be set if the pattern has backreferences and uses RegexOptions.IgnoreCase</summary>
+        private readonly CultureInfo? _culture;
 
         // Delegate is lazily created to avoid forcing JIT'ing until the regex is actually executed.
         private CompiledRegexRunner.ScanDelegate? _scan;
 
-        public CompiledRegexRunnerFactory(DynamicMethod scanMethod)
+        public CompiledRegexRunnerFactory(DynamicMethod scanMethod, CultureInfo? culture)
         {
             _scanMethod = scanMethod;
+            _culture = culture;
         }
 
         protected internal override RegexRunner CreateInstance() =>
             new CompiledRegexRunner(
-                _scan ??= _scanMethod.CreateDelegate<CompiledRegexRunner.ScanDelegate>());
+                _scan ??= _scanMethod.CreateDelegate<CompiledRegexRunner.ScanDelegate>(), _culture);
     }
 }

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.Debug.cs

@@ -44,13 +44,12 @@ internal void SaveDGML(TextWriter writer, bool nfa, bool addDotStar, bool revers
         }
 
         /// <summary>
-        /// Generates two files IgnoreCaseRelation.cs and UnicodeCategoryRanges.cs for the namespace System.Text.RegularExpressions.Symbolic.Unicode
+        /// Generates UnicodeCategoryRanges.cs for the namespace System.Text.RegularExpressions.Symbolic.Unicode
         /// in the given directory path. Only avaliable in DEBUG mode.
         /// </summary>
         [ExcludeFromCodeCoverage(Justification = "Debug only")]
         internal static void GenerateUnicodeTables(string path)
         {
-            IgnoreCaseRelationGenerator.Generate("System.Text.RegularExpressions.Symbolic.Unicode", "IgnoreCaseRelation", path);
             UnicodeCategoryRangesGenerator.Generate("System.Text.RegularExpressions.Symbolic.Unicode", "UnicodeCategoryRanges", path);
         }
 

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.cs

@@ -67,7 +67,7 @@ internal Regex(string pattern, CultureInfo? culture)
             RegexTree tree = Init(pattern, RegexOptions.None, s_defaultMatchTimeout, ref culture);
 
             // Create the interpreter factory.
-            factory = new RegexInterpreterFactory(tree, culture);
+            factory = new RegexInterpreterFactory(tree);
 
             // NOTE: This overload _does not_ delegate to the one that takes options, in order
             // to avoid unnecessarily rooting the support for RegexOptions.NonBacktracking/Compiler
@@ -101,7 +101,7 @@ internal Regex(string pattern, RegexOptions options, TimeSpan matchTimeout, Cult
                 }
 
                 // If no factory was created, fall back to creating one for the interpreter.
-                factory ??= new RegexInterpreterFactory(tree, culture);
+                factory ??= new RegexInterpreterFactory(tree);
             }
         }
 

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCaseBehavior.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Globalization;
+
+namespace System.Text.RegularExpressions
+{
+    /// <summary>
+    /// When a regular expression specifies the option <see cref="RegexOptions.IgnoreCase"/> then comparisons between the input and the
+    /// pattern will made case-insensitively. In order to support this, we need to define which case mappings shall be  used for the comparisons.
+    /// A case mapping exists whenever you have two characters 'A' and 'B', where either 'A' is the ToLower() representation of 'B' or both 'A' and 'B' lowercase to the
+    /// same character. Note that we don't consider a mapping when the only relationship between 'A' and 'B' is that one is the ToUpper() representation of the other. This
+    /// is for backwards compatibility since, in Regex, we have only consider ToLower() for case insensitive comparisons. Given the case mappings vary depending on the culture,
+    /// Regex supports 3 main different behaviors or mappings: Invariant, NonTurkish, and Turkish. This is in order to match the behavior of all .NET supported cultures
+    /// current behavior for ToLower(). As a side note, there should be no cases where 'A'.ToLower() == 'B' but 'A'.ToLower() != 'B'.ToLower(). This aspect is important since
+    /// for backreferences we make use a.ToLower() == b.ToLower() for comparisons so if there was such a case then it would lead to inconsistencies between how we handle
+    /// backreferences vs how we handle other case insensitive comparisons.
+    /// </summary>
+    internal enum RegexCaseBehavior
+    {
+        /// <summary>
+        /// Invariant case-mappings are used. This includes all of the common mappings across cultures. This behavior is used when either the  user
+        /// specified <see cref="RegexOptions.CultureInvariant"/> or when the CurrentCulture is <see cref="CultureInfo.InvariantCulture"/>.
+        /// </summary>
+        Invariant,
+
+        /// <summary>
+        /// These are all the same mappings used by Invariant behavior, with an additional one: \u0130 => \u0069
+        /// This mode will be used when CurrentCulture is not Invariant or any of the tr/az cultures.
+        /// </summary>
+        NonTurkish,
+
+        /// <summary>
+        /// These are all the same mappings used by non-Turkish behavior, with the exception of: \u0049 => \u0069 which mapping doesn't exist
+        /// on this behavior and with the additional mapping of: \u0069 => \u0131. This mode will be used when CurrentCulture is any of the tr/az cultures.
+        /// </summary>
+        Turkish
+    }
+}