[clang] [C23] Allow casting from a null pointer constant to nullptr_t (PR #133742)

[Aaron Ballman via cfe-commits]

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@@ -93,6 +91,9 @@ void test() {
   (int *)null_val;    // ok
   (int *)nullptr;     // ok
   (nullptr_t)nullptr; // ok
+  (nullptr_t)0;       // ok
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AaronBallman wrote:

I added that test coverage in fb9deab74e5dc9a9227732fcd95c1aadacf86d44, thanks for the suggestion!

https://github.com/llvm/llvm-project/pull/133742