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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::is_lint_allowed;
use clippy_utils::macros::span_is_local;
use clippy_utils::source::snippet;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, HirId};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use unicode_normalization::UnicodeNormalization;
declare_clippy_lint! {
/// ### What it does
/// Checks for invisible Unicode characters in the code.
///
/// ### Why is this bad?
/// Having an invisible character in the code makes for all
/// sorts of April fools, but otherwise is very much frowned upon.
///
/// ### Example
/// You don't see it, but there may be a zero-width space or soft hyphen
/// somewhere in this text.
#[clippy::version = "1.49.0"]
pub INVISIBLE_CHARACTERS,
correctness,
"using an invisible character in a string literal, which is confusing"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for non-ASCII characters in string and char literals.
///
/// ### Why is this bad?
/// Yeah, we know, the 90's called and wanted their charset
/// back. Even so, there still are editors and other programs out there that
/// don't work well with Unicode. So if the code is meant to be used
/// internationally, on multiple operating systems, or has other portability
/// requirements, activating this lint could be useful.
///
/// ### Example
/// ```rust
/// let x = String::from("€");
/// ```
///
/// Use instead:
/// ```rust
/// let x = String::from("\u{20ac}");
/// ```
#[clippy::version = "pre 1.29.0"]
pub NON_ASCII_LITERAL,
restriction,
"using any literal non-ASCII chars in a string literal instead of using the `\\u` escape"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for string literals that contain Unicode in a form
/// that is not equal to its
/// [NFC-recomposition](http://www.unicode.org/reports/tr15/#Norm_Forms).
///
/// ### Why is this bad?
/// If such a string is compared to another, the results
/// may be surprising.
///
/// ### Example
/// You may not see it, but "à"" and "à"" aren't the same string. The
/// former when escaped is actually `"a\u{300}"` while the latter is `"\u{e0}"`.
#[clippy::version = "pre 1.29.0"]
pub UNICODE_NOT_NFC,
pedantic,
"using a Unicode literal not in NFC normal form (see [Unicode tr15](http://www.unicode.org/reports/tr15/) for further information)"
}
declare_lint_pass!(Unicode => [INVISIBLE_CHARACTERS, NON_ASCII_LITERAL, UNICODE_NOT_NFC]);
impl LateLintPass<'_> for Unicode {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) {
if let ExprKind::Lit(ref lit) = expr.kind {
if let LitKind::Str(_, _) | LitKind::Char(_) = lit.node {
check_str(cx, lit.span, expr.hir_id);
}
}
}
}
fn escape<T: Iterator<Item = char>>(s: T) -> String {
let mut result = String::new();
for c in s {
if c as u32 > 0x7F {
for d in c.escape_unicode() {
result.push(d);
}
} else {
result.push(c);
}
}
result
}
fn check_str(cx: &LateContext<'_>, span: Span, id: HirId) {
if !span_is_local(span) {
return;
}
let string = snippet(cx, span, "");
if string.chars().any(|c| ['\u{200B}', '\u{ad}', '\u{2060}'].contains(&c)) {
span_lint_and_sugg(
cx,
INVISIBLE_CHARACTERS,
span,
"invisible character detected",
"consider replacing the string with",
string
.replace('\u{200B}', "\\u{200B}")
.replace('\u{ad}', "\\u{AD}")
.replace('\u{2060}', "\\u{2060}"),
Applicability::MachineApplicable,
);
}
if string.chars().any(|c| c as u32 > 0x7F) {
span_lint_and_sugg(
cx,
NON_ASCII_LITERAL,
span,
"literal non-ASCII character detected",
"consider replacing the string with",
if is_lint_allowed(cx, UNICODE_NOT_NFC, id) {
escape(string.chars())
} else {
escape(string.nfc())
},
Applicability::MachineApplicable,
);
}
if is_lint_allowed(cx, NON_ASCII_LITERAL, id) && string.chars().zip(string.nfc()).any(|(a, b)| a != b) {
span_lint_and_sugg(
cx,
UNICODE_NOT_NFC,
span,
"non-NFC Unicode sequence detected",
"consider replacing the string with",
string.nfc().collect::<String>(),
Applicability::MachineApplicable,
);
}
}
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