lang: Remove 3 lifetime definitions from Context

lang/src/context.rs

@@ -21,22 +21,22 @@ use std::fmt;
 ///     Ok(())
 /// }
 /// ```
-pub struct Context<'a, 'b, 'c, 'info, T: Bumps> {
+pub struct Context<'info, T: 'info + Bumps> {
     /// Currently executing program id.
-    pub program_id: &'a Pubkey,
+    pub program_id: &'info Pubkey,
     /// Deserialized accounts.
-    pub accounts: &'b mut T,
+    pub accounts: &'info mut T,
     /// Remaining accounts given but not deserialized or validated.
     /// Be very careful when using this directly.
-    pub remaining_accounts: &'c [AccountInfo<'info>],
+    pub remaining_accounts: &'info [AccountInfo<'info>],
     /// Bump seeds found during constraint validation. This is provided as a
     /// convenience so that handlers don't have to recalculate bump seeds or
     /// pass them in as arguments.
     /// Type is the bumps struct generated by #[derive(Accounts)]
     pub bumps: T::Bumps,
 }
 
-impl<'a, 'b, 'c, 'info, T> fmt::Debug for Context<'a, 'b, 'c, 'info, T>
+impl<'info, T> fmt::Debug for Context<'info, T>
 where
     T: fmt::Debug + Bumps,
 {
@@ -50,14 +50,14 @@ where
     }
 }
 
-impl<'a, 'b, 'c, 'info, T> Context<'a, 'b, 'c, 'info, T>
+impl<'info, T> Context<'info, T>
 where
-    T: Bumps + Accounts<'info, T::Bumps>,
+    T: 'info + Bumps + Accounts<'info, T::Bumps>,
 {
     pub fn new(
-        program_id: &'a Pubkey,
-        accounts: &'b mut T,
-        remaining_accounts: &'c [AccountInfo<'info>],
+        program_id: &'info Pubkey,
+        accounts: &'info mut T,
+        remaining_accounts: &'info [AccountInfo<'info>],
         bumps: T::Bumps,
     ) -> Self {
         Self {

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

@@ -72,9 +72,9 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
         /// If no match is found, the fallback function is executed if it exists, or an error is
         /// returned if it doesn't exist.
         fn dispatch<'info>(
-            program_id: &Pubkey,
+            program_id: &'info Pubkey,
             accounts: &'info [AccountInfo<'info>],
-            data: &[u8],
+            data: &'info [u8],
         ) -> anchor_lang::Result<()> {
             #(#global_ixs)*
 

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

@@ -36,14 +36,22 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
         ///
         /// The `entry` function here, defines the standard entry to a Solana
         /// program, where execution begins.
-        pub fn entry<'info>(program_id: &Pubkey, accounts: &'info [AccountInfo<'info>], data: &[u8]) -> anchor_lang::solana_program::entrypoint::ProgramResult {
+        pub fn entry<'info>(
+            program_id: &'info Pubkey,
+            accounts: &'info [AccountInfo<'info>],
+            data: &'info [u8]
+        ) -> anchor_lang::solana_program::entrypoint::ProgramResult {
             try_entry(program_id, accounts, data).map_err(|e| {
                 e.log();
                 e.into()
             })
         }
 
-        fn try_entry<'info>(program_id: &Pubkey, accounts: &'info [AccountInfo<'info>], data: &[u8]) -> anchor_lang::Result<()> {
+        fn try_entry<'info>(
+            program_id: &'info Pubkey,
+            accounts: &'info [AccountInfo<'info>],
+            data: &'info [u8]
+        ) -> anchor_lang::Result<()> {
             #[cfg(feature = "anchor-debug")]
             {
                 msg!("anchor-debug is active");

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

@@ -100,7 +100,7 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
             let ix_arg_names: Vec<&syn::Ident> = ix.args.iter().map(|arg| &arg.name).collect();
             let ix_name = generate_ix_variant_name(ix.raw_method.sig.ident.to_string());
             let ix_method_name = &ix.raw_method.sig.ident;
-            let anchor = &ix.anchor_ident;
+            let accounts_struct_name = &ix.anchor_ident;
             let variant_arm = generate_ix_variant(ix.raw_method.sig.ident.to_string(), &ix.args);
             let ix_name_log = format!("Instruction: {ix_name}");
             let ret_type = &ix.returns.ty.to_token_stream();
@@ -117,9 +117,9 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                 #(#cfgs)*
                 #[inline(never)]
                 pub fn #ix_method_name<'info>(
-                    __program_id: &Pubkey,
-                    __accounts: &'info[AccountInfo<'info>],
-                    __ix_data: &[u8],
+                    __program_id: &'info Pubkey,
+                    __accounts: &'info [AccountInfo<'info>],
+                    __ix_data: &'info [u8],
                 ) -> anchor_lang::Result<()> {
                     #[cfg(not(feature = "no-log-ix-name"))]
                     anchor_lang::prelude::msg!(#ix_name_log);
@@ -130,13 +130,13 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                     let instruction::#variant_arm = ix;
 
                     // Bump collector.
-                    let mut __bumps = <#anchor as anchor_lang::Bumps>::Bumps::default();
+                    let mut __bumps = <#accounts_struct_name as anchor_lang::Bumps>::Bumps::default();
 
                     let mut __reallocs = std::collections::BTreeSet::new();
 
                     // Deserialize accounts.
-                    let mut __remaining_accounts: &[AccountInfo] = __accounts;
-                    let mut __accounts = #anchor::try_accounts(
+                    let mut __remaining_accounts = __accounts;
+                    let mut __accounts = #accounts_struct_name::try_accounts(
                         __program_id,
                         &mut __remaining_accounts,
                         __ix_data,
@@ -148,7 +148,21 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
                     let result = #program_name::#ix_method_name(
                         anchor_lang::context::Context::new(
                             __program_id,
-                            &mut __accounts,
+                            // SAFETY: The transmute shortens the inner `AccountInfo` lifetimes to
+                            // match the lifetimes of other arguments. All references are going to
+                            // be valid at least for the duration of the user-defined instruction
+                            // handlers.
+                            //
+                            // This is done to avoid having to define multiple lifetimes for the
+                            // `Context` struct, which requies Anchor users to do the same in
+                            // various cases (e.g. remaining accounts usage), resulting in a poor
+                            // developer experience.
+                            unsafe {
+                                ::core::mem::transmute::<
+                                    &mut #accounts_struct_name<'info>,
+                                    &mut #accounts_struct_name<'_>
+                                >(&mut __accounts)
+                            },
                             __remaining_accounts,
                             __bumps,
                         ),

tests/misc/programs/remaining-accounts/src/lib.rs

@@ -22,9 +22,7 @@ pub mod remaining_accounts {
         Ok(())
     }
 
-    pub fn test_remaining_accounts<'c: 'info, 'info>(
-        ctx: Context<'_, '_, 'c, 'info, TestRemainingAccounts>,
-    ) -> Result<()> {
+    pub fn test_remaining_accounts(ctx: Context<TestRemainingAccounts>) -> Result<()> {
         let remaining_accounts_iter = &mut ctx.remaining_accounts.iter();
 
         let token_account =