[zero_prefixed_literal] Do not advise to use octal form if not possible

clippy_lints/src/misc_early/zero_prefixed_literal.rs

@@ -6,6 +6,7 @@ use rustc_lint::EarlyContext;
 use super::ZERO_PREFIXED_LITERAL;
 
 pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str) {
+ let trimmed_lit_snip = lit_snip.trim_start_matches(|c| c == '_' || c == '0');
  span_lint_and_then(
  cx,
  ZERO_PREFIXED_LITERAL,
@@ -15,15 +16,18 @@ pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str) {
  diag.span_suggestion(
  lit.span,
  "if you mean to use a decimal constant, remove the `0` to avoid confusion",
- lit_snip.trim_start_matches(|c| c == '_' || c == '0').to_string(),
- Applicability::MaybeIncorrect,
- );
- diag.span_suggestion(
- lit.span,
- "if you mean to use an octal constant, use `0o`",
- format!("0o{}", lit_snip.trim_start_matches(|c| c == '_' || c == '0')),
+ trimmed_lit_snip.to_string(),
  Applicability::MaybeIncorrect,
  );
+ // do not advise to use octal form if the literal cannot be expressed in base 8.
+ if !lit_snip.contains(|c| c == '8' || c == '9') {
+ diag.span_suggestion(
+ lit.span,
+ "if you mean to use an octal constant, use `0o`",
+ format!("0o{trimmed_lit_snip}"),
+ Applicability::MaybeIncorrect,
+ );
+ }
  },
  );
 }

tests/ui/literals.rs

@@ -40,3 +40,10 @@ fn main() {
  let ok26 = 0x6_A0_BF;
  let ok27 = 0b1_0010_0101;
 }
+
+fn issue9651() {
+ // lint but octal form is not possible here
+ let _ = 08;
+ let _ = 09;
+ let _ = 089;
+}

tests/ui/literals.stderr

@@ -135,5 +135,38 @@ error: digits of hex or binary literal not grouped by four
 LL | let fail25 = 0b01_100_101;
  | ^^^^^^^^^^^^ help: consider: `0b0110_0101`
 
-error: aborting due to 18 previous errors
+error: this is a decimal constant
+ --> $DIR/literals.rs:46:13
+ |
+LL | let _ = 08;
+ | ^^
+ |
+help: if you mean to use a decimal constant, remove the `0` to avoid confusion
+ |
+LL | let _ = 8;
+ | ~
+
+error: this is a decimal constant
+ --> $DIR/literals.rs:47:13
+ |
+LL | let _ = 09;
+ | ^^
+ |
+help: if you mean to use a decimal constant, remove the `0` to avoid confusion
+ |
+LL | let _ = 9;
+ | ~
+
+error: this is a decimal constant
+ --> $DIR/literals.rs:48:13
+ |
+LL | let _ = 089;
+ | ^^^
+ |
+help: if you mean to use a decimal constant, remove the `0` to avoid confusion
+ |
+LL | let _ = 89;
+ | ~~
+
+error: aborting due to 21 previous errors