trace in miri - Rust
Description: Constructs an event at the trace level.

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## trace

# Macro trace

    macro_rules! trace {
        (
            name : $name:expr, target : $target:expr, parent : $parent:expr, {
            $($field:tt)* }, $($arg:tt)*
        ) => { ... };
        (
            name : $name:expr, target : $target:expr, parent : $parent:expr,
            $($k:ident).+ $($field:tt)*
        ) => { ... };
        (
            name : $name:expr, target : $target:expr, parent : $parent:expr, ?
            $($k:ident).+ $($field:tt)*
        ) => { ... };
        (
            name : $name:expr, target : $target:expr, parent : $parent:expr, %
            $($k:ident).+ $($field:tt)*
        ) => { ... };
        (name : $name:expr, target : $target:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
        (name : $name:expr, target : $target:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
        (name : $name:expr, target : $target:expr, $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, target : $target:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, target : $target:expr, % $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, target : $target:expr, $($arg:tt)+) => { ... };
        (target : $target:expr, parent : $parent:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
        (target : $target:expr, parent : $parent:expr, $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, parent : $parent:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, parent : $parent:expr, % $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
        (name : $name:expr, parent : $parent:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
        (name : $name:expr, parent : $parent:expr, $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, parent : $parent:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, parent : $parent:expr, % $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
        (name : $name:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
        (name : $name:expr, $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, % $($k:ident).+ $($field:tt)*) => { ... };
        (name : $name:expr, $($arg:tt)+) => { ... };
        (target : $target:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
        (target : $target:expr, $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, % $($k:ident).+ $($field:tt)*) => { ... };
        (target : $target:expr, $($arg:tt)+) => { ... };
        (parent : $parent:expr, { $($field:tt)+ }, $($arg:tt)+) => { ... };
        (parent : $parent:expr, $($k:ident).+ = $($field:tt)*) => { ... };
        (parent : $parent:expr, ? $($k:ident).+ = $($field:tt)*) => { ... };
        (parent : $parent:expr, % $($k:ident).+ = $($field:tt)*) => { ... };
        (parent : $parent:expr, $($k:ident).+, $($field:tt)*) => { ... };
        (parent : $parent:expr, ? $($k:ident).+, $($field:tt)*) => { ... };
        (parent : $parent:expr, % $($k:ident).+, $($field:tt)*) => { ... };
        (parent : $parent:expr, $($arg:tt)+) => { ... };
        ({ $($field:tt)+ }, $($arg:tt)+) => { ... };
        ($($k:ident).+ = $($field:tt)*) => { ... };
        (? $($k:ident).+ = $($field:tt)*) => { ... };
        (% $($k:ident).+ = $($field:tt)*) => { ... };
        ($($k:ident).+, $($field:tt)*) => { ... };
        (? $($k:ident).+, $($field:tt)*) => { ... };
        (% $($k:ident).+, $($field:tt)*) => { ... };
        (? $($k:ident).+) => { ... };
        (% $($k:ident).+) => { ... };
        ($($k:ident).+) => { ... };
        ($($arg:tt)+) => { ... };
    }

Expand description

Constructs an event at the trace level.

This functions similarly to the `event!` macro. See the top-level documentation for details on the syntax accepted by this macro.

## §Examples

    use tracing::trace;
    let pos = Position { x: 3.234, y: -1.223 };
    let origin_dist = pos.dist(Position::ORIGIN);

    trace!(position = ?pos, ?origin_dist);
    trace!(
        target: "app_events",
        position = ?pos,
        "x is {} and y is {}",
        if pos.x >= 0.0 { "positive" } else { "negative" },
        if pos.y >= 0.0 { "positive" } else { "negative" }
    );
    trace!(name: "completed", position = ?pos);