From 85002b09a1858ea8a7e692f969c3c5946febc898 Mon Sep 17 00:00:00 2001
From: y21 <30553356+y21@users.noreply.github.com>
Date: Fri, 9 Jun 2023 04:57:07 +0200
Subject: [PATCH 1/2] handle exponent without digits

---
 clippy_utils/src/numeric_literal.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clippy_utils/src/numeric_literal.rs b/clippy_utils/src/numeric_literal.rs
index c225398ad2a..bbe4149fe2a 100644
--- a/clippy_utils/src/numeric_literal.rs
+++ b/clippy_utils/src/numeric_literal.rs
@@ -161,7 +161,7 @@ impl<'a> NumericLiteral<'a> {
         }
 
         if let Some((separator, exponent)) = self.exponent {
-            if exponent != "0" {
+            if !exponent.is_empty() && exponent != "0" {
                 output.push_str(separator);
                 Self::group_digits(&mut output, exponent, group_size, true, false);
             }

From bbb9204008297fc326fcf4dfbc07cee12f173081 Mon Sep 17 00:00:00 2001
From: y21 <30553356+y21@users.noreply.github.com>
Date: Fri, 9 Jun 2023 15:49:35 +0200
Subject: [PATCH 2/2] add test

---
 rustfmt.toml                      |  1 +
 tests/ui/crashes/ice-10912.rs     |  4 ++++
 tests/ui/crashes/ice-10912.stderr | 16 ++++++++++++++++
 3 files changed, 21 insertions(+)
 create mode 100644 tests/ui/crashes/ice-10912.rs
 create mode 100644 tests/ui/crashes/ice-10912.stderr

diff --git a/rustfmt.toml b/rustfmt.toml
index 10d39762043..18b2a33469d 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -5,3 +5,4 @@ wrap_comments = true
 edition = "2021"
 error_on_line_overflow = true
 version = "Two"
+ignore = ["tests/ui/crashes/ice-10912.rs"]
diff --git a/tests/ui/crashes/ice-10912.rs b/tests/ui/crashes/ice-10912.rs
new file mode 100644
index 00000000000..69d7f2f395f
--- /dev/null
+++ b/tests/ui/crashes/ice-10912.rs
@@ -0,0 +1,4 @@
+#![warn(clippy::unreadable_literal)]
+fn f2() -> impl Sized { && 3.14159265358979323846E }
+
+fn main() {}
diff --git a/tests/ui/crashes/ice-10912.stderr b/tests/ui/crashes/ice-10912.stderr
new file mode 100644
index 00000000000..a74ce731577
--- /dev/null
+++ b/tests/ui/crashes/ice-10912.stderr
@@ -0,0 +1,16 @@
+error: expected at least one digit in exponent
+  --> $DIR/ice-10912.rs:2:28
+   |
+LL | fn f2() -> impl Sized { && 3.14159265358979323846E }
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: long literal lacking separators
+  --> $DIR/ice-10912.rs:2:28
+   |
+LL | fn f2() -> impl Sized { && 3.14159265358979323846E }
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^ help: consider: `3.141_592_653_589_793_238_46`
+   |
+   = note: `-D clippy::unreadable-literal` implied by `-D warnings`
+
+error: aborting due to 2 previous errors
+