[clang] [clang][AST] Treat unsigned _BitInt(1) as boolean-valued (PR #195793)

[Yanzuo Liu via cfe-commits]

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@@ -142,6 +142,11 @@ bool Expr::isKnownToHaveBooleanValue(bool Semantic) const {
   // If this is a non-scalar-integer type, we don't care enough to try.
   if (!E->getType()->isIntegralOrEnumerationType()) return false;
 
+  if (!Semantic)
+    if (const auto *BIT = E->getType()->getAs<BitIntType>())
+      if (BIT->isUnsigned() && BIT->getNumBits() == 1)
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zwuis wrote:

```cpp
if (const auto *BIT = ...;
    BIT && ...)
```

https://github.com/llvm/llvm-project/pull/195793