fix: revert MSRV changes (#789)

* Revert "chore: bump MSRV to 1.81 & use `core::error::Error` in place of `std` (#780)"

This reverts commit 7b84276.

* Revert "chore: address MSRV TODOs for 1.81 (#781)"

This reverts commit d37a5aa.

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
         rust: [
             "stable",
             "nightly",
-            "1.81", # MSRV
+            "1.79", # MSRV
           ]
         flags: [
             # No features
@@ -35,10 +35,10 @@ jobs:
         include:
           # MSRV features
           - os: "ubuntu-latest"
-            rust: "1.81" # MSRV
+            rust: "1.79" # MSRV
             flags: "--features json"
           - os: "windows-latest"
-            rust: "1.81" # MSRV
+            rust: "1.79" # MSRV
             flags: "--features json"
           # All features
           - os: "ubuntu-latest"
@@ -57,10 +57,10 @@ jobs:
           cache-on-failure: true
       # Only run tests on latest stable and above
       - name: build
-        if: ${{ matrix.rust == '1.81' }} # MSRV
+        if: ${{ matrix.rust == '1.79' }} # MSRV
         run: cargo build --workspace ${{ matrix.flags }}
       - name: test
-        if: ${{ matrix.rust != '1.81' }} # MSRV
+        if: ${{ matrix.rust != '1.79' }} # MSRV
         run: cargo test --workspace ${{ matrix.flags }}
 
   miri:

Cargo.toml

@@ -5,7 +5,7 @@ resolver = "2"
 [workspace.package]
 version = "0.8.9"
 edition = "2021"
-rust-version = "1.81"
+rust-version = "1.79"
 authors = ["Alloy Contributors"]
 license = "MIT OR Apache-2.0"
 homepage = "https://github.com/alloy-rs/core"

README.md

@@ -56,7 +56,7 @@ When updating this, also update:
 - .github/workflows/ci.yml
 -->
 
-The current MSRV (minimum supported rust version) is 1.81.
+The current MSRV (minimum supported rust version) is 1.79.
 
 Alloy will keep a rolling MSRV policy of **at least** two versions behind the
 latest stable release (so if the latest stable release is 1.58, we would

clippy.toml

@@ -1 +1 @@
-msrv = "1.81"
+msrv = "1.79"

crates/dyn-abi/src/coerce.rs

@@ -256,7 +256,8 @@ enum Error {
     EmptyHexStringWithoutPrefix,
 }
 
-impl core::error::Error for Error {}
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

crates/primitives/src/postgres.rs

@@ -63,7 +63,7 @@ pub enum ToSqlError {
     Overflow(usize, Type),
 }
 
-impl core::error::Error for ToSqlError {}
+impl std::error::Error for ToSqlError {}
 
 /// Convert to Postgres types.
 ///
@@ -225,7 +225,7 @@ pub enum FromSqlError {
     ParseError(Type),
 }
 
-impl core::error::Error for FromSqlError {}
+impl std::error::Error for FromSqlError {}
 
 impl<'a, const BITS: usize, const LIMBS: usize> FromSql<'a> for Signed<BITS, LIMBS> {
     fn accepts(ty: &Type) -> bool {

crates/primitives/src/signed/errors.rs

@@ -48,7 +48,8 @@ impl fmt::Display for ParseSignedError {
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct BigIntConversionError;
 
-impl core::error::Error for BigIntConversionError {}
+#[cfg(feature = "std")]
+impl std::error::Error for BigIntConversionError {}
 
 impl fmt::Display for BigIntConversionError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

crates/sol-type-parser/src/error.rs

@@ -8,7 +8,8 @@ pub type Result<T, E = Error> = core::result::Result<T, E>;
 #[derive(Clone, PartialEq, Eq)]
 pub struct Error(Repr);
 
-impl core::error::Error for Error {}
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}
 
 impl fmt::Debug for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

crates/sol-type-parser/src/input.rs

@@ -18,7 +18,8 @@ impl fmt::Display for CustomError {
     }
 }
 
-impl core::error::Error for CustomError {}
+#[cfg(feature = "std")]
+impl std::error::Error for CustomError {}
 
 pub type Input<'a> = winnow::Stateful<&'a str, RecursionCheck>;
 

crates/sol-types/src/abi/encoder.rs

@@ -43,12 +43,6 @@ impl Encoder {
         }
     }
 
-    /// Return a reference to the encoded words.
-    #[inline]
-    pub fn words(&self) -> &[Word] {
-        &self.buf
-    }
-
     /// Finish the encoding process, returning the encoded words.
     ///
     /// Use `into_bytes` instead to flatten the words into bytes.
@@ -59,18 +53,16 @@ impl Encoder {
         self.buf
     }
 
-    /// Return a reference to the encoded bytes.
-    #[inline]
-    pub fn bytes(&self) -> &[u8] {
-        // SAFETY: `#[repr(transparent)] FixedBytes<N>([u8; N])`
-        unsafe { &*(self.words() as *const [Word] as *const [[u8; 32]]) }.as_flattened()
-    }
-
     /// Finish the encoding process, returning the encoded bytes.
     #[inline]
     pub fn into_bytes(self) -> Vec<u8> {
+        // TODO: remove once `Vec::into_flattened` is stabilized.
+        // unsafe { mem::transmute::<Vec<_>, Vec<[u8; 32]>>(self.buf) }.into_flattened()
+
         // SAFETY: `#[repr(transparent)] FixedBytes<N>([u8; N])`
-        unsafe { mem::transmute::<Vec<Word>, Vec<[u8; 32]>>(self.finish()) }.into_flattened()
+        crate::impl_core::into_flattened::<u8, 32>(unsafe {
+            mem::transmute::<Vec<Word>, Vec<[u8; 32]>>(self.buf)
+        })
     }
 
     /// Determine the current suffix offset.

crates/sol-types/src/impl_core.rs

@@ -1,7 +1,16 @@
 //! Modified implementations of unstable libcore functions.
 
+use alloc::vec::Vec;
 use core::mem::{self, MaybeUninit};
 
+trait Ext {
+    const IS_ZST: bool;
+}
+
+impl<T> Ext for T {
+    const IS_ZST: bool = mem::size_of::<Self>() == 0;
+}
+
 /// [`core::array::try_from_fn`]
 #[inline]
 pub(crate) fn try_from_fn<F, T, E, const N: usize>(mut cb: F) -> Result<[T; N], E>
@@ -79,3 +88,34 @@ pub(crate) unsafe fn array_assume_init<T, const N: usize>(array: [MaybeUninit<T>
 unsafe fn transpose<T, const N: usize>(array: [MaybeUninit<T>; N]) -> MaybeUninit<[T; N]> {
     mem::transmute_copy::<[MaybeUninit<T>; N], MaybeUninit<[T; N]>>(&mem::ManuallyDrop::new(&array))
 }
+
+// TODO(MSRV-1.80): remove
+/// [`Vec::into_flattened`].
+#[inline]
+pub(crate) fn into_flattened<T, const N: usize>(vec: Vec<[T; N]>) -> Vec<T> {
+    let (ptr, len, cap) = into_raw_parts(vec);
+    let (new_len, new_cap) = if T::IS_ZST {
+        (len.checked_mul(N).expect("vec len overflow"), usize::MAX)
+    } else {
+        // SAFETY:
+        // - `cap * N` cannot overflow because the allocation is already in
+        // the address space.
+        // - Each `[T; N]` has `N` valid elements, so there are `len * N`
+        // valid elements in the allocation.
+        unsafe { (len.checked_mul(N).unwrap_unchecked(), cap.checked_mul(N).unwrap_unchecked()) }
+    };
+    // SAFETY:
+    // - `ptr` was allocated by `self`
+    // - `ptr` is well-aligned because `[T; N]` has the same alignment as `T`.
+    // - `new_cap` refers to the same sized allocation as `cap` because
+    // `new_cap * size_of::<T>()` == `cap * size_of::<[T; N]>()`
+    // - `len` <= `cap`, so `len * N` <= `cap * N`.
+    unsafe { Vec::from_raw_parts(ptr.cast(), new_len, new_cap) }
+}
+
+/// [`Vec::into_raw_parts`]
+#[inline(always)]
+fn into_raw_parts<T>(vec: Vec<T>) -> (*mut T, usize, usize) {
+    let mut me = mem::ManuallyDrop::new(vec);
+    (me.as_mut_ptr(), me.len(), me.capacity())
+}

crates/sol-types/src/types/error.rs

@@ -103,7 +103,8 @@ impl fmt::Display for Revert {
     }
 }
 
-impl core::error::Error for Revert {}
+#[cfg(feature = "std")]
+impl std::error::Error for Revert {}
 
 impl AsRef<str> for Revert {
     #[inline]
@@ -263,7 +264,8 @@ impl fmt::Display for Panic {
     }
 }
 
-impl core::error::Error for Panic {}
+#[cfg(feature = "std")]
+impl std::error::Error for Panic {}
 
 impl SolError for Panic {
     type Parameters<'a> = (crate::sol_data::Uint<256>,);

crates/sol-types/src/types/interface/mod.rs

@@ -2,6 +2,9 @@ use crate::{alloc::string::ToString, Error, Panic, Result, Revert, SolError};
 use alloc::{string::String, vec::Vec};
 use core::{convert::Infallible, fmt, iter::FusedIterator, marker::PhantomData};
 
+#[cfg(feature = "std")]
+use std::error::Error as StdError;
+
 mod event;
 pub use event::SolEventInterface;
 
@@ -208,9 +211,10 @@ impl<T: fmt::Display> fmt::Display for ContractError<T> {
     }
 }
 
-impl<T: core::error::Error + 'static> core::error::Error for ContractError<T> {
+#[cfg(feature = "std")]
+impl<T: StdError + 'static> StdError for ContractError<T> {
     #[inline]
-    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
+    fn source(&self) -> Option<&(dyn StdError + 'static)> {
         match self {
             Self::CustomError(error) => Some(error),
             Self::Panic(panic) => Some(panic),

crates/syn-solidity/tests/contracts.rs

@@ -100,7 +100,7 @@ impl Drop for GitPatcher<'_> {
     }
 }
 
-fn parse_file(path: &Path) -> Result<File, Box<dyn core::error::Error>> {
+fn parse_file(path: &Path) -> Result<File, Box<dyn std::error::Error>> {
     let solidity = fs::read_to_string(path)?;
     syn::parse_str(&solidity).map_err(Into::into)
 }