From df99de522a17e7a0c4b75dfdad596862081127d5 Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Mon, 10 Feb 2020 20:42:04 +0300
Subject: [PATCH 1/2] proc_macro: Stabilize `Span::resolved_at` and
 `Span::located_at`

---
 src/libproc_macro/lib.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libproc_macro/lib.rs b/src/libproc_macro/lib.rs
index 3cbe852de7b5a..6e49d9829a2e1 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -352,14 +352,14 @@ impl Span {
 
     /// Creates a new span with the same line/column information as `self` but
     /// that resolves symbols as though it were at `other`.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_span_resolved_at", since = "1.43.0")]
     pub fn resolved_at(&self, other: Span) -> Span {
         Span(self.0.resolved_at(other.0))
     }
 
     /// Creates a new span with the same name resolution behavior as `self` but
     /// with the line/column information of `other`.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_span_located_at", since = "1.43.0")]
     pub fn located_at(&self, other: Span) -> Span {
         other.resolved_at(*self)
     }

From 966a295e8cc210d7b50185d16cb46a7ae1874531 Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Sat, 18 Apr 2020 18:49:03 +0300
Subject: [PATCH 2/2] Add a test for `Span::resolved_at` and `Span::located_at`

---
 .../auxiliary/resolved-located-at.rs          | 32 +++++++++++++++++++
 src/test/ui/proc-macro/resolved-located-at.rs | 12 +++++++
 .../ui/proc-macro/resolved-located-at.stderr  | 21 ++++++++++++
 3 files changed, 65 insertions(+)
 create mode 100644 src/test/ui/proc-macro/auxiliary/resolved-located-at.rs
 create mode 100644 src/test/ui/proc-macro/resolved-located-at.rs
 create mode 100644 src/test/ui/proc-macro/resolved-located-at.stderr

diff --git a/src/test/ui/proc-macro/auxiliary/resolved-located-at.rs b/src/test/ui/proc-macro/auxiliary/resolved-located-at.rs
new file mode 100644
index 0000000000000..9416c133e5661
--- /dev/null
+++ b/src/test/ui/proc-macro/auxiliary/resolved-located-at.rs
@@ -0,0 +1,32 @@
+// force-host
+// no-prefer-dynamic
+
+#![feature(proc_macro_def_site)]
+#![feature(proc_macro_diagnostic)]
+#![feature(proc_macro_hygiene)]
+#![feature(proc_macro_quote)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro]
+pub fn resolve_located_at(input: TokenStream) -> TokenStream {
+    match &*input.into_iter().collect::<Vec<_>>() {
+        [a, b, ..] => {
+            // The error is reported at input `a`.
+            let mut diag = Diagnostic::new(Level::Error, "expected error");
+            diag.set_spans(Span::def_site().located_at(a.span()));
+            diag.emit();
+
+            // Resolves to `struct S;` at def site, but the error is reported at input `b`.
+            let s = TokenTree::Ident(Ident::new("S", b.span().resolved_at(Span::def_site())));
+            quote!({
+                struct S;
+
+                $s
+            })
+        }
+        _ => panic!("unexpected input"),
+    }
+}
diff --git a/src/test/ui/proc-macro/resolved-located-at.rs b/src/test/ui/proc-macro/resolved-located-at.rs
new file mode 100644
index 0000000000000..9976284e222e6
--- /dev/null
+++ b/src/test/ui/proc-macro/resolved-located-at.rs
@@ -0,0 +1,12 @@
+// aux-build:resolved-located-at.rs
+
+#![feature(proc_macro_hygiene)]
+
+#[macro_use]
+extern crate resolved_located_at;
+
+fn main() {
+    resolve_located_at!(a b)
+    //~^ ERROR expected error
+    //~| ERROR mismatched types
+}
diff --git a/src/test/ui/proc-macro/resolved-located-at.stderr b/src/test/ui/proc-macro/resolved-located-at.stderr
new file mode 100644
index 0000000000000..0df7ced27a777
--- /dev/null
+++ b/src/test/ui/proc-macro/resolved-located-at.stderr
@@ -0,0 +1,21 @@
+error: expected error
+  --> $DIR/resolved-located-at.rs:9:25
+   |
+LL |     resolve_located_at!(a b)
+   |                         ^
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0308]: mismatched types
+  --> $DIR/resolved-located-at.rs:9:27
+   |
+LL | fn main() {
+   |           - expected `()` because of default return type
+LL |     resolve_located_at!(a b)
+   |                           ^ expected `()`, found struct `main::S`
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.