lang, ts: account versioning

CHANGELOG.md

@@ -11,6 +11,11 @@ incremented for features.
 
 ## [Unreleased]
 
+### Breaking
+
+* ts: `BorshAccountsCoder.accountDiscriminator` method has been replaced with `BorshAccountHeader.discriminator` ([#]()).
+* lang, ts: 8 byte account discriminator has been replaced with a versioned account header ([#]()).
+
 ## [0.21.0] - 2022-02-07
 
 ### Fixes

Cargo.lock

@@ -303,7 +303,7 @@ checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
 
 [[package]]
 name = "avm"
-version = "0.20.1"
+version = "0.21.0"
 dependencies = [
  "anyhow",
  "cfg-if 1.0.0",

client/src/lib.rs

@@ -291,12 +291,22 @@ fn handle_program_log<T: anchor_lang::Event + anchor_lang::AnchorDeserialize>(
         };
 
         let mut slice: &[u8] = &borsh_bytes[..];
+
+        #[cfg(feature = "deprecated-layout")]
         let disc: [u8; 8] = {
             let mut disc = [0; 8];
             disc.copy_from_slice(&borsh_bytes[..8]);
             slice = &slice[8..];
             disc
         };
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc: [u8; 4] = {
+            let mut disc = [0; 4];
+            disc.copy_from_slice(&borsh_bytes[2..6]);
+            slice = &slice[8..];
+            disc
+        };
+
         let mut event = None;
         if disc == T::discriminator() {
             let e: T = anchor_lang::AnchorDeserialize::deserialize(&mut slice)

lang/attribute/account/src/lib.rs

@@ -88,6 +88,21 @@ pub fn account(
     let account_name = &account_strct.ident;
     let (impl_gen, type_gen, where_clause) = account_strct.generics.split_for_impl();
 
+    let owner_impl = {
+        if namespace.is_empty() {
+            quote! {
+                #[automatically_derived]
+                impl #impl_gen anchor_lang::Owner for #account_name #type_gen #where_clause {
+                    fn owner() -> Pubkey {
+                        crate::ID
+                    }
+                }
+            }
+        } else {
+            quote! {}
+        }
+    };
+
     let discriminator: proc_macro2::TokenStream = {
         // Namespace the discriminator to prevent collisions.
         let discriminator_preimage = {
@@ -99,25 +114,46 @@ pub fn account(
             }
         };
 
-        let mut discriminator = [0u8; 8];
-        discriminator.copy_from_slice(
-            &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..8],
-        );
-        format!("{:?}", discriminator).parse().unwrap()
+        if cfg!(feature = "deprecated-layout") {
+            let mut discriminator = [0u8; 8];
+            discriminator.copy_from_slice(
+                &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..8],
+            );
+            format!("{:?}", discriminator).parse().unwrap()
+        } else {
+            let mut discriminator = [0u8; 4];
+            discriminator.copy_from_slice(
+                &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..4],
+            );
+            format!("{:?}", discriminator).parse().unwrap()
+        }
     };
 
-    let owner_impl = {
-        if namespace.is_empty() {
+    let disc_bytes = {
+        if cfg!(feature = "deprecated-layout") {
             quote! {
-                #[automatically_derived]
-                impl #impl_gen anchor_lang::Owner for #account_name #type_gen #where_clause {
-                    fn owner() -> Pubkey {
-                        crate::ID
-                    }
+                let given_disc = &buf[..8];
+            }
+        } else {
+            quote! {
+                let given_disc = &buf[2..6];
+            }
+        }
+    };
+
+    let disc_fn = {
+        if cfg!(feature = "deprecated-layout") {
+            quote! {
+                fn discriminator() -> [u8; 8] {
+                    #discriminator
                 }
             }
         } else {
-            quote! {}
+            quote! {
+                fn discriminator() -> [u8; 4] {
+                    #discriminator
+                }
+            }
         }
     };
 
@@ -137,9 +173,7 @@ pub fn account(
 
                 #[automatically_derived]
                 impl #impl_gen anchor_lang::Discriminator for #account_name #type_gen #where_clause {
-                    fn discriminator() -> [u8; 8] {
-                        #discriminator
-                    }
+                    #disc_fn
                 }
 
                 // This trait is useful for clients deserializing accounts.
@@ -147,10 +181,11 @@ pub fn account(
                 #[automatically_derived]
                 impl #impl_gen anchor_lang::AccountDeserialize for #account_name #type_gen #where_clause {
                     fn try_deserialize(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
-                        if buf.len() < #discriminator.len() {
+                        // Header is always 8 bytes.
+                        if buf.len() < 8 {
                             return Err(anchor_lang::__private::ErrorCode::AccountDiscriminatorNotFound.into());
                         }
-                        let given_disc = &buf[..8];
+                        #disc_bytes
                         if &#discriminator != given_disc {
                             return Err(anchor_lang::__private::ErrorCode::AccountDiscriminatorMismatch.into());
                         }
@@ -176,7 +211,6 @@ pub fn account(
                 #[automatically_derived]
                 impl #impl_gen anchor_lang::AccountSerialize for #account_name #type_gen #where_clause {
                     fn try_serialize<W: std::io::Write>(&self, writer: &mut W) -> std::result::Result<(), ProgramError> {
-                        writer.write_all(&#discriminator).map_err(|_| anchor_lang::__private::ErrorCode::AccountDidNotSerialize)?;
                         AnchorSerialize::serialize(
                             self,
                             writer
@@ -192,7 +226,7 @@ pub fn account(
                         if buf.len() < #discriminator.len() {
                             return Err(anchor_lang::__private::ErrorCode::AccountDiscriminatorNotFound.into());
                         }
-                        let given_disc = &buf[..8];
+                        #disc_bytes
                         if &#discriminator != given_disc {
                             return Err(anchor_lang::__private::ErrorCode::AccountDiscriminatorMismatch.into());
                         }
@@ -208,9 +242,7 @@ pub fn account(
 
                 #[automatically_derived]
                 impl #impl_gen anchor_lang::Discriminator for #account_name #type_gen #where_clause {
-                    fn discriminator() -> [u8; 8] {
-                        #discriminator
-                    }
+                    #disc_fn
                 }
 
                 #owner_impl

lang/attribute/event/src/lib.rs

@@ -18,13 +18,42 @@ pub fn event(
 
     let discriminator: proc_macro2::TokenStream = {
         let discriminator_preimage = format!("event:{}", event_name);
-        let mut discriminator = [0u8; 8];
-        discriminator.copy_from_slice(
-            &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..8],
-        );
+
+        #[cfg(feature = "deprecated-layout")]
+        let discriminator = {
+            let mut discriminator = [0u8; 8];
+            discriminator.copy_from_slice(
+                &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..8],
+            );
+            discriminator
+        };
+        #[cfg(not(feature = "deprecated-layout"))]
+        let discriminator = {
+            let mut discriminator = [0u8; 4];
+            discriminator.copy_from_slice(
+                &anchor_syn::hash::hash(discriminator_preimage.as_bytes()).to_bytes()[..4],
+            );
+            discriminator
+        };
         format!("{:?}", discriminator).parse().unwrap()
     };
 
+    let discriminator_trait_impl = {
+        if cfg!(feature = "deprecated_layout") {
+            quote! {
+                fn discriminator() -> [u8; 8] {
+                    #discriminator
+                }
+            }
+        } else {
+            quote! {
+                fn discriminator() -> [u8; 4] {
+                    #discriminator
+                }
+            }
+        }
+    };
+
     proc_macro::TokenStream::from(quote! {
         #[derive(anchor_lang::__private::EventIndex, AnchorSerialize, AnchorDeserialize)]
         #event_strct
@@ -38,9 +67,7 @@ pub fn event(
         }
 
         impl anchor_lang::Discriminator for #event_name {
-            fn discriminator() -> [u8; 8] {
-                #discriminator
-            }
+            #discriminator_trait_impl
         }
     })
 }

lang/src/accounts/account.rs

@@ -334,7 +334,10 @@ impl<'info, T: AccountSerialize + AccountDeserialize + Owner + Clone> AccountsEx
         if &T::owner() == program_id {
             let info = self.to_account_info();
             let mut data = info.try_borrow_mut_data()?;
-            let dst: &mut [u8] = &mut data;
+
+            // Chop off the header.
+            let dst: &mut [u8] = &mut data[8..];
+
             let mut cursor = std::io::Cursor::new(dst);
             self.account.try_serialize(&mut cursor)?;
         }
@@ -405,3 +408,10 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Owner + Clone> DerefMut for
         &mut self.account
     }
 }
+
+#[cfg(not(feature = "deprecated-layout"))]
+impl<'a, T: AccountSerialize + AccountDeserialize + Owner + Clone> Bump for Account<'a, T> {
+    fn seed(&self) -> u8 {
+        self.info.data.borrow()[1]
+    }
+}

lang/src/accounts/account_loader.rs

@@ -1,10 +1,7 @@
 //! Type facilitating on demand zero copy deserialization.
 
 use crate::error::ErrorCode;
-use crate::{
-    Accounts, AccountsClose, AccountsExit, Owner, ToAccountInfo, ToAccountInfos, ToAccountMetas,
-    ZeroCopy,
-};
+use crate::*;
 use arrayref::array_ref;
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
@@ -14,7 +11,6 @@ use solana_program::pubkey::Pubkey;
 use std::cell::{Ref, RefMut};
 use std::collections::BTreeMap;
 use std::fmt;
-use std::io::Write;
 use std::marker::PhantomData;
 use std::mem;
 use std::ops::DerefMut;
@@ -24,8 +20,6 @@ use std::ops::DerefMut;
 /// Note that using accounts in this way is distinctly different from using,
 /// for example, the [`Account`](./struct.Account.html). Namely,
 /// one must call
-/// - `load_init` after initializing an account (this will ignore the missing
-/// account discriminator that gets added only after the user's instruction code)
 /// - `load` when the account is not mutable
 /// - `load_mut` when the account is mutable
 ///
@@ -117,7 +111,7 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
         }
     }
 
-    /// Constructs a new `Loader` from a previously initialized account.
+    /// Constructs a new `AccountLoader` from a previously initialized account.
     #[inline(never)]
     pub fn try_from(
         acc_info: &AccountInfo<'info>,
@@ -127,7 +121,11 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
         }
         let data: &[u8] = &acc_info.try_borrow_data()?;
         // Discriminator must match.
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
@@ -135,7 +133,7 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
         Ok(AccountLoader::new(acc_info.clone()))
     }
 
-    /// Constructs a new `Loader` from an uninitialized account.
+    /// Constructs a new `AccountLoader` from an uninitialized account.
     #[inline(never)]
     pub fn try_from_unchecked(
         _program_id: &Pubkey,
@@ -146,16 +144,18 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
         }
         Ok(AccountLoader::new(acc_info.clone()))
     }
-
     /// Returns a Ref to the account data structure for reading.
     pub fn load(&self) -> Result<Ref<T>, ProgramError> {
         let data = self.acc_info.try_borrow_data()?;
 
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
-
         Ok(Ref::map(data, |data| {
             bytemuck::from_bytes(&data[8..mem::size_of::<T>() + 8])
         }))
@@ -171,7 +171,11 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
 
         let data = self.acc_info.try_borrow_mut_data()?;
 
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
@@ -180,30 +184,6 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
             bytemuck::from_bytes_mut(&mut data.deref_mut()[8..mem::size_of::<T>() + 8])
         }))
     }
-
-    /// Returns a `RefMut` to the account data structure for reading or writing.
-    /// Should only be called once, when the account is being initialized.
-    pub fn load_init(&self) -> Result<RefMut<T>, ProgramError> {
-        // AccountInfo api allows you to borrow mut even if the account isn't
-        // writable, so add this check for a better dev experience.
-        if !self.acc_info.is_writable {
-            return Err(ErrorCode::AccountNotMutable.into());
-        }
-
-        let data = self.acc_info.try_borrow_mut_data()?;
-
-        // The discriminator should be zero, since we're initializing.
-        let mut disc_bytes = [0u8; 8];
-        disc_bytes.copy_from_slice(&data[..8]);
-        let discriminator = u64::from_le_bytes(disc_bytes);
-        if discriminator != 0 {
-            return Err(ErrorCode::AccountDiscriminatorAlreadySet.into());
-        }
-
-        Ok(RefMut::map(data, |data| {
-            bytemuck::from_bytes_mut(&mut data.deref_mut()[8..mem::size_of::<T>() + 8])
-        }))
-    }
 }
 
 impl<'info, T: ZeroCopy + Owner> Accounts<'info> for AccountLoader<'info, T> {
@@ -227,10 +207,7 @@ impl<'info, T: ZeroCopy + Owner> Accounts<'info> for AccountLoader<'info, T> {
 impl<'info, T: ZeroCopy + Owner> AccountsExit<'info> for AccountLoader<'info, T> {
     // The account *cannot* be loaded when this is called.
     fn exit(&self, _program_id: &Pubkey) -> ProgramResult {
-        let mut data = self.acc_info.try_borrow_mut_data()?;
-        let dst: &mut [u8] = &mut data;
-        let mut cursor = std::io::Cursor::new(dst);
-        cursor.write_all(&T::discriminator()).unwrap();
+        // No-op.
         Ok(())
     }
 }
@@ -263,3 +240,10 @@ impl<'info, T: ZeroCopy + Owner> ToAccountInfos<'info> for AccountLoader<'info,
         vec![self.acc_info.clone()]
     }
 }
+
+#[cfg(not(feature = "deprecated-layout"))]
+impl<'a, T: ZeroCopy + Owner> Bump for AccountLoader<'a, T> {
+    fn seed(&self) -> u8 {
+        self.acc_info.data.borrow()[1]
+    }
+}

lang/src/accounts/loader.rs

@@ -1,7 +1,5 @@
 use crate::error::ErrorCode;
-use crate::{
-    Accounts, AccountsClose, AccountsExit, ToAccountInfo, ToAccountInfos, ToAccountMetas, ZeroCopy,
-};
+use crate::*;
 use arrayref::array_ref;
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
@@ -11,7 +9,6 @@ use solana_program::pubkey::Pubkey;
 use std::cell::{Ref, RefMut};
 use std::collections::BTreeMap;
 use std::fmt;
-use std::io::Write;
 use std::marker::PhantomData;
 use std::ops::DerefMut;
 
@@ -62,8 +59,13 @@ impl<'info, T: ZeroCopy> Loader<'info, T> {
             return Err(ErrorCode::AccountOwnedByWrongProgram.into());
         }
         let data: &[u8] = &acc_info.try_borrow_data()?;
+
         // Discriminator must match.
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
@@ -89,7 +91,11 @@ impl<'info, T: ZeroCopy> Loader<'info, T> {
     pub fn load(&self) -> Result<Ref<T>, ProgramError> {
         let data = self.acc_info.try_borrow_data()?;
 
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
@@ -108,7 +114,11 @@ impl<'info, T: ZeroCopy> Loader<'info, T> {
 
         let data = self.acc_info.try_borrow_mut_data()?;
 
+        #[cfg(feature = "deprecated-layout")]
         let disc_bytes = array_ref![data, 0, 8];
+        #[cfg(not(feature = "deprecated-layout"))]
+        let disc_bytes = array_ref![data, 2, 4];
+
         if disc_bytes != &T::discriminator() {
             return Err(ErrorCode::AccountDiscriminatorMismatch.into());
         }
@@ -117,31 +127,6 @@ impl<'info, T: ZeroCopy> Loader<'info, T> {
             bytemuck::from_bytes_mut(&mut data.deref_mut()[8..])
         }))
     }
-
-    /// Returns a `RefMut` to the account data structure for reading or writing.
-    /// Should only be called once, when the account is being initialized.
-    #[allow(deprecated)]
-    pub fn load_init(&self) -> Result<RefMut<T>, ProgramError> {
-        // AccountInfo api allows you to borrow mut even if the account isn't
-        // writable, so add this check for a better dev experience.
-        if !self.acc_info.is_writable {
-            return Err(ErrorCode::AccountNotMutable.into());
-        }
-
-        let data = self.acc_info.try_borrow_mut_data()?;
-
-        // The discriminator should be zero, since we're initializing.
-        let mut disc_bytes = [0u8; 8];
-        disc_bytes.copy_from_slice(&data[..8]);
-        let discriminator = u64::from_le_bytes(disc_bytes);
-        if discriminator != 0 {
-            return Err(ErrorCode::AccountDiscriminatorAlreadySet.into());
-        }
-
-        Ok(RefMut::map(data, |data| {
-            bytemuck::from_bytes_mut(&mut data.deref_mut()[8..])
-        }))
-    }
 }
 
 #[allow(deprecated)]
@@ -167,10 +152,7 @@ impl<'info, T: ZeroCopy> Accounts<'info> for Loader<'info, T> {
 impl<'info, T: ZeroCopy> AccountsExit<'info> for Loader<'info, T> {
     // The account *cannot* be loaded when this is called.
     fn exit(&self, _program_id: &Pubkey) -> ProgramResult {
-        let mut data = self.acc_info.try_borrow_mut_data()?;
-        let dst: &mut [u8] = &mut data;
-        let mut cursor = std::io::Cursor::new(dst);
-        cursor.write_all(&T::discriminator()).unwrap();
+        // No-op.
         Ok(())
     }
 }
@@ -207,3 +189,10 @@ impl<'info, T: ZeroCopy> ToAccountInfos<'info> for Loader<'info, T> {
         vec![self.acc_info.clone()]
     }
 }
+
+#[cfg(not(feature = "deprecated-layout"))]
+impl<'a, T: ZeroCopy> Bump for Loader<'a, T> {
+    fn seed(&self) -> u8 {
+        self.acc_info.data.borrow()[1]
+    }
+}

lang/src/accounts/program_account.rs

@@ -1,10 +1,7 @@
 #[allow(deprecated)]
 use crate::accounts::cpi_account::CpiAccount;
 use crate::error::ErrorCode;
-use crate::{
-    AccountDeserialize, AccountSerialize, Accounts, AccountsClose, AccountsExit, ToAccountInfo,
-    ToAccountInfos, ToAccountMetas,
-};
+use crate::*;
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
 use solana_program::instruction::AccountMeta;
@@ -102,7 +99,10 @@ impl<'info, T: AccountSerialize + AccountDeserialize + Clone> AccountsExit<'info
     fn exit(&self, _program_id: &Pubkey) -> ProgramResult {
         let info = self.to_account_info();
         let mut data = info.try_borrow_mut_data()?;
-        let dst: &mut [u8] = &mut data;
+
+        // Chop off the header.
+        let dst: &mut [u8] = &mut data[8..];
+
         let mut cursor = std::io::Cursor::new(dst);
         self.inner.account.try_serialize(&mut cursor)?;
         Ok(())
@@ -181,3 +181,10 @@ where
         Self::new(a.to_account_info(), Deref::deref(&a).clone())
     }
 }
+
+#[cfg(not(feature = "deprecated-layout"))]
+impl<'a, T: AccountSerialize + AccountDeserialize + Clone> Bump for ProgramAccount<'a, T> {
+    fn seed(&self) -> u8 {
+        self.inner.info.data.borrow()[1]
+    }
+}

lang/src/lib.rs

@@ -200,7 +200,10 @@ pub trait EventData: AnchorSerialize + Discriminator {
 
 /// 8 byte unique identifier for a type.
 pub trait Discriminator {
+    #[cfg(feature = "deprecated-layout")]
     fn discriminator() -> [u8; 8];
+    #[cfg(not(feature = "deprecated-layout"))]
+    fn discriminator() -> [u8; 4];
 }
 
 /// Bump seed for program derived addresses.

lang/syn/src/codegen/accounts/constraints.rs

@@ -142,22 +142,43 @@ fn generate_constraint_address(f: &Field, c: &ConstraintAddress) -> proc_macro2:
     }
 }
 
-pub fn generate_constraint_init(f: &Field, c: &ConstraintInitGroup) -> proc_macro2::TokenStream {
-    generate_constraint_init_group(f, c)
-}
-
 pub fn generate_constraint_zeroed(f: &Field, _c: &ConstraintZeroed) -> proc_macro2::TokenStream {
     let field = &f.ident;
     let ty_decl = f.ty_decl();
-    let from_account_info = f.from_account_info_unchecked(None);
+    let account_ty = f.account_ty();
+    let from_account_info = f.from_account_info(None);
+    let header_write = {
+        if cfg!(feature = "deprecated-layout") {
+            quote! {
+                use std::io::{Write, Cursor};
+                use anchor_lang::Discriminator;
+                let __dst: &mut [u8] = &mut __data;
+                let mut __cursor = Cursor::new(__dst);
+                Write::write_all(&mut __cursor, &#account_ty::discriminator()).unwrap();
+            }
+        } else {
+            quote! {
+                use std::io::{Write, Cursor};
+                use anchor_lang::Discriminator;
+                let __dst: &mut [u8] = &mut __data[2..];
+                let mut __cursor = Cursor::new(__dst);
+                Write::write_all(&mut __cursor, &#account_ty::discriminator()).unwrap();
+            }
+        }
+    };
+    // Check the *entire* account header is zero.
     quote! {
         let #field: #ty_decl = {
-            let mut __data: &[u8] = &#field.try_borrow_data()?;
-            let mut __disc_bytes = [0u8; 8];
-            __disc_bytes.copy_from_slice(&__data[..8]);
-            let __discriminator = u64::from_le_bytes(__disc_bytes);
-            if __discriminator != 0 {
-                return Err(anchor_lang::__private::ErrorCode::ConstraintZero.into());
+            {
+                let mut __data: &mut [u8] = &mut #field.try_borrow_mut_data()?;
+                let mut __header_bytes = [0u8; 8];
+                __header_bytes.copy_from_slice(&__data[..8]);
+                let __header = u64::from_le_bytes(__header_bytes);
+                if __header != 0 {
+                    return Err(anchor_lang::__private::ErrorCode::ConstraintZero.into());
+                }
+
+                #header_write
             }
             #from_account_info
         };
@@ -276,7 +297,7 @@ pub fn generate_constraint_rent_exempt(
     }
 }
 
-fn generate_constraint_init_group(f: &Field, c: &ConstraintInitGroup) -> proc_macro2::TokenStream {
+fn generate_constraint_init(f: &Field, c: &ConstraintInitGroup) -> proc_macro2::TokenStream {
     let field = &f.ident;
     let ty_decl = f.ty_decl();
     let if_needed = if c.if_needed {
@@ -295,7 +316,7 @@ fn generate_constraint_init_group(f: &Field, c: &ConstraintInitGroup) -> proc_ma
     };
 
     // Convert from account info to account context wrapper type.
-    let from_account_info = f.from_account_info_unchecked(Some(&c.kind));
+    let from_account_info = f.from_account_info(Some(&c.kind));
 
     // PDA bump seeds.
     let (find_pda, seeds_with_bump) = match &c.seeds {
@@ -512,6 +533,45 @@ fn generate_constraint_init_group(f: &Field, c: &ConstraintInitGroup) -> proc_ma
             let create_account =
                 generate_create_account(field, quote! {space}, owner.clone(), seeds_with_bump);
 
+            // Write the 8 byte header.
+            let header_write = {
+                match &f.ty {
+                    Ty::Account(_)
+                    | Ty::ProgramAccount(_)
+                    | Ty::Loader(_)
+                    | Ty::AccountLoader(_) => {
+                        let account_ty = f.account_ty();
+                        if cfg!(feature = "deprecated-layout") {
+                            quote! {
+                                {
+                                    use std::io::{Write, Cursor};
+                                    use anchor_lang::Discriminator;
+
+                                    let mut __data = actual_field.try_borrow_mut_data()?;
+                                    let __dst: &mut [u8] = &mut __data;
+                                    let mut __cursor = Cursor::new(__dst);
+                                    Write::write_all(&mut __cursor, &#account_ty::discriminator()).unwrap();
+                                }
+                            }
+                        } else {
+                            quote! {
+                                {
+                                    use std::io::{Write, Seek, SeekFrom, Cursor};
+                                    use anchor_lang::Discriminator;
+
+                                    let mut __data = actual_field.try_borrow_mut_data()?;
+                                    let __dst: &mut [u8] = &mut __data;
+                                    let mut __cursor = Cursor::new(__dst);
+                                    Seek::seek(&mut __cursor, SeekFrom::Start(2)).unwrap();
+                                    Write::write_all(&mut __cursor, &#account_ty::discriminator()).unwrap();
+                                }
+                            }
+                        }
+                    }
+                    _ => quote! {},
+                }
+            };
+
             // Put it all together.
             quote! {
                 // Define the bump variable.
@@ -534,6 +594,10 @@ fn generate_constraint_init_group(f: &Field, c: &ConstraintInitGroup) -> proc_ma
                         #create_account
                     }
 
+                    // Write the account header into the account data before
+                    // deserializing.
+                    #header_write
+
                     // Convert from account info to account context wrapper type.
                     let pa: #ty_decl = #from_account_info;
 

lang/syn/src/codegen/program/handlers.rs

@@ -89,7 +89,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                 let seed = anchor_lang::idl::IdlAccount::seed();
                 let owner = accounts.program.key;
                 let to = Pubkey::create_with_seed(&base, seed, owner).unwrap();
-                // Space: account discriminator || authority pubkey || vec len || vec data
+                // Space: account header || authority pubkey || vec len || vec data
                 let space = 8 + 32 + 4 + data_len as usize;
                 let rent = Rent::get()?;
                 let lamports = rent.minimum_balance(space);
@@ -130,6 +130,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                 let mut data = accounts.to.try_borrow_mut_data()?;
                 let dst: &mut [u8] = &mut data;
                 let mut cursor = std::io::Cursor::new(dst);
+                std::io::Seek::seek(&mut cursor, std::io::SeekFrom::Start(8)).unwrap();
                 idl_account.try_serialize(&mut cursor)?;
 
                 Ok(())
@@ -201,6 +202,34 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                 let ix_name: proc_macro2::TokenStream =
                     generate_ctor_variant_name().parse().unwrap();
                 let ix_name_log = format!("Instruction: {}", ix_name);
+                let header_write = {
+                    if cfg!(feature = "deprecated-layout") {
+                        quote! {
+                            {
+                                use std::io::{Write, Cursor};
+                                use anchor_lang::Discriminator;
+
+                                let mut __data = ctor_accounts.to.try_borrow_mut_data()?;
+                                let __dst: &mut [u8] = &mut __data;
+                                let mut __cursor = Cursor::new(__dst);
+                                Write::write_all(&mut __cursor, &#name::discriminator()).unwrap();
+                            }
+                        }
+                    } else {
+                        quote! {
+                            {
+                                use std::io::{Write, Cursor, SeekFrom, Seek};
+                                use anchor_lang::Discriminator;
+
+                                let mut __data = ctor_accounts.to.try_borrow_mut_data()?;
+                                let __dst: &mut [u8] = &mut __data;
+                                let mut __cursor = Cursor::new(__dst);
+                                Seek::seek(&mut __cursor, SeekFrom::Start(2)).unwrap();
+                                Write::write_all(&mut __cursor, &#name::discriminator()).unwrap();
+                            }
+                        }
+                    }
+                };
                 if state.is_zero_copy {
                     quote! {
                         // One time state account initializer. Will faill on subsequent
@@ -254,14 +283,17 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                                 &[seeds],
                             )?;
 
+                            // Initialize the header.
+                            #header_write
+
                             // Zero copy deserialize.
-                            let loader: anchor_lang::accounts::loader::Loader<#mod_name::#name> = anchor_lang::accounts::loader::Loader::try_from_unchecked(program_id, &ctor_accounts.to)?;
+                            let loader: anchor_lang::accounts::loader::Loader<#mod_name::#name> = anchor_lang::accounts::loader::Loader::try_from(program_id, &ctor_accounts.to)?;
 
                             // Invoke the ctor in a new lexical scope so that
                             // the zero-copy RefMut gets dropped. Required
                             // so that we can subsequently run the exit routine.
                             {
-                                let mut instance = loader.load_init()?;
+                                let mut instance = loader.load_mut()?;
                                 instance.new(
                                     anchor_lang::context::Context::new(
                                         program_id,
@@ -344,11 +376,15 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                                 &[seeds],
                             )?;
 
+                            // Initialize the account header.
+                            #header_write
+
                             // Serialize the state and save it to storage.
                             ctor_user_def_accounts.exit(program_id)?;
                             let mut data = ctor_accounts.to.try_borrow_mut_data()?;
                             let dst: &mut [u8] = &mut data;
                             let mut cursor = std::io::Cursor::new(dst);
+                            std::io::Seek::seek(&mut cursor, std::io::SeekFrom::Start(8)).unwrap();
                             instance.try_serialize(&mut cursor)?;
 
                             Ok(())
@@ -500,6 +536,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                                     let mut data = acc_info.try_borrow_mut_data()?;
                                     let dst: &mut [u8] = &mut data;
                                     let mut cursor = std::io::Cursor::new(dst);
+																		std::io::Seek::seek(&mut cursor, std::io::SeekFrom::Start(8)).unwrap();
                                     state.try_serialize(&mut cursor)?;
 
                                     Ok(())
@@ -628,6 +665,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                                             let mut data = acc_info.try_borrow_mut_data()?;
                                             let dst: &mut [u8] = &mut data;
                                             let mut cursor = std::io::Cursor::new(dst);
+																						std::io::Seek::seek(&mut cursor, std::io::SeekFrom::Start(8)).unwrap();
                                             state.try_serialize(&mut cursor)?;
 
                                             Ok(())

lang/syn/src/idl/file.rs

@@ -238,6 +238,7 @@ pub fn parse(
         .collect::<Vec<IdlConst>>();
 
     Ok(Some(Idl {
+        layout_version: "0.1.0".to_string(),
         version,
         name: p.name.to_string(),
         state,

lang/syn/src/idl/mod.rs

@@ -5,7 +5,11 @@ pub mod file;
 pub mod pda;
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "camelCase")]
 pub struct Idl {
+    // Version of the idl protocol.
+    pub layout_version: String,
+    // Version of the program.
     pub version: String,
     pub name: String,
     #[serde(skip_serializing_if = "Vec::is_empty", default)]

lang/syn/src/lib.rs

@@ -26,6 +26,13 @@ pub(crate) mod hash;
 pub mod idl;
 pub mod parser;
 
+// Layout indices.
+pub const LAYOUT_VERSION: u8 = 0;
+pub const LAYOUT_VERSION_INDEX: u8 = 0;
+pub const LAYOUT_BUMP_INDEX: u8 = 1;
+pub const LAYOUT_DISCRIMINATOR_INDEX: u8 = 2;
+pub const LAYOUT_UNUSED_INDEX: u8 = 6;
+
 #[derive(Debug)]
 pub struct Program {
     pub state: Option<State>,
@@ -273,7 +280,7 @@ impl Field {
 
     // TODO: remove the option once `CpiAccount` is completely removed (not
     //       just deprecated).
-    pub fn from_account_info_unchecked(&self, kind: Option<&InitKind>) -> proc_macro2::TokenStream {
+    pub fn from_account_info(&self, kind: Option<&InitKind>) -> proc_macro2::TokenStream {
         let field = &self.ident;
         let container_ty = self.container_ty();
         match &self.ty {
@@ -284,13 +291,13 @@ impl Field {
             Ty::Account(AccountTy { boxed, .. }) => {
                 if *boxed {
                     quote! {
-                        Box::new(#container_ty::try_from_unchecked(
+                        Box::new(#container_ty::try_from(
                             &#field,
                         )?)
                     }
                 } else {
                     quote! {
-                        #container_ty::try_from_unchecked(
+                        #container_ty::try_from(
                             &#field,
                         )?
                     }
@@ -298,7 +305,14 @@ impl Field {
             }
             Ty::CpiAccount(_) => {
                 quote! {
-                    #container_ty::try_from_unchecked(
+                    #container_ty::try_from(
+                        &#field,
+                    )?
+                }
+            }
+            Ty::AccountLoader(_) => {
+                quote! {
+                    #container_ty::try_from(
                         &#field,
                     )?
                 }
@@ -314,7 +328,7 @@ impl Field {
                     },
                 };
                 quote! {
-                    #container_ty::try_from_unchecked(
+                    #container_ty::try_from(
                         #owner_addr,
                         &#field,
                     )?

tests/chat/programs/chat/src/lib.rs

@@ -19,7 +19,7 @@ pub mod chat {
         let given_name = name.as_bytes();
         let mut name = [0u8; 280];
         name[..given_name.len()].copy_from_slice(given_name);
-        let mut chat = ctx.accounts.chat_room.load_init()?;
+        let mut chat = ctx.accounts.chat_room.load_mut()?;
         chat.name = name;
         Ok(())
     }

tests/misc/programs/misc/src/lib.rs

@@ -122,7 +122,7 @@ pub mod misc {
     }
 
     pub fn test_pda_init_zero_copy(ctx: Context<TestPdaInitZeroCopy>) -> ProgramResult {
-        let mut acc = ctx.accounts.my_pda.load_init()?;
+        let mut acc = ctx.accounts.my_pda.load_mut()?;
         acc.data = 9;
         acc.bump = *ctx.bumps.get("my_pda").unwrap();
         Ok(())
@@ -152,7 +152,7 @@ pub mod misc {
     }
 
     pub fn test_init_zero_copy(ctx: Context<TestInitZeroCopy>) -> ProgramResult {
-        let mut data = ctx.accounts.data.load_init()?;
+        let mut data = ctx.accounts.data.load_mut()?;
         data.data = 10;
         data.bump = 2;
         Ok(())

tests/zero-copy/programs/zero-copy/src/lib.rs

@@ -14,7 +14,7 @@ pub mod zero_copy {
     use super::*;
 
     pub fn create_foo(ctx: Context<CreateFoo>) -> ProgramResult {
-        let foo = &mut ctx.accounts.foo.load_init()?;
+        let foo = &mut ctx.accounts.foo.load_mut()?;
         foo.authority = *ctx.accounts.authority.key;
         foo.set_second_authority(ctx.accounts.authority.key);
         Ok(())
@@ -33,7 +33,7 @@ pub mod zero_copy {
     }
 
     pub fn create_bar(ctx: Context<CreateBar>) -> ProgramResult {
-        let bar = &mut ctx.accounts.bar.load_init()?;
+        let bar = &mut ctx.accounts.bar.load_mut()?;
         bar.authority = *ctx.accounts.authority.key;
         Ok(())
     }

tests/zero-copy/programs/zero-copy/tests/compute_unit_test.rs

@@ -21,8 +21,11 @@ async fn update_foo() {
     let authority = Keypair::new();
     let foo_pubkey = Pubkey::new_unique();
     let foo_account = {
-        let mut foo_data = Vec::new();
+        // Write header.
+        let mut foo_data = vec![0, 0];
         foo_data.extend_from_slice(&zero_copy::Foo::discriminator());
+        foo_data.extend_from_slice(&[0, 0]);
+        // Write data.
         foo_data.extend_from_slice(bytemuck::bytes_of(&zero_copy::Foo {
             authority: authority.pubkey(),
             ..zero_copy::Foo::default()

ts/src/coder/borsh/accounts.ts

@@ -1,3 +1,4 @@
+import { GetProgramAccountsFilter } from "@solana/web3.js";
 import bs58 from "bs58";
 import { Buffer } from "buffer";
 import { Layout } from "buffer-layout";
@@ -7,11 +8,18 @@ import { Idl, IdlTypeDef } from "../../idl.js";
 import { IdlCoder } from "./idl.js";
 import { AccountsCoder } from "../index.js";
 import { accountSize } from "../common.js";
+import * as features from "../../utils/features";
+
+/**
+ * Number of bytes of the account header.
+ */
+const ACCOUNT_HEADER_SIZE = 8;
 
 /**
  * Number of bytes of the account discriminator.
  */
-export const ACCOUNT_DISCRIMINATOR_SIZE = 8;
+const ACCOUNT_DISCRIMINATOR_SIZE = 4;
+const DEPRECATED_ACCOUNT_DISCRIMINATOR_SIZE = 4;
 
 /**
  * Encodes and decodes account objects.
@@ -49,22 +57,21 @@ export class BorshAccountsCoder<A extends string = string>
     }
     const len = layout.encode(account, buffer);
     let accountData = buffer.slice(0, len);
-    let discriminator = BorshAccountsCoder.accountDiscriminator(accountName);
-    return Buffer.concat([discriminator, accountData]);
+    let header = BorshAccountHeader.encode(accountName);
+    return Buffer.concat([header, accountData]);
   }
 
   public decode<T = any>(accountName: A, data: Buffer): T {
-    // Assert the account discriminator is correct.
-    const discriminator = BorshAccountsCoder.accountDiscriminator(accountName);
-    if (discriminator.compare(data.slice(0, 8))) {
+    const expectedDiscriminator = BorshAccountHeader.discriminator(accountName);
+    const givenDisc = BorshAccountHeader.parseDiscriminator(data);
+    if (expectedDiscriminator.compare(givenDisc)) {
       throw new Error("Invalid account discriminator");
     }
     return this.decodeUnchecked(accountName, data);
   }
 
   public decodeUnchecked<T = any>(accountName: A, ix: Buffer): T {
-    // Chop off the discriminator before decoding.
-    const data = ix.slice(ACCOUNT_DISCRIMINATOR_SIZE);
+    const data = ix.slice(BorshAccountHeader.size()); // Chop off the header.
     const layout = this.accountLayouts.get(accountName);
     if (!layout) {
       throw new Error(`Unknown account: ${accountName}`);
@@ -72,20 +79,40 @@ export class BorshAccountsCoder<A extends string = string>
     return layout.decode(data);
   }
 
-  public memcmp(accountName: A, appendData?: Buffer): any {
-    const discriminator = BorshAccountsCoder.accountDiscriminator(accountName);
+  public memcmp(accountName: A): GetProgramAccountsFilter {
+    const discriminator = BorshAccountHeader.discriminator(accountName);
     return {
-      offset: 0,
-      bytes: bs58.encode(
-        appendData ? Buffer.concat([discriminator, appendData]) : discriminator
-      ),
+      memcmp: {
+        offset: BorshAccountHeader.discriminatorOffset(),
+        bytes: bs58.encode(discriminator),
+      },
     };
   }
 
+  public memcmpDataOffset(): number {
+    return BorshAccountHeader.size();
+  }
+
   public size(idlAccount: IdlTypeDef): number {
-    return (
-      ACCOUNT_DISCRIMINATOR_SIZE + (accountSize(this.idl, idlAccount) ?? 0)
-    );
+    return BorshAccountHeader.size() + (accountSize(this.idl, idlAccount) ?? 0);
+  }
+}
+
+export class BorshAccountHeader {
+  /**
+   * Returns the default account header for an account with the given name.
+   */
+  public static encode(accountName: string, nameSpace?: string): Buffer {
+    if (features.isSet("deprecated-layout")) {
+      return BorshAccountHeader.discriminator(accountName, nameSpace);
+    } else {
+      return Buffer.concat([
+        Buffer.from([0]), // Version.
+        Buffer.from([0]), // Bump.
+        BorshAccountHeader.discriminator(accountName), // Disc.
+        Buffer.from([0, 0]), // Unused.
+      ]);
+    }
   }
 
   /**
@@ -93,9 +120,46 @@ export class BorshAccountsCoder<A extends string = string>
    *
    * @param name The name of the account to calculate the discriminator.
    */
-  public static accountDiscriminator(name: string): Buffer {
+  public static discriminator(name: string, nameSpace?: string): Buffer {
     return Buffer.from(
-      sha256.digest(`account:${camelcase(name, { pascalCase: true })}`)
-    ).slice(0, ACCOUNT_DISCRIMINATOR_SIZE);
+      sha256.digest(
+        `${nameSpace ?? "account"}:${camelcase(name, { pascalCase: true })}`
+      )
+    ).slice(0, BorshAccountHeader.discriminatorSize());
+  }
+
+  public static discriminatorSize(): number {
+    return features.isSet("deprecated-layout")
+      ? DEPRECATED_ACCOUNT_DISCRIMINATOR_SIZE
+      : ACCOUNT_DISCRIMINATOR_SIZE;
+  }
+
+  /**
+   * Returns the account data index at which the discriminator starts.
+   */
+  public static discriminatorOffset(): number {
+    if (features.isSet("deprecated-layout")) {
+      return 0;
+    } else {
+      return 2;
+    }
+  }
+
+  /**
+   * Returns the byte size of the account header.
+   */
+  public static size(): number {
+    return ACCOUNT_HEADER_SIZE;
+  }
+
+  /**
+   * Returns the discriminator from the given account data.
+   */
+  public static parseDiscriminator(data: Buffer): Buffer {
+    if (features.isSet("deprecated-layout")) {
+      return data.slice(0, 8);
+    } else {
+      return data.slice(2, 6);
+    }
   }
 }

ts/src/coder/borsh/event.ts

@@ -6,6 +6,7 @@ import { Idl, IdlEvent, IdlTypeDef } from "../../idl.js";
 import { Event, EventData } from "../../program/event.js";
 import { IdlCoder } from "./idl.js";
 import { EventCoder } from "../index.js";
+import * as features from "../../utils/features";
 
 export class BorshEventCoder implements EventCoder {
   /**
@@ -41,7 +42,7 @@ export class BorshEventCoder implements EventCoder {
       idl.events === undefined
         ? []
         : idl.events.map((e) => [
-            base64.fromByteArray(eventDiscriminator(e.name)),
+					base64.fromByteArray(EventHeader.discriminator(e.name)),
             e.name,
           ])
     );
@@ -57,7 +58,7 @@ export class BorshEventCoder implements EventCoder {
     } catch (e) {
       return null;
     }
-    const disc = base64.fromByteArray(logArr.slice(0, 8));
+		const disc = base64.fromByteArray(EventHeader.parseDiscriminator(logArr));
 
     // Only deserialize if the discriminator implies a proper event.
     const eventName = this.discriminators.get(disc);
@@ -69,7 +70,7 @@ export class BorshEventCoder implements EventCoder {
     if (!layout) {
       throw new Error(`Unknown event: ${eventName}`);
     }
-    const data = layout.decode(logArr.slice(8)) as EventData<
+    const data = layout.decode(logArr.slice(EventHeader.size())) as EventData<
       E["fields"][number],
       T
     >;
@@ -78,5 +79,31 @@ export class BorshEventCoder implements EventCoder {
 }
 
 export function eventDiscriminator(name: string): Buffer {
-  return Buffer.from(sha256.digest(`event:${name}`)).slice(0, 8);
+  return EventHeader.discriminator(name);
+}
+
+class EventHeader {
+  public static parseDiscriminator(data: Buffer): Buffer {
+    if (features.isSet("deprecated-layout")) {
+      return data.slice(0, 8);
+    } else {
+      return data.slice(0, 4);
+    }
+  }
+
+  public static size(): number {
+    if (features.isSet("deprecated-layout")) {
+      return 8;
+    } else {
+      return 4;
+    }
+  }
+
+  public static discriminator(name: string): Buffer {
+    if (features.isSet("deprecated-layout")) {
+      return Buffer.from(sha256.digest(`event:${name}`)).slice(0, 8);
+    } else {
+      return Buffer.from(sha256.digest(`event:${name}`)).slice(0, 4);
+    }
+  }
 }

ts/src/coder/borsh/index.ts

@@ -6,7 +6,7 @@ import { BorshStateCoder } from "./state.js";
 import { Coder } from "../index.js";
 
 export { BorshInstructionCoder } from "./instruction.js";
-export { BorshAccountsCoder, ACCOUNT_DISCRIMINATOR_SIZE } from "./accounts.js";
+export { BorshAccountsCoder, BorshAccountHeader } from "./accounts.js";
 export { BorshEventCoder, eventDiscriminator } from "./event.js";
 export { BorshStateCoder, stateDiscriminator } from "./state.js";
 

ts/src/coder/borsh/state.ts

@@ -4,6 +4,7 @@ import { sha256 } from "js-sha256";
 import { Idl } from "../../idl.js";
 import { IdlCoder } from "./idl.js";
 import * as features from "../../utils/features.js";
+import { BorshAccountHeader } from "./accounts";
 
 export class BorshStateCoder {
   private layout: Layout;
@@ -19,15 +20,16 @@ export class BorshStateCoder {
     const buffer = Buffer.alloc(1000); // TODO: use a tighter buffer.
     const len = this.layout.encode(account, buffer);
 
-    const disc = await stateDiscriminator(name);
+    let ns = features.isSet("anchor-deprecated-state") ? "account" : "state";
+    const header = BorshAccountHeader.encode(name, ns);
     const accData = buffer.slice(0, len);
 
-    return Buffer.concat([disc, accData]);
+    return Buffer.concat([header, accData]);
   }
 
-  public decode<T = any>(ix: Buffer): T {
-    // Chop off discriminator.
-    const data = ix.slice(8);
+  public decode<T = any>(data: Buffer): T {
+    // Chop off header.
+    data = data.slice(BorshAccountHeader.size());
     return this.layout.decode(data);
   }
 }
@@ -35,5 +37,8 @@ export class BorshStateCoder {
 // Calculates unique 8 byte discriminator prepended to all anchor state accounts.
 export async function stateDiscriminator(name: string): Promise<Buffer> {
   let ns = features.isSet("anchor-deprecated-state") ? "account" : "state";
-  return Buffer.from(sha256.digest(`${ns}:${name}`)).slice(0, 8);
+  return Buffer.from(sha256.digest(`${ns}:${name}`)).slice(
+    0,
+    BorshAccountHeader.discriminatorSize()
+  );
 }

ts/src/coder/index.ts

@@ -1,3 +1,4 @@
+import { GetProgramAccountsFilter } from "@solana/web3.js";
 import { IdlEvent, IdlTypeDef } from "../idl.js";
 import { Event } from "../program/event.js";
 
@@ -38,7 +39,8 @@ export interface AccountsCoder<A extends string = string> {
   encode<T = any>(accountName: A, account: T): Promise<Buffer>;
   decode<T = any>(accountName: A, ix: Buffer): T;
   decodeUnchecked<T = any>(accountName: A, ix: Buffer): T;
-  memcmp(accountName: A, appendData?: Buffer): any;
+  memcmp(accountName: A): GetProgramAccountsFilter;
+  memcmpDataOffset(): number;
   size(idlAccount: IdlTypeDef): number;
 }
 

ts/src/coder/spl-token/accounts.ts

@@ -1,3 +1,4 @@
+import { GetProgramAccountsFilter } from "@solana/web3.js";
 import * as BufferLayout from "buffer-layout";
 import { publicKey, uint64, coption, bool } from "./buffer-layout.js";
 import { AccountsCoder } from "../index.js";
@@ -44,8 +45,7 @@ export class SplTokenAccountsCoder<A extends string = string>
     }
   }
 
-  // TODO: this won't use the appendData.
-  public memcmp(accountName: A, _appendData?: Buffer): any {
+		public memcmp(accountName: A): GetProgramAccountsFilter {
     switch (accountName) {
       case "Token": {
         return {
@@ -63,6 +63,10 @@ export class SplTokenAccountsCoder<A extends string = string>
     }
   }
 
+  public memcmpDataOffset(): number {
+    return 0;
+  }
+
   public size(idlAccount: IdlTypeDef): number {
     return accountSize(this.idl, idlAccount) ?? 0;
   }

ts/src/idl.ts

@@ -3,6 +3,7 @@ import { PublicKey } from "@solana/web3.js";
 import * as borsh from "@project-serum/borsh";
 
 export type Idl = {
+  layoutVersion: string;
   version: string;
   name: string;
   instructions: IdlInstruction[];

ts/src/program/namespace/account.ts

@@ -1,3 +1,4 @@
+import * as bs58 from 'bs58';
 import camelCase from "camelcase";
 import EventEmitter from "eventemitter3";
 import {
@@ -201,19 +202,25 @@ export class AccountClient<
   async all(
     filters?: Buffer | GetProgramAccountsFilter[]
   ): Promise<ProgramAccount<T>[]> {
+    const typeFilter = [this.coder.accounts.memcmp(this._idlAccount.name)];
+    const dataFilter =
+      filters instanceof Buffer
+        ? [
+            {
+              memcmp: {
+                offset: this.coder.accounts.memcmpDataOffset(),
+                bytes: bs58.encode(filters),
+              },
+            },
+          ]
+        : [];
+    const miscFilters = Array.isArray(filters) ? filters : [];
+
     let resp = await this._provider.connection.getProgramAccounts(
       this._programId,
       {
         commitment: this._provider.connection.commitment,
-        filters: [
-          {
-            memcmp: this.coder.accounts.memcmp(
-              this._idlAccount.name,
-              filters instanceof Buffer ? filters : undefined
-            ),
-          },
-          ...(Array.isArray(filters) ? filters : []),
-        ],
+        filters: typeFilter.concat(dataFilter).concat(miscFilters),
       }
     );
     return resp.map(({ pubkey, account }) => {

ts/src/program/namespace/state.ts

@@ -24,6 +24,7 @@ import InstructionNamespaceFactory from "./instruction.js";
 import RpcNamespaceFactory from "./rpc.js";
 import TransactionNamespaceFactory from "./transaction.js";
 import { IdlTypes, TypeDef } from "./types.js";
+import * as features from "../../utils/features.js";
 
 export default class StateFactory {
   public static build<IDL extends Idl>(
@@ -172,10 +173,19 @@ export class StateClient<IDL extends Idl> {
     if (!state) {
       throw new Error("State is not specified in IDL.");
     }
+
     const expectedDiscriminator = await stateDiscriminator(state.struct.name);
-    if (expectedDiscriminator.compare(accountInfo.data.slice(0, 8))) {
-      throw new Error("Invalid account discriminator");
+
+    if (features.isSet("deprecated-layout")) {
+      if (expectedDiscriminator.compare(accountInfo.data.slice(0, 8))) {
+        throw new Error("Invalid state discriminator");
+      }
+    } else {
+      if (expectedDiscriminator.compare(accountInfo.data.slice(2, 6))) {
+        throw new Error("Invalid state discriminator");
+      }
     }
+
     return this.coder.state.decode(accountInfo.data);
   }
 

ts/src/spl/token.ts

@@ -19,6 +19,7 @@ export function coder(): SplTokenCoder {
  * SplToken IDL.
  */
 export type SplToken = {
+	layoutVersion: "custom";
   version: "0.1.0";
   name: "spl_token";
   instructions: [
@@ -624,6 +625,7 @@ export type SplToken = {
 };
 
 export const IDL: SplToken = {
+	layoutVersion: "custom",
   version: "0.1.0",
   name: "spl_token",
   instructions: [

ts/src/utils/features.ts

@@ -1,4 +1,8 @@
-const _AVAILABLE_FEATURES = new Set(["anchor-deprecated-state", "debug-logs"]);
+const _AVAILABLE_FEATURES = new Set([
+	"anchor-deprecated-state",
+	"debug-logs",
+	"deprecated-layout",
+]);
 
 const _FEATURES = new Map();
 

ts/tests/events.spec.ts

@@ -12,6 +12,7 @@ describe("Events", () => {
       "Program J2XMGdW2qQLx7rAdwWtSZpTXDgAQ988BLP9QTgUZvm54 success",
     ];
     const idl = {
+			layoutVersion: "0.1.0",
       version: "0.0.0",
       name: "basic_0",
       instructions: [

ts/tests/transaction.spec.ts

@@ -15,6 +15,7 @@ describe("Transaction", () => {
     data: Buffer.from("post"),
   });
   const idl = {
+		layoutVersion: "0.1.0",
     version: "0.0.0",
     name: "basic_0",
     instructions: [