Auto merge of #93534 - ehuss:rollup-9ecozo9, r=ehuss

Rollup of 9 pull requests

Successful merges:

 - #91343 (Fix suggestion to slice if scrutinee is a `Result` or `Option`)
 - #93019 (If an integer is entered with an upper-case base prefix (0Xbeef, 0O755, 0B1010), suggest to make it lowercase)
 - #93090 (`impl Display for io::ErrorKind`)
 - #93456 (Remove an unnecessary transmute from opaque::Encoder)
 - #93492 (Hide failed command unless in verbose mode)
 - #93504 (kmc-solid: Increase the default stack size)
 - #93513 (Allow any pretty printed line to have at least 60 chars)
 - #93532 (Update books)
 - #93533 (Update cargo)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 25 insertions, 0 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 693dd0051da..0115d498a7f 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1700,6 +1700,19 @@ impl<'a> Parser<'a> {
             s.len() > 1 && s.starts_with(first_chars) && s[1..].chars().all(|c| c.is_ascii_digit())
         }
 
+        // Try to lowercase the prefix if it's a valid base prefix.
+        fn fix_base_capitalisation(s: &str) -> Option<String> {
+            if let Some(stripped) = s.strip_prefix("B") {
+                Some(format!("0b{stripped}"))
+            } else if let Some(stripped) = s.strip_prefix("O") {
+                Some(format!("0o{stripped}"))
+            } else if let Some(stripped) = s.strip_prefix("X") {
+                Some(format!("0x{stripped}"))
+            } else {
+                None
+            }
+        }
+
         let token::Lit { kind, suffix, .. } = lit;
         match err {
             // `NotLiteral` is not an error by itself, so we don't report
@@ -1724,6 +1737,18 @@ impl<'a> Parser<'a> {
                     self.struct_span_err(span, &msg)
                         .help("valid widths are 8, 16, 32, 64 and 128")
                         .emit();
+                } else if let Some(fixed) = fix_base_capitalisation(suf) {
+                    let msg = "invalid base prefix for number literal";
+
+                    self.struct_span_err(span, &msg)
+                        .note("base prefixes (`0xff`, `0b1010`, `0o755`) are lowercase")
+                        .span_suggestion(
+                            span,
+                            "try making the prefix lowercase",
+                            fixed,
+                            Applicability::MaybeIncorrect,
+                        )
+                        .emit();
                 } else {
                     let msg = format!("invalid suffix `{}` for number literal", suf);
                     self.struct_span_err(span, &msg)