[llvm] 7b9cf0f - [ADT] Tighten static_assert in Bitfields (#165099)

[via llvm-commits]

Author: Kazu Hirata
Date: 2025-10-25T10:04:46-07:00
New Revision: 7b9cf0fe8d7bd77cd5d6747cfed6ecdded64fca3

URL: https://github.com/llvm/llvm-project/commit/7b9cf0fe8d7bd77cd5d6747cfed6ecdded64fca3
DIFF: https://github.com/llvm/llvm-project/commit/7b9cf0fe8d7bd77cd5d6747cfed6ecdded64fca3.diff

LOG: [ADT] Tighten static_assert in Bitfields (#165099)

This patch tightens the static_assert.  FirstBit and LastBit are
0-based bit indices of a bitfield, so they must be strictly less than
StorageBits.

Added: 
    

Modified: 
    llvm/include/llvm/ADT/Bitfields.h

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/Bitfields.h b/llvm/include/llvm/ADT/Bitfields.h
index 1fbc41c472581..be9546e9cc4cb 100644
--- a/llvm/include/llvm/ADT/Bitfields.h
+++ b/llvm/include/llvm/ADT/Bitfields.h
@@ -100,8 +100,8 @@ template <typename Bitfield, typename StorageType> struct Impl {
   using IntegerType = typename Bitfield::IntegerType;
 
   static constexpr size_t StorageBits = sizeof(StorageType) * CHAR_BIT;
-  static_assert(Bitfield::FirstBit <= StorageBits, "Data must fit in mask");
-  static_assert(Bitfield::LastBit <= StorageBits, "Data must fit in mask");
+  static_assert(Bitfield::FirstBit < StorageBits, "Data must fit in mask");
+  static_assert(Bitfield::LastBit < StorageBits, "Data must fit in mask");
   static constexpr StorageType LowMask =
       maskTrailingOnes<StorageType>(Bitfield::Bits);
   static constexpr StorageType Mask = LowMask << Bitfield::Shift;