1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

use rustc::lint::*;
use rustc::hir::*;
use syntax::ast::{LitKind, NodeId};
use syntax::codemap::Span;
use unicode_normalization::UnicodeNormalization;
use utils::{is_allowed, snippet, span_help_and_lint};

/// **What it does:** Checks for the Unicode zero-width space 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
/// somewhere in this text.
declare_clippy_lint! {
    pub ZERO_WIDTH_SPACE,
    correctness,
    "using a zero-width space in a string literal, which is confusing"
}

/// **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 = "Hä?"
/// ```
declare_clippy_lint! {
    pub NON_ASCII_LITERAL,
    pedantic,
    "using any literal non-ASCII chars in a string literal instead of \
     using the `\\u` escape"
}

/// **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}"`.
declare_clippy_lint! {
    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)"
}


#[derive(Copy, Clone)]
pub struct Unicode;

impl LintPass for Unicode {
    fn get_lints(&self) -> LintArray {
        lint_array!(ZERO_WIDTH_SPACE, NON_ASCII_LITERAL, UNICODE_NOT_NFC)
    }
}

impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Unicode {
    fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
        if let ExprLit(ref lit) = expr.node {
            if let LitKind::Str(_, _) = lit.node {
                check_str(cx, lit.span, expr.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: NodeId) {
    let string = snippet(cx, span, "");
    if string.contains('\u{200B}') {
        span_help_and_lint(
            cx,
            ZERO_WIDTH_SPACE,
            span,
            "zero-width space detected",
            &format!(
                "Consider replacing the string with:\n\"{}\"",
                string.replace("\u{200B}", "\\u{200B}")
            ),
        );
    }
    if string.chars().any(|c| c as u32 > 0x7F) {
        span_help_and_lint(
            cx,
            NON_ASCII_LITERAL,
            span,
            "literal non-ASCII character detected",
            &format!(
                "Consider replacing the string with:\n\"{}\"",
                if is_allowed(cx, UNICODE_NOT_NFC, id) {
                    escape(string.chars())
                } else {
                    escape(string.nfc())
                }
            ),
        );
    }
    if is_allowed(cx, NON_ASCII_LITERAL, id) && string.chars().zip(string.nfc()).any(|(a, b)| a != b) {
        span_help_and_lint(
            cx,
            UNICODE_NOT_NFC,
            span,
            "non-nfc unicode sequence detected",
            &format!("Consider replacing the string with:\n\"{}\"", string.nfc().collect::<String>()),
        );
    }
}