src/tools/clippy/clippy_lints/src/cargo/feature_name.rs

   1 use cargo_metadata::Metadata;
   2 use clippy_utils::diagnostics::span_lint_and_help;
   3 use rustc_lint::LateContext;
   4 use rustc_span::source_map::DUMMY_SP;
   5
   6 use super::{NEGATIVE_FEATURE_NAMES, REDUNDANT_FEATURE_NAMES};
   7
   8 static PREFIXES: [&str; 8] = ["no-", "no_", "not-", "not_", "use-", "use_", "with-", "with_"];
   9 static SUFFIXES: [&str; 2] = ["-support", "_support"];
  10
  11 pub(super) fn check(cx: &LateContext<'_>, metadata: &Metadata) {
  12     for package in &metadata.packages {
  13         let mut features: Vec<&String> = package.features.keys().collect();
  14         features.sort();
  15         for feature in features {
  16             let prefix_opt = {
  17                 let i = PREFIXES.partition_point(|prefix| prefix < &feature.as_str());
  18                 if i > 0 && feature.starts_with(PREFIXES[i - 1]) {
  19                     Some(PREFIXES[i - 1])
  20                 } else {
  21                     None
  22                 }
  23             };
  24             if let Some(prefix) = prefix_opt {
  25                 lint(cx, feature, prefix, true);
  26             }
  27
  28             let suffix_opt: Option<&str> = {
  29                 let i = SUFFIXES.partition_point(|suffix| {
  30                     suffix.bytes().rev().cmp(feature.bytes().rev()) == std::cmp::Ordering::Less
  31                 });
  32                 if i > 0 && feature.ends_with(SUFFIXES[i - 1]) {
  33                     Some(SUFFIXES[i - 1])
  34                 } else {
  35                     None
  36                 }
  37             };
  38             if let Some(suffix) = suffix_opt {
  39                 lint(cx, feature, suffix, false);
  40             }
  41         }
  42     }
  43 }
  44
  45 fn is_negative_prefix(s: &str) -> bool {
  46     s.starts_with("no")
  47 }
  48
  49 fn lint(cx: &LateContext<'_>, feature: &str, substring: &str, is_prefix: bool) {
  50     let is_negative = is_prefix && is_negative_prefix(substring);
  51     span_lint_and_help(
  52         cx,
  53         if is_negative {
  54             NEGATIVE_FEATURE_NAMES
  55         } else {
  56             REDUNDANT_FEATURE_NAMES
  57         },
  58         DUMMY_SP,
  59         &format!(
  60             "the \"{substring}\" {} in the feature name \"{feature}\" is {}",
  61             if is_prefix { "prefix" } else { "suffix" },
  62             if is_negative { "negative" } else { "redundant" }
  63         ),
  64         None,
  65         &format!(
  66             "consider renaming the feature to \"{}\"{}",
  67             if is_prefix {
  68                 feature.strip_prefix(substring)
  69             } else {
  70                 feature.strip_suffix(substring)
  71             }
  72             .unwrap(),
  73             if is_negative {
  74                 ", but make sure the feature adds functionality"
  75             } else {
  76                 ""
  77             }
  78         ),
  79     );
  80 }
  81
  82 #[test]
  83 fn test_prefixes_sorted() {
  84     let mut sorted_prefixes = PREFIXES;
  85     sorted_prefixes.sort_unstable();
  86     assert_eq!(PREFIXES, sorted_prefixes);
  87     let mut sorted_suffixes = SUFFIXES;
  88     sorted_suffixes.sort_by(|a, b| a.bytes().rev().cmp(b.bytes().rev()));
  89     assert_eq!(SUFFIXES, sorted_suffixes);
  90 }