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Diffstat (limited to '')
-rw-r--r-- | vendor/tracing-core/src/field.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/vendor/tracing-core/src/field.rs b/vendor/tracing-core/src/field.rs index c9869ce2c..e103c75a9 100644 --- a/vendor/tracing-core/src/field.rs +++ b/vendor/tracing-core/src/field.rs @@ -145,6 +145,16 @@ pub struct Field { pub struct Empty; /// Describes the fields present on a span. +/// +/// ## Equality +/// +/// In well-behaved applications, two `FieldSet`s [initialized] with equal +/// [callsite identifiers] will have identical fields. Consequently, in release +/// builds, [`FieldSet::eq`] *only* checks that its arguments have equal +/// callsites. However, the equality of field names is checked in debug builds. +/// +/// [initialized]: Self::new +/// [callsite identifiers]: callsite::Identifier pub struct FieldSet { /// The names of each field on the described span. names: &'static [&'static str], @@ -911,6 +921,40 @@ impl fmt::Display for FieldSet { } } +impl Eq for FieldSet {} + +impl PartialEq for FieldSet { + fn eq(&self, other: &Self) -> bool { + if core::ptr::eq(&self, &other) { + true + } else if cfg!(not(debug_assertions)) { + // In a well-behaving application, two `FieldSet`s can be assumed to + // be totally equal so long as they share the same callsite. + self.callsite == other.callsite + } else { + // However, when debug-assertions are enabled, do NOT assume that + // the application is well-behaving; check every the field names of + // each `FieldSet` for equality. + + // `FieldSet` is destructured here to ensure a compile-error if the + // fields of `FieldSet` change. + let Self { + names: lhs_names, + callsite: lhs_callsite, + } = self; + + let Self { + names: rhs_names, + callsite: rhs_callsite, + } = &other; + + // Check callsite equality first, as it is probably cheaper to do + // than str equality. + lhs_callsite == rhs_callsite && lhs_names == rhs_names + } + } +} + // ===== impl Iter ===== impl Iterator for Iter { |