Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2369 insertions, 0 deletions

diff --git a/third_party/rust/tracing/src/macros.rs b/third_party/rust/tracing/src/macros.rs
new file mode 100644
index 0000000000..3222abb741
--- /dev/null
+++ b/third_party/rust/tracing/src/macros.rs
@@ -0,0 +1,2369 @@
+/// Constructs a new span.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// Creating a new span:
+/// ```
+/// # use tracing::{span, Level};
+/// # fn main() {
+/// let span = span!(Level::TRACE, "my span");
+/// let _enter = span.enter();
+/// // do work inside the span...
+/// # }
+/// ```
+#[macro_export]
+macro_rules! span {
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, $name:expr) => {
+        $crate::span!(target: $target, parent: $parent, $lvl, $name,)
+    };
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, $name:expr, $($fields:tt)*) => {
+        {
+            use $crate::__macro_support::Callsite as _;
+            static CALLSITE: $crate::__macro_support::MacroCallsite = $crate::callsite2! {
+                name: $name,
+                kind: $crate::metadata::Kind::SPAN,
+                target: $target,
+                level: $lvl,
+                fields: $($fields)*
+            };
+            let mut interest = $crate::subscriber::Interest::never();
+            if $crate::level_enabled!($lvl)
+                && { interest = CALLSITE.interest(); !interest.is_never() }
+                && CALLSITE.is_enabled(interest)
+            {
+                let meta = CALLSITE.metadata();
+                // span with explicit parent
+                $crate::Span::child_of(
+                    $parent,
+                    meta,
+                    &$crate::valueset!(meta.fields(), $($fields)*),
+                )
+            } else {
+                let span = CALLSITE.disabled_span();
+                $crate::if_log_enabled! {{
+                    span.record_all(&$crate::valueset!(CALLSITE.metadata().fields(), $($fields)*));
+                }};
+                span
+            }
+        }
+    };
+    (target: $target:expr, $lvl:expr, $name:expr, $($fields:tt)*) => {
+        {
+            use $crate::__macro_support::Callsite as _;
+            static CALLSITE: $crate::__macro_support::MacroCallsite = $crate::callsite2! {
+                name: $name,
+                kind: $crate::metadata::Kind::SPAN,
+                target: $target,
+                level: $lvl,
+                fields: $($fields)*
+            };
+            let mut interest = $crate::subscriber::Interest::never();
+            if $crate::level_enabled!($lvl)
+                && { interest = CALLSITE.interest(); !interest.is_never() }
+                && CALLSITE.is_enabled(interest)
+            {
+                let meta = CALLSITE.metadata();
+                // span with contextual parent
+                $crate::Span::new(
+                    meta,
+                    &$crate::valueset!(meta.fields(), $($fields)*),
+                )
+            } else {
+                let span = CALLSITE.disabled_span();
+                $crate::if_log_enabled! {{
+                    span.record_all(&$crate::valueset!(CALLSITE.metadata().fields(), $($fields)*));
+                }};
+                span
+            }
+        }
+    };
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, $name:expr) => {
+        $crate::span!(target: $target, parent: $parent, $lvl, $name,)
+    };
+    (parent: $parent:expr, $lvl:expr, $name:expr, $($fields:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            $name,
+            $($fields)*
+        )
+    };
+    (parent: $parent:expr, $lvl:expr, $name:expr) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            $name,
+        )
+    };
+    (target: $target:expr, $lvl:expr, $name:expr, $($fields:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $lvl,
+            $name,
+            $($fields)*
+        )
+    };
+    (target: $target:expr, $lvl:expr, $name:expr) => {
+        $crate::span!(target: $target, $lvl, $name,)
+    };
+    ($lvl:expr, $name:expr, $($fields:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $lvl,
+            $name,
+            $($fields)*
+        )
+    };
+    ($lvl:expr, $name:expr) => {
+        $crate::span!(
+            target: module_path!(),
+            $lvl,
+            $name,
+        )
+    };
+}
+
+/// Constructs a span at the trace level.
+///
+/// [Fields] and [attributes] are set using the same syntax as the [`span!`]
+/// macro.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+/// [attributes]: index.html#configuring-attributes
+/// [Fields]: index.html#recording-fields
+/// [`span!`]: macro.span.html
+///
+/// # Examples
+///
+/// ```rust
+/// # use tracing::{trace_span, span, Level};
+/// # fn main() {
+/// trace_span!("my_span");
+/// // is equivalent to:
+/// span!(Level::TRACE, "my_span");
+/// # }
+/// ```
+///
+/// ```rust
+/// # use tracing::{trace_span, span, Level};
+/// # fn main() {
+/// let span = trace_span!("my span");
+/// span.in_scope(|| {
+///     // do work inside the span...
+/// });
+/// # }
+/// ```
+#[macro_export]
+macro_rules! trace_span {
+    (target: $target:expr, parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            parent: $parent,
+            $crate::Level::TRACE,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, parent: $parent:expr, $name:expr) => {
+        $crate::trace_span!(target: $target, parent: $parent, $name,)
+    };
+    (parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            $name,
+            $($field)*
+        )
+    };
+    (parent: $parent:expr, $name:expr) => {
+        $crate::trace_span!(parent: $parent, $name,)
+    };
+    (target: $target:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $crate::Level::TRACE,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, $name:expr) => {
+        $crate::trace_span!(target: $target, $name,)
+    };
+    ($name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            $name,
+            $($field)*
+        )
+    };
+    ($name:expr) => { $crate::trace_span!($name,) };
+}
+
+/// Constructs a span at the debug level.
+///
+/// [Fields] and [attributes] are set using the same syntax as the [`span!`]
+/// macro.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+/// [attributes]: index.html#configuring-attributes
+/// [Fields]: index.html#recording-fields
+/// [`span!`]: macro.span.html
+///
+/// # Examples
+///
+/// ```rust
+/// # use tracing::{debug_span, span, Level};
+/// # fn main() {
+/// debug_span!("my_span");
+/// // is equivalent to:
+/// span!(Level::DEBUG, "my_span");
+/// # }
+/// ```
+///
+/// ```rust
+/// # use tracing::debug_span;
+/// # fn main() {
+/// let span = debug_span!("my span");
+/// span.in_scope(|| {
+///     // do work inside the span...
+/// });
+/// # }
+/// ```
+#[macro_export]
+macro_rules! debug_span {
+    (target: $target:expr, parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            parent: $parent,
+            $crate::Level::DEBUG,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, parent: $parent:expr, $name:expr) => {
+        $crate::debug_span!(target: $target, parent: $parent, $name,)
+    };
+    (parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            $name,
+            $($field)*
+        )
+    };
+    (parent: $parent:expr, $name:expr) => {
+        $crate::debug_span!(parent: $parent, $name,)
+    };
+    (target: $target:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $crate::Level::DEBUG,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, $name:expr) => {
+        $crate::debug_span!(target: $target, $name,)
+    };
+    ($name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            $name,
+            $($field)*
+        )
+    };
+    ($name:expr) => {$crate::debug_span!($name,)};
+}
+
+/// Constructs a span at the info level.
+///
+/// [Fields] and [attributes] are set using the same syntax as the [`span!`]
+/// macro.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+/// [attributes]: index.html#configuring-attributes
+/// [Fields]: index.html#recording-fields
+/// [`span!`]: macro.span.html
+///
+/// # Examples
+///
+/// ```rust
+/// # use tracing::{span, info_span, Level};
+/// # fn main() {
+/// info_span!("my_span");
+/// // is equivalent to:
+/// span!(Level::INFO, "my_span");
+/// # }
+/// ```
+///
+/// ```rust
+/// # use tracing::info_span;
+/// # fn main() {
+/// let span = info_span!("my span");
+/// span.in_scope(|| {
+///     // do work inside the span...
+/// });
+/// # }
+/// ```
+#[macro_export]
+macro_rules! info_span {
+    (target: $target:expr, parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            parent: $parent,
+            $crate::Level::INFO,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, parent: $parent:expr, $name:expr) => {
+        $crate::info_span!(target: $target, parent: $parent, $name,)
+    };
+    (parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            $name,
+            $($field)*
+        )
+    };
+    (parent: $parent:expr, $name:expr) => {
+        $crate::info_span!(parent: $parent, $name,)
+    };
+    (target: $target:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $crate::Level::INFO,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, $name:expr) => {
+        $crate::info_span!(target: $target, $name,)
+    };
+    ($name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            $name,
+            $($field)*
+        )
+    };
+    ($name:expr) => {$crate::info_span!($name,)};
+}
+
+/// Constructs a span at the warn level.
+///
+/// [Fields] and [attributes] are set using the same syntax as the [`span!`]
+/// macro.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+/// [attributes]: index.html#configuring-attributes
+/// [Fields]: index.html#recording-fields
+/// [`span!`]: macro.span.html
+///
+/// # Examples
+///
+/// ```rust
+/// # use tracing::{warn_span, span, Level};
+/// # fn main() {
+/// warn_span!("my_span");
+/// // is equivalent to:
+/// span!(Level::WARN, "my_span");
+/// # }
+/// ```
+///
+/// ```rust
+/// use tracing::warn_span;
+/// # fn main() {
+/// let span = warn_span!("my span");
+/// span.in_scope(|| {
+///     // do work inside the span...
+/// });
+/// # }
+/// ```
+#[macro_export]
+macro_rules! warn_span {
+    (target: $target:expr, parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            parent: $parent,
+            $crate::Level::WARN,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, parent: $parent:expr, $name:expr) => {
+        $crate::warn_span!(target: $target, parent: $parent, $name,)
+    };
+    (parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            $name,
+            $($field)*
+        )
+    };
+    (parent: $parent:expr, $name:expr) => {
+        $crate::warn_span!(parent: $parent, $name,)
+    };
+    (target: $target:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $crate::Level::WARN,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, $name:expr) => {
+        $crate::warn_span!(target: $target, $name,)
+    };
+    ($name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            $name,
+            $($field)*
+        )
+    };
+    ($name:expr) => {$crate::warn_span!($name,)};
+}
+/// Constructs a span at the error level.
+///
+/// [Fields] and [attributes] are set using the same syntax as the [`span!`]
+/// macro.
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+/// [attributes]: index.html#configuring-attributes
+/// [Fields]: index.html#recording-fields
+/// [`span!`]: macro.span.html
+///
+/// # Examples
+///
+/// ```rust
+/// # use tracing::{span, error_span, Level};
+/// # fn main() {
+/// error_span!("my_span");
+/// // is equivalent to:
+/// span!(Level::ERROR, "my_span");
+/// # }
+/// ```
+///
+/// ```rust
+/// # use tracing::error_span;
+/// # fn main() {
+/// let span = error_span!("my span");
+/// span.in_scope(|| {
+///     // do work inside the span...
+/// });
+/// # }
+/// ```
+#[macro_export]
+macro_rules! error_span {
+    (target: $target:expr, parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            parent: $parent,
+            $crate::Level::ERROR,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, parent: $parent:expr, $name:expr) => {
+        $crate::error_span!(target: $target, parent: $parent, $name,)
+    };
+    (parent: $parent:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            $name,
+            $($field)*
+        )
+    };
+    (parent: $parent:expr, $name:expr) => {
+        $crate::error_span!(parent: $parent, $name,)
+    };
+    (target: $target:expr, $name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: $target,
+            $crate::Level::ERROR,
+            $name,
+            $($field)*
+        )
+    };
+    (target: $target:expr, $name:expr) => {
+        $crate::error_span!(target: $target, $name,)
+    };
+    ($name:expr, $($field:tt)*) => {
+        $crate::span!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            $name,
+            $($field)*
+        )
+    };
+    ($name:expr) => {$crate::error_span!($name,)};
+}
+
+/// Constructs a new `Event`.
+///
+/// The event macro is invoked with a `Level` and up to 32 key-value fields.
+/// Optionally, a format string and arguments may follow the fields; this will
+/// be used to construct an implicit field named "message".
+///
+/// See [the top-level documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::{event, Level};
+///
+/// # fn main() {
+/// let data = (42, "forty-two");
+/// let private_data = "private";
+/// let error = "a bad error";
+///
+/// event!(Level::ERROR, %error, "Received error");
+/// event!(
+///     target: "app_events",
+///     Level::WARN,
+///     private_data,
+///     ?data,
+///     "App warning: {}",
+///     error
+/// );
+/// event!(Level::INFO, the_answer = data.0);
+/// # }
+/// ```
+///
+// /// Note that *unlike `span!`*, `event!` requires a value for all fields. As
+// /// events are recorded immediately when the macro is invoked, there is no
+// /// opportunity for fields to be recorded later. A trailing comma on the final
+// /// field is valid.
+// ///
+// /// For example, the following does not compile:
+// /// ```rust,compile_fail
+// /// # #[macro_use]
+// /// # extern crate tracing;
+// /// # use tracing::Level;
+// /// # fn main() {
+// /// event!(Level::INFO, foo = 5, bad_field, bar = "hello")
+// /// #}
+// /// ```
+#[macro_export]
+macro_rules! event {
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* } )=> (
+        $crate::__tracing_log!(
+            target: $target,
+            $lvl,
+            $($fields)*
+        );
+
+        if $crate::level_enabled!($lvl) {
+            use $crate::__macro_support::*;
+            static CALLSITE: $crate::__macro_support::MacroCallsite = $crate::callsite2! {
+                name: concat!(
+                    "event ",
+                    file!(),
+                    ":",
+                    line!()
+                ),
+                kind: $crate::metadata::Kind::EVENT,
+                target: $target,
+                level: $lvl,
+                fields: $($fields)*
+            };
+            let interest = CALLSITE.interest();
+            if !interest.is_never() && CALLSITE.is_enabled(interest)  {
+                let meta = CALLSITE.metadata();
+                // event with explicit parent
+                $crate::Event::child_of(
+                    $parent,
+                    meta,
+                    &$crate::valueset!(meta.fields(), $($fields)*)
+                );
+            }
+        }
+    );
+
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: $target,
+            parent: $parent,
+            $lvl,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, $($k:ident).+ = $($fields:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $lvl, { $($k).+ = $($fields)* })
+    );
+    (target: $target:expr, parent: $parent:expr, $lvl:expr, $($arg:tt)+) => (
+        $crate::event!(target: $target, parent: $parent, $lvl, { $($arg)+ })
+    );
+    (target: $target:expr, $lvl:expr, { $($fields:tt)* } )=> ({
+        $crate::__tracing_log!(
+            target: $target,
+            $lvl,
+            $($fields)*
+        );
+        if $crate::level_enabled!($lvl) {
+            use $crate::__macro_support::*;
+            static CALLSITE: $crate::__macro_support::MacroCallsite = $crate::callsite2! {
+                name: concat!(
+                    "event ",
+                    file!(),
+                    ":",
+                    line!()
+                ),
+                kind: $crate::metadata::Kind::EVENT,
+                target: $target,
+                level: $lvl,
+                fields: $($fields)*
+            };
+            let interest = CALLSITE.interest();
+            if !interest.is_never() && CALLSITE.is_enabled(interest)  {
+                let meta = CALLSITE.metadata();
+                // event with contextual parent
+                $crate::Event::dispatch(
+                    meta,
+                    &$crate::valueset!(meta.fields(), $($fields)*)
+                );
+            }
+        }
+    });
+    (target: $target:expr, $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: $target,
+            $lvl,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    (target: $target:expr, $lvl:expr, $($k:ident).+ = $($fields:tt)* ) => (
+        $crate::event!(target: $target, $lvl, { $($k).+ = $($fields)* })
+    );
+    (target: $target:expr, $lvl:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $lvl, { $($arg)+ })
+    );
+    (parent: $parent:expr, $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            parent: $parent,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $lvl,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $lvl:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: module_path!(), parent: $parent, $lvl, { $($arg)+ })
+    );
+    ( $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    ( $lvl:expr, { $($fields:tt)* }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { message = format_args!($($arg)+), $($fields)* }
+        )
+    );
+    ($lvl:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { $($k).+ = $($field)*}
+        )
+    );
+    ($lvl:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { $($k).+, $($field)*}
+        )
+    );
+    ($lvl:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    ($lvl:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $lvl,
+            { %$($k).+, $($field)*}
+        )
+    );
+    ($lvl:expr, ?$($k:ident).+) => (
+        $crate::event!($lvl, ?$($k).+,)
+    );
+    ($lvl:expr, %$($k:ident).+) => (
+        $crate::event!($lvl, %$($k).+,)
+    );
+    ($lvl:expr, $($k:ident).+) => (
+        $crate::event!($lvl, $($k).+,)
+    );
+    ( $lvl:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: module_path!(), $lvl, { $($arg)+ })
+    );
+}
+
+/// Constructs an event at the trace level.
+///
+/// This functions similarly to the [`event!`] macro. See [the top-level
+/// documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [`event!`]: macro.event.html
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::trace;
+/// # #[derive(Debug, Copy, Clone)] struct Position { x: f32, y: f32 }
+/// # impl Position {
+/// # const ORIGIN: Self = Self { x: 0.0, y: 0.0 };
+/// # fn dist(&self, other: Position) -> f32 {
+/// #    let x = (other.x - self.x).exp2(); let y = (self.y - other.y).exp2();
+/// #    (x + y).sqrt()
+/// # }
+/// # }
+/// # fn main() {
+/// 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" }
+/// );
+/// # }
+/// ```
+#[macro_export]
+macro_rules! trace {
+    (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::TRACE, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, parent: $parent:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::TRACE, {}, $($arg)+)
+    );
+    (parent: $parent:expr, { $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::TRACE,
+            {},
+            $($arg)+
+        )
+    );
+    (target: $target:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, $crate::Level::TRACE, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::TRACE, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::TRACE, {}, $($arg)+)
+    );
+    ({ $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    ($($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { $($k).+ = $($field)*}
+        )
+    );
+    ($($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { $($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (%$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { ?$($k).+ }
+        )
+    );
+    (%$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { %$($k).+ }
+        )
+    );
+    ($($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { $($k).+ }
+        )
+    );
+    ($($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            {},
+            $($arg)+
+        )
+    );
+}
+
+/// Constructs an event at the debug level.
+///
+/// This functions similarly to the [`event!`] macro. See [the top-level
+/// documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [`event!`]: macro.event.html
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::debug;
+/// # fn main() {
+/// # #[derive(Debug)] struct Position { x: f32, y: f32 }
+///
+/// let pos = Position { x: 3.234, y: -1.223 };
+///
+/// debug!(?pos.x, ?pos.y);
+/// debug!(target: "app_events", position = ?pos, "New position");
+/// # }
+/// ```
+#[macro_export]
+macro_rules! debug {
+    (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::DEBUG, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, parent: $parent:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::DEBUG, {}, $($arg)+)
+    );
+    (parent: $parent:expr, { $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::DEBUG,
+            {},
+            $($arg)+
+        )
+    );
+    (target: $target:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, $crate::Level::DEBUG, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::DEBUG, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::DEBUG, {}, $($arg)+)
+    );
+    ({ $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    ($($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (%$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    ($($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { $($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (%$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { ?$($k).+ }
+        )
+    );
+    (%$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { %$($k).+ }
+        )
+    );
+    ($($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            { $($k).+ }
+        )
+    );
+    ($($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::DEBUG,
+            {},
+            $($arg)+
+        )
+    );
+}
+
+/// Constructs an event at the info level.
+///
+/// This functions similarly to the [`event!`] macro. See [the top-level
+/// documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [`event!`]: macro.event.html
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::info;
+/// # // this is so the test will still work in no-std mode
+/// # #[derive(Debug)]
+/// # pub struct Ipv4Addr;
+/// # impl Ipv4Addr { fn new(o1: u8, o2: u8, o3: u8, o4: u8) -> Self { Self } }
+/// # fn main() {
+/// # struct Connection { port: u32, speed: f32 }
+/// use tracing::field;
+///
+/// let addr = Ipv4Addr::new(127, 0, 0, 1);
+/// let conn = Connection { port: 40, speed: 3.20 };
+///
+/// info!(conn.port, "connected to {:?}", addr);
+/// info!(
+///     target: "connection_events",
+///     ip = ?addr,
+///     conn.port,
+///     ?conn.speed,
+/// );
+/// # }
+/// ```
+#[macro_export]
+macro_rules! info {
+     (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, parent: $parent:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, {}, $($arg)+)
+    );
+    (parent: $parent:expr, { $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::INFO,
+            {},
+            $($arg)+
+        )
+    );
+    (target: $target:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, $crate::Level::INFO, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::INFO, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::INFO, {}, $($arg)+)
+    );
+    ({ $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    ($($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (%$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    ($($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { $($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (%$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { ?$($k).+ }
+        )
+    );
+    (%$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { %$($k).+ }
+        )
+    );
+    ($($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            { $($k).+ }
+        )
+    );
+    ($($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::INFO,
+            {},
+            $($arg)+
+        )
+    );
+}
+
+/// Constructs an event at the warn level.
+///
+/// This functions similarly to the [`event!`] macro. See [the top-level
+/// documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [`event!`]: macro.event.html
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::warn;
+/// # fn main() {
+///
+/// let warn_description = "Invalid Input";
+/// let input = &[0x27, 0x45];
+///
+/// warn!(?input, warning = warn_description);
+/// warn!(
+///     target: "input_events",
+///     warning = warn_description,
+///     "Received warning for input: {:?}", input,
+/// );
+/// # }
+/// ```
+#[macro_export]
+macro_rules! warn {
+     (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::WARN, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, parent: $parent:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::WARN, {}, $($arg)+)
+    );
+    (parent: $parent:expr, { $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::WARN,
+            {},
+            $($arg)+
+        )
+    );
+    (target: $target:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, $crate::Level::WARN, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::WARN, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::WARN, {}, $($arg)+)
+    );
+    ({ $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    ($($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (%$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    ($($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { $($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (%$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { ?$($k).+ }
+        )
+    );
+    (%$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { %$($k).+ }
+        )
+    );
+    ($($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            { $($k).+ }
+        )
+    );
+    ($($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::WARN,
+            {},
+            $($arg)+
+        )
+    );
+}
+
+/// Constructs an event at the error level.
+///
+/// This functions similarly to the [`event!`] macro. See [the top-level
+/// documentation][lib] for details on the syntax accepted by
+/// this macro.
+///
+/// [`event!`]: macro.event.html
+/// [lib]: index.html#using-the-macros
+///
+/// # Examples
+///
+/// ```rust
+/// use tracing::error;
+/// # fn main() {
+///
+/// let (err_info, port) = ("No connection", 22);
+///
+/// error!(port, error = %err_info);
+/// error!(target: "app_events", "App Error: {}", err_info);
+/// error!({ info = err_info }, "error on port: {}", port);
+/// # }
+/// ```
+#[macro_export]
+macro_rules! error {
+     (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::ERROR, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, parent: $parent:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, parent: $parent:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, parent: $parent, $crate::Level::ERROR, {}, $($arg)+)
+    );
+    (parent: $parent:expr, { $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { $($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, ?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, %$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (parent: $parent:expr, $($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            parent: $parent,
+            $crate::Level::ERROR,
+            {},
+            $($arg)+
+        )
+    );
+    (target: $target:expr, { $($field:tt)* }, $($arg:tt)* ) => (
+        $crate::event!(target: $target, $crate::Level::ERROR, { $($field)* }, $($arg)*)
+    );
+    (target: $target:expr, $($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, ?$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, %$($k:ident).+ $($field:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::ERROR, { $($k).+ $($field)+ })
+    );
+    (target: $target:expr, $($arg:tt)+ ) => (
+        $crate::event!(target: $target, $crate::Level::ERROR, {}, $($arg)+)
+    );
+    ({ $($field:tt)+ }, $($arg:tt)+ ) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { $($field)+ },
+            $($arg)+
+        )
+    );
+    ($($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { $($k).+ = $($field)*}
+        )
+    );
+    (?$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { ?$($k).+ = $($field)*}
+        )
+    );
+    (%$($k:ident).+ = $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::TRACE,
+            { %$($k).+ = $($field)*}
+        )
+    );
+    ($($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { $($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { ?$($k).+, $($field)*}
+        )
+    );
+    (%$($k:ident).+, $($field:tt)*) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { %$($k).+, $($field)*}
+        )
+    );
+    (?$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { ?$($k).+ }
+        )
+    );
+    (%$($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { %$($k).+ }
+        )
+    );
+    ($($k:ident).+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            { $($k).+ }
+        )
+    );
+    ($($arg:tt)+) => (
+        $crate::event!(
+            target: module_path!(),
+            $crate::Level::ERROR,
+            {},
+            $($arg)+
+        )
+    );
+}
+
+/// Constructs a new static callsite for a span or event.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! callsite {
+    (name: $name:expr, kind: $kind:expr, fields: $($fields:tt)*) => {{
+        $crate::callsite! {
+            name: $name,
+            kind: $kind,
+            target: module_path!(),
+            level: $crate::Level::TRACE,
+            fields: $($fields)*
+        }
+    }};
+    (
+        name: $name:expr,
+        kind: $kind:expr,
+        level: $lvl:expr,
+        fields: $($fields:tt)*
+    ) => {{
+        $crate::callsite! {
+            name: $name,
+            kind: $kind,
+            target: module_path!(),
+            level: $lvl,
+            fields: $($fields)*
+        }
+    }};
+    (
+        name: $name:expr,
+        kind: $kind:expr,
+        target: $target:expr,
+        level: $lvl:expr,
+        fields: $($fields:tt)*
+    ) => {{
+        use $crate::__macro_support::MacroCallsite;
+        static META: $crate::Metadata<'static> = {
+            $crate::metadata! {
+                name: $name,
+                target: $target,
+                level: $lvl,
+                fields: $crate::fieldset!( $($fields)* ),
+                callsite: &CALLSITE,
+                kind: $kind,
+            }
+        };
+        static CALLSITE: MacroCallsite = MacroCallsite::new(&META);
+        CALLSITE.register();
+        &CALLSITE
+    }};
+}
+
+/// Constructs a new static callsite for a span or event.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! callsite2 {
+    (name: $name:expr, kind: $kind:expr, fields: $($fields:tt)*) => {{
+        $crate::callsite2! {
+            name: $name,
+            kind: $kind,
+            target: module_path!(),
+            level: $crate::Level::TRACE,
+            fields: $($fields)*
+        }
+    }};
+    (
+        name: $name:expr,
+        kind: $kind:expr,
+        level: $lvl:expr,
+        fields: $($fields:tt)*
+    ) => {{
+        $crate::callsite2! {
+            name: $name,
+            kind: $kind,
+            target: module_path!(),
+            level: $lvl,
+            fields: $($fields)*
+        }
+    }};
+    (
+        name: $name:expr,
+        kind: $kind:expr,
+        target: $target:expr,
+        level: $lvl:expr,
+        fields: $($fields:tt)*
+    ) => {{
+        use $crate::__macro_support::MacroCallsite;
+        static META: $crate::Metadata<'static> = {
+            $crate::metadata! {
+                name: $name,
+                target: $target,
+                level: $lvl,
+                fields: $crate::fieldset!( $($fields)* ),
+                callsite: &CALLSITE,
+                kind: $kind,
+            }
+        };
+        MacroCallsite::new(&META)
+    }};
+}
+
+#[macro_export]
+// TODO: determine if this ought to be public API?`
+#[doc(hidden)]
+macro_rules! level_enabled {
+    ($lvl:expr) => {
+        $lvl <= $crate::level_filters::STATIC_MAX_LEVEL
+            && $lvl <= $crate::level_filters::LevelFilter::current()
+    };
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! valueset {
+
+    // === base case ===
+    (@ { $(,)* $($val:expr),* $(,)* }, $next:expr $(,)*) => {
+        &[ $($val),* ]
+    };
+
+    // === recursive case (more tts) ===
+
+    // TODO(#1138): determine a new syntax for uninitialized span fields, and
+    // re-enable this.
+    // (@{ $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = _, $($rest:tt)*) => {
+    //     $crate::valueset!(@ { $($out),*, (&$next, None) }, $next, $($rest)*)
+    // };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = ?$val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$val) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = %$val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$val) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = $val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$val as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$($k).+ as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, ?$($k:ident).+, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$($k).+) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, %$($k:ident).+, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$($k).+) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = ?$val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$val) as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = %$val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$val) as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = $val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$val as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$($k).+ as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, ?$($k:ident).+) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$($k).+) as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, %$($k:ident).+) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$($k).+) as &Value)) },
+            $next,
+        )
+    };
+
+    // Handle literal names
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = ?$val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$val) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = %$val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$val) as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = $val:expr, $($rest:tt)*) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$val as &Value)) },
+            $next,
+            $($rest)*
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = ?$val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&debug(&$val) as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = %$val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&display(&$val) as &Value)) },
+            $next,
+        )
+    };
+    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = $val:expr) => {
+        $crate::valueset!(
+            @ { $($out),*, (&$next, Some(&$val as &Value)) },
+            $next,
+        )
+    };
+
+    // Remainder is unparseable, but exists --- must be format args!
+    (@ { $(,)* $($out:expr),* }, $next:expr, $($rest:tt)+) => {
+        $crate::valueset!(@ { (&$next, Some(&format_args!($($rest)+) as &Value)), $($out),* }, $next, )
+    };
+
+    // === entry ===
+    ($fields:expr, $($kvs:tt)+) => {
+        {
+            #[allow(unused_imports)]
+            use $crate::field::{debug, display, Value};
+            let mut iter = $fields.iter();
+            $fields.value_set($crate::valueset!(
+                @ { },
+                iter.next().expect("FieldSet corrupted (this is a bug)"),
+                $($kvs)+
+            ))
+        }
+    };
+    ($fields:expr,) => {
+        {
+            $fields.value_set(&[])
+        }
+    };
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! fieldset {
+    // == base case ==
+    (@ { $(,)* $($out:expr),* $(,)* } $(,)*) => {
+        &[ $($out),* ]
+    };
+
+    // == recursive cases (more tts) ==
+    (@ { $(,)* $($out:expr),* } $($k:ident).+ = ?$val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } $($k:ident).+ = %$val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } $($k:ident).+ = $val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+    // TODO(#1138): determine a new syntax for uninitialized span fields, and
+    // re-enable this.
+    // (@ { $($out:expr),* } $($k:ident).+ = _, $($rest:tt)*) => {
+    //     $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    // };
+    (@ { $(,)* $($out:expr),* } ?$($k:ident).+, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } %$($k:ident).+, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } $($k:ident).+, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $crate::__tracing_stringify!($($k).+) } $($rest)*)
+    };
+
+    // Handle literal names
+    (@ { $(,)* $($out:expr),* } $k:literal = ?$val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $k } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } $k:literal = %$val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $k } $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* } $k:literal = $val:expr, $($rest:tt)*) => {
+        $crate::fieldset!(@ { $($out),*, $k } $($rest)*)
+    };
+
+    // Remainder is unparseable, but exists --- must be format args!
+    (@ { $(,)* $($out:expr),* } $($rest:tt)+) => {
+        $crate::fieldset!(@ { "message", $($out),*, })
+    };
+
+    // == entry ==
+    ($($args:tt)*) => {
+        $crate::fieldset!(@ { } $($args)*,)
+    };
+
+}
+
+#[cfg(feature = "log")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! level_to_log {
+    ($level:expr) => {
+        match $level {
+            $crate::Level::ERROR => $crate::log::Level::Error,
+            $crate::Level::WARN => $crate::log::Level::Warn,
+            $crate::Level::INFO => $crate::log::Level::Info,
+            $crate::Level::DEBUG => $crate::log::Level::Debug,
+            _ => $crate::log::Level::Trace,
+        }
+    };
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __tracing_stringify {
+    ($s:expr) => {
+        stringify!($s)
+    };
+}
+
+#[cfg(not(feature = "log"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __tracing_log {
+    (target: $target:expr, $level:expr, $($field:tt)+ ) => {};
+}
+
+#[cfg(feature = "log")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __mk_format_string {
+    // === base case ===
+    (@ { $(,)* $($out:expr),* $(,)* } $(,)*) => {
+        concat!( $($out),*)
+    };
+
+    // === recursive case (more tts), ===
+    // ====== shorthand field syntax ===
+    (@ { $(,)* $($out:expr),* }, ?$($k:ident).+, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={:?} " }, $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* }, %$($k:ident).+, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={} " }, $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* }, $($k:ident).+, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={:?} " }, $($rest)*)
+    };
+    // ====== kv field syntax ===
+    (@ { $(,)* $($out:expr),* }, message = $val:expr, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, "{} " }, $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* }, $($k:ident).+ = ?$val:expr, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={:?} " }, $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* }, $($k:ident).+ = %$val:expr, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={} " }, $($rest)*)
+    };
+    (@ { $(,)* $($out:expr),* }, $($k:ident).+ = $val:expr, $($rest:tt)*) => {
+        $crate::__mk_format_string!(@ { $($out),*, $crate::__tracing_stringify!($($k).+), "={:?} " }, $($rest)*)
+    };
+
+    // === rest is unparseable --- must be fmt args ===
+    (@ { $(,)* $($out:expr),* }, $($rest:tt)+) => {
+        $crate::__mk_format_string!(@ { "{} ", $($out),* }, )
+    };
+
+    // === entry ===
+    ($($kvs:tt)+) => {
+        $crate::__mk_format_string!(@ { }, $($kvs)+,)
+    };
+    () => {
+        ""
+    }
+}
+
+#[cfg(feature = "log")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __mk_format_args {
+    // === finished --- called into by base cases ===
+    (@ { $(,)* $($out:expr),* $(,)* }, $fmt:expr, fields: $(,)*) => {
+        format_args!($fmt, $($out),*)
+    };
+
+    // === base case (no more tts) ===
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = ?$val:expr $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: )
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = %$val:expr $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: )
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = $val:expr $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: )
+    };
+    // ====== shorthand field syntax ===
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: ?$($k:ident).+ $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields:)
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: %$($k:ident).+ $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields: )
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ $(,)*) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields: )
+    };
+
+    // === recursive case (more tts) ===
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = ?$val:expr, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: $($rest)+)
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = %$val:expr, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: $($rest)+)
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+ = $val:expr, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, $val }, $fmt, fields: $($rest)+)
+    };
+    // ====== shorthand field syntax ===
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: ?$($k:ident).+, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields: $($rest)+)
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: %$($k:ident).+, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields: $($rest)+)
+    };
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($k:ident).+, $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { $($out),*, &$($k).+ }, $fmt, fields: $($rest)+)
+    };
+
+    // === rest is unparseable --- must be fmt args ===
+    (@ { $(,)* $($out:expr),* }, $fmt:expr, fields: $($rest:tt)+) => {
+        $crate::__mk_format_args!(@ { format_args!($($rest)+), $($out),* }, $fmt, fields: )
+    };
+
+    // === entry ===
+    ($($kv:tt)*) => {
+        {
+            #[allow(unused_imports)]
+            use $crate::field::{debug, display};
+            // use $crate::__mk_format_string;
+            $crate::__mk_format_args!(@ { }, $crate::__mk_format_string!($($kv)*), fields: $($kv)*)
+        }
+    };
+}
+
+#[cfg(feature = "log")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __tracing_log {
+    (target: $target:expr, $level:expr, $($field:tt)+ ) => {
+        $crate::if_log_enabled! {{
+            use $crate::log;
+            let level = $crate::level_to_log!($level);
+            if level <= log::STATIC_MAX_LEVEL && level <= log::max_level() {
+                let log_meta = log::Metadata::builder()
+                    .level(level)
+                    .target($target)
+                    .build();
+                let logger = log::logger();
+                if logger.enabled(&log_meta) {
+                    logger.log(&log::Record::builder()
+                        .file(Some(file!()))
+                        .module_path(Some(module_path!()))
+                        .line(Some(line!()))
+                        .metadata(log_meta)
+                        .args($crate::__mk_format_args!($($field)+))
+                        .build());
+                }
+            }
+        }}
+    };
+}
+
+#[cfg(not(feature = "log"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! if_log_enabled {
+    ($e:expr;) => {
+        $crate::if_log_enabled! { $e }
+    };
+    ($if_log:block) => {
+        $crate::if_log_enabled! { $if_log else {} }
+    };
+    ($if_log:block else $else_block:block) => {
+        $else_block
+    };
+}
+
+#[cfg(all(feature = "log", not(feature = "log-always")))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! if_log_enabled {
+    ($e:expr;) => {
+        $crate::if_log_enabled! { $e }
+    };
+    ($if_log:block) => {
+        $crate::if_log_enabled! { $if_log else {} }
+    };
+    ($if_log:block else $else_block:block) => {
+        if !$crate::dispatcher::has_been_set() {
+            $if_log
+        } else {
+            $else_block
+        }
+    };
+}
+
+#[cfg(all(feature = "log", feature = "log-always"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! if_log_enabled {
+    ($e:expr;) => {
+        $crate::if_log_enabled! { $e }
+    };
+    ($if_log:block) => {
+        $crate::if_log_enabled! { $if_log else {} }
+    };
+    ($if_log:block else $else_block:block) => {
+        #[allow(unused_braces)]
+        $if_log
+    };
+}