Add libstd support to Rust BPF (#5788)

programs/bpf/rust/external_spend/Cargo.toml

@@ -13,7 +13,6 @@ edition = "2018"
 
 [dependencies]
 solana-sdk-bpf-utils = { path = "../../../../sdk/bpf/rust/rust-utils", version = "0.19.0-pre0" }
-solana-sdk-bpf-no-std = { path = "../../../../sdk/bpf/rust/rust-no-std", version = "0.19.0-pre0" }
 
 [workspace]
 members = []

programs/bpf/rust/external_spend/Xargo.toml

@@ -1,6 +1,2 @@
-[dependencies.compiler_builtins]
-path = "../../../../sdk/bpf/dependencies/rust-bpf-sysroot/src/compiler-builtins"
-features = ["c", "mem"]
-
-[target.bpfel-unknown-unknown.dependencies]
-alloc = { path = "../../../../sdk/bpf/dependencies/rust-bpf-sysroot/src/liballoc" }
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

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

@@ -1,15 +1,8 @@
 //! @brief Example Rust-based BPF program that moves a lamport from one account to another
 
-#![no_std]
-#![allow(unreachable_code)]
-#![allow(unused_attributes)]
-
-#[cfg(not(test))]
-extern crate solana_sdk_bpf_no_std;
 extern crate solana_sdk_bpf_utils;
-
+use solana_sdk_bpf_utils::entrypoint;
 use solana_sdk_bpf_utils::entrypoint::*;
-use solana_sdk_bpf_utils::{entrypoint, info};
 
 entrypoint!(process_instruction);
 fn process_instruction(ka: &mut [SolKeyedAccount], _info: &SolClusterInfo, _data: &[u8]) -> bool {
@@ -18,6 +11,5 @@ fn process_instruction(ka: &mut [SolKeyedAccount], _info: &SolClusterInfo, _data
     // is seen by the runtime and fails as expected
     *ka[0].lamports -= 1;
 
-    info!("Success");
     true
 }