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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197

use crate::fmt;

/// A struct containing information about the location of a panic.
///
/// This structure is created by [`PanicInfo::location()`].
///
/// [`PanicInfo::location()`]: crate::panic::PanicInfo::location
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
///     if let Some(location) = panic_info.location() {
///         println!("panic occurred in file '{}' at line {}", location.file(), location.line());
///     } else {
///         println!("panic occurred but can't get location information...");
///     }
/// }));
///
/// panic!("Normal panic");
/// ```
///
/// # Comparisons
///
/// Comparisons for equality and ordering are made in file, line, then column priority.
/// Files are compared as strings, not `Path`, which could be unexpected.
/// See [`Location::file`]'s documentation for more discussion.
#[lang = "panic_location"]
#[derive(Copy, Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub struct Location<'a> {
    file: &'a str,
    line: u32,
    col: u32,
}

impl<'a> Location<'a> {
    /// Returns the source location of the caller of this function. If that function's caller is
    /// annotated then its call location will be returned, and so on up the stack to the first call
    /// within a non-tracked function body.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::panic::Location;
    ///
    /// /// Returns the [`Location`] at which it is called.
    /// #[track_caller]
    /// fn get_caller_location() -> &'static Location<'static> {
    ///     Location::caller()
    /// }
    ///
    /// /// Returns a [`Location`] from within this function's definition.
    /// fn get_just_one_location() -> &'static Location<'static> {
    ///     get_caller_location()
    /// }
    ///
    /// let fixed_location = get_just_one_location();
    /// assert_eq!(fixed_location.file(), file!());
    /// assert_eq!(fixed_location.line(), 14);
    /// assert_eq!(fixed_location.column(), 5);
    ///
    /// // running the same untracked function in a different location gives us the same result
    /// let second_fixed_location = get_just_one_location();
    /// assert_eq!(fixed_location.file(), second_fixed_location.file());
    /// assert_eq!(fixed_location.line(), second_fixed_location.line());
    /// assert_eq!(fixed_location.column(), second_fixed_location.column());
    ///
    /// let this_location = get_caller_location();
    /// assert_eq!(this_location.file(), file!());
    /// assert_eq!(this_location.line(), 28);
    /// assert_eq!(this_location.column(), 21);
    ///
    /// // running the tracked function in a different location produces a different value
    /// let another_location = get_caller_location();
    /// assert_eq!(this_location.file(), another_location.file());
    /// assert_ne!(this_location.line(), another_location.line());
    /// assert_ne!(this_location.column(), another_location.column());
    /// ```
    #[must_use]
    #[stable(feature = "track_caller", since = "1.46.0")]
    #[rustc_const_unstable(feature = "const_caller_location", issue = "76156")]
    #[track_caller]
    #[inline]
    pub const fn caller() -> &'static Location<'static> {
        crate::intrinsics::caller_location()
    }

    /// Returns the name of the source file from which the panic originated.
    ///
    /// # `&str`, not `&Path`
    ///
    /// The returned name refers to a source path on the compiling system, but it isn't valid to
    /// represent this directly as a `&Path`. The compiled code may run on a different system with
    /// a different `Path` implementation than the system providing the contents and this library
    /// does not currently have a different "host path" type.
    ///
    /// The most surprising behavior occurs when "the same" file is reachable via multiple paths in
    /// the module system (usually using the `#[path = "..."]` attribute or similar), which can
    /// cause what appears to be identical code to return differing values from this function.
    ///
    /// # Cross-compilation
    ///
    /// This value is not suitable for passing to `Path::new` or similar constructors when the host
    /// platform and target platform differ.
    ///
    /// # Examples
    ///
    /// ```should_panic
    /// use std::panic;
    ///
    /// panic::set_hook(Box::new(|panic_info| {
    ///     if let Some(location) = panic_info.location() {
    ///         println!("panic occurred in file '{}'", location.file());
    ///     } else {
    ///         println!("panic occurred but can't get location information...");
    ///     }
    /// }));
    ///
    /// panic!("Normal panic");
    /// ```
    #[must_use]
    #[stable(feature = "panic_hooks", since = "1.10.0")]
    #[inline]
    pub fn file(&self) -> &str {
        self.file
    }

    /// Returns the line number from which the panic originated.
    ///
    /// # Examples
    ///
    /// ```should_panic
    /// use std::panic;
    ///
    /// panic::set_hook(Box::new(|panic_info| {
    ///     if let Some(location) = panic_info.location() {
    ///         println!("panic occurred at line {}", location.line());
    ///     } else {
    ///         println!("panic occurred but can't get location information...");
    ///     }
    /// }));
    ///
    /// panic!("Normal panic");
    /// ```
    #[must_use]
    #[stable(feature = "panic_hooks", since = "1.10.0")]
    #[inline]
    pub fn line(&self) -> u32 {
        self.line
    }

    /// Returns the column from which the panic originated.
    ///
    /// # Examples
    ///
    /// ```should_panic
    /// use std::panic;
    ///
    /// panic::set_hook(Box::new(|panic_info| {
    ///     if let Some(location) = panic_info.location() {
    ///         println!("panic occurred at column {}", location.column());
    ///     } else {
    ///         println!("panic occurred but can't get location information...");
    ///     }
    /// }));
    ///
    /// panic!("Normal panic");
    /// ```
    #[must_use]
    #[stable(feature = "panic_col", since = "1.25.0")]
    #[inline]
    pub fn column(&self) -> u32 {
        self.col
    }
}

#[unstable(
    feature = "panic_internals",
    reason = "internal details of the implementation of the `panic!` and related macros",
    issue = "none"
)]
impl<'a> Location<'a> {
    #[doc(hidden)]
    pub const fn internal_constructor(file: &'a str, line: u32, col: u32) -> Self {
        Location { file, line, col }
    }
}

#[stable(feature = "panic_hook_display", since = "1.26.0")]
impl fmt::Display for Location<'_> {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "{}:{}:{}", self.file, self.line, self.col)
    }
}