--- /dev/null
+use crate::utils::{is_allowed, snippet, span_lint_and_sugg};
+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.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:** You don't see it, but there may be a zero-width space or soft hyphen
+ /// somewhere in this text.
+ 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 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.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// let x = String::from("€");
+ /// ```
+ /// Could be written as:
+ /// ```rust
+ /// let x = String::from("\u{20ac}");
+ /// ```
+ pub NON_ASCII_LITERAL,
+ pedantic,
+ "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.
+ ///
+ /// **Known problems** None.
+ ///
+ /// **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}"`.
+ 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(_, _) = 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) {
+ 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_allowed(cx, UNICODE_NOT_NFC, id) {
+ escape(string.chars())
+ } else {
+ escape(string.nfc())
+ },
+ Applicability::MachineApplicable,
+ );
+ }
+ if is_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,
+ );
+ }
+}