Auto merge of #5129 - JohnTitor:use-checked-sub, r=flip1995

Use `checked_sub` to avoid index out of bounds

(Fixes) #4681 (possibly)

The issue likely occurs due to `lit_snip.len() < suffix.len() + 1`. You can see similar backtrace to change it to `lit_snip.len() - suffix.len() - 1000` or something then run `cargo test --release`.
But I couldn't come up with the test so I'd leave the issue open if we want.

changelog: Fix potential ICE in `misc_early`
This commit is contained in:
bors 2020-02-03 16:47:25 +00:00
commit a39589480b

View file

@ -488,7 +488,11 @@ impl MiscEarlyLints {
LitIntType::Unsuffixed => "",
};
let maybe_last_sep_idx = lit_snip.len() - suffix.len() - 1;
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
// Do not lint when literal is unsuffixed.
if !suffix.is_empty() && lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
span_lint_and_sugg(
@ -502,7 +506,7 @@ impl MiscEarlyLints {
);
}
if lit_snip.starts_with("0x") {
if lit_snip.starts_with("0x") && maybe_last_sep_idx >= 3 {
let mut seen = (false, false);
for ch in lit_snip.as_bytes()[2..=maybe_last_sep_idx].iter() {
match ch {
@ -546,7 +550,11 @@ impl MiscEarlyLints {
}
} else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
let suffix = float_ty.name_str();
let maybe_last_sep_idx = lit_snip.len() - suffix.len() - 1;
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
if lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
span_lint_and_sugg(
cx,