Migrate from generic_const_exprs to generic_const_args

.cargo/config.toml

@@ -0,0 +1,7 @@
+# This wildcard allows to merge whatever user might have configured in their home folder
+[target.'cfg(all())']
+# TODO: `-Znext-solver=globally` is a requirement for `generic_const_args`, `-Zmin-recursion-limit=256` is in turn
+#  needed for some crates due to `-Znext-solver=globally`
+rustflags = ["-Znext-solver=globally", "-Zmin-recursion-limit=256"]
+rustdocflags = ["-Znext-solver=globally", "-Zmin-recursion-limit=256"]
+# TODO: Specify `miriflags` is/when it is supported: https://github.com/rust-lang/cargo/issues/17079

.github/workflows/gh-pages.yml

@@ -38,7 +38,9 @@ jobs:
           cargo -Zgitoxide -Zgit doc --locked --all --no-deps --lib --all-features
           cp -r target/doc gh-pages/rust-docs
         env:
-          RUSTDOCFLAGS: "-D rustdoc::broken-intra-doc-links -D rustdoc::private_intra_doc_links -Z unstable-options --enable-index-page"
+          # TODO: `-Znext-solver=globally` is a requirement for `generic_const_args`, `-Zmin-recursion-limit=256` is in
+          #  turn needed for some crates due to `-Znext-solver=globally`
+          RUSTDOCFLAGS: -Znext-solver=globally -Zmin-recursion-limit=256 -D rustdoc::broken-intra-doc-links -D rustdoc::private_intra_doc_links -Z unstable-options --enable-index-page
 
       - name: Install Hugo
         uses: peaceiris/actions-hugo@75d2e84710de30f6ff7268e08f310b60ef14033f #v3.0.0

.github/workflows/rust.yml

@@ -15,10 +15,14 @@ env:
   # Not needed in CI, should make things a bit faster
   CARGO_INCREMENTAL: 0
   CARGO_TERM_COLOR: always
-  # Build smaller artifacts to avoid running out of space in CI and make it a bit faster
-  RUSTFLAGS: -C strip=symbols
+  # Build smaller artifacts to avoid running out of space in CI and make it a bit faster.
+  # TODO: `-Znext-solver=globally` is a requirement for `generic_const_args`, `-Zmin-recursion-limit=256` is in turn
+  #  needed for some crates due to `-Znext-solver=globally`
+  RUSTFLAGS: -Znext-solver=globally -Zmin-recursion-limit=256 -C strip=symbols
   # Needed for things like file system access
-  MIRIFLAGS: -Zmiri-disable-isolation
+  # TODO: `-Znext-solver=globally` is a requirement for `generic_const_args`, `-Zmin-recursion-limit=256` is in turn
+  #  needed for some crates due to `-Znext-solver=globally`
+  MIRIFLAGS: -Znext-solver=globally -Zmin-recursion-limit=256 -Zmiri-disable-isolation
   RUST_BACKTRACE: full
 
 jobs:
@@ -97,7 +101,8 @@ jobs:
       - &riscv-support-step
         name: RISC-V support
         run: |
-          echo "command=${{ env.command }} -Zbuild-std" >> $GITHUB_ENV
+          # TODO: Everything after `-Zbuild-std` is a workaround to get `-Znext-solver=globally` working with cross-compilation
+          echo "command=${{ env.command }} -Zbuild-std -Ztarget-applies-to-host -Zhost-config --config 'host.rustflags=[\"-Znext-solver=globally\"]'" >> $GITHUB_ENV
           echo "RUSTFLAGS=${{ env.RUSTFLAGS }} -C linker=riscv64-linux-gnu-gcc" >> $GITHUB_ENV
           # TODO: Temporary workaround for https://github.com/rust-lang/cc-rs/issues/1654
           echo "CC_riscv64_unknown_none_abundance=riscv64-linux-gnu-gcc" >> $GITHUB_ENV

Cargo.toml

@@ -296,8 +296,6 @@ doc_markdown = "allow"
 ignore_without_reason = "allow"
 ignored_unit_patterns = "allow"
 indexing_slicing = "allow"
-# TODO: Currently used for very context-specific workarounds for `generic_const_exprs` that would be awkward to rewrite
-items_after_statements = "allow"
 many_single_char_names = "allow"
 min_ident_chars = "allow"
 missing_assert_message = "allow"
@@ -330,3 +328,7 @@ non_zero_suggestions = "allow"
 redundant_type_annotations = "allow"
 # TODO: Re-enable once false-positive is resolved: https://github.com/rust-lang/rust-clippy/issues/17039
 unnecessary_safety_comment = "allow"
+
+[patch.crates-io]
+# TODO: Remove once `3.7.6` or newer is released
+parity-scale-codec-derive = { git = "https://github.com/paritytech/parity-scale-codec", rev = "a6a501af9db4302261aa4fa0c012781352e833a3" }

crates/contracts/core/ab-contract-file/src/instruction.rs

@@ -10,7 +10,7 @@ pub struct ContractRegisters {
     regs: [u64; 32],
 }
 
-impl const RegisterFile<ContractRegister> for ContractRegisters {
+const impl RegisterFile<ContractRegister> for ContractRegisters {
     #[inline(always)]
     fn read(&self, reg: ContractRegister) -> u64 {
         if reg == ContractRegister::Zero {
@@ -101,7 +101,7 @@ pub enum ContractRegister {
     T6 = 31,
 }
 
-impl const Default for ContractRegister {
+const impl Default for ContractRegister {
     #[inline(always)]
     fn default() -> Self {
         Self::Zero
@@ -151,7 +151,7 @@ impl fmt::Debug for ContractRegister {
     }
 }
 
-impl const PartialEq for ContractRegister {
+const impl PartialEq for ContractRegister {
     #[inline(always)]
     fn eq(&self, other: &Self) -> bool {
         // This is quite ugly, but the default `derive` isn't `const` there doesn't seem to be a
@@ -192,9 +192,9 @@ impl const PartialEq for ContractRegister {
     }
 }
 
-impl const Eq for ContractRegister {}
+const impl Eq for ContractRegister {}
 
-impl const Register for ContractRegister {
+const impl Register for ContractRegister {
     const ZERO: Self = Self::Zero;
     const SP: Self = Self::Sp;
     const RA: Self = Self::Ra;
@@ -241,7 +241,7 @@ impl const Register for ContractRegister {
 }
 
 /// SAFETY: `Self::from_bits()` returns `Some()` for `1`, `8`, `9` and `18..=27`
-unsafe impl const ZcmpRegister for ContractRegister {
+const unsafe impl ZcmpRegister for ContractRegister {
     const RVE: bool = false;
 }
 
@@ -264,7 +264,7 @@ unsafe impl const ZcmpRegister for ContractRegister {
 pub enum ContractInstruction<Reg = ContractRegister> {}
 
 #[instruction]
-impl<Reg> const Instruction for ContractInstruction<Reg>
+const impl<Reg> Instruction for ContractInstruction<Reg>
 where
     Reg: [const] Register<Type = u64>,
 {

crates/contracts/core/ab-contract-file/src/lib.rs

@@ -41,10 +41,6 @@
     trusted_len,
     try_blocks
 )]
-#![expect(incomplete_features, reason = "generic_const_exprs")]
-// TODO: This feature is not actually used in this crate, but is added as a workaround for
-//  https://github.com/rust-lang/rust/issues/141492
-#![feature(generic_const_exprs)]
 #![no_std]
 
 pub mod instruction;

crates/contracts/core/ab-contracts-common/src/metadata.rs

@@ -142,7 +142,7 @@ pub enum ContractMetadataKind {
     Return,
 }
 
-impl const TryFrom<u8> for ContractMetadataKind {
+const impl TryFrom<u8> for ContractMetadataKind {
     type Error = ();
 
     #[inline(always)]

crates/contracts/core/ab-contracts-macros-impl/src/contract.rs

@@ -122,6 +122,7 @@ fn process_trait_definition(mut item_trait: ItemTrait) -> Result<TokenStream, Er
         #ext_trait
 
         /// FFI code generated by procedural macro
+        #[expect(clippy::inline_modules, reason = "Macro-generated code")]
         pub mod ffi {
             use super::*;
 
@@ -261,6 +262,7 @@ fn process_trait_impl(mut item_impl: ItemImpl, trait_name: &Ident) -> Result<Tok
         }
 
         /// FFI code generated by procedural macro
+        #[expect(clippy::inline_modules, reason = "Macro-generated code")]
         pub mod #ffi_mod_ident {
             use super::*;
 
@@ -518,6 +520,7 @@ fn process_struct_impl(mut item_impl: ItemImpl) -> Result<TokenStream, Error> {
         #ext_trait
 
         /// FFI code generated by procedural macro
+        #[expect(clippy::inline_modules, reason = "Macro-generated code")]
         pub mod ffi {
             use super::*;
 

crates/contracts/core/ab-contracts-macros-impl/src/contract/method.rs

@@ -616,6 +616,7 @@ impl MethodDetails {
         let metadata = self.generate_metadata(fn_sig, trait_name)?;
 
         Ok(quote_spanned! {fn_sig.span() =>
+            #[expect(clippy::inline_modules, reason = "Macro-generated code")]
             pub mod #original_method_name {
                 use super::*;
 
@@ -637,6 +638,7 @@ impl MethodDetails {
         let metadata = self.generate_metadata(fn_sig, trait_name)?;
 
         Ok(quote_spanned! {fn_sig.span() =>
+            #[expect(clippy::inline_modules, reason = "Macro-generated code")]
             pub mod #original_method_name {
                 use super::*;
 
@@ -1082,6 +1084,7 @@ impl MethodDetails {
 
             quote! {
                 #[doc(hidden)]
+                #[expect(clippy::inline_modules, reason = "Macro-generated code")]
                 pub mod fn_pointer {
                     use super::*;
 

crates/contracts/core/ab-contracts-tooling/src/build.rs

@@ -40,10 +40,12 @@ pub fn build_cdylib(options: BuildOptions<'_>) -> anyhow::Result<PathBuf> {
         .env_remove("RUSTFLAGS")
         .env_remove("CARGO_ENCODED_RUSTFLAGS")
         // Hack for enabling RISC-V Zknh backend in `sha2` crate since it is a nightly-only feature,
-        // and they really don't like using normal features for it
+        // and they really don't like using normal features for it.
+        // `-Znext-solver=globally` is needed for `generic_const_args` in various crates.
         .env(
             "RUSTFLAGS",
-            "--cfg sha2_backend=\"riscv-zknh\" --cfg sha2_backend_riscv_zknh=\"compact\"",
+            r#"--cfg sha2_backend="riscv-zknh" --cfg sha2_backend_riscv_zknh="compact"
+            -Znext-solver=globally"#,
         )
         .args([
             "rustc",
@@ -55,6 +57,14 @@ pub fn build_cdylib(options: BuildOptions<'_>) -> anyhow::Result<PathBuf> {
             target_specification_path
                 .to_str()
                 .context("Path to target specification file is not valid UTF-8")?,
+        ])
+        // `-Znext-solver=globally` is needed for `generic_const_args` in various crates, it is not
+        // propagated to the target's build script by default, hence such hacks
+        .args([
+            "-Ztarget-applies-to-host",
+            "-Zhost-config",
+            "--config",
+            r#"host.rustflags=["-Znext-solver=globally"]"#,
         ]);
 
     if env::var("MIRI_SYSROOT").is_ok() {

crates/contracts/system/ab-system-contract-simple-wallet-base/src/payload.rs

@@ -50,7 +50,7 @@ pub enum TransactionMethodContext {
     Wallet,
 }
 
-impl const TryFrom<u8> for TransactionMethodContext {
+const impl TryFrom<u8> for TransactionMethodContext {
     type Error = ();
 
     #[inline(always)]

crates/execution/ab-riscv-act4-runner/src/abundance_rv32i_max/instruction.rs

@@ -28,7 +28,7 @@ pub(crate) type AbundanceRv32IMaxInstruction = AbundanceRv32IMaxInstructionProto
 pub(crate) enum AbundanceRv32IMaxInstructionPrototype<Reg> {}
 
 #[instruction]
-impl<Reg> const Instruction for AbundanceRv32IMaxInstructionPrototype<Reg>
+const impl<Reg> Instruction for AbundanceRv32IMaxInstructionPrototype<Reg>
 where
     Reg: [const] Register<Type = u32>,
 {

crates/execution/ab-riscv-act4-runner/src/abundance_rv32i_max/interpreter.rs

@@ -8,7 +8,7 @@ const VLEN: u32 = 1024;
 
 pub(crate) struct AbundanceRv32IMaxExtState {
     csrs: BTreeMap<u16, u32>,
-    vregs: VectorRegisterFile<{ Self::VLENB as usize }>,
+    vregs: VectorRegisterFile<const { Self::VLENB }>,
 }
 
 impl AbundanceRv32IMaxExtState {
@@ -95,11 +95,11 @@ impl VectorRegisters for AbundanceRv32IMaxExtState
 where
     Self: Csrs<<AbundanceRv32IMaxInstruction as Instruction>::Reg>,
 {
-    fn read_vregs(&self) -> &VectorRegisterFile<{ Self::VLENB as usize }> {
+    fn read_vregs(&self) -> &VectorRegisterFile<{ Self::VLENB }> {
         &self.vregs
     }
 
-    fn write_vregs(&mut self) -> &mut VectorRegisterFile<{ Self::VLENB as usize }> {
+    fn write_vregs(&mut self) -> &mut VectorRegisterFile<{ Self::VLENB }> {
         &mut self.vregs
     }
 

crates/execution/ab-riscv-act4-runner/src/abundance_rv64i_max/instruction.rs

@@ -28,7 +28,7 @@ pub(crate) type AbundanceRv64IMaxInstruction = AbundanceRv64IMaxInstructionProto
 pub(crate) enum AbundanceRv64IMaxInstructionPrototype<Reg> {}
 
 #[instruction]
-impl<Reg> const Instruction for AbundanceRv64IMaxInstructionPrototype<Reg>
+const impl<Reg> Instruction for AbundanceRv64IMaxInstructionPrototype<Reg>
 where
     Reg: [const] Register<Type = u64>,
 {

crates/execution/ab-riscv-act4-runner/src/abundance_rv64i_max/interpreter.rs

@@ -8,7 +8,7 @@ const VLEN: u32 = 1024;
 
 pub(crate) struct AbundanceRv64IMaxExtState {
     csrs: BTreeMap<u16, u64>,
-    vregs: VectorRegisterFile<{ Self::VLENB as usize }>,
+    vregs: VectorRegisterFile<const { Self::VLENB }>,
 }
 
 impl AbundanceRv64IMaxExtState {
@@ -98,11 +98,11 @@ impl VectorRegisters for AbundanceRv64IMaxExtState
 where
     Self: Csrs<<AbundanceRv64IMaxInstruction as Instruction>::Reg>,
 {
-    fn read_vregs(&self) -> &VectorRegisterFile<{ Self::VLENB as usize }> {
+    fn read_vregs(&self) -> &VectorRegisterFile<{ Self::VLENB }> {
         &self.vregs
     }
 
-    fn write_vregs(&mut self) -> &mut VectorRegisterFile<{ Self::VLENB as usize }> {
+    fn write_vregs(&mut self) -> &mut VectorRegisterFile<{ Self::VLENB }> {
         &mut self.vregs
     }
 

crates/execution/ab-riscv-act4-runner/src/instruction.rs

@@ -14,7 +14,7 @@ use std::ops::ControlFlow;
 pub(crate) enum MachineModePlaceholder<Reg> {}
 
 #[instruction]
-impl<Reg> const Instruction for MachineModePlaceholder<Reg>
+const impl<Reg> Instruction for MachineModePlaceholder<Reg>
 where
     Reg: [const] Register,
 {

crates/execution/ab-riscv-act4-runner/src/main.rs

@@ -1,11 +1,14 @@
-#![expect(incomplete_features, reason = "generic_const_exprs")]
+#![expect(incomplete_features, reason = "generic_const_*")]
 #![feature(
     const_cmp,
     const_trait_impl,
     const_try,
     const_try_residual,
-    generic_const_exprs,
+    generic_const_args,
+    generic_const_items,
+    inherent_associated_types,
     iter_array_chunks,
+    min_generic_const_args,
     signed_bigint_helpers,
     try_blocks
 )]
@@ -42,6 +45,8 @@ const RAM_BASE: u64 = 0x8000_0000;
 const RAM_SIZE: usize = 0x80000;
 const MRET_INSTRUCTION: u32 = 0x3020_0073;
 
+type const SIZE_OF<T>: usize = const { size_of::<T>() };
+
 /// RISC-V ISA
 #[derive(Debug, Clone, Copy, ValueEnum)]
 enum Isa {
@@ -443,7 +448,7 @@ fn run_rv32i_max_test(
         }
     }
 
-    check_signature(&elf, &state.memory)
+    check_signature::<_, _, 4, _>(&elf, &state.memory)
 }
 
 // TODO: It doesn't seem to be possible to make this generic over the instruction type at the moment
@@ -576,16 +581,15 @@ fn run_rv64i_max_test(
         }
     }
 
-    check_signature(&elf, &state.memory)
+    check_signature::<_, _, 8, _>(&elf, &state.memory)
 }
 
-fn check_signature<const RAM_BASE: u64, const RAM_SIZE: usize, Reg>(
+fn check_signature<const RAM_BASE: u64, const RAM_SIZE: usize, const SIZE_OF_REG: usize, Reg>(
     elf: &ParsedElf<Reg>,
     memory: &BasicMemory<RAM_BASE, RAM_SIZE>,
 ) -> Result<(), TestError<Reg::Type>>
 where
     Reg: Register<Type: BasicInt>,
-    [(); size_of::<Reg::Type>()]:,
 {
     let Some(tohost) = memory.tohost_value::<Reg::Type>(elf.tohost_addr)? else {
         return Err(TestError::Test(anyhow::anyhow!(
@@ -624,10 +628,17 @@ where
         });
     }
 
+    // TODO: Using `SIZE_OF::<Reg::Type>` causes ICE:
+    //  https://github.com/rust-lang/rust/issues/156744
+    assert_eq!(SIZE_OF::<Reg::Type>, SIZE_OF_REG);
+
     for (word, (actual, expected)) in actual_signature
         .iter()
         .copied()
-        .array_chunks::<{ size_of::<Reg::Type>() }>()
+        // TODO: Using `SIZE_OF::<Reg::Type>` causes ICE:
+        //  https://github.com/rust-lang/rust/issues/156744
+        // .array_chunks::<{ SIZE_OF::<Reg::Type> }>()
+        .array_chunks::<SIZE_OF_REG>()
         .map(|bytes| {
             // SAFETY: Correct size with all bit patterns being valid
             unsafe { bytes.as_ptr().cast::<Reg::Type>().read_unaligned() }
@@ -636,7 +647,10 @@ where
             expected_signature
                 .iter()
                 .copied()
-                .array_chunks::<{ size_of::<Reg::Type>() }>()
+                // TODO: Using `SIZE_OF::<Reg::Type>` causes ICE:
+                //  https://github.com/rust-lang/rust/issues/156744
+                // .array_chunks::<{ SIZE_OF::<Reg::Type> }>()
+                .array_chunks::<SIZE_OF_REG>()
                 .map(|bytes| {
                     // SAFETY: Correct size with all bit patterns being valid
                     unsafe { bytes.as_ptr().cast::<Reg::Type>().read_unaligned() }