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

sdk/src/program_error.rs

@@ -3,12 +3,9 @@ use num_traits::ToPrimitive;
 
 /// Reasons the program may fail
 pub enum ProgramError {
-    /// CustomError allows programs to implement program-specific error types and see
-    /// them returned by the Solana runtime. A CustomError may be any type that is represented
-    /// as or serialized to a u32 integer.
-    ///
-    /// NOTE: u64 requires special serialization to avoid the loss of precision in JS clients and
-    /// so is not used for now.
+    /// Allows on-chain programs to implement program-specific error types and see them returned
+    /// by the Solana runtime. A program-specific error may be any type that is represented as
+    /// or serialized to a u32 integer.
     CustomError(u32),
     /// The arguments provided to a program instruction where invalid
     InvalidArgument,
@@ -34,47 +31,28 @@ pub enum ProgramError {
     AccountBorrowFailed,
 }
 
-/// 32bit representations of builtin program errors returned by the entry point
-const BUILTIN_ERROR_START: u32 = 0x8000_0000; // 31st bit set
-const INVALID_ARGUMENT: u32 = BUILTIN_ERROR_START;
-const INVALID_INSTRUCTION_DATA: u32 = BUILTIN_ERROR_START + 1;
-const INVALID_ACCOUNT_DATA: u32 = BUILTIN_ERROR_START + 2;
-const ACCOUNT_DATA_TOO_SMALL: u32 = BUILTIN_ERROR_START + 3;
-const INSUFFICIENT_FUNDS: u32 = BUILTIN_ERROR_START + 4;
-const INCORRECT_PROGRAM_ID: u32 = BUILTIN_ERROR_START + 5;
-const MISSING_REQUIRED_SIGNATURES: u32 = BUILTIN_ERROR_START + 6;
-const ACCOUNT_ALREADY_INITIALIZED: u32 = BUILTIN_ERROR_START + 7;
-const UNINITIALIZED_ACCOUNT: u32 = BUILTIN_ERROR_START + 8;
-const NOT_ENOUGH_ACCOUNT_KEYS: u32 = BUILTIN_ERROR_START + 9;
-const ACCOUNT_BORROW_FAILED: u32 = BUILTIN_ERROR_START + 10;
-
-/// Is this a builtin error? (is 31th bit set?)
-fn is_builtin(error: u32) -> bool {
-    (error & BUILTIN_ERROR_START) != 0
+/// Builtin return values occupy the upper 32 bits
+const BUILTIN_BIT_SHIFT: usize = 32;
+macro_rules! to_builtin {
+    ($error:expr) => {
+        ($error as u64) << BUILTIN_BIT_SHIFT
+    };
 }
 
-/// If a program defined error conflicts with a builtin error
-/// its 30th bit is set before returning to distinguish it.
-/// The side effect is that the original error's 30th bit
-/// value is lost, be aware.
-const CONFLICTING_ERROR_MARK: u32 = 0x4000_0000; // 30st bit set
+const CUSTOM_ZERO: u64 = to_builtin!(1);
+const INVALID_ARGUMENT: u64 = to_builtin!(2);
+const INVALID_INSTRUCTION_DATA: u64 = to_builtin!(3);
+const INVALID_ACCOUNT_DATA: u64 = to_builtin!(4);
+const ACCOUNT_DATA_TOO_SMALL: u64 = to_builtin!(5);
+const INSUFFICIENT_FUNDS: u64 = to_builtin!(6);
+const INCORRECT_PROGRAM_ID: u64 = to_builtin!(7);
+const MISSING_REQUIRED_SIGNATURES: u64 = to_builtin!(8);
+const ACCOUNT_ALREADY_INITIALIZED: u64 = to_builtin!(9);
+const UNINITIALIZED_ACCOUNT: u64 = to_builtin!(10);
+const NOT_ENOUGH_ACCOUNT_KEYS: u64 = to_builtin!(11);
+const ACCOUNT_BORROW_FAILED: u64 = to_builtin!(12);
 
-/// Is this error marked as conflicting? (is 30th bit set?)
-fn is_marked_conflicting(error: u32) -> bool {
-    (error & CONFLICTING_ERROR_MARK) != 0
-}
-
-/// Mark as a conflicting error
-fn mark_conflicting(error: u32) -> u32 {
-    error | CONFLICTING_ERROR_MARK
-}
-
-/// Unmark as a conflicting error
-fn unmark_conflicting(error: u32) -> u32 {
-    error & !CONFLICTING_ERROR_MARK
-}
-
-impl From<ProgramError> for u32 {
+impl From<ProgramError> for u64 {
     fn from(error: ProgramError) -> Self {
         match error {
             ProgramError::InvalidArgument => INVALID_ARGUMENT,
@@ -89,10 +67,10 @@ impl From<ProgramError> for u32 {
             ProgramError::NotEnoughAccountKeys => NOT_ENOUGH_ACCOUNT_KEYS,
             ProgramError::AccountBorrowFailed => ACCOUNT_BORROW_FAILED,
             ProgramError::CustomError(error) => {
-                if error == 0 || is_builtin(error) {
-                    mark_conflicting(error)
+                if error == 0 {
+                    CUSTOM_ZERO
                 } else {
-                    error
+                    error as u64
                 }
             }
         }
@@ -104,8 +82,9 @@ where
     T: ToPrimitive,
 {
     fn from(error: T) -> Self {
-        let error = error.to_u32().unwrap_or(0xbad_c0de);
+        let error = error.to_u64().unwrap_or(0xbad_c0de);
         match error {
+            CUSTOM_ZERO => InstructionError::CustomError(0),
             INVALID_ARGUMENT => InstructionError::InvalidArgument,
             INVALID_INSTRUCTION_DATA => InstructionError::InvalidInstructionData,
             INVALID_ACCOUNT_DATA => InstructionError::InvalidAccountData,
@@ -118,10 +97,11 @@ where
             NOT_ENOUGH_ACCOUNT_KEYS => InstructionError::NotEnoughAccountKeys,
             ACCOUNT_BORROW_FAILED => InstructionError::AccountBorrowFailed,
             _ => {
-                if is_marked_conflicting(error) {
-                    InstructionError::ConflictingError(unmark_conflicting(error))
+                // A valid custom error has no bits set in the upper 32
+                if error >> BUILTIN_BIT_SHIFT == 0 {
+                    InstructionError::CustomError(error as u32)
                 } else {
-                    InstructionError::CustomError(error)
+                    InstructionError::InvalidError
                 }
             }
         }