[clang] [clang] Allow C-style casts in constexpr in MS compatible mode (PR #197005)

[Shafik Yaghmour via cfe-commits]

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@@ -18,6 +18,23 @@ using namespace clang::interp;
 
 State::~State() {}
 
+// With -fms-compatibility we allow pointer to integer casts
+// followed by nullptr casts.
+void State::clearDiagIfNeeded(diag::kind DiagId) {
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shafik wrote:

The mechanics of this feel pretty mysterious to me, can you add some more comments, explaining how it accomplishes the intent commented above.

https://github.com/llvm/llvm-project/pull/197005