From 422fde3f9eb2db7b7165b9f688e2894c5fbaa138 Mon Sep 17 00:00:00 2001
From: AndyJado <101876416+AndyJado@users.noreply.github.com>
Date: Thu, 1 Sep 2022 17:49:06 +0800
Subject: [PATCH 1/2] lifetime defined here err

---
 compiler/rustc_borrowck/src/diagnostics/region_name.rs |  7 ++++++-
 compiler/rustc_borrowck/src/session_diagnostics.rs     | 10 ++++++++++
 .../rustc_error_messages/locales/en-US/borrowck.ftl    |  3 +++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index a87e8bd5ba16f..83f21d7b8e60a 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -10,6 +10,7 @@ use rustc_middle::ty::{self, DefIdTree, RegionVid, Ty};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 
+use crate::session_diagnostics::RegionNameLables;
 use crate::{nll::ToRegionVid, universal_regions::DefiningTy, MirBorrowckCtxt};
 
 /// A name for a particular region used in emitting diagnostics. This name could be a generated
@@ -106,7 +107,11 @@ impl RegionName {
         match &self.source {
             RegionNameSource::NamedFreeRegion(span)
             | RegionNameSource::NamedEarlyBoundRegion(span) => {
-                diag.span_label(*span, format!("lifetime `{self}` defined here"));
+                let name = format!("{self}");
+                diag.subdiagnostic(RegionNameLables::LifetimeDefinedHere {
+                    span: *span,
+                    rg_name: name,
+                });
             }
             RegionNameSource::SynthesizedFreeEnvRegion(span, note) => {
                 diag.span_label(*span, format!("lifetime `{self}` represents this closure's body"));
diff --git a/compiler/rustc_borrowck/src/session_diagnostics.rs b/compiler/rustc_borrowck/src/session_diagnostics.rs
index 5d750c6ca8c7b..0da5678a34865 100644
--- a/compiler/rustc_borrowck/src/session_diagnostics.rs
+++ b/compiler/rustc_borrowck/src/session_diagnostics.rs
@@ -157,3 +157,13 @@ pub(crate) enum RequireStaticErr {
         multi_span: MultiSpan,
     },
 }
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum RegionNameLables {
+    #[label(borrowck::lifetime_defined_here)]
+    LifetimeDefinedHere {
+        rg_name: String,
+        #[primary_span]
+        span: Span,
+    },
+}
diff --git a/compiler/rustc_error_messages/locales/en-US/borrowck.ftl b/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
index 67f2156f32e50..8e8380c4da2ca 100644
--- a/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
@@ -58,3 +58,6 @@ borrowck_returned_lifetime_short =
 
 borrowck_used_impl_require_static =
     the used `impl` has a `'static` requirement
+
+borrowck_lifetime_defined_here =
+    lifetime `{$rg_name}` defined here

From c770ac03f1566e02184c06c0ef9e929b09f01da0 Mon Sep 17 00:00:00 2001
From: AndyJado <101876416+AndyJado@users.noreply.github.com>
Date: Thu, 1 Sep 2022 20:30:13 +0800
Subject: [PATCH 2/2] explain_borrow bug

---
 .../src/diagnostics/explain_borrow.rs            | 16 ++++++++--------
 .../rustc_borrowck/src/session_diagnostics.rs    | 12 ++++++++++++
 .../locales/en-US/borrowck.ftl                   |  3 +++
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index 2f61849c383c5..af8492ed04328 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -16,6 +16,7 @@ use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, DesugaringKind, Span};
 
 use crate::region_infer::BlameConstraint;
+use crate::session_diagnostics::RequireBorrowLasts;
 use crate::{
     borrow_set::BorrowData, nll::ConstraintDescription, region_infer::Cause, MirBorrowckCtxt,
     WriteKind,
@@ -257,15 +258,14 @@ impl<'tcx> BorrowExplanation<'tcx> {
                         ),
                     );
                 } else {
-                    err.span_label(
+                    //FIXME: src/test/ui/consts/const-eval/const-eval-intrinsic-promotion.rs
+                    let sub_label = RequireBorrowLasts::Lasts {
+                        category: category.description(),
+                        borrow_desc,
+                        region_name,
                         span,
-                        format!(
-                            "{}requires that {}borrow lasts for `{}`",
-                            category.description(),
-                            borrow_desc,
-                            region_name,
-                        ),
-                    );
+                    };
+                    err.subdiagnostic(sub_label);
                 };
 
                 self.add_lifetime_bound_suggestion_to_diagnostic(err, &category, span, region_name);
diff --git a/compiler/rustc_borrowck/src/session_diagnostics.rs b/compiler/rustc_borrowck/src/session_diagnostics.rs
index 0da5678a34865..202c70e39f05d 100644
--- a/compiler/rustc_borrowck/src/session_diagnostics.rs
+++ b/compiler/rustc_borrowck/src/session_diagnostics.rs
@@ -167,3 +167,15 @@ pub(crate) enum RegionNameLables {
         span: Span,
     },
 }
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum RequireBorrowLasts<'a> {
+    #[label(borrowck::outlive_constraint_need_borrow_lasts_for)]
+    Lasts {
+        category: &'a str,
+        borrow_desc: &'a str,
+        region_name: &'a RegionName,
+        #[primary_span]
+        span: Span,
+    },
+}
diff --git a/compiler/rustc_error_messages/locales/en-US/borrowck.ftl b/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
index 8e8380c4da2ca..ba9500a2426f9 100644
--- a/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/borrowck.ftl
@@ -61,3 +61,6 @@ borrowck_used_impl_require_static =
 
 borrowck_lifetime_defined_here =
     lifetime `{$rg_name}` defined here
+
+borrowck_outlive_constraint_need_borrow_lasts_for =
+    {$category}requires that `{$borrow_desc}` lasts for `{$region_name}`