Ava Chow 28a523fb94 Merge bitcoin/bitcoin#35097: util: Return uint64_t from _MiB and _GiB operators
fa43da21f1 refactor: Run ShouldWarnOversizedDbCache calculation in u64 (MarcoFalke)
fa5801762e util: Return uint64_t from _MiB and _GiB operators (MarcoFalke)
fa9ddb01c9 test: Use MiB operator directly in cuckoocache_tests (MarcoFalke)

Pull request description:

  Currently, the `_MiB` literal operator returns a value of type `size_t`. This is brittle and confusing:

  * It is inherently impossible to represent larger values, like storage device usage.
  * Similarly, it is not possible to even type an upper cap on the memory, see the failure in https://github.com/bitcoin/bitcoin/pull/34692#issuecomment-3973281952
  * Using `size_t` isn't required here. The function is evaluated at compile time, and even 32-bit compilers can evaluate an `uint64_t` at compile time.
  * Using `size_t` here encourages it to be used in more places, which will likely lead to more bugs and CVEs, such as https://github.com/bitcoin/bitcoin/pull/34109, https://github.com/bitcoin/bitcoin/pull/33724, etc.

  Fix all issues, by:

  * Marking the operator `consteval`, to ensure it is really only called at compile-time.
  * Returning an `uint64_t` value.
  * Using it in the place where it was previously not possible.

  Review note:

  This should have no downside, because the C++11 narrowing checks continue to work as expected. For example, typing `uint8_t{1_MiB};` will continue to fail with the correct error message `error: constant expression evaluates to 1048576 which cannot be narrowed to type 'uint8_t' (aka 'unsigned char') [-Wc++11-narrowing]` (like it does on current master).

ACKs for top commit:
  l0rinc:
    ACK fa43da21f1
  achow101:
    ACK fa43da21f1
  hebasto:
    ACK fa43da21f1, I have reviewed the code and it looks OK.
  hodlinator:
    ACK fa43da21f1

Tree-SHA512: e19f6bd18c519c2a56d44fbc9e65b02e630bc71170f02a8a8955bf5c9bb2924b55ec2f810de2bbc961162aa668b7383c9fe9b5261fa1de7d9e8413003c32fa87
2026-04-24 14:52:49 -07:00

Bitcoin Core integration/staging tree

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