<p dir="auto">Code:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="macro_rules! macro_ {
    ($t:ty) =&gt; {
        #[test]
        fn test() { }
    }
}

struct Foo;
struct Bar;
macro_!(Foo);
macro_!(Bar);"><pre class="notranslate"><code class="notranslate">macro_rules! macro_ {
    ($t:ty) =&gt; {
        #[test]
        fn test() { }
    }
}

struct Foo;
struct Bar;
macro_!(Foo);
macro_!(Bar);
</code></pre></div>
<p dir="auto">Error:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="a.rs:4:9: 4:22 error: duplicate definition of value `test` [E0428]
a.rs:4         fn test() { }
               ^~~~~~~~~~~~~
a.rs:1:1: 6:2 note: in expansion of macro_!
a.rs:11:1: 11:14 note: expansion site
a.rs:4:9: 4:22 help: run `rustc --explain E0428` to see a detailed explanation
a.rs:4:9: 4:22 note: first definition of value `test` here
a.rs:4         fn test() { }
               ^~~~~~~~~~~~~
a.rs:1:1: 6:2 note: in expansion of macro_!
a.rs:10:1: 10:14 note: expansion site
error: aborting due to previous error"><pre class="notranslate"><code class="notranslate">a.rs:4:9: 4:22 error: duplicate definition of value `test` [E0428]
a.rs:4         fn test() { }
               ^~~~~~~~~~~~~
a.rs:1:1: 6:2 note: in expansion of macro_!
a.rs:11:1: 11:14 note: expansion site
a.rs:4:9: 4:22 help: run `rustc --explain E0428` to see a detailed explanation
a.rs:4:9: 4:22 note: first definition of value `test` here
a.rs:4         fn test() { }
               ^~~~~~~~~~~~~
a.rs:1:1: 6:2 note: in expansion of macro_!
a.rs:10:1: 10:14 note: expansion site
error: aborting due to previous error
</code></pre></div>
<p dir="auto">TaskBuilder::spawn() is causing a "conditional jump or move depends on uninitialized values(s)" error in valgrind.</p>
<p dir="auto"><code class="notranslate">fn main() { spawn(proc() {}) }</code><br>
Is the absolute minimum required to reproduce, and the error message is still present if a TaskBuilder is created and TaskBuilder::spawn() is called directly. Tested on <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/rust-lang/rust/commit/18c451fc497a23944b7b759cca5ff0b0be1122fd/hovercard" href="https://github.com/rust-lang/rust/commit/18c451fc497a23944b7b759cca5ff0b0be1122fd"><tt>18c451f</tt></a> (most recent master as of this post).</p>