From a661671ae37eece708d894eb25d58ec7dd2fd9a7 Mon Sep 17 00:00:00 2001
From: David Renshaw <dwrenshaw@gmail.com>
Date: Fri, 31 Dec 2021 12:26:10 -0500
Subject: [PATCH 1/2] [rustc_builtin_macros] add indices to
 format_foreign::printf::Substitution::Escape

---
 .../src/format_foreign.rs                     | 28 ++++++++-----------
 src/test/ui/macros/issue-92267.rs             |  3 ++
 src/test/ui/macros/issue-92267.stderr         | 16 +++++++++++
 3 files changed, 31 insertions(+), 16 deletions(-)
 create mode 100644 src/test/ui/macros/issue-92267.rs
 create mode 100644 src/test/ui/macros/issue-92267.stderr

diff --git a/compiler/rustc_builtin_macros/src/format_foreign.rs b/compiler/rustc_builtin_macros/src/format_foreign.rs
index bfddd7073ff..ecd16736e7c 100644
--- a/compiler/rustc_builtin_macros/src/format_foreign.rs
+++ b/compiler/rustc_builtin_macros/src/format_foreign.rs
@@ -7,28 +7,29 @@ pub(crate) mod printf {
     pub enum Substitution<'a> {
         /// A formatted output substitution with its internal byte offset.
         Format(Format<'a>),
-        /// A literal `%%` escape.
-        Escape,
+        /// A literal `%%` escape, with its start and end indices.
+        Escape((usize, usize)),
     }
 
     impl<'a> Substitution<'a> {
         pub fn as_str(&self) -> &str {
             match *self {
                 Substitution::Format(ref fmt) => fmt.span,
-                Substitution::Escape => "%%",
+                Substitution::Escape(_) => "%%",
             }
         }
 
         pub fn position(&self) -> Option<InnerSpan> {
             match *self {
                 Substitution::Format(ref fmt) => Some(fmt.position),
-                _ => None,
+                Substitution::Escape((start, end)) => Some(InnerSpan::new(start, end)),
             }
         }
 
         pub fn set_position(&mut self, start: usize, end: usize) {
-            if let Substitution::Format(ref mut fmt) = self {
-                fmt.position = InnerSpan::new(start, end);
+            match self {
+                Substitution::Format(ref mut fmt) => fmt.position = InnerSpan::new(start, end),
+                Substitution::Escape(ref mut pos) => *pos = (start, end),
             }
         }
 
@@ -39,7 +40,7 @@ pub(crate) mod printf {
         pub fn translate(&self) -> Result<String, Option<String>> {
             match *self {
                 Substitution::Format(ref fmt) => fmt.translate(),
-                Substitution::Escape => Err(None),
+                Substitution::Escape(_) => Err(None),
             }
         }
     }
@@ -304,14 +305,9 @@ pub(crate) mod printf {
         fn next(&mut self) -> Option<Self::Item> {
             let (mut sub, tail) = parse_next_substitution(self.s)?;
             self.s = tail;
-            match sub {
-                Substitution::Format(_) => {
-                    if let Some(inner_span) = sub.position() {
-                        sub.set_position(inner_span.start + self.pos, inner_span.end + self.pos);
-                        self.pos += inner_span.end;
-                    }
-                }
-                Substitution::Escape => self.pos += 2,
+            if let Some(InnerSpan { start, end }) = sub.position() {
+                sub.set_position(start + self.pos, end + self.pos);
+                self.pos += end;
             }
             Some(sub)
         }
@@ -340,7 +336,7 @@ pub(crate) mod printf {
         let at = {
             let start = s.find('%')?;
             if let '%' = s[start + 1..].chars().next()? {
-                return Some((Substitution::Escape, &s[start + 2..]));
+                return Some((Substitution::Escape((start, start + 2)), &s[start + 2..]));
             }
 
             Cur::new_at(s, start)
diff --git a/src/test/ui/macros/issue-92267.rs b/src/test/ui/macros/issue-92267.rs
new file mode 100644
index 00000000000..f1daaeb743e
--- /dev/null
+++ b/src/test/ui/macros/issue-92267.rs
@@ -0,0 +1,3 @@
+// check-fail
+
+pub fn main() { println!("🦀%%%", 0) } //~ ERROR argument never used
diff --git a/src/test/ui/macros/issue-92267.stderr b/src/test/ui/macros/issue-92267.stderr
new file mode 100644
index 00000000000..d2d66c81198
--- /dev/null
+++ b/src/test/ui/macros/issue-92267.stderr
@@ -0,0 +1,16 @@
+error: argument never used
+  --> $DIR/issue-92267.rs:3:34
+   |
+LL | pub fn main() { println!("🦀%%%", 0) }
+   |                                   ^ argument never used
+   |
+note: format specifiers use curly braces, and the conversion specifier `
+      ` is unknown or unsupported
+  --> $DIR/issue-92267.rs:3:30
+   |
+LL | pub fn main() { println!("🦀%%%", 0) }
+   |                               ^^
+   = note: printf formatting not supported; see the documentation for `std::fmt`
+
+error: aborting due to previous error
+

From 4a7f276cb67673ad2550ee7ef91caa0706565679 Mon Sep 17 00:00:00 2001
From: David Renshaw <dwrenshaw@gmail.com>
Date: Fri, 31 Dec 2021 12:51:27 -0500
Subject: [PATCH 2/2] update tests

---
 .../rustc_builtin_macros/src/format_foreign/printf/tests.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/compiler/rustc_builtin_macros/src/format_foreign/printf/tests.rs b/compiler/rustc_builtin_macros/src/format_foreign/printf/tests.rs
index 1336aab7316..fc7442470ac 100644
--- a/compiler/rustc_builtin_macros/src/format_foreign/printf/tests.rs
+++ b/compiler/rustc_builtin_macros/src/format_foreign/printf/tests.rs
@@ -13,9 +13,9 @@ macro_rules! assert_eq_pnsat {
 fn test_escape() {
     assert_eq!(pns("has no escapes"), None);
     assert_eq!(pns("has no escapes, either %"), None);
-    assert_eq!(pns("*so* has a %% escape"), Some((S::Escape, " escape")));
-    assert_eq!(pns("%% leading escape"), Some((S::Escape, " leading escape")));
-    assert_eq!(pns("trailing escape %%"), Some((S::Escape, "")));
+    assert_eq!(pns("*so* has a %% escape"), Some((S::Escape((11, 13)), " escape")));
+    assert_eq!(pns("%% leading escape"), Some((S::Escape((0, 2)), " leading escape")));
+    assert_eq!(pns("trailing escape %%"), Some((S::Escape((16, 18)), "")));
 }
 
 #[test]