diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 848e142e59ce9..b412f3df9263e 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -131,7 +131,7 @@ impl<'a> StringReader<'a> {
     ) -> DiagnosticBuilder<'a, !> {
         self.sess
             .span_diagnostic
-            .struct_span_fatal(self.mk_sp(from_pos, to_pos), &format!("{}: {}", m, escaped_char(c)))
+            .struct_span_fatal(self.mk_sp(from_pos, to_pos), &format!("{m}: {}", escaped_char(c)))
     }
 
     fn struct_err_span_char(
@@ -143,7 +143,7 @@ impl<'a> StringReader<'a> {
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         self.sess
             .span_diagnostic
-            .struct_span_err(self.mk_sp(from_pos, to_pos), &format!("{}: {}", m, escaped_char(c)))
+            .struct_span_err(self.mk_sp(from_pos, to_pos), &format!("{m}: {}", escaped_char(c)))
     }
 
     /// Detect usages of Unicode codepoints changing the direction of the text on screen and loudly
@@ -217,7 +217,7 @@ impl<'a> StringReader<'a> {
                 self.sess.symbol_gallery.insert(sym, span);
                 if is_raw_ident {
                     if !sym.can_be_raw() {
-                        self.err_span(span, &format!("`{}` cannot be a raw identifier", sym));
+                        self.err_span(span, &format!("`{sym}` cannot be a raw identifier"));
                     }
                     self.sess.raw_identifier_spans.borrow_mut().push(span);
                 }
@@ -481,7 +481,7 @@ impl<'a> StringReader<'a> {
 
     /// As symbol_from, with an explicit endpoint.
     fn symbol_from_to(&self, start: BytePos, end: BytePos) -> Symbol {
-        debug!("taking an ident from {:?} to {:?}", start, end);
+        debug!("taking an ident from {start:?} to {end:?}");
         Symbol::intern(self.str_from_to(start, end))
     }
 
@@ -607,7 +607,7 @@ impl<'a> StringReader<'a> {
     fn report_unknown_prefix(&self, start: BytePos) {
         let prefix_span = self.mk_sp(start, self.pos);
         let prefix_str = self.str_from_to(start, self.pos);
-        let msg = format!("prefix `{}` is unknown", prefix_str);
+        let msg = format!("prefix `{prefix_str}` is unknown");
 
         let expn_data = prefix_span.ctxt().outer_expn_data();
 
@@ -650,8 +650,7 @@ impl<'a> StringReader<'a> {
             self.pos,
             &format!(
                 "too many `#` symbols: raw strings may be delimited \
-                by up to 255 `#` symbols, but found {}",
-                found
+                by up to 255 `#` symbols, but found {found}"
             ),
         )
     }
@@ -699,7 +698,7 @@ impl<'a> StringReader<'a> {
             if c != '_' && c.to_digit(base).is_none() {
                 let lo = content_start + BytePos(2 + idx);
                 let hi = content_start + BytePos(2 + idx + c.len_utf8() as u32);
-                self.err_span_(lo, hi, &format!("invalid digit for a base {} literal", base));
+                self.err_span_(lo, hi, &format!("invalid digit for a base {base} literal"));
             }
         }
     }
diff --git a/compiler/rustc_parse/src/lexer/tokentrees.rs b/compiler/rustc_parse/src/lexer/tokentrees.rs
index aa70912dcde4c..b3cf4467be89b 100644
--- a/compiler/rustc_parse/src/lexer/tokentrees.rs
+++ b/compiler/rustc_parse/src/lexer/tokentrees.rs
@@ -225,7 +225,7 @@ impl<'a> TokenTreesReader<'a> {
                 // An unexpected closing delimiter (i.e., there is no
                 // matching opening delimiter).
                 let token_str = token_to_string(&self.token);
-                let msg = format!("unexpected closing delimiter: `{}`", token_str);
+                let msg = format!("unexpected closing delimiter: `{token_str}`");
                 let mut err =
                     self.string_reader.sess.span_diagnostic.struct_span_err(self.token.span, &msg);
 
diff --git a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
index 273827864f1a4..2d9ca7b543a06 100644
--- a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
+++ b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
@@ -121,7 +121,7 @@ pub(crate) fn emit_unescape_error(
                 handler.span_suggestion(
                     span_with_quotes,
                     msg,
-                    format!("{}\"{}\"", prefix, lit),
+                    format!("{prefix}\"{lit}\""),
                     Applicability::MachineApplicable,
                 );
             }
@@ -137,7 +137,7 @@ pub(crate) fn emit_unescape_error(
                 "character constant must be escaped"
             };
             handler
-                .struct_span_err(span, &format!("{}: `{}`", msg, escaped_char(c)))
+                .struct_span_err(span, &format!("{msg}: `{}`", escaped_char(c)))
                 .span_suggestion(
                     char_span,
                     "escape the character",
@@ -173,7 +173,7 @@ pub(crate) fn emit_unescape_error(
             let label =
                 if mode.is_bytes() { "unknown byte escape" } else { "unknown character escape" };
             let ec = escaped_char(c);
-            let mut diag = handler.struct_span_err(span, &format!("{}: `{}`", label, ec));
+            let mut diag = handler.struct_span_err(span, &format!("{label}: `{ec}`"));
             diag.span_label(span, label);
             if c == '{' || c == '}' && !mode.is_bytes() {
                 diag.help(
@@ -214,10 +214,7 @@ pub(crate) fn emit_unescape_error(
             };
             let c = escaped_char(c);
 
-            handler
-                .struct_span_err(span, &format!("{}: `{}`", msg, c))
-                .span_label(span, msg)
-                .emit();
+            handler.struct_span_err(span, &format!("{msg}: `{c}`")).span_label(span, msg).emit();
         }
         EscapeError::NonAsciiCharInByte => {
             assert!(mode.is_bytes());
@@ -228,7 +225,7 @@ pub(crate) fn emit_unescape_error(
             } else {
                 String::new()
             };
-            err.span_label(span, &format!("byte constant must be ASCII{}", postfix));
+            err.span_label(span, &format!("byte constant must be ASCII{postfix}"));
             if (c as u32) <= 0xFF {
                 err.span_suggestion(
                     span,
@@ -246,10 +243,7 @@ pub(crate) fn emit_unescape_error(
                 utf8.push(c);
                 err.span_suggestion(
                     span,
-                    &format!(
-                        "if you meant to use the UTF-8 encoding of {:?}, use \\xHH escapes",
-                        c
-                    ),
+                    &format!("if you meant to use the UTF-8 encoding of {c:?}, use \\xHH escapes"),
                     utf8.as_bytes()
                         .iter()
                         .map(|b: &u8| format!("\\x{:X}", *b))
@@ -263,13 +257,13 @@ pub(crate) fn emit_unescape_error(
             assert!(mode.is_bytes());
             let (c, span) = last_char();
             let postfix = if unicode_width::UnicodeWidthChar::width(c).unwrap_or(1) == 0 {
-                format!(" but is {:?}", c)
+                format!(" but is {c:?}")
             } else {
                 String::new()
             };
             handler
                 .struct_span_err(span, "raw byte string must be ASCII")
-                .span_label(span, &format!("must be ASCII{}", postfix))
+                .span_label(span, &format!("must be ASCII{postfix}"))
                 .emit();
         }
         EscapeError::OutOfRangeHexEscape => {
@@ -281,10 +275,7 @@ pub(crate) fn emit_unescape_error(
         EscapeError::LeadingUnderscoreUnicodeEscape => {
             let (c, span) = last_char();
             let msg = "invalid start of unicode escape";
-            handler
-                .struct_span_err(span, &format!("{}: `{}`", msg, c))
-                .span_label(span, msg)
-                .emit();
+            handler.struct_span_err(span, &format!("{msg}: `{c}`")).span_label(span, msg).emit();
         }
         EscapeError::OverlongUnicodeEscape => {
             handler
diff --git a/compiler/rustc_parse/src/lexer/unicode_chars.rs b/compiler/rustc_parse/src/lexer/unicode_chars.rs
index 2c68cc5895c6e..cfda56542fdc5 100644
--- a/compiler/rustc_parse/src/lexer/unicode_chars.rs
+++ b/compiler/rustc_parse/src/lexer/unicode_chars.rs
@@ -343,7 +343,7 @@ pub(super) fn check_for_substitution<'a>(
     let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
 
     let Some((_ascii_char, ascii_name, token)) = ASCII_ARRAY.iter().find(|&&(c, _, _)| c == ascii_char) else {
-        let msg = format!("substitution character not found for '{}'", ch);
+        let msg = format!("substitution character not found for '{ch}'");
         reader.sess.span_diagnostic.span_bug_no_panic(span, &msg);
         return None;
     };
@@ -352,8 +352,7 @@ pub(super) fn check_for_substitution<'a>(
     if let Some(s) = peek_delimited(&reader.src[reader.src_index(pos)..], '“', '”') {
         let msg = format!(
             "Unicode characters '“' (Left Double Quotation Mark) and \
-             '”' (Right Double Quotation Mark) look like '{}' ({}), but are not",
-            ascii_char, ascii_name
+             '”' (Right Double Quotation Mark) look like '{ascii_char}' ({ascii_name}), but are not"
         );
         err.span_suggestion(
             Span::with_root_ctxt(
@@ -366,8 +365,7 @@ pub(super) fn check_for_substitution<'a>(
         );
     } else {
         let msg = format!(
-            "Unicode character '{}' ({}) looks like '{}' ({}), but it is not",
-            ch, u_name, ascii_char, ascii_name
+            "Unicode character '{ch}' ({u_name}) looks like '{ascii_char}' ({ascii_name}), but it is not"
         );
         err.span_suggestion(span, &msg, ascii_char, Applicability::MaybeIncorrect);
     }
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index acdbddf4099e6..0dbdb9adebca5 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -117,8 +117,8 @@ impl<'a> Parser<'a> {
         inner_parse_policy: InnerAttrPolicy<'_>,
     ) -> PResult<'a, ast::Attribute> {
         debug!(
-            "parse_attribute: inner_parse_policy={:?} self.token={:?}",
-            inner_parse_policy, self.token
+            "parse_attribute: inner_parse_policy={inner_parse_policy:?} self.token={:?}",
+            self.token
         );
         let lo = self.token.span;
         // Attributes can't have attributes of their own [Editor's note: not with that attitude]
@@ -191,7 +191,7 @@ impl<'a> Parser<'a> {
                 };
                 err.span_label(
                     item.span,
-                    &format!("the inner {} doesn't annotate this {}", attr_name, item.kind.descr()),
+                    &format!("the inner {attr_name} doesn't annotate this {}", item.kind.descr()),
                 );
                 err.span_suggestion_verbose(
                     replacement_span,
@@ -323,7 +323,7 @@ impl<'a> Parser<'a> {
 
     pub(crate) fn parse_unsuffixed_lit(&mut self) -> PResult<'a, ast::Lit> {
         let lit = self.parse_lit()?;
-        debug!("checking if {:?} is unusuffixed", lit);
+        debug!("checking if {lit:?} is unusuffixed");
 
         if !lit.kind.is_unsuffixed() {
             self.struct_span_err(lit.span, "suffixed literals are not allowed in attributes")
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index 6c750ff428f53..c54b4c3193e81 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -147,13 +147,11 @@ impl CreateTokenStream for LazyTokenStreamImpl {
             // another replace range will capture the *replaced* tokens for the inner
             // range, not the original tokens.
             for (range, new_tokens) in replace_ranges.iter().rev() {
-                assert!(!range.is_empty(), "Cannot replace an empty range: {:?}", range);
+                assert!(!range.is_empty(), "Cannot replace an empty range: {range:?}");
                 // Replace ranges are only allowed to decrease the number of tokens.
                 assert!(
                     range.len() >= new_tokens.len(),
-                    "Range {:?} has greater len than {:?}",
-                    range,
-                    new_tokens
+                    "Range {range:?} has greater len than {new_tokens:?}"
                 );
 
                 // Replace any removed tokens with `FlatToken::Empty`.
@@ -408,22 +406,19 @@ fn make_token_stream(
             FlatToken::Token(Token { kind: TokenKind::CloseDelim(delim), span }) => {
                 let frame_data = stack
                     .pop()
-                    .unwrap_or_else(|| panic!("Token stack was empty for token: {:?}", token));
+                    .unwrap_or_else(|| panic!("Token stack was empty for token: {token:?}"));
 
                 let (open_delim, open_sp) = frame_data.open_delim_sp.unwrap();
                 assert_eq!(
                     open_delim, delim,
-                    "Mismatched open/close delims: open={:?} close={:?}",
-                    open_delim, span
+                    "Mismatched open/close delims: open={open_delim:?} close={span:?}"
                 );
                 let dspan = DelimSpan::from_pair(open_sp, span);
                 let stream = AttrAnnotatedTokenStream::new(frame_data.inner);
                 let delimited = AttrAnnotatedTokenTree::Delimited(dspan, delim, stream);
                 stack
                     .last_mut()
-                    .unwrap_or_else(|| {
-                        panic!("Bottom token frame is missing for token: {:?}", token)
-                    })
+                    .unwrap_or_else(|| panic!("Bottom token frame is missing for token: {token:?}"))
                     .inner
                     .push((delimited, Spacing::Alone));
             }
@@ -456,9 +451,9 @@ fn make_token_stream(
                 spacing,
             ));
         } else {
-            panic!("Unexpected last token {:?}", last_token)
+            panic!("Unexpected last token {last_token:?}")
         }
     }
-    assert!(stack.is_empty(), "Stack should be empty: final_buf={:?} stack={:?}", final_buf, stack);
+    assert!(stack.is_empty(), "Stack should be empty: final_buf={final_buf:?} stack={stack:?}");
     AttrAnnotatedTokenStream::new(final_buf.inner)
 }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 33bebfc2c9ab5..5329e03f3376d 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1077,7 +1077,7 @@ impl<'a> Parser<'a> {
                 }
                 components.push(Punct(c));
             } else {
-                panic!("unexpected character in a float token: {:?}", c)
+                panic!("unexpected character in a float token: {c:?}")
             }
         }
         if !ident_like.is_empty() {
@@ -1149,7 +1149,7 @@ impl<'a> Parser<'a> {
                 self.error_unexpected_after_dot();
                 base
             }
-            _ => panic!("unexpected components in a float token: {:?}", components),
+            _ => panic!("unexpected components in a float token: {components:?}"),
         }
     }