rustc_middle: link span_as_caller_location FIXME to a tracking issue

Author: cachebag

compiler/rustc_const_eval/src/util/caller_location.rs

@@ -2,7 +2,7 @@ use rustc_abi::FieldIdx;
 use rustc_hir::LangItem;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{bug, mir};
-use rustc_span::Symbol;
+use rustc_span::{Span, Symbol};
 use tracing::trace;
 
 use crate::const_eval::{CanAccessMutGlobal, CompileTimeInterpCx, mk_eval_cx_to_read_const_val};
@@ -54,14 +54,15 @@ fn alloc_caller_location<'tcx>(
 
 pub(crate) fn const_caller_location_provider(
     tcx: TyCtxt<'_>,
+    span: Span,
     file: Symbol,
     line: u32,
     col: u32,
 ) -> mir::ConstValue {
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx_to_read_const_val(
         tcx,
-        rustc_span::DUMMY_SP, // FIXME: use a proper span here?
+        span,
         ty::TypingEnv::fully_monomorphized(),
         CanAccessMutGlobal::No,
     );

compiler/rustc_middle/src/hooks/mod.rs

@@ -53,7 +53,7 @@ declare_hooks! {
     hook try_destructure_mir_constant_for_user_output(val: mir::ConstValue, ty: Ty<'tcx>) -> Option<mir::DestructuredConstant<'tcx>>;
 
     /// Getting a &core::panic::Location referring to a span.
-    hook const_caller_location(file: rustc_span::Symbol, line: u32, col: u32) -> mir::ConstValue;
+    hook const_caller_location(span: rustc_span::Span, file: rustc_span::Symbol, line: u32, col: u32) -> mir::ConstValue;
 
     /// Returns `true` if this def is a function-like thing that is eligible for
     /// coverage instrumentation under `-Cinstrument-coverage`.

compiler/rustc_middle/src/mir/consts.rs

@@ -586,6 +586,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
         let caller = self.sess.source_map().lookup_char_pos(topmost.lo());
         self.const_caller_location(
+            topmost,
             Symbol::intern(
                 &caller
                     .file