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The x86 code contains several macros that following this pattern:

macro_rules! expr {
    () => { true; }
}

fn bar(_val: bool) {}

fn main() {
    bar(expr!());
}

Here, we have a macro expr! that expands to tokens sequence with
a trailing semicolon.

Currently, the trailing semicolon is ignored when the macro is invoked
in expression position, due to rust-lang/rust#33953
If this behavior is changed, then a large number of macro invocations in
stdarch will stop compiling.

Regardless of whether nor not this change is made, removing the
semicolon more clearly expresses the intent of the code - these macros
are designed to expand to the result of a function call, not ignore its
results (as the ; would suggest).

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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Amanieu (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

The x86 code contains several macros that following this pattern:

```rust
macro_rules! expr {
    () => { true; }
}

fn bar(_val: bool) {}

fn main() {
    bar(expr!());
}
```

Here, we have a macro `expr!` that expands to tokens sequence with
a trailing semicolon.

Currently, the trailing semicolon is ignored when the macro is invoked
in expression position, due to rust-lang/rust#33953
If this behavior is changed, then a large number of macro invocations in
`stdarch` will stop compiling.

Regardless of whether nor not this change is made, removing the
semicolon more clearly expresses the intent of the code - these macros
are designed to expand to the result of a function call, not ignore its
results (as the `;` would suggest).
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3 participants