lang: Fix using `Vec<u8>` type with `declare_program!` (#2966)

CHANGELOG.md

@@ -28,6 +28,7 @@ The minor version will be incremented upon a breaking change and the patch versi
 - idl: Fix potential panic on external type resolution ([#2954](https://github.com/coral-xyz/anchor/pull/2954)).
 - lang: Fix using defined types in instruction parameters with `declare_program!` ([#2959](https://github.com/coral-xyz/anchor/pull/2959)).
 - lang: Fix using const generics with `declare_program!` ([#2965](https://github.com/coral-xyz/anchor/pull/2965)).
+- lang: Fix using `Vec<u8>` type with `declare_program!` ([#2966](https://github.com/coral-xyz/anchor/pull/2966)).
 
 ### Breaking
 

lang/attribute/program/src/declare_program/common.rs

@@ -59,7 +59,7 @@ pub fn convert_idl_type_to_str(ty: &IdlType) -> String {
         IdlType::I128 => "i128".into(),
         IdlType::U256 => "u256".into(),
         IdlType::I256 => "i256".into(),
-        IdlType::Bytes => "bytes".into(),
+        IdlType::Bytes => "Vec<u8>".into(),
         IdlType::String => "String".into(),
         IdlType::Pubkey => "Pubkey".into(),
         IdlType::Option(ty) => format!("Option<{}>", convert_idl_type_to_str(ty)),