anchor_attribute_error/
lib.rs

1extern crate proc_macro;
2
3use {
4    anchor_syn::{
5        codegen,
6        parser::error::{self as error_parser, ErrorInput},
7        ErrorArgs,
8    },
9    proc_macro::TokenStream,
10    quote::quote,
11    syn::{parse_macro_input, Expr},
12};
13
14/// Generates `Error` and `type Result<T> = Result<T, Error>` types to be
15/// used as return types from Anchor instruction handlers. Importantly, the
16/// attribute implements
17/// [`From`](https://doc.rust-lang.org/std/convert/trait.From.html) on the
18/// `ErrorCode` to support converting from the user defined error enum *into*
19/// the generated `Error`.
20///
21/// # Example
22///
23/// ```ignore
24/// use anchor_lang::prelude::*;
25///
26/// #[program]
27/// mod errors {
28///     use super::*;
29///     pub fn hello(_ctx: Context<Hello>) -> Result<()> {
30///         Err(error!(MyError::Hello))
31///     }
32/// }
33///
34/// #[derive(Accounts)]
35/// pub struct Hello {}
36///
37/// #[error_code]
38/// pub enum MyError {
39///     #[msg("This is an error message clients will automatically display")]
40///     Hello,
41/// }
42/// ```
43///
44/// Note that we generate a new `Error` type so that we can return either the
45/// user defined error enum *or* a
46/// [`ProgramError`](../solana_program/enum.ProgramError.html), which is used
47/// pervasively, throughout solana program crates. The generated `Error` type
48/// should almost never be used directly, as the user defined error is
49/// preferred. In the example above, `error!(MyError::Hello)`.
50///
51/// # Msg
52///
53/// The `#[msg(..)]` attribute is inert, and is used only as a marker so that
54/// parsers  and IDLs can map error codes to error messages.
55#[proc_macro_attribute]
56pub fn error_code(
57    args: proc_macro::TokenStream,
58    input: proc_macro::TokenStream,
59) -> proc_macro::TokenStream {
60    let args = match args.is_empty() {
61        true => None,
62        false => Some(parse_macro_input!(args as ErrorArgs)),
63    };
64    let mut error_enum = parse_macro_input!(input as syn::ItemEnum);
65    let error = codegen::error::generate(error_parser::parse(&mut error_enum, args));
66    proc_macro::TokenStream::from(error)
67}
68
69/// Generates an [`Error::AnchorError`](../../anchor_lang/error/enum.Error.html) that includes file and line information.
70///
71/// # Example
72/// ```rust,ignore
73/// #[program]
74/// mod errors {
75///     use super::*;
76///     pub fn example(_ctx: Context<Example>) -> Result<()> {
77///         Err(error!(MyError::Hello))
78///     }
79/// }
80///
81/// #[error_code]
82/// pub enum MyError {
83///     #[msg("This is an error message clients will automatically display")]
84///     Hello,
85/// }
86/// ```
87#[proc_macro]
88pub fn error(ts: proc_macro::TokenStream) -> TokenStream {
89    let input = parse_macro_input!(ts as ErrorInput);
90    let error_code = input.error_code;
91    create_error(error_code, true, None)
92}
93
94fn create_error(error_code: Expr, source: bool, account_name: Option<Expr>) -> TokenStream {
95    let error_origin = match (source, account_name) {
96        (false, None) => quote! { None },
97        (false, Some(account_name)) => quote! {
98            Some(anchor_lang::error::ErrorOrigin::AccountName(#account_name.to_string()))
99        },
100        (true, _) => quote! {
101            Some(anchor_lang::error::ErrorOrigin::Source(anchor_lang::error::Source {
102                filename: file!(),
103                line: line!()
104            }))
105        },
106    };
107
108    TokenStream::from(quote! {
109        anchor_lang::error::Error::from(
110            anchor_lang::error::AnchorError {
111                error_name: #error_code.name(),
112                error_code_number: #error_code.into(),
113                error_msg: #error_code.to_string(),
114                error_origin: #error_origin,
115                compared_values: None
116            }
117        )
118    })
119}
anchor_attribute_error/lib.rs

anchor_attribute_error/
lib.rs
