macros: Allow field path segments to be keywords

tracing-attributes/tests/fields.rs

@@ -1,4 +1,4 @@
-use tracing::collect::with_default;
+use tracing::{collect::with_default, error, error_span, field};
 use tracing_attributes::instrument;
 use tracing_mock::{collector, expect, span::NewSpan};
 
@@ -34,6 +34,9 @@ fn fn_string(s: String) {
     let _ = s;
 }
 
+#[instrument(fields(keywords.impl.type.fn = _arg), skip(_arg))]
+fn fn_keyword_ident_in_field(_arg: &str) {}
+
 #[derive(Debug)]
 struct HasField {
     my_field: &'static str,
@@ -146,6 +149,40 @@ fn string_field() {
     });
 }
 
+#[test]
+fn keyword_ident_in_field_name() {
+    let span = expect::span().with_fields(
+        expect::field("keywords.impl.type.fn")
+            .with_value(&"test")
+            .only(),
+    );
+    run_test(span, || fn_keyword_ident_in_field("test"));
+}
+
+#[test]
+fn keyword_ident_in_field_name_event_macro() {
+    let (collector, handle) = collector::mock()
+        .event(expect::event().with_fields(expect::field("crate").with_value(&"tracing")))
+        .only()
+        .run_with_handle();
+
+    with_default(collector, || error!(crate = "tracing", "message"));
+    handle.assert_finished();
+}
+
+#[test]
+fn keyword_ident_in_field_name_span_macro() {
+    #[derive(Debug)]
+    struct Foo;
+
+    let span =
+        expect::span().with_fields(expect::field("self").with_value(&field::debug(Foo)).only());
+    run_test(span, || {
+        let guard = error_span!("span", self = ?Foo).entered();
+        drop(guard);
+    });
+}
+
 fn run_test<F: FnOnce() -> T, T>(span: NewSpan, fun: F) {
     let (collector, handle) = collector::mock()
         .new_span(span)

tracing/src/macros.rs

@@ -3069,8 +3069,8 @@ macro_rules! level_to_log {
 #[doc(hidden)]
 #[macro_export]
 macro_rules! __tracing_stringify {
-    ($s:expr) => {
-        stringify!($s)
+    ($($t:tt)*) => {
+        stringify!($($t)*)
     };
 }