From bb9978646a9f758165294e53c1e95004277dc7d3 Mon Sep 17 00:00:00 2001
From: Pavel Krymets <pavel@krymets.com>
Date: Wed, 7 Oct 2020 08:33:48 -0700
Subject: [PATCH] Support regions without names in Update-Snippets (#15746)

Fixes: https://github.com/Azure/azure-sdk-for-net/issues/15744
---
 eng/SnippetGenerator/DirectoryProcessor.cs | 26 +++++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/eng/SnippetGenerator/DirectoryProcessor.cs b/eng/SnippetGenerator/DirectoryProcessor.cs
index 2f4f304458bf4..0605b8ae5d380 100644
--- a/eng/SnippetGenerator/DirectoryProcessor.cs
+++ b/eng/SnippetGenerator/DirectoryProcessor.cs
@@ -204,11 +204,19 @@ private List<Snippet> GetSnippetsInDirectory(string baseDirectory)
             var list = new List<Snippet>();
             foreach (var file in Directory.GetFiles(baseDirectory, "*.cs", SearchOption.AllDirectories))
             {
-                var syntaxTree = CSharpSyntaxTree.ParseText(
-                    File.ReadAllText(file),
-                    new CSharpParseOptions(LanguageVersion.Preview),
-                    path: file);
-                list.AddRange(GetAllSnippets(syntaxTree));
+                try
+                {
+                    var syntaxTree = CSharpSyntaxTree.ParseText(
+                        File.ReadAllText(file),
+                        new CSharpParseOptions(LanguageVersion.Preview),
+                        path: file);
+
+                    list.AddRange(GetAllSnippets(syntaxTree));
+                }
+                catch (Exception e)
+                {
+                    throw new InvalidOperationException($"Failed to discover snippets from file {file}", e);
+                }
             }
 
             return list;
@@ -222,7 +230,13 @@ private Snippet[] GetAllSnippets(SyntaxTree syntaxTree)
 
             foreach (var region in directiveWalker.Regions)
             {
-                var syntaxTrivia = region.Item1.EndOfDirectiveToken.LeadingTrivia.First(t => t.IsKind(SyntaxKind.PreprocessingMessageTrivia));
+                var leadingTrivia = region.Item1.EndOfDirectiveToken.LeadingTrivia;
+                if (!leadingTrivia.Any())
+                {
+                    // Skip unnamed regions
+                    continue;
+                }
+                var syntaxTrivia = leadingTrivia.First(t => t.IsKind(SyntaxKind.PreprocessingMessageTrivia));
                 var fromBounds = TextSpan.FromBounds(
                     region.Item1.GetLocation().SourceSpan.End,
                     region.Item2.GetLocation().SourceSpan.Start);