Fix early param lifetimes in generic_const_exprs

Author: ouz-a

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -258,8 +258,8 @@ 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_arg_position_impl_trait(fr))
+            .or_else(|| self.give_name_if_anonymous_region_appears_in_early_param(fr));
         if let Some(value) = &value {
             self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone());
         }
@@ -966,4 +966,23 @@ 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.rs

@@ -0,0 +1,16 @@
+#![feature(generic_const_exprs)]
+//~^ WARN the feature `generic_const_exprs` is incomplete
+
+struct DataWrapper<'static> {
+    //~^ ERROR invalid lifetime parameter name: `'static`
+    data: &'a [u8; Self::SIZE],
+    //~^ ERROR use of undeclared lifetime name `'a`
+    //~^^ ERROR lifetime may not live long enough
+}
+
+impl DataWrapper<'a> {
+    //~^ ERROR undeclared lifetime
+    const SIZE: usize = 14;
+}
+
+fn main(){}

tests/ui/borrowck/generic_const_early_param.stderr

@@ -0,0 +1,45 @@
+error[E0262]: invalid lifetime parameter name: `'static`
+  --> $DIR/generic_const_early_param.rs:4:20
+   |
+LL | struct DataWrapper<'static> {
+   |                    ^^^^^^^ 'static is a reserved lifetime name
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/generic_const_early_param.rs:6:12
+   |
+LL | struct DataWrapper<'static> {
+   |                    - help: consider introducing lifetime `'a` here: `'a,`
+LL |
+LL |     data: &'a [u8; Self::SIZE],
+   |            ^^ undeclared lifetime
+
+error[E0261]: use of undeclared lifetime name `'a`
+  --> $DIR/generic_const_early_param.rs:11:18
+   |
+LL | impl DataWrapper<'a> {
+   |     -            ^^ undeclared lifetime
+   |     |
+   |     help: consider introducing lifetime `'a` here: `<'a>`
+
+warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/generic_const_early_param.rs:1:12
+   |
+LL | #![feature(generic_const_exprs)]
+   |            ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+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`
+
+error: aborting due to 4 previous errors; 1 warning emitted
+
+Some errors have detailed explanations: E0261, E0262.
+For more information about an error, try `rustc --explain E0261`.