Function clippy_utils::source::walk_span_to_context
source · pub fn walk_span_to_context(span: Span, outer: SyntaxContext) -> Option<Span>
Expand description
Walks the span up to the target context, thereby returning the macro call site if the span is
inside a macro expansion, or the original span if it is not. Note this will return None
in the
case of the span being in a macro expansion, but the target context is from expanding a macro
argument.
Given the following
ⓘ
macro_rules! m { ($e:expr) => { f($e) }; }
g(m!(0))
If called with a span of the call to f
and a context of the call to g
this will return a
span containing m!(0)
. However, if called with a span of the literal 0
this will give a span
containing 0
as the context is the same as the outer context.
This will traverse through multiple macro calls. Given the following:
ⓘ
macro_rules! m { ($e:expr) => { n!($e, 0) }; }
macro_rules! n { ($e:expr, $f:expr) => { f($e, $f) }; }
g(m!(0))
If called with a span of the call to f
and a context of the call to g
this will return a
span containing m!(0)
.