src/test/ui/proc-macro/amputate-span.fixed

   1 // aux-build:amputate-span.rs
   2 // run-rustfix
   3 // edition:2018
   4 // compile-flags: --extern amputate_span
   5
   6 // This test has been crafted to ensure the following things:
   7 //
   8 // 1. There's a resolution error that prompts the compiler to suggest
   9 //    adding a `use` item.
  10 //
  11 // 2. There are no `use` or `extern crate` items in the source
  12 //    code. In fact, there is only one item, the `fn main`
  13 //    declaration.
  14 //
  15 // 3. The single `fn main` declaration has an attribute attached to it
  16 //    that just deletes the first token from the given item.
  17 //
  18 // You need all of these conditions to hold in order to replicate the
  19 // scenario that yielded issue 87613, where the compiler's suggestion
  20 // looks like:
  21 //
  22 // ```
  23 // help: consider importing this struct
  24 //    |
  25 // 47 | hey */ async use std::process::Command;
  26 //    |              ++++++++++++++++++++++++++
  27 // ```
  28 //
  29 // The first condition is necessary to force the compiler issue a
  30 // suggestion. The second condition is necessary to force the
  31 // suggestion to be issued at a span associated with the sole
  32 // `fn`-item of this crate. The third condition is necessary in order
  33 // to yield the weird state where the associated span of the `fn`-item
  34 // does not actually cover all of the original source code of the
  35 // `fn`-item (which is why we are calling it an "amputated" span
  36 // here).
  37 //
  38 // Note that satisfying conditions 2 and 3 requires the use of the
  39 // `--extern` compile flag.
  40 //
  41 // You might ask yourself: What code would do such a thing?  The
  42 // answer is: the #[tokio::main] attribute does *exactly* this (as
  43 // well as injecting some other code into the `fn main` that it
  44 // constructs).
  45
  46 use std::process::Command;
  47
  48 #[amputate_span::drop_first_token]
  49 /* what the
  50 hey */ async fn main() {
  51     Command::new("git"); //~ ERROR [E0433]
  52 }
  53
  54 // (The /* ... */ comment in the above is not part of the original
  55 // bug. It is just meant to illustrate one particular facet of the
  56 // original non-ideal behavior, where we were transcribing the
  57 // trailing comment as part of the emitted suggestion, for better or
  58 // for worse.)
  59
  60 #[allow(dead_code)]
  61 mod inner {
  62     use std::process::Command;
  63
  64 #[amputate_span::drop_first_token]
  65         /* another interesting
  66     case */ async fn foo() {
  67         Command::new("git"); //~ ERROR [E0433]
  68     }
  69 }