Rollup merge of #65973 - eddyb:caller-location-panic, r=petrochenkov

caller_location: point to macro invocation sites, like file!/line!, and use in core::panic!.

The main change here is to `core::panic!`, trying to fix this remaining regression: https://github.com/rust-lang/rust/pull/65927#issuecomment-547625147

However, in order for `caller_location` to be usable from macros the same way `file!()`/`line!()` are, it needs to have the same behavior (of extracting the macro invocation site `Span` and using that).

Arguably we would've had to do this at some point anyway, if we want to use `#[track_caller]` to replace the `file!()`/`line!()` uses from macros, but I'm not sure the RFC mentions this at all.

r? @petrochenkov cc @anp @nnethercote

1 files changed, 1 insertions, 12 deletions

diff --git a/src/libsyntax_expand/base.rs b/src/libsyntax_expand/base.rs
index 6cc7b7da53b..d02251eb746 100644
--- a/src/libsyntax_expand/base.rs
+++ b/src/libsyntax_expand/base.rs
@@ -953,18 +953,7 @@ impl<'a> ExtCtxt<'a> {
     ///
     /// Stops backtracing at include! boundary.
     pub fn expansion_cause(&self) -> Option<Span> {
-        let mut expn_id = self.current_expansion.id;
-        let mut last_macro = None;
-        loop {
-            let expn_data = expn_id.expn_data();
-            // Stop going up the backtrace once include! is encountered
-            if expn_data.is_root() || expn_data.kind.descr() == sym::include {
-                break;
-            }
-            expn_id = expn_data.call_site.ctxt().outer_expn();
-            last_macro = Some(expn_data.call_site);
-        }
-        last_macro
+        self.current_expansion.id.expansion_cause()
     }
 
     pub fn struct_span_warn<S: Into<MultiSpan>>(&self,