[clang] Add check in SemaChecking for multiple unsequenced volatile accesses (PR #180955)

[Shafik Yaghmour via cfe-commits]

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@@ -14192,11 +14194,22 @@ class SequenceChecker : public ConstEvaluatedExprVisitor<SequenceChecker> {
     if (OtherKind == UK_Use)
       std::swap(Mod, ModOrUse);
 
+    unsigned DiagID = 0;
+    switch (WarnKind) {
+    case WK_UseAndMod:
+      DiagID = diag::warn_unsequenced_mod_use;
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shafik wrote:

Your tests are only covering one of these diagnostics, we need tests that cover all three. IF we don't then we are likely to introduce regressions or perhaps it is likely there is uncaught bug.

https://github.com/llvm/llvm-project/pull/180955