[llvm] [llvm] Support building with c++23 (PR #154372)

[Kyle Krüger via llvm-commits]

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@@ -615,7 +623,7 @@ bool SwitchMatcher::addMatcher(Matcher &Candidate) {
 }
 
 void SwitchMatcher::finalize() {
-  assert(Condition == nullptr && "Already finalized");
+  assert(Condition.get() == nullptr && "Already finalized");
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kykrueger wrote:

I added it because accessing an uninitialized unique_ptr seems to be undefined, meanwhile calling its getter is defined behavior to return a nullptr.
The code does indeed compile when leaving these get calls out, but I'm not sure if we can rely on it.

https://github.com/llvm/llvm-project/pull/154372