bjoernager/rust
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Rollup merge of #105161 - cassaundra:numeric-literal-error, r=nnethercote

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Refine when invalid prefix case error arises

Fix cases where the "invalid base prefix for number literal" error arises with suffixes that look erroneously capitalized but which are actually invalid.
This commit is contained in:
Matthias Krüger 2022-12-14 10:31:05 +01:00 • committed by GitHub
commit 8ed0384ca4
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3 changed files with 107 additions and 10 deletions
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33
compiler/rustc_session/src/errors.rs
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@ -291,20 +291,33 @@ pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span:
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}"))
// Try to lowercase the prefix if the prefix and suffix are valid.
fn fix_base_capitalisation(prefix: &str, suffix: &str) -> Option<String> {
let mut chars = suffix.chars();
let base_char = chars.next().unwrap();
let base = match base_char {
'B' => 2,
'O' => 8,
'X' => 16,
_ => return None,
};
// check that the suffix contains only base-appropriate characters
let valid = prefix == "0"
&& chars
.filter(|c| *c != '_')
.take_while(|c| *c != 'i' && *c != 'u')
.all(|c| c.to_digit(base).is_some());
if valid {
Some(format!("0{}{}", base_char.to_ascii_lowercase(), &suffix[1..]))
} else {
None
}
}
let token::Lit { kind, suffix, .. } = lit;
let token::Lit { kind, symbol, suffix, .. } = lit;
match err {
// `LexerError` is an error, but it was already reported
// by lexer, so here we don't report it the second time.
@ -320,7 +333,7 @@ pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span:
if looks_like_width_suffix(&['i', 'u'], suf) {
// If it looks like a width, try to be helpful.
sess.emit_err(InvalidIntLiteralWidth { span, width: suf[1..].into() });
} else if let Some(fixed) = fix_base_capitalisation(suf) {
} else if let Some(fixed) = fix_base_capitalisation(symbol.as_str(), suf) {
sess.emit_err(InvalidNumLiteralBasePrefix { span, fixed });
} else {
sess.emit_err(InvalidNumLiteralSuffix { span, suffix: suf.to_string() });