Confirms that dobang is not, in fact, simple (#9413)

* I can confirm that dobang is not, in fact, simple

* add test to verify do-bang behavior

Author: baronfel

src/fsharp/TypeChecker.fs

@@ -8883,6 +8883,7 @@ and TcComputationExpression cenv env overallTy mWhole (interpExpr: Expr) builder
             clauses |> List.forall (fun (Clause(_, _, clauseComp, _, _)) -> isSimpleExpr clauseComp)
         | SynExpr.YieldOrReturnFrom _ -> false
         | SynExpr.YieldOrReturn _ -> false
+        | SynExpr.DoBang _ -> false
         | _ -> true
 
     let basicSynExpr = 

tests/FSharp.Test.Utilities/CompilerAssert.fs

@@ -419,6 +419,7 @@ let main argv = 0"""
     static member ExecutionHasOutput(cmpl: Compilation, expectedOutput: string) =
         CompilerAssert.Execute(cmpl, newProcess = true, onOutput = (fun output -> Assert.AreEqual(expectedOutput, output)))
 
+    /// Assert that the given source code compiles with the `defaultProjectOptions`, with no errors or warnings
     static member Pass (source: string) =
         lock gate <| fun () ->
             let parseResults, fileAnswer = checker.ParseAndCheckFileInProject("test.fs", 0, SourceText.ofString source, defaultProjectOptions) |> Async.RunSynchronously