1 files changed, 142 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/unicode.rs b/src/tools/clippy/clippy_lints/src/unicode.rs
new file mode 100644
index 000000000..cc64d17be
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/unicode.rs
@@ -0,0 +1,142 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::is_lint_allowed;
+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) {
+    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,
+        );
+    }
+}