[Clang] [Sema] Ensure noexcept(typeid(E)) checks if E throws when needed (#95846)

3ad31e12ccfc7db25f3cbedc4ee966e7099ac78f changed it so that not all
potentially-evaluated `typeid`s were marked as potentially-throwing, but
I forgot to check the subexpression if the null check of the `typeid`
didn't potentially-throw. This adds that check.

1 files changed, 10 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index c914448..d226e3b 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1111,13 +1111,22 @@ static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
 }
 
 static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
+  // A typeid of a type is a constant and does not throw.
   if (DC->isTypeOperand())
     return CT_Cannot;
 
   if (DC->isValueDependent())
     return CT_Dependent;
 
-  return DC->hasNullCheck() ? CT_Can : CT_Cannot;
+  // If this operand is not evaluated it cannot possibly throw.
+  if (!DC->isPotentiallyEvaluated())
+    return CT_Cannot;
+
+  // Can throw std::bad_typeid if a nullptr is dereferenced.
+  if (DC->hasNullCheck())
+    return CT_Can;
+
+  return S.canThrow(DC->getExprOperand());
 }
 
 CanThrowResult Sema::canThrow(const Stmt *S) {