Add interest bearing mint extension

CHANGELOG.md

@@ -55,6 +55,7 @@ The minor version will be incremented upon a breaking change and the patch versi
 - cli: Add short alias for the `idl build` command ([#3283](https://github.com/coral-xyz/anchor/pull/3283)).
 - cli: Add `--program-id` option to `idl convert` command ([#3309](https://github.com/coral-xyz/anchor/pull/3309)).
 - lang: Generate documentation of constants in `declare_program!` ([#3311](https://github.com/coral-xyz/anchor/pull/3311)).
+- spl: Add 'Interest Bearing Config` Extension ([#3278](https://github.com/coral-xyz/anchor/pull/3278)).
 - cli: Add support for fetching legacy IDLs ([#3324](https://github.com/coral-xyz/anchor/pull/3324)).
 - avm: Add short alias for `install` and `list` commands ([#3326](https://github.com/coral-xyz/anchor/pull/3326)).
 - avm: Add Windows support for renaming anchor binary ([#3325](https://github.com/coral-xyz/anchor/pull/3325)).

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

@@ -688,6 +688,8 @@ fn generate_constraint_init_group(
             metadata_pointer_metadata_address,
             close_authority,
             permanent_delegate,
+            interest_bearing_mint_rate,
+            interest_bearing_mint_authority,
             transfer_hook_authority,
             transfer_hook_program_id,
         } => {
@@ -805,6 +807,10 @@ fn generate_constraint_init_group(
                 extensions.push(quote! {::anchor_spl::token_interface::spl_token_2022::extension::ExtensionType::PermanentDelegate});
             }
 
+            if interest_bearing_mint_rate.is_some() {
+                extensions.push(quote! {::anchor_spl::token_interface::spl_token_2022::extension::ExtensionType::InterestBearingConfig});
+            }
+
             let mint_space = if extensions.is_empty() {
                 quote! { ::anchor_spl::token::Mint::LEN }
             } else {
@@ -864,6 +870,18 @@ fn generate_constraint_init_group(
                 None => quote! { Option::<&anchor_lang::prelude::Pubkey>::None },
             };
 
+            let interest_bearing_mint_rate = match interest_bearing_mint_rate {
+                Some(ibmr) => quote! { Option::<i16>::Some(#ibmr) },
+                None => quote! { Option::<i16>::None },
+            };
+
+            let interest_bearing_mint_authority = match interest_bearing_mint_authority {
+                Some(ibma) => {
+                    quote! { Option::<anchor_lang::prelude::Pubkey>::Some(#ibma.key()) }
+                }
+                None => quote! { Option::<anchor_lang::prelude::Pubkey>::None },
+            };
+
             let transfer_hook_authority = match transfer_hook_authority {
                 Some(tha) => quote! { Option::<anchor_lang::prelude::Pubkey>::Some(#tha.key()) },
                 None => quote! { Option::<anchor_lang::prelude::Pubkey>::None },
@@ -946,6 +964,12 @@ fn generate_constraint_init_group(
                                             mint: #field.to_account_info(),
                                         }), #permanent_delegate.unwrap())?;
                                     },
+                                    ::anchor_spl::token_interface::spl_token_2022::extension::ExtensionType::InterestBearingConfig => {
+                                        ::anchor_spl::token_interface::interest_bearing_mint_initialize(anchor_lang::context::CpiContext::new(#token_program.to_account_info(), ::anchor_spl::token_interface::InterestBearingMintInitialize {
+                                            token_program_id: #token_program.to_account_info(),
+                                            mint: #field.to_account_info(),
+                                        }), #interest_bearing_mint_authority, #interest_bearing_mint_rate.unwrap())?;
+                                    },
                                     // All extensions specified by the user should be implemented.
                                     // If this line runs, it means there is a bug in the codegen.
                                     _ => unimplemented!("{e:?}"),

lang/syn/src/lib.rs

@@ -783,6 +783,8 @@ pub enum ConstraintToken {
     ExtensionTokenHookAuthority(Context<ConstraintExtensionAuthority>),
     ExtensionTokenHookProgramId(Context<ConstraintExtensionTokenHookProgramId>),
     ExtensionPermanentDelegate(Context<ConstraintExtensionPermanentDelegate>),
+    ExtensionInterestBearingMintRate(Context<ConstraintExtensionInterestBearingMintRate>),
+    ExtensionInterestBearingMintAuthority(Context<ConstraintExtensionAuthority>),
 }
 
 impl Parse for ConstraintToken {
@@ -905,6 +907,11 @@ pub struct ConstraintExtensionAuthority {
     pub authority: Expr,
 }
 
+#[derive(Debug, Clone)]
+pub struct ConstraintBool {
+    pub enable: Expr,
+}
+
 #[derive(Debug, Clone)]
 pub struct ConstraintExtensionGroupPointerGroupAddress {
     pub group_address: Expr,
@@ -930,6 +937,11 @@ pub struct ConstraintExtensionPermanentDelegate {
     pub permanent_delegate: Expr,
 }
 
+#[derive(Debug, Clone)]
+pub struct ConstraintExtensionInterestBearingMintRate {
+    pub rate: Expr,
+}
+
 #[derive(Debug, Clone)]
 #[allow(clippy::large_enum_variant)]
 pub enum InitKind {
@@ -965,6 +977,8 @@ pub enum InitKind {
         metadata_pointer_metadata_address: Option<Expr>,
         close_authority: Option<Expr>,
         permanent_delegate: Option<Expr>,
+        interest_bearing_mint_rate: Option<Expr>,
+        interest_bearing_mint_authority: Option<Expr>,
         transfer_hook_authority: Option<Expr>,
         transfer_hook_program_id: Option<Expr>,
     },

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

@@ -230,6 +230,35 @@ pub fn parse_token(stream: ParseStream) -> ParseResult<ConstraintToken> {
                         _ => return Err(ParseError::new(ident.span(), "Invalid attribute")),
                     }
                 }
+                "interest_bearing_mint" => {
+                    stream.parse::<Token![:]>()?;
+                    stream.parse::<Token![:]>()?;
+                    let kw = stream.call(Ident::parse_any)?.to_string();
+                    stream.parse::<Token![=]>()?;
+
+                    let span = ident
+                        .span()
+                        .join(stream.span())
+                        .unwrap_or_else(|| ident.span());
+
+                    match kw.as_str() {
+                        "rate" => ConstraintToken::ExtensionInterestBearingMintRate(Context::new(
+                            span,
+                            ConstraintExtensionInterestBearingMintRate {
+                                rate: stream.parse()?,
+                            },
+                        )),
+                        "authority" => {
+                            ConstraintToken::ExtensionInterestBearingMintAuthority(Context::new(
+                                span,
+                                ConstraintExtensionAuthority {
+                                    authority: stream.parse()?,
+                                },
+                            ))
+                        }
+                        _ => return Err(ParseError::new(ident.span(), "Invalid attribute")),
+                    }
+                }
                 "transfer_hook" => {
                     stream.parse::<Token![:]>()?;
                     stream.parse::<Token![:]>()?;
@@ -525,6 +554,7 @@ pub struct ConstraintGroupBuilder<'ty> {
     pub mint_freeze_authority: Option<Context<ConstraintMintFreezeAuthority>>,
     pub mint_decimals: Option<Context<ConstraintMintDecimals>>,
     pub mint_token_program: Option<Context<ConstraintTokenProgram>>,
+    // mint extensions.
     pub extension_group_pointer_authority: Option<Context<ConstraintExtensionAuthority>>,
     pub extension_group_pointer_group_address:
         Option<Context<ConstraintExtensionGroupPointerGroupAddress>>,
@@ -538,6 +568,9 @@ pub struct ConstraintGroupBuilder<'ty> {
     pub extension_transfer_hook_authority: Option<Context<ConstraintExtensionAuthority>>,
     pub extension_transfer_hook_program_id: Option<Context<ConstraintExtensionTokenHookProgramId>>,
     pub extension_permanent_delegate: Option<Context<ConstraintExtensionPermanentDelegate>>,
+    pub extension_interest_bearing_mint_rate:
+        Option<Context<ConstraintExtensionInterestBearingMintRate>>,
+    pub extension_interest_bearing_mint_authority: Option<Context<ConstraintExtensionAuthority>>,
     pub bump: Option<Context<ConstraintTokenBump>>,
     pub program_seed: Option<Context<ConstraintProgramSeed>>,
     pub realloc: Option<Context<ConstraintRealloc>>,
@@ -583,6 +616,8 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             extension_transfer_hook_authority: None,
             extension_transfer_hook_program_id: None,
             extension_permanent_delegate: None,
+            extension_interest_bearing_mint_rate: None,
+            extension_interest_bearing_mint_authority: None,
             bump: None,
             program_seed: None,
             realloc: None,
@@ -795,6 +830,8 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             extension_transfer_hook_authority,
             extension_transfer_hook_program_id,
             extension_permanent_delegate,
+            extension_interest_bearing_mint_rate,
+            extension_interest_bearing_mint_authority,
             bump,
             program_seed,
             realloc,
@@ -975,6 +1012,7 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
                             )),
                         },
                         token_program: token_token_program.map(|tp| tp.into_inner().token_program),
+
                     }
                 } else if let Some(at) = &associated_token {
                     InitKind::AssociatedToken {
@@ -1003,6 +1041,8 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
                         metadata_pointer_metadata_address: extension_metadata_pointer_metadata_address.map(|mpma| mpma.into_inner().metadata_address),
                         close_authority: extension_close_authority.map(|ca| ca.into_inner().authority),
                         permanent_delegate: extension_permanent_delegate.map(|pd| pd.into_inner().permanent_delegate),
+                        interest_bearing_mint_rate: extension_interest_bearing_mint_rate.map(|ibmr| ibmr.into_inner().rate),
+                        interest_bearing_mint_authority: extension_interest_bearing_mint_authority.map(|ibma| ibma.into_inner().authority),
                         transfer_hook_authority: extension_transfer_hook_authority.map(|tha| tha.into_inner().authority),
                         transfer_hook_program_id: extension_transfer_hook_program_id.map(|thpid| thpid.into_inner().program_id),
                     }
@@ -1093,6 +1133,12 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             ConstraintToken::ExtensionPermanentDelegate(c) => {
                 self.add_extension_permanent_delegate(c)
             }
+            ConstraintToken::ExtensionInterestBearingMintRate(c) => {
+                self.add_extension_interest_bearing_mint_rate(c)
+            }
+            ConstraintToken::ExtensionInterestBearingMintAuthority(c) => {
+                self.add_extension_interest_bearing_mint_authority(c)
+            }
         }
     }
 
@@ -1675,4 +1721,32 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
         self.extension_permanent_delegate.replace(c);
         Ok(())
     }
+
+    fn add_extension_interest_bearing_mint_rate(
+        &mut self,
+        c: Context<ConstraintExtensionInterestBearingMintRate>,
+    ) -> ParseResult<()> {
+        if self.extension_interest_bearing_mint_rate.is_some() {
+            return Err(ParseError::new(
+                c.span(),
+                "extension interest bearing mint rate already provided",
+            ));
+        }
+        self.extension_interest_bearing_mint_rate.replace(c);
+        Ok(())
+    }
+
+    fn add_extension_interest_bearing_mint_authority(
+        &mut self,
+        c: Context<ConstraintExtensionAuthority>,
+    ) -> ParseResult<()> {
+        if self.extension_interest_bearing_mint_authority.is_some() {
+            return Err(ParseError::new(
+                c.span(),
+                "extension interest bearing mint rate authority already provided",
+            ));
+        }
+        self.extension_interest_bearing_mint_authority.replace(c);
+        Ok(())
+    }
 }

tests/spl/token-extensions/programs/token-extensions/src/instructions.rs

@@ -5,7 +5,7 @@ use anchor_spl::{
     token_2022::spl_token_2022::extension::{
         group_member_pointer::GroupMemberPointer, metadata_pointer::MetadataPointer,
         mint_close_authority::MintCloseAuthority, permanent_delegate::PermanentDelegate,
-        transfer_hook::TransferHook,
+        transfer_hook::TransferHook, interest_bearing_mint::{InterestBearingConfig, BasisPoints},
     },
     token_interface::{
         get_mint_extension_data, spl_token_metadata_interface::state::TokenMetadata,
@@ -53,6 +53,8 @@ pub struct CreateMintAccount<'info> {
         extensions::transfer_hook::program_id = crate::ID,
         extensions::close_authority::authority = authority,
         extensions::permanent_delegate::delegate = authority,
+        extensions::interest_bearing_mint::authority = authority,
+        extensions::interest_bearing_mint::rate = 100,
     )]
     pub mint: Box<InterfaceAccount<'info, Mint>>,
     #[account(
@@ -150,6 +152,12 @@ pub fn handler(ctx: Context<CreateMintAccount>, args: CreateMintAccountArgs) ->
         group_member_pointer.member_address,
         OptionalNonZeroPubkey::try_from(mint_key)?
     );
+    let interest_bearing_config = get_mint_extension_data::<InterestBearingConfig>(mint_data)?;
+    assert_eq!(
+        interest_bearing_config.rate_authority,
+        OptionalNonZeroPubkey::try_from(authority_key)?
+    );
+    assert_eq!(interest_bearing_config.current_rate, BasisPoints::from(100));
     // transfer minimum rent to mint account
     update_account_lamports_to_minimum_balance(
         ctx.accounts.mint.to_account_info(),