Regression in follow-on diagnostic behavior after removing delayed typos

[AaronBallman]

With the removal of delayed typos, Clang now emits some follow-on diagnostics it previously did not. The crux of the issue was that delayed typos would result in a RecoveryExpr being made, but without delayed typos, sometimes the invalid statement is dropped entirely now. This leads to follow-on diagnostics, like the following:

constexpr int error() { // pre-cxx23-error {{no return statement in constexpr function}}
  return invalid;
}

The previous AST was:

`-FunctionDecl 0x15abc3dacd8 <C:\Users\aballman\OneDrive - Intel Corporation\Desktop\test.cpp:1:1, col:39> col:15 constexpr foo 'int ()' implicit-inline
  `-CompoundStmt 0x15abc3dae40 <col:21, col:39>
    `-ReturnStmt 0x15abc3dae30 <col:23, col:30>
      `-RecoveryExpr 0x15abc3dae10 <col:30> '<dependent type>' contains-errors lvalue

and the current AST is now:

`-FunctionDecl 0x2958326acd8 <C:\Users\aballman\OneDrive - Intel Corporation\Desktop\test.cpp:1:1, col:39> col:15 invalid constexpr foo 'int ()' implicit-inline
  `-CompoundStmt 0x2958326adf8 <col:21, col:39>

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Aaron Ballman (AaronBallman)

With the removal of delayed typos, Clang now emits some follow-on diagnostics it previously did not. The crux of the issue was that delayed typos would result in a `RecoveryExpr` being made, but without delayed typos, sometimes the invalid statement is dropped entirely now. This leads to follow-on diagnostics, like the following: ``` constexpr int error() { // pre-cxx23-error {{no return statement in constexpr function}} return invalid; } ``` The previous AST was: ``` `-FunctionDecl 0x15abc3dacd8 <C:\Users\aballman\OneDrive - Intel Corporation\Desktop\test.cpp:1:1, col:39> col:15 constexpr foo 'int ()' implicit-inline `-CompoundStmt 0x15abc3dae40 <col:21, col:39> `-ReturnStmt 0x15abc3dae30 <col:23, col:30> `-RecoveryExpr 0x15abc3dae10 <col:30> '<dependent type>' contains-errors lvalue ``` and the current AST is now: ``` `-FunctionDecl 0x2958326acd8 <C:\Users\aballman\OneDrive - Intel Corporation\Desktop\test.cpp:1:1, col:39> col:15 invalid constexpr foo 'int ()' implicit-inline `-CompoundStmt 0x2958326adf8 <col:21, col:39> ```