[clang] [C23] Fixed the value of BOOL_WIDTH (PR #117364)

[Timm Baeder via cfe-commits]

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@@ -1103,7 +1103,15 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   assert(TI.getCharWidth() == 8 && "Only support 8-bit char so far");
   Builder.defineMacro("__CHAR_BIT__", Twine(TI.getCharWidth()));
 
-  Builder.defineMacro("__BOOL_WIDTH__", Twine(TI.getBoolWidth()));
+  // The macro is specifying the number of bits in the width, not the number of
+  // bits the object requires for its in-memory representation, which is what
+  // getBoolWidth() will return. The bool/_Bool data type is only ever one bit
+  // wide. See C23 6.2.6.2p2 for the rules in C. Note that
+  // C++23 [basic.fundamental]p10 allows an implementation-defined value
+  // representation for bool; when lowing to LLVM, Clang represents bool as an
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tbaederr wrote:

```suggestion
  // representation for bool; when lowering to LLVM, Clang represents bool as an
```

https://github.com/llvm/llvm-project/pull/117364