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Rollup merge of #93019 - 5225225:uppercase-suffix, r=wesleywiser

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If an integer is entered with an upper-case base prefix (0Xbeef, 0O755, 0B1010), suggest to make it lowercase

The current error for this case isn't really great, it just complains about the whole thing past the `0` being an invalid suffix.
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Eric Huss 2022-01-31 20:12:55 -08:00 • committed by GitHub
commit d7c0b4f706
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25
compiler/rustc_parse/src/parser/expr.rs
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@ -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)