rust/clippy_lints/src/misc_early.rs
Matthias Krüger 3a96d6b603 rustup https://github.com/rust-lang/rust/pull/57907/
for file in `fd \.rs$` ; do sed  -i  s/span_suggestion_with_applicability/span_suggestion/g $file ; done

for file in `fd \.rs$` ; do sed  -i  s/span_suggestion_short_with_applicability/span_suggestion_short/g $file ; done

for file in `fd \.rs$` ; do sed  -i  s/span_suggestions_with_applicability/span_suggestions/g $file ; done
2019-01-27 13:33:56 +01:00

478 lines
16 KiB
Rust

use crate::utils::{constants, snippet, snippet_opt, span_help_and_lint, span_lint, span_lint_and_then};
use if_chain::if_chain;
use rustc::lint::{in_external_macro, EarlyContext, EarlyLintPass, LintArray, LintContext, LintPass};
use rustc::{declare_tool_lint, lint_array};
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::Applicability;
use std::char;
use syntax::ast::*;
use syntax::source_map::Span;
use syntax::visit::{walk_expr, FnKind, Visitor};
/// **What it does:** Checks for structure field patterns bound to wildcards.
///
/// **Why is this bad?** Using `..` instead is shorter and leaves the focus on
/// the fields that are actually bound.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let { a: _, b: ref b, c: _ } = ..
/// ```
declare_clippy_lint! {
pub UNNEEDED_FIELD_PATTERN,
style,
"struct fields bound to a wildcard instead of using `..`"
}
/// **What it does:** Checks for function arguments having the similar names
/// differing by an underscore.
///
/// **Why is this bad?** It affects code readability.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// fn foo(a: i32, _a: i32) {}
/// ```
declare_clippy_lint! {
pub DUPLICATE_UNDERSCORE_ARGUMENT,
style,
"function arguments having names which only differ by an underscore"
}
/// **What it does:** Detects closures called in the same expression where they
/// are defined.
///
/// **Why is this bad?** It is unnecessarily adding to the expression's
/// complexity.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// (|| 42)()
/// ```
declare_clippy_lint! {
pub REDUNDANT_CLOSURE_CALL,
complexity,
"throwaway closures called in the expression they are defined"
}
/// **What it does:** Detects expressions of the form `--x`.
///
/// **Why is this bad?** It can mislead C/C++ programmers to think `x` was
/// decremented.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// --x;
/// ```
declare_clippy_lint! {
pub DOUBLE_NEG,
style,
"`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
}
/// **What it does:** Warns on hexadecimal literals with mixed-case letter
/// digits.
///
/// **Why is this bad?** It looks confusing.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let y = 0x1a9BAcD;
/// ```
declare_clippy_lint! {
pub MIXED_CASE_HEX_LITERALS,
style,
"hex literals whose letter digits are not consistently upper- or lowercased"
}
/// **What it does:** Warns if literal suffixes are not separated by an
/// underscore.
///
/// **Why is this bad?** It is much less readable.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let y = 123832i32;
/// ```
declare_clippy_lint! {
pub UNSEPARATED_LITERAL_SUFFIX,
pedantic,
"literals whose suffix is not separated by an underscore"
}
/// **What it does:** Warns if an integral constant literal starts with `0`.
///
/// **Why is this bad?** In some languages (including the infamous C language
/// and most of its
/// family), this marks an octal constant. In Rust however, this is a decimal
/// constant. This could
/// be confusing for both the writer and a reader of the constant.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// In Rust:
/// ```rust
/// fn main() {
/// let a = 0123;
/// println!("{}", a);
/// }
/// ```
///
/// prints `123`, while in C:
///
/// ```c
/// #include <stdio.h>
///
/// int main() {
/// int a = 0123;
/// printf("%d\n", a);
/// }
/// ```
///
/// prints `83` (as `83 == 0o123` while `123 == 0o173`).
declare_clippy_lint! {
pub ZERO_PREFIXED_LITERAL,
complexity,
"integer literals starting with `0`"
}
/// **What it does:** Warns if a generic shadows a built-in type.
///
/// **Why is this bad?** This gives surprising type errors.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// impl<u32> Foo<u32> {
/// fn impl_func(&self) -> u32 {
/// 42
/// }
/// }
/// ```
declare_clippy_lint! {
pub BUILTIN_TYPE_SHADOW,
style,
"shadowing a builtin type"
}
#[derive(Copy, Clone)]
pub struct MiscEarly;
impl LintPass for MiscEarly {
fn get_lints(&self) -> LintArray {
lint_array!(
UNNEEDED_FIELD_PATTERN,
DUPLICATE_UNDERSCORE_ARGUMENT,
REDUNDANT_CLOSURE_CALL,
DOUBLE_NEG,
MIXED_CASE_HEX_LITERALS,
UNSEPARATED_LITERAL_SUFFIX,
ZERO_PREFIXED_LITERAL,
BUILTIN_TYPE_SHADOW
)
}
fn name(&self) -> &'static str {
"MiscEarlyLints"
}
}
// Used to find `return` statements or equivalents e.g. `?`
struct ReturnVisitor {
found_return: bool,
}
impl ReturnVisitor {
fn new() -> Self {
Self { found_return: false }
}
}
impl<'ast> Visitor<'ast> for ReturnVisitor {
fn visit_expr(&mut self, ex: &'ast Expr) {
if let ExprKind::Ret(_) = ex.node {
self.found_return = true;
} else if let ExprKind::Try(_) = ex.node {
self.found_return = true;
}
walk_expr(self, ex)
}
}
impl EarlyLintPass for MiscEarly {
fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
for param in &gen.params {
if let GenericParamKind::Type { .. } = param.kind {
let name = param.ident.as_str();
if constants::BUILTIN_TYPES.contains(&&*name) {
span_lint(
cx,
BUILTIN_TYPE_SHADOW,
param.ident.span,
&format!("This generic shadows the built-in type `{}`", name),
);
}
}
}
}
fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat, _: &mut bool) {
if let PatKind::Struct(ref npat, ref pfields, _) = pat.node {
let mut wilds = 0;
let type_name = npat
.segments
.last()
.expect("A path must have at least one segment")
.ident
.name;
for field in pfields {
if let PatKind::Wild = field.node.pat.node {
wilds += 1;
}
}
if !pfields.is_empty() && wilds == pfields.len() {
span_help_and_lint(
cx,
UNNEEDED_FIELD_PATTERN,
pat.span,
"All the struct fields are matched to a wildcard pattern, consider using `..`.",
&format!("Try with `{} {{ .. }}` instead", type_name),
);
return;
}
if wilds > 0 {
let mut normal = vec![];
for field in pfields {
match field.node.pat.node {
PatKind::Wild => {},
_ => {
if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
normal.push(n);
}
},
}
}
for field in pfields {
if let PatKind::Wild = field.node.pat.node {
wilds -= 1;
if wilds > 0 {
span_lint(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"You matched a field with a wildcard pattern. Consider using `..` instead",
);
} else {
span_help_and_lint(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"You matched a field with a wildcard pattern. Consider using `..` \
instead",
&format!("Try with `{} {{ {}, .. }}`", type_name, normal[..].join(", ")),
);
}
}
}
}
}
}
fn check_fn(&mut self, cx: &EarlyContext<'_>, _: FnKind<'_>, decl: &FnDecl, _: Span, _: NodeId) {
let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();
for arg in &decl.inputs {
if let PatKind::Ident(_, ident, None) = arg.pat.node {
let arg_name = ident.to_string();
if arg_name.starts_with('_') {
if let Some(correspondence) = registered_names.get(&arg_name[1..]) {
span_lint(
cx,
DUPLICATE_UNDERSCORE_ARGUMENT,
*correspondence,
&format!(
"`{}` already exists, having another argument having almost the same \
name makes code comprehension and documentation more difficult",
arg_name[1..].to_owned()
),
);;
}
} else {
registered_names.insert(arg_name, arg.pat.span);
}
}
}
}
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
if in_external_macro(cx.sess(), expr.span) {
return;
}
match expr.node {
ExprKind::Call(ref paren, _) => {
if let ExprKind::Paren(ref closure) = paren.node {
if let ExprKind::Closure(_, _, _, ref decl, ref block, _) = closure.node {
let mut visitor = ReturnVisitor::new();
visitor.visit_expr(block);
if !visitor.found_return {
span_lint_and_then(
cx,
REDUNDANT_CLOSURE_CALL,
expr.span,
"Try not to call a closure in the expression where it is declared.",
|db| {
if decl.inputs.is_empty() {
let hint = snippet(cx, block.span, "..").into_owned();
db.span_suggestion(
expr.span,
"Try doing something like: ",
hint,
Applicability::MachineApplicable, // snippet
);
}
},
);
}
}
}
},
ExprKind::Unary(UnOp::Neg, ref inner) => {
if let ExprKind::Unary(UnOp::Neg, _) = inner.node {
span_lint(
cx,
DOUBLE_NEG,
expr.span,
"`--x` could be misinterpreted as pre-decrement by C programmers, is usually a no-op",
);
}
},
ExprKind::Lit(ref lit) => self.check_lit(cx, lit),
_ => (),
}
}
fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
for w in block.stmts.windows(2) {
if_chain! {
if let StmtKind::Local(ref local) = w[0].node;
if let Option::Some(ref t) = local.init;
if let ExprKind::Closure(..) = t.node;
if let PatKind::Ident(_, ident, _) = local.pat.node;
if let StmtKind::Semi(ref second) = w[1].node;
if let ExprKind::Assign(_, ref call) = second.node;
if let ExprKind::Call(ref closure, _) = call.node;
if let ExprKind::Path(_, ref path) = closure.node;
then {
if ident == path.segments[0].ident {
span_lint(
cx,
REDUNDANT_CLOSURE_CALL,
second.span,
"Closure called just once immediately after it was declared",
);
}
}
}
}
}
}
impl MiscEarly {
fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
if_chain! {
if let LitKind::Int(value, ..) = lit.node;
if let Some(src) = snippet_opt(cx, lit.span);
if let Some(firstch) = src.chars().next();
if char::to_digit(firstch, 10).is_some();
then {
let mut prev = '\0';
for ch in src.chars() {
if ch == 'i' || ch == 'u' {
if prev != '_' {
span_lint(cx, UNSEPARATED_LITERAL_SUFFIX, lit.span,
"integer type suffix should be separated by an underscore");
}
break;
}
prev = ch;
}
if src.starts_with("0x") {
let mut seen = (false, false);
for ch in src.chars() {
match ch {
'a' ..= 'f' => seen.0 = true,
'A' ..= 'F' => seen.1 = true,
'i' | 'u' => break, // start of suffix already
_ => ()
}
}
if seen.0 && seen.1 {
span_lint(cx, MIXED_CASE_HEX_LITERALS, lit.span,
"inconsistent casing in hexadecimal literal");
}
} else if src.starts_with("0b") || src.starts_with("0o") {
/* nothing to do */
} else if value != 0 && src.starts_with('0') {
span_lint_and_then(cx,
ZERO_PREFIXED_LITERAL,
lit.span,
"this is a decimal constant",
|db| {
db.span_suggestion(
lit.span,
"if you mean to use a decimal constant, remove the `0` to remove confusion",
src.trim_start_matches(|c| c == '_' || c == '0').to_string(),
Applicability::MaybeIncorrect,
);
db.span_suggestion(
lit.span,
"if you mean to use an octal constant, use `0o`",
format!("0o{}", src.trim_start_matches(|c| c == '_' || c == '0')),
Applicability::MaybeIncorrect,
);
});
}
}
}
if_chain! {
if let LitKind::Float(..) = lit.node;
if let Some(src) = snippet_opt(cx, lit.span);
if let Some(firstch) = src.chars().next();
if char::to_digit(firstch, 10).is_some();
then {
let mut prev = '\0';
for ch in src.chars() {
if ch == 'f' {
if prev != '_' {
span_lint(cx, UNSEPARATED_LITERAL_SUFFIX, lit.span,
"float type suffix should be separated by an underscore");
}
break;
}
prev = ch;
}
}
}
}
}