Merge pull request #9504 from TyOverby/allow-cancelation

allow cancelation exceptions through the PE stream diagnostic filter

src/Compilers/CSharp/Test/Emit/Emit/CompilationEmitTests.cs

@@ -2976,5 +2976,24 @@ public static void Main()
                 // error CS8104: An error occurred while writing the Portable Executable file.
                 Diagnostic(ErrorCode.ERR_PeWritingFailure).WithArguments("I/O error occurred.").WithLocation(1, 1));
         }
+
+        [Fact]
+        [WorkItem(9308, "https://github.com/dotnet/roslyn/issues/9308")]
+        public void FailingEmitterAllowsCancelationExceptionsThrough()
+        {
+            string source = @"
+public class X
+{
+    public static void Main()
+    {
+  
+    }
+}";
+            var compilation = CreateCompilationWithMscorlib(source);
+            var broken = new BrokenStream();
+            broken.BreakHow = 3;
+
+            Assert.Throws<OperationCanceledException>(() => compilation.Emit(broken));
+        }
     }
 }

src/Compilers/Core/Portable/PEWriter/PeWriter.cs

@@ -96,7 +96,7 @@ internal sealed class PeWriter
 
                 return peWriter.WritePeToStream(mdWriter, getPeStream, getPortablePdbStreamOpt, nativePdbWriterOpt);
             }
-            catch (Exception ex) when (!(ex is PdbWritingException || ex is ResourceException || ex is PermissionSetFileReadException))
+            catch (Exception ex) when (!(ex is PdbWritingException || ex is ResourceException || ex is PermissionSetFileReadException || ex is OperationCanceledException))
             {
                 throw new PeWritingException(ex);
             }

src/Test/Utilities/Shared/Pe/BrokenStream.cs

@@ -68,7 +68,13 @@ public override void SetLength(long value)
         public override void Write(byte[] buffer, int offset, int count)
         {
             if (BreakHow == 0)
+            {
                 throw new IOException();
+            }
+            if (BreakHow == 3)
+            {
+                throw new OperationCanceledException();
+            }
         }
     }
 }