[clang] [clang][Interp] Add basic support for _BitInt (PR #68069)

[Timm Baeder via cfe-commits]

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@@ -582,11 +598,21 @@ def CastIntegralFloating : Opcode {
 
 // Cast a floating to an integer type
 def CastFloatingIntegral : Opcode {
-  let Types = [AluTypeClass];
+  let Types = [FixedSizeIntegralTypes];
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tbaederr wrote:

The type classes for these get kinda confusing... but I just can't come up with the correct syntax to define them inline.

https://github.com/llvm/llvm-project/pull/68069