From 5eb81f2744c09f7210bfec13cc9c9afcdfde7aa3 Mon Sep 17 00:00:00 2001
From: Jonas Nyrup <jnyrup@gmail.com>
Date: Fri, 18 Feb 2022 16:37:29 +0100
Subject: [PATCH] Annotated [Not]MatchRegex with [StringSyntax("Regex")]

---
 .../Primitives/StringAssertions.cs            |  7 ++-
 Src/FluentAssertions/StringSyntaxAttribute.cs | 52 +++++++++++++++++++
 docs/_pages/releases.md                       |  1 +
 3 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 Src/FluentAssertions/StringSyntaxAttribute.cs

diff --git a/Src/FluentAssertions/Primitives/StringAssertions.cs b/Src/FluentAssertions/Primitives/StringAssertions.cs
index c75f0ddce1..83ff92ec69 100644
--- a/Src/FluentAssertions/Primitives/StringAssertions.cs
+++ b/Src/FluentAssertions/Primitives/StringAssertions.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Text.RegularExpressions;
 using FluentAssertions.Common;
@@ -399,7 +400,8 @@ public AndConstraint<TAssertions> NotMatchEquivalentOf(string wildcardPattern, s
         /// <param name="becauseArgs">
         /// Zero or more objects to format using the placeholders in <paramref name="because" />.
         /// </param>
-        public AndConstraint<TAssertions> MatchRegex([RegexPattern] string regularExpression, string because = "", params object[] becauseArgs)
+        public AndConstraint<TAssertions> MatchRegex([RegexPattern][StringSyntax("Regex")] string regularExpression,
+            string because = "", params object[] becauseArgs)
         {
             Guard.ThrowIfArgumentIsNull(regularExpression, nameof(regularExpression), "Cannot match string against <null>. Provide a regex pattern or use the BeNull method.");
 
@@ -475,7 +477,8 @@ public AndConstraint<TAssertions> MatchRegex(Regex regularExpression, string bec
         /// <param name="becauseArgs">
         /// Zero or more objects to format using the placeholders in <paramref name="because" />.
         /// </param>
-        public AndConstraint<TAssertions> NotMatchRegex([RegexPattern] string regularExpression, string because = "", params object[] becauseArgs)
+        public AndConstraint<TAssertions> NotMatchRegex([RegexPattern][StringSyntax("Regex")] string regularExpression,
+            string because = "", params object[] becauseArgs)
         {
             Guard.ThrowIfArgumentIsNull(regularExpression, nameof(regularExpression), "Cannot match string against <null>. Provide a regex pattern or use the NotBeNull method.");
 
diff --git a/Src/FluentAssertions/StringSyntaxAttribute.cs b/Src/FluentAssertions/StringSyntaxAttribute.cs
new file mode 100644
index 0000000000..13ce1ad65e
--- /dev/null
+++ b/Src/FluentAssertions/StringSyntaxAttribute.cs
@@ -0,0 +1,52 @@
+// copied from https://raw.githubusercontent.com/dotnet/runtime/main/src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/StringSyntaxAttribute.cs
+#if !NET7_0_OR_GREATER
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>Specifies the syntax used in a string.</summary>
+    [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
+#if SYSTEM_PRIVATE_CORELIB
+    public
+#else
+    internal
+#endif
+    sealed class StringSyntaxAttribute : Attribute
+    {
+        /// <summary>Initializes the <see cref="StringSyntaxAttribute"/> with the identifier of the syntax used.</summary>
+        /// <param name="syntax">The syntax identifier.</param>
+        public StringSyntaxAttribute(string syntax)
+        {
+            Syntax = syntax;
+            Arguments = Array.Empty<object?>();
+        }
+
+        /// <summary>Initializes the <see cref="StringSyntaxAttribute"/> with the identifier of the syntax used.</summary>
+        /// <param name="syntax">The syntax identifier.</param>
+        /// <param name="arguments">Optional arguments associated with the specific syntax employed.</param>
+        public StringSyntaxAttribute(string syntax, params object?[] arguments)
+        {
+            Syntax = syntax;
+            Arguments = arguments;
+        }
+
+        /// <summary>Gets the identifier of the syntax used.</summary>
+        public string Syntax { get; }
+
+        /// <summary>Optional arguments associated with the specific syntax employed.</summary>
+        public object?[] Arguments { get; }
+
+        /// <summary>The syntax identifier for strings containing date and time format specifiers.</summary>
+        public const string DateTimeFormat = nameof(DateTimeFormat);
+
+        /// <summary>The syntax identifier for strings containing JavaScript Object Notation (JSON).</summary>
+        public const string Json = nameof(Json);
+
+        /// <summary>The syntax identifier for strings containing regular expressions.</summary>
+        public const string Regex = nameof(Regex);
+    }
+}
+#endif
diff --git a/docs/_pages/releases.md b/docs/_pages/releases.md
index bbaf88671c..ab0e3359c5 100644
--- a/docs/_pages/releases.md
+++ b/docs/_pages/releases.md
@@ -10,6 +10,7 @@ sidebar:
 ## Unreleased
 
 ### What's New
+* Annotated `[Not]MatchRegex(string)` with `[StringSyntax("Regex")]` which IDEs can use to colorize the regular expression argument - [#1816](https://github.com/fluentassertions/fluentassertions/pull/1816)
 
 ### Fixes