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Add a `byte-array` proc-macro crate for converting strings into byte arrays that don't use static initializers, and use it to implement `eprintln`, an `unreachable` that prints the line number, and other macros.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| //! Minimal versions of standard-library panicking and printing macros. | ||
| //! | ||
| //! We're avoiding static initializers, so we can't have things like string | ||
| //! literals. Replace the standard assert macros with simpler implementations. | ||
| /// A minimal `eprint` for debugging. | ||
| #[allow(unused_macros)] | ||
| macro_rules! eprint { | ||
| ($arg:tt) => {{ | ||
| // We have to expand string literals into byte arrays to prevent them | ||
| // from getting statically initialized. | ||
| let message = byte_array::str!($arg); | ||
| crate::bindings::wasi_stderr::print(&message); | ||
| }}; | ||
| } | ||
|
|
||
| /// A minimal `eprintln` for debugging. | ||
| #[allow(unused_macros)] | ||
| macro_rules! eprintln { | ||
| ($arg:tt) => {{ | ||
| // We have to expand string literals into byte arrays to prevent them | ||
| // from getting statically initialized. | ||
| let message = byte_array::str_nl!($arg); | ||
| crate::bindings::wasi_stderr::print(&message); | ||
| }}; | ||
| } | ||
|
|
||
| pub(crate) fn eprint_u32(x: u32) { | ||
| if x == 0 { | ||
| eprint!("0"); | ||
| } else { | ||
| eprint_u32_impl(x) | ||
| } | ||
|
|
||
| fn eprint_u32_impl(x: u32) { | ||
| if x != 0 { | ||
| eprint_u32_impl(x / 10); | ||
|
|
||
| let digit = [b'0' + ((x % 10) as u8)]; | ||
| crate::bindings::wasi_stderr::print(&digit); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// A minimal `unreachable`. | ||
| macro_rules! unreachable { | ||
| () => {{ | ||
| eprint!("unreachable executed at line "); | ||
| crate::macros::eprint_u32(line!()); | ||
| wasm32::unreachable() | ||
| }}; | ||
|
|
||
| ($arg:tt) => {{ | ||
| eprint!("unreachable executed at line "); | ||
| crate::macros::eprint_u32(line!()); | ||
| eprint!(": "); | ||
| eprintln!($arg); | ||
| wasm32::unreachable() | ||
| }}; | ||
| } | ||
|
|
||
| /// A minimal `assert`. | ||
| macro_rules! assert { | ||
| ($cond:expr $(,)?) => { | ||
| if !$cond { | ||
| unreachable!("assertion failed") | ||
| } | ||
| }; | ||
| } | ||
|
|
||
| /// A minimal `assert_eq`. | ||
| macro_rules! assert_eq { | ||
| ($left:expr, $right:expr $(,)?) => { | ||
| assert!($left == $right); | ||
| }; | ||
| } |