Simplify language version check in Regex generator (#81678)

* Simplify language version check in Regex generator

* Fix build

diff --git a/src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs b/src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs
index 2dd5c6d..bda1f16 100644 (file)
--- a/src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs
+++ b/src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs
@@ -36,7 +36,7 @@ namespace System.Text.RegularExpressions.Generator
             "#pragma warning disable CS0219 // Variable assigned but never used",
         };
 
-        private record struct CompilationData(bool AllowUnsafe, bool CheckOverflow);
+        private record struct CompilationData(bool AllowUnsafe, bool CheckOverflow, LanguageVersion LanguageVersion);
 
         public void Initialize(IncrementalGeneratorInitializationContext context)
         {
@@ -46,7 +46,7 @@ namespace System.Text.RegularExpressions.Generator
                 context.CompilationProvider
                 .Select((x, _) =>
                     x.Options is CSharpCompilationOptions options ?
-                        new CompilationData(options.AllowUnsafe, options.CheckOverflow) :
+                        new CompilationData(options.AllowUnsafe, options.CheckOverflow, ((CSharpCompilation)x).LanguageVersion) :
                         default);
 
             // Produces one entry per generated regex.  This may be:
@@ -78,7 +78,7 @@ namespace System.Text.RegularExpressions.Generator
 
                     // If we're unable to generate a full implementation for this regex, report a diagnostic.
                     // We'll still output a limited implementation that just caches a new Regex(...).
-                    if (!SupportsCodeGeneration(regexMethod, out string? reason))
+                    if (!SupportsCodeGeneration(regexMethod, methodOrDiagnosticAndCompilationData.Right.LanguageVersion, out string? reason))
                     {
                         return (regexMethod, reason, Diagnostic.Create(DiagnosticDescriptors.LimitedSourceGeneration, regexMethod.MethodSyntax.GetLocation()));
                     }
@@ -271,9 +271,9 @@ namespace System.Text.RegularExpressions.Generator
         // It also provides a human-readable string to explain the reason. It will be emitted by the source generator
         // as a comment into the C# code, hence there's no need to localize.
         /// </remarks>
-        private static bool SupportsCodeGeneration(RegexMethod method, [NotNullWhen(false)] out string? reason)
+        private static bool SupportsCodeGeneration(RegexMethod method, LanguageVersion languageVersion, [NotNullWhen(false)] out string? reason)
         {
-            if (method.MethodSyntax.SyntaxTree.Options is CSharpParseOptions { LanguageVersion: <= LanguageVersion.CSharp10 })
+            if (languageVersion <= LanguageVersion.CSharp10)
             {
                 reason = "the language version must be C# 11 or higher.";
                 return false;