alternate solution

Author: ouz-a

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -27,15 +27,15 @@ use rustc_middle::ty::TypeVisitor;
 use rustc_middle::ty::{self, RegionVid, Ty};
 use rustc_middle::ty::{Region, TyCtxt};
 use rustc_span::symbol::{kw, Ident};
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::{Span, Symbol, DUMMY_SP};
 
 use crate::borrowck_errors;
 use crate::session_diagnostics::{
     FnMutError, FnMutReturnTypeErr, GenericDoesNotLiveLongEnough, LifetimeOutliveErr,
     LifetimeReturnCategoryErr, RequireStaticErr, VarHereDenote,
 };
 
-use super::{OutlivesSuggestionBuilder, RegionName};
+use super::{OutlivesSuggestionBuilder, RegionName, RegionNameSource};
 use crate::region_infer::{BlameConstraint, ExtraConstraintInfo};
 use crate::{
     nll::ConstraintDescription,
@@ -763,7 +763,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         let err = LifetimeOutliveErr { span: *span };
         let mut diag = self.infcx.tcx.sess.create_err(err);
 
-        let fr_name = self.give_region_a_name(*fr).unwrap();
+        // If we can't find name here we just make it up to avoid ICEs.
+        let fr_name = self
+            .give_region_a_name(*fr)
+            .unwrap_or(RegionName { name: Symbol::intern("'_"), source: RegionNameSource::Static });
         fr_name.highlight_region_name(&mut diag);
         let outlived_fr_name = self.give_region_a_name(*outlived_fr).unwrap();
         outlived_fr_name.highlight_region_name(&mut diag);

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -258,8 +258,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             .or_else(|| self.give_name_if_anonymous_region_appears_in_output(fr))
             .or_else(|| self.give_name_if_anonymous_region_appears_in_yield_ty(fr))
             .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr))
-            .or_else(|| self.give_name_if_anonymous_region_appears_in_arg_position_impl_trait(fr))
-            .or_else(|| self.give_name_if_anonymous_region_appears_in_early_param(fr));
+            .or_else(|| self.give_name_if_anonymous_region_appears_in_arg_position_impl_trait(fr));
         if let Some(value) = &value {
             self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone());
         }
@@ -966,23 +965,4 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             }
         })
     }
-
-    fn give_name_if_anonymous_region_appears_in_early_param(
-        &self,
-        fr: RegionVid,
-    ) -> Option<RegionName> {
-        let error_region = self.to_error_region(fr)?;
-        let tcx = self.infcx.tcx;
-
-        match *error_region {
-            ty::ReEarlyParam(ebr) => {
-                let span = tcx.hir().span_if_local(ebr.def_id).unwrap_or(DUMMY_SP);
-                Some(RegionName {
-                    name: ebr.name,
-                    source: RegionNameSource::NamedEarlyParamRegion(span),
-                })
-            }
-            _ => None,
-        }
-    }
 }

tests/ui/borrowck/generic_const_early_param.stderr

@@ -33,9 +33,6 @@ LL | #![feature(generic_const_exprs)]
 error: lifetime may not live long enough
   --> $DIR/generic_const_early_param.rs:6:20
    |
-LL | struct DataWrapper<'static> {
-   |                    ------- lifetime `'_` defined here
-LL |
 LL |     data: &'a [u8; Self::SIZE],
    |                    ^^^^^^^^^^ requires that `'_` must outlive `'static`