lang: remove redundant discriminator checks

lang/src/accounts/account_loader.rs

@@ -22,8 +22,6 @@ use std::ops::DerefMut;
 /// Note that using accounts in this way is distinctly different from using,
 /// for example, the [`Account`](crate::accounts::account::Account). 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
 ///
@@ -51,7 +49,7 @@ use std::ops::DerefMut;
 ///     use super::*;
 ///
 ///     pub fn create_bar(ctx: Context<CreateBar>, data: u64) -> Result<()> {
-///         let bar = &mut ctx.accounts.bar.load_init()?;
+///         let bar = &mut ctx.accounts.bar.load_mut()?;
 ///         bar.authority = ctx.accounts.authority.key();
 ///         bar.data = data;
 ///         Ok(())
@@ -154,15 +152,6 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
     pub fn load(&self) -> Result<Ref<T>> {
         let data = self.acc_info.try_borrow_data()?;
         let disc = T::DISCRIMINATOR;
-        if data.len() < disc.len() {
-            return Err(ErrorCode::AccountDiscriminatorNotFound.into());
-        }
-
-        let given_disc = &data[..disc.len()];
-        if given_disc != disc {
-            return Err(ErrorCode::AccountDiscriminatorMismatch.into());
-        }
-
         Ok(Ref::map(data, |data| {
             bytemuck::from_bytes(&data[disc.len()..mem::size_of::<T>() + disc.len()])
         }))
@@ -178,41 +167,6 @@ impl<'info, T: ZeroCopy + Owner> AccountLoader<'info, T> {
 
         let data = self.acc_info.try_borrow_mut_data()?;
         let disc = T::DISCRIMINATOR;
-        if data.len() < disc.len() {
-            return Err(ErrorCode::AccountDiscriminatorNotFound.into());
-        }
-
-        let given_disc = &data[..disc.len()];
-        if given_disc != disc {
-            return Err(ErrorCode::AccountDiscriminatorMismatch.into());
-        }
-
-        Ok(RefMut::map(data, |data| {
-            bytemuck::from_bytes_mut(
-                &mut data.deref_mut()[disc.len()..mem::size_of::<T>() + disc.len()],
-            )
-        }))
-    }
-
-    /// 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>> {
-        // 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 disc = T::DISCRIMINATOR;
-        let given_disc = &data[..disc.len()];
-        let has_disc = given_disc.iter().any(|b| *b != 0);
-        if has_disc {
-            return Err(ErrorCode::AccountDiscriminatorAlreadySet.into());
-        }
-
         Ok(RefMut::map(data, |data| {
             bytemuck::from_bytes_mut(
                 &mut data.deref_mut()[disc.len()..mem::size_of::<T>() + disc.len()],

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

@@ -18,7 +18,7 @@ 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-optional/src/lib.rs

@@ -109,13 +109,6 @@ pub mod misc_optional {
         Ok(())
     }
 
-    pub fn test_pda_init_zero_copy(ctx: Context<TestPdaInitZeroCopy>) -> Result<()> {
-        let mut acc = ctx.accounts.my_pda.as_ref().unwrap().load_init()?;
-        acc.data = 9;
-        acc.bump = ctx.bumps.my_pda.unwrap();
-        Ok(())
-    }
-
     pub fn test_pda_mut_zero_copy(ctx: Context<TestPdaMutZeroCopy>) -> Result<()> {
         let mut acc = ctx.accounts.my_pda.as_mut().unwrap().load_mut()?;
         acc.data = 1234;
@@ -139,8 +132,8 @@ pub mod misc_optional {
         Ok(())
     }
 
-    pub fn test_init_zero_copy(ctx: Context<TestInitZeroCopy>) -> Result<()> {
-        let mut data = ctx.accounts.data.as_ref().unwrap().load_init()?;
+    pub fn test_mut_zero_copy(ctx: Context<TestInitZeroCopy>) -> Result<()> {
+        let mut data = ctx.accounts.data.as_ref().unwrap().load_mut()?;
         data.data = 10;
         data.bump = 2;
         Ok(())

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

@@ -103,13 +103,6 @@ pub mod misc {
         Ok(())
     }
 
-    pub fn test_pda_init_zero_copy(ctx: Context<TestPdaInitZeroCopy>) -> Result<()> {
-        let mut acc = ctx.accounts.my_pda.load_init()?;
-        acc.data = 9;
-        acc.bump = ctx.bumps.my_pda;
-        Ok(())
-    }
-
     pub fn test_pda_mut_zero_copy(ctx: Context<TestPdaMutZeroCopy>) -> Result<()> {
         let mut acc = ctx.accounts.my_pda.load_mut()?;
         acc.data = 1234;
@@ -134,7 +127,7 @@ pub mod misc {
     }
 
     pub fn test_init_zero_copy(ctx: Context<TestInitZeroCopy>) -> Result<()> {
-        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>) -> Result<()> {
-        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>) -> Result<()> {
-        let bar = &mut ctx.accounts.bar.load_init()?;
+        let bar = &mut ctx.accounts.bar.load_mut()?;
         bar.authority = *ctx.accounts.authority.key;
         Ok(())
     }