fix: prefix macro calls with ::core to avoid clashing with local macros (#3024)

fix: prefix macro calls with `__macro_support ` to avoid clashes with local macros

Fixes: <#3023>

This ensures that the tracing lib correctly builds when a crate is named
`core`. See #2761 and
#2762 for more info.

Author: joshka

tracing-core/src/lib.rs

@@ -147,6 +147,14 @@
 #[cfg(not(feature = "std"))]
 extern crate alloc;
 
+#[doc(hidden)]
+pub mod __macro_support {
+    // Re-export the `core` functions that are used in macros. This allows
+    // a crate to be named `core` and avoid name clashes.
+    // See here: https://github.com/tokio-rs/tracing/issues/2761
+    pub use core::{file, line, module_path, option::Option};
+}
+
 /// Statically constructs an [`Identifier`] for the provided [`Callsite`].
 ///
 /// This may be used in contexts such as static initializers.
@@ -244,9 +252,9 @@ macro_rules! metadata {
             $name,
             $target,
             $level,
-            ::core::option::Option::Some(file!()),
-            ::core::option::Option::Some(line!()),
-            ::core::option::Option::Some(module_path!()),
+            $crate::__macro_support::Option::Some($crate::__macro_support::file!()),
+            $crate::__macro_support::Option::Some($crate::__macro_support::line!()),
+            $crate::__macro_support::Option::Some($crate::__macro_support::module_path!()),
             $crate::field::FieldSet::new($fields, $crate::identify_callsite!($callsite)),
             $kind,
         )

tracing/src/lib.rs

@@ -988,7 +988,7 @@ pub mod __macro_support {
     // Re-export the `core` functions that are used in macros. This allows
     // a crate to be named `core` and avoid name clashes.
     // See here: https://github.com/tokio-rs/tracing/issues/2761
-    pub use core::{concat, format_args, iter::Iterator, option::Option};
+    pub use core::{concat, file, format_args, iter::Iterator, line, option::Option};
 
     /// Callsite implementation used by macro-generated code.
     ///

tracing/src/macros.rs

@@ -694,9 +694,9 @@ macro_rules! event {
         static __CALLSITE: $crate::callsite::DefaultCallsite = $crate::callsite2! {
             name: $crate::__macro_support::concat!(
                 "event ",
-                file!(),
+                $crate::__macro_support::file!(),
                 ":",
-                line!()
+                $crate::__macro_support::line!()
             ),
             kind: $crate::metadata::Kind::EVENT,
             target: $target,
@@ -855,9 +855,9 @@ macro_rules! event {
         static __CALLSITE: $crate::callsite::DefaultCallsite = $crate::callsite2! {
             name: $crate::__macro_support::concat!(
                 "event ",
-                file!(),
+                $crate::__macro_support::file!(),
                 ":",
-                line!()
+                $crate::__macro_support::line!()
             ),
             kind: $crate::metadata::Kind::EVENT,
             target: $target,
@@ -1188,9 +1188,9 @@ macro_rules! enabled {
             static __CALLSITE: $crate::callsite::DefaultCallsite = $crate::callsite2! {
                 name: $crate::__macro_support::concat!(
                     "enabled ",
-                    file!(),
+                    $crate::__macro_support::file!(),
                     ":",
-                    line!()
+                    $crate::__macro_support::line!()
                 ),
                 kind: $kind.hint(),
                 target: $target,