rust/clippy_lints/src/enum_variants.rs

311 lines
10 KiB
Rust

//! lint on enum variants that are prefixed or suffixed by the same characters
use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_hir};
use clippy_utils::source::is_present_in_source;
use clippy_utils::str_utils::{camel_case_split, count_match_end, count_match_start};
use rustc_hir::{EnumDef, Item, ItemKind, OwnerId, Variant};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
use rustc_span::symbol::Symbol;
declare_clippy_lint! {
/// ### What it does
/// Detects enumeration variants that are prefixed or suffixed
/// by the same characters.
///
/// ### Why is this bad?
/// Enumeration variant names should specify their variant,
/// not repeat the enumeration name.
///
/// ### Limitations
/// Characters with no casing will be considered when comparing prefixes/suffixes
/// This applies to numbers and non-ascii characters without casing
/// e.g. `Foo1` and `Foo2` is considered to have different prefixes
/// (the prefixes are `Foo1` and `Foo2` respectively), as also `Bar螃`, `Bar蟹`
///
/// ### Example
/// ```rust
/// enum Cake {
/// BlackForestCake,
/// HummingbirdCake,
/// BattenbergCake,
/// }
/// ```
/// Use instead:
/// ```rust
/// enum Cake {
/// BlackForest,
/// Hummingbird,
/// Battenberg,
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub ENUM_VARIANT_NAMES,
style,
"enums where all variants share a prefix/postfix"
}
declare_clippy_lint! {
/// ### What it does
/// Detects type names that are prefixed or suffixed by the
/// containing module's name.
///
/// ### Why is this bad?
/// It requires the user to type the module name twice.
///
/// ### Example
/// ```rust
/// mod cake {
/// struct BlackForestCake;
/// }
/// ```
///
/// Use instead:
/// ```rust
/// mod cake {
/// struct BlackForest;
/// }
/// ```
#[clippy::version = "1.33.0"]
pub MODULE_NAME_REPETITIONS,
pedantic,
"type names prefixed/postfixed with their containing module's name"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for modules that have the same name as their
/// parent module
///
/// ### Why is this bad?
/// A typical beginner mistake is to have `mod foo;` and
/// again `mod foo { ..
/// }` in `foo.rs`.
/// The expectation is that items inside the inner `mod foo { .. }` are then
/// available
/// through `foo::x`, but they are only available through
/// `foo::foo::x`.
/// If this is done on purpose, it would be better to choose a more
/// representative module name.
///
/// ### Example
/// ```ignore
/// // lib.rs
/// mod foo;
/// // foo.rs
/// mod foo {
/// ...
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub MODULE_INCEPTION,
style,
"modules that have the same name as their parent module"
}
pub struct EnumVariantNames {
modules: Vec<(Symbol, String, OwnerId)>,
threshold: u64,
avoid_breaking_exported_api: bool,
allow_private_module_inception: bool,
}
impl EnumVariantNames {
#[must_use]
pub fn new(threshold: u64, avoid_breaking_exported_api: bool, allow_private_module_inception: bool) -> Self {
Self {
modules: Vec::new(),
threshold,
avoid_breaking_exported_api,
allow_private_module_inception,
}
}
}
impl_lint_pass!(EnumVariantNames => [
ENUM_VARIANT_NAMES,
MODULE_NAME_REPETITIONS,
MODULE_INCEPTION
]);
fn check_enum_start(cx: &LateContext<'_>, item_name: &str, variant: &Variant<'_>) {
let name = variant.ident.name.as_str();
let item_name_chars = item_name.chars().count();
if count_match_start(item_name, name).char_count == item_name_chars
&& name.chars().nth(item_name_chars).map_or(false, |c| !c.is_lowercase())
&& name.chars().nth(item_name_chars + 1).map_or(false, |c| !c.is_numeric())
{
span_lint_hir(
cx,
ENUM_VARIANT_NAMES,
variant.hir_id,
variant.span,
"variant name starts with the enum's name",
);
}
}
fn check_enum_end(cx: &LateContext<'_>, item_name: &str, variant: &Variant<'_>) {
let name = variant.ident.name.as_str();
let item_name_chars = item_name.chars().count();
if count_match_end(item_name, name).char_count == item_name_chars {
span_lint_hir(
cx,
ENUM_VARIANT_NAMES,
variant.hir_id,
variant.span,
"variant name ends with the enum's name",
);
}
}
fn check_variant(cx: &LateContext<'_>, threshold: u64, def: &EnumDef<'_>, item_name: &str, span: Span) {
if (def.variants.len() as u64) < threshold {
return;
}
let first = &def.variants[0].ident.name.as_str();
let mut pre = camel_case_split(first);
let mut post = pre.clone();
post.reverse();
for var in def.variants {
check_enum_start(cx, item_name, var);
check_enum_end(cx, item_name, var);
let name = var.ident.name.as_str();
let variant_split = camel_case_split(name);
if variant_split.len() == 1 {
return;
}
pre = pre
.iter()
.zip(variant_split.iter())
.take_while(|(a, b)| a == b)
.map(|e| *e.0)
.collect();
post = post
.iter()
.zip(variant_split.iter().rev())
.take_while(|(a, b)| a == b)
.map(|e| *e.0)
.collect();
}
let (what, value) = match (have_no_extra_prefix(&pre), post.is_empty()) {
(true, true) => return,
(false, _) => ("pre", pre.join("")),
(true, false) => {
post.reverse();
("post", post.join(""))
},
};
span_lint_and_help(
cx,
ENUM_VARIANT_NAMES,
span,
&format!("all variants have the same {what}fix: `{value}`"),
None,
&format!(
"remove the {what}fixes and use full paths to \
the variants instead of glob imports"
),
);
}
#[must_use]
fn have_no_extra_prefix(prefixes: &[&str]) -> bool {
prefixes.iter().all(|p| p == &"" || p == &"_")
}
#[must_use]
fn to_camel_case(item_name: &str) -> String {
let mut s = String::new();
let mut up = true;
for c in item_name.chars() {
if c.is_uppercase() {
// we only turn snake case text into CamelCase
return item_name.to_string();
}
if c == '_' {
up = true;
continue;
}
if up {
up = false;
s.extend(c.to_uppercase());
} else {
s.push(c);
}
}
s
}
impl LateLintPass<'_> for EnumVariantNames {
fn check_item_post(&mut self, _cx: &LateContext<'_>, _item: &Item<'_>) {
let last = self.modules.pop();
assert!(last.is_some());
}
#[expect(clippy::similar_names)]
fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
let item_name = item.ident.name.as_str();
let item_camel = to_camel_case(item_name);
if !item.span.from_expansion() && is_present_in_source(cx, item.span) {
if let [.., (mod_name, mod_camel, owner_id)] = &*self.modules {
// constants don't have surrounding modules
if !mod_camel.is_empty() {
if mod_name == &item.ident.name
&& let ItemKind::Mod(..) = item.kind
&& (!self.allow_private_module_inception || cx.tcx.visibility(owner_id.def_id).is_public())
{
span_lint(
cx,
MODULE_INCEPTION,
item.span,
"module has the same name as its containing module",
);
}
// The `module_name_repetitions` lint should only trigger if the item has the module in its
// name. Having the same name is accepted.
if cx.tcx.visibility(item.owner_id).is_public() && item_camel.len() > mod_camel.len() {
let matching = count_match_start(mod_camel, &item_camel);
let rmatching = count_match_end(mod_camel, &item_camel);
let nchars = mod_camel.chars().count();
let is_word_beginning = |c: char| c == '_' || c.is_uppercase() || c.is_numeric();
if matching.char_count == nchars {
match item_camel.chars().nth(nchars) {
Some(c) if is_word_beginning(c) => span_lint(
cx,
MODULE_NAME_REPETITIONS,
item.ident.span,
"item name starts with its containing module's name",
),
_ => (),
}
}
if rmatching.char_count == nchars {
span_lint(
cx,
MODULE_NAME_REPETITIONS,
item.ident.span,
"item name ends with its containing module's name",
);
}
}
}
}
}
if let ItemKind::Enum(ref def, _) = item.kind {
if !(self.avoid_breaking_exported_api && cx.effective_visibilities.is_exported(item.owner_id.def_id)) {
check_variant(cx, self.threshold, def, item_name, item.span);
}
}
self.modules.push((item.ident.name, item_camel, item.owner_id));
}
}