From 184b1569e5d20c1cbb0ce01b858ac3b0ef49d370 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Thu, 10 Nov 2022 11:59:23 -0500
Subject: [PATCH 1/3] Fix regex fixer to maintain string literal syntax

---
 .../gen/UpgradeToGeneratedRegexCodeFixer.cs   |  5 +-
 .../UpgradeToGeneratedRegexAnalyzerTests.cs   | 55 ++++++++++++++++++-
 2 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
index bf98ce298ecff0..20b07f4e744145 100644
--- a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
+++ b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
@@ -276,7 +276,10 @@ static RegexOptions GetRegexOptionsFromArgument(ImmutableArray<IArgumentOperatio
                 }
                 else
                 {
-                    return generator.LiteralExpression(argument.Value.ConstantValue.Value);
+                    SyntaxNode syntax = argument.Syntax;
+                    return syntax is ArgumentSyntax { NameColon: not null } argumentSyntax ?
+                        argumentSyntax.WithNameColon(null) :
+                        syntax;
                 }
             }
 
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
index 18c9e25b6717b5..f71accc369b5e0 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
@@ -792,7 +792,7 @@ public async Task LeadingAndTrailingTriviaIsPreservedByFixer()
 static class Class
 {
     public static string CollapseWhitespace(this string text) =>
-        [|Regex.Replace(text, @"" \s+"" , ""  "")|];
+        [|Regex.Replace(text, "" \\s+"" , ""  "")|];
 }";
 
             string expectedFixedCode = @"using System.Text.RegularExpressions;
@@ -808,6 +808,59 @@ public static string CollapseWhitespace(this string text) =>
             await VerifyCS.VerifyCodeFixAsync(test, expectedFixedCode);
         }
 
+        [Fact]
+        public async Task VerbatimStringLiteralSyntaxPreservedByFixer()
+        {
+            string test = @"using System.Text.RegularExpressions;
+
+static class Class
+{
+    public static string CollapseWhitespace(this string text) =>
+        [|Regex.Replace(text, @"" \s+"" , @""  "")|];
+}";
+
+            string expectedFixedCode = @"using System.Text.RegularExpressions;
+
+static partial class Class
+{
+    public static string CollapseWhitespace(this string text) =>
+        MyRegex().Replace(text, @""  "");
+    [GeneratedRegex(@"" \s+"")]
+    private static partial Regex MyRegex();
+}";
+
+            await VerifyCS.VerifyCodeFixAsync(test, expectedFixedCode);
+        }
+
+        [Fact]
+        public async Task RawStringLiteralSyntaxPreservedByFixer()
+        {
+            string test = @"using System.Text.RegularExpressions;
+
+static class Class
+{
+    public static string CollapseWhitespace(this string text) =>
+        [|Regex.Replace(text, """"""
+                              \s+
+                              """""",
+                              """""""" hello """""" world """""""")|];
+}";
+
+            string expectedFixedCode = @"using System.Text.RegularExpressions;
+
+static partial class Class
+{
+    public static string CollapseWhitespace(this string text) =>
+        MyRegex().Replace(text, """""""" hello """""" world """""""");
+    [GeneratedRegex(""""""
+                              \s+
+                              """""")]
+    private static partial Regex MyRegex();
+}";
+
+            await VerifyCS.VerifyCodeFixAsync(test, expectedFixedCode);
+        }
+
         [Fact]
         public async Task TestAsArgument()
         {

From bf2d3ddddf854279c94481967b4e1a8846a027bf Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Thu, 10 Nov 2022 13:13:27 -0500
Subject: [PATCH 2/3] Simplify

---
 .../gen/UpgradeToGeneratedRegexCodeFixer.cs                  | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
index 20b07f4e744145..0025bf7f8edc23 100644
--- a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
+++ b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
@@ -276,10 +276,7 @@ static RegexOptions GetRegexOptionsFromArgument(ImmutableArray<IArgumentOperatio
                 }
                 else
                 {
-                    SyntaxNode syntax = argument.Syntax;
-                    return syntax is ArgumentSyntax { NameColon: not null } argumentSyntax ?
-                        argumentSyntax.WithNameColon(null) :
-                        syntax;
+                    return argument.Value.Syntax;
                 }
             }
 

From 4408c0ff3c833bf2670a064006551b999b464a86 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Thu, 10 Nov 2022 14:02:32 -0500
Subject: [PATCH 3/3] Still transform interpolated strings

---
 .../gen/UpgradeToGeneratedRegexCodeFixer.cs   |  6 +++-
 .../UpgradeToGeneratedRegexAnalyzerTests.cs   | 35 +++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
index 0025bf7f8edc23..442976d648b834 100644
--- a/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
+++ b/src/libraries/System.Text.RegularExpressions/gen/UpgradeToGeneratedRegexCodeFixer.cs
@@ -274,9 +274,13 @@ static RegexOptions GetRegexOptionsFromArgument(ImmutableArray<IArgumentOperatio
                     string optionsLiteral = Literal(((RegexOptions)(int)argument.Value.ConstantValue.Value).ToString());
                     return SyntaxFactory.ParseExpression(optionsLiteral);
                 }
+                else if (argument.Value is ILiteralOperation literalOperation)
+                {
+                    return literalOperation.Syntax;
+                }
                 else
                 {
-                    return argument.Value.Syntax;
+                    return generator.LiteralExpression(argument.Value.ConstantValue.Value);
                 }
             }
 
diff --git a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
index f71accc369b5e0..9dafdf410201aa 100644
--- a/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
+++ b/src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/UpgradeToGeneratedRegexAnalyzerTests.cs
@@ -861,6 +861,41 @@ public static string CollapseWhitespace(this string text) =>
             await VerifyCS.VerifyCodeFixAsync(test, expectedFixedCode);
         }
 
+        [Fact]
+        public async Task InterpolatedStringLiteralSyntaxPreservedByFixer()
+        {
+            string test = @"using System.Text.RegularExpressions;
+
+partial class Program
+{
+    static void Main(string[] args)
+    {
+        const string pattern = @""a|b\s\n"";
+        const string pattern2 = $""{pattern}2"";
+
+        Regex regex = [|new Regex(pattern2)|];
+    }
+}";
+
+            string expectedFixedCode = @"using System.Text.RegularExpressions;
+
+partial class Program
+{
+    static void Main(string[] args)
+    {
+        const string pattern = @""a|b\s\n"";
+        const string pattern2 = $""{pattern}2"";
+
+        Regex regex = MyRegex();
+    }
+
+    [GeneratedRegex(""a|b\\s\\n2"")]
+    private static partial Regex MyRegex();
+}";
+
+            await VerifyCS.VerifyCodeFixAsync(test, expectedFixedCode);
+        }
+
         [Fact]
         public async Task TestAsArgument()
         {