rust/tests/ui/proc-macro/amputate-span.rs

66 lines
2.2 KiB
Rust

//@ aux-build:amputate-span.rs
//@ run-rustfix
//@ edition:2018
//@ compile-flags: --extern amputate_span
// This test has been crafted to ensure the following things:
//
// 1. There's a resolution error that prompts the compiler to suggest
// adding a `use` item.
//
// 2. There are no `use` or `extern crate` items in the source
// code. In fact, there is only one item, the `fn main`
// declaration.
//
// 3. The single `fn main` declaration has an attribute attached to it
// that just deletes the first token from the given item.
//
// You need all of these conditions to hold in order to replicate the
// scenario that yielded issue 87613, where the compiler's suggestion
// looks like:
//
// ```
// help: consider importing this struct
// |
// 47 | hey */ async use std::process::Command;
// | ++++++++++++++++++++++++++
// ```
//
// The first condition is necessary to force the compiler issue a
// suggestion. The second condition is necessary to force the
// suggestion to be issued at a span associated with the sole
// `fn`-item of this crate. The third condition is necessary in order
// to yield the weird state where the associated span of the `fn`-item
// does not actually cover all of the original source code of the
// `fn`-item (which is why we are calling it an "amputated" span
// here).
//
// Note that satisfying conditions 2 and 3 requires the use of the
// `--extern` compile flag.
//
// You might ask yourself: What code would do such a thing? The
// answer is: the #[tokio::main] attribute does *exactly* this (as
// well as injecting some other code into the `fn main` that it
// constructs).
#[amputate_span::drop_first_token]
/* what the
hey */ async fn main() {
Command::new("git"); //~ ERROR [E0433]
}
// (The /* ... */ comment in the above is not part of the original
// bug. It is just meant to illustrate one particular facet of the
// original non-ideal behavior, where we were transcribing the
// trailing comment as part of the emitted suggestion, for better or
// for worse.)
#[allow(dead_code)]
mod inner {
#[amputate_span::drop_first_token]
/* another interesting
case */ async fn foo() {
Command::new("git"); //~ ERROR [E0433]
}
}