Remove program error footgun and cleaner developer experience (#8042)

programs/bpf/rust/128bit/src/lib.rs

@@ -4,7 +4,7 @@ extern crate solana_sdk;
 use solana_sdk::entrypoint::SUCCESS;
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     let x: u128 = 1;
     let y = x.rotate_right(1);
     assert_eq!(y, 170_141_183_460_469_231_731_687_303_715_884_105_728);

programs/bpf/rust/alloc/src/lib.rs

@@ -7,7 +7,7 @@ use solana_sdk::{entrypoint::SUCCESS, info};
 use std::{alloc::Layout, mem};
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     unsafe {
         // Confirm large allocation fails
 

programs/bpf/rust/dep_crate/src/lib.rs

@@ -5,7 +5,7 @@ use byteorder::{ByteOrder, LittleEndian};
 use solana_sdk::entrypoint::SUCCESS;
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     let mut buf = [0; 4];
     LittleEndian::write_u32(&mut buf, 1_000_000);
     assert_eq!(1_000_000, LittleEndian::read_u32(&buf));

programs/bpf/rust/error_handling/src/lib.rs

@@ -9,15 +9,11 @@ use thiserror::Error;
 
 /// Custom program errors
 #[derive(Error, Debug, Clone, PartialEq, FromPrimitive)]
-// Clippy compains about 0x8000_002d, but we don't care about C compatibility here
-#[allow(clippy::enum_clike_unportable_variant)]
 pub enum MyError {
+    #[error("Default enum start")]
+    DefaultEnumStart,
     #[error("The Answer")]
     TheAnswer = 42,
-    #[error("Conflicting with success")]
-    ConflictingSuccess = 0,
-    #[error("Conflicting with builtin")]
-    ConflictingBuiltin = 0x8000_002d,
 }
 impl From<MyError> for ProgramError {
     fn from(e: MyError) -> Self {
@@ -41,16 +37,12 @@ fn process_instruction(
             Err(ProgramError::InvalidAccountData)
         }
         3 => {
-            info!("return custom error");
-            Err(MyError::TheAnswer.into())
+            info!("return default enum start value");
+            Err(MyError::DefaultEnumStart.into())
         }
         4 => {
-            info!("return error that conflicts with success");
-            Err(MyError::ConflictingSuccess.into())
-        }
-        5 => {
-            info!("return error that conflicts with builtin");
-            Err(MyError::ConflictingBuiltin.into())
+            info!("return custom error");
+            Err(MyError::TheAnswer.into())
         }
         6 => {
             let data = accounts[0].try_borrow_mut_data()?;

programs/bpf/rust/iter/src/lib.rs

@@ -4,7 +4,7 @@ extern crate solana_sdk;
 use solana_sdk::{entrypoint::SUCCESS, info};
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     const ITERS: usize = 100;
     let ones = [1_u64; ITERS];
     let mut sum: u64 = 0;

programs/bpf/rust/many_args/src/lib.rs

@@ -5,7 +5,7 @@ extern crate solana_sdk;
 use solana_sdk::{entrypoint::SUCCESS, info};
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     info!("Call same package");
     assert_eq!(crate::helper::many_args(1, 2, 3, 4, 5, 6, 7, 8, 9), 45);
 

programs/bpf/rust/panic/src/lib.rs

@@ -3,6 +3,6 @@
 extern crate solana_sdk;
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     panic!();
 }

programs/bpf/rust/param_passing/src/lib.rs

@@ -5,7 +5,7 @@ use solana_bpf_rust_param_passing_dep::{Data, TestDep};
 use solana_sdk::{entrypoint::SUCCESS, info};
 
 #[no_mangle]
-pub extern "C" fn entrypoint(_input: *mut u8) -> u32 {
+pub extern "C" fn entrypoint(_input: *mut u8) -> u64 {
     let array = [0xA, 0xB, 0xC, 0xD, 0xE, 0xF];
     let data = Data {
         twentyone: 21u64,