Validate hash literals at compile time #405
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I have created the `bhash` macro, short for block hash, that enforces a compile time check on the literal (must be 64 hex digits). It uses the pattern `const _: () = ...;`, where the right side is evaluated at compile time. All the `bhash!(literals)` will be checked at compile time, even if they are not accessed at runtime (see https://doc.rust-lang.org/reference/items/constant-items.html#evaluation). In other words, code that contains invalid literals won't compile (while currently it would compile and the program would panic at runtime only if the value is used). Also an IDE with cargo check lints will now display the error immediately.
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Another benefit is that it makes the hash parameters and test literals more concise, avoiding the |
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This is pretty cool! Perhaps this approach can be useful for other stuff, like Stumps and Txid? ack ac4fe53 |
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Yes! It seems neat, I will be checking those as well |
lucad70
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Mar 11, 2025
I have created the `bhash` macro, short for block hash, that enforces a compile time check on the literal (must be 64 hex digits). It uses the pattern `const _: () = ...;`, where the right side is evaluated at compile time. All the `bhash!(literals)` will be checked at compile time, even if they are not accessed at runtime (see https://doc.rust-lang.org/reference/items/constant-items.html#evaluation). In other words, code that contains invalid literals won't compile (while currently it would compile and the program would panic at runtime only if the value is used). Also an IDE with cargo check lints will now display the error immediately.
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What is the purpose of this pull request?
bhashWhich crates are being modified?
Description
I have created the
bhashmacro, short for block hash, that enforces a compile time check on the literal (must be 64 hex digits).It uses the pattern
const _: () = ...;, where the right side is evaluated at compile time. All thebhash!(literals)will be checked at compile time, even if they are not accessed at runtime (see https://doc.rust-lang.org/reference/items/constant-items.html#evaluation).In other words, code that contains invalid literals won't compile (while currently it would compile and the program would panic at runtime only if the value is used). Also an IDE with cargo check lints will now display the error immediately.
Notes to the reviewers
You can verify that this works, you can try to mess with any hash values and then try to compile: it won't.
error[E0080]: evaluation of constant value failed --> crates/floresta-chain/src/pruned_utreexo/chain_state.rs:1495:13 | 1495 | ... bhash!("572ac401b94915dde6c4957b706abdb13b5824b000cad7f6065ebd9aea6dad1... | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Hash literal is not exactly 64 hex digits', crates/floresta-chain/src/pruned_utreexo/chain_state.rs:1495:13 | = note: this error originates in the macro `$crate::panic::panic_2021` which comes from the expansion of the macro `bhash`