Add assert_matches!(expr, pat).
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@ -110,6 +110,58 @@ macro_rules! assert_ne {
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});
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}
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/// Asserts that an expression matches a pattern.
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///
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/// On panic, this macro will print the value of the expression with its
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/// debug representation.
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///
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/// Like [`assert!`], this macro has a second form, where a custom
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/// panic message can be provided.
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///
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/// # Examples
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///
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/// ```
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/// let a = 1u32.checked_add(2);
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/// let b = 1u32.checked_sub(2);
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/// assert_matches!(a, Some(_));
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/// assert_matches!(b, None);
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/// ```
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#[macro_export]
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#[unstable(feature = "assert_matches", issue = "none")]
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#[allow_internal_unstable(core_panic)]
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macro_rules! assert_matches {
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($left:expr, $right:pat $(,)?) => ({
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match &$left {
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left_val => {
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if let $right = left_val {
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// OK
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} else {
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$crate::panicking::assert_matches_failed(
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&*left_val,
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$crate::stringify!($right),
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$crate::option::Option::None
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);
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}
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}
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}
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});
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($left:expr, $right:expr, $($arg:tt)+) => ({
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match &$left {
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left_val => {
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if let $right = left_val {
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// OK
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} else {
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$crate::panicking::assert_matches_failed(
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&*left_val,
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$crate::stringify!($right),
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$crate::option::Option::Some($crate::format_args!($($arg)+))
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);
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}
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}
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}
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});
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}
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/// Asserts that a boolean expression is `true` at runtime.
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///
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/// This will invoke the [`panic!`] macro if the provided expression cannot be
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@ -97,6 +97,7 @@ pub fn panic_fmt(fmt: fmt::Arguments<'_>) -> ! {
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pub enum AssertKind {
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Eq,
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Ne,
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Match,
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}
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/// Internal function for `assert_eq!` and `assert_ne!` macros
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@ -113,32 +114,54 @@ where
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T: fmt::Debug + ?Sized,
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U: fmt::Debug + ?Sized,
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{
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#[track_caller]
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fn inner(
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kind: AssertKind,
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left: &dyn fmt::Debug,
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right: &dyn fmt::Debug,
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args: Option<fmt::Arguments<'_>>,
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) -> ! {
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let op = match kind {
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AssertKind::Eq => "==",
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AssertKind::Ne => "!=",
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};
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assert_failed_inner(kind, &left, &right, args)
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}
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match args {
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Some(args) => panic!(
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r#"assertion failed: `(left {} right)`
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left: `{:?}`,
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right: `{:?}: {}`"#,
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op, left, right, args
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),
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None => panic!(
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r#"assertion failed: `(left {} right)`
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left: `{:?}`,
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right: `{:?}`"#,
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op, left, right,
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),
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/// Internal function for `assert_match!`
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#[cold]
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#[track_caller]
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#[doc(hidden)]
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pub fn assert_matches_failed<T: fmt::Debug + ?Sized>(
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left: &T,
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right: &str,
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args: Option<fmt::Arguments<'_>>,
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) -> ! {
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// Use the Display implementation to display the pattern.
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struct Pattern<'a>(&'a str);
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impl fmt::Debug for Pattern<'_> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt::Display::fmt(self.0, f)
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}
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}
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inner(kind, &left, &right, args)
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assert_failed_inner(AssertKind::Match, &left, &Pattern(right), args);
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}
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/// Non-generic version of the above functions, to avoid code bloat.
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#[track_caller]
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fn assert_failed_inner(
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kind: AssertKind,
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left: &dyn fmt::Debug,
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right: &dyn fmt::Debug,
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args: Option<fmt::Arguments<'_>>,
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) -> ! {
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let op = match kind {
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AssertKind::Eq => "==",
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AssertKind::Ne => "!=",
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AssertKind::Match => "matches",
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};
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match args {
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Some(args) => panic!(
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r#"assertion failed: `(left {} right)`
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left: `{:?}`,
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right: `{:?}: {}`"#,
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op, left, right, args
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),
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None => panic!(
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r#"assertion failed: `(left {} right)`
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left: `{:?}`,
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right: `{:?}`"#,
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op, left, right,
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),
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}
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}
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@ -228,6 +228,7 @@
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#![feature(arbitrary_self_types)]
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#![feature(array_error_internals)]
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#![feature(asm)]
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#![feature(assert_matches)]
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#![feature(associated_type_bounds)]
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#![feature(atomic_mut_ptr)]
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#![feature(box_syntax)]
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@ -550,8 +551,8 @@ pub use std_detect::detect;
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#[stable(feature = "rust1", since = "1.0.0")]
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#[allow(deprecated, deprecated_in_future)]
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pub use core::{
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assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, matches, r#try, todo,
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unimplemented, unreachable, write, writeln,
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assert_eq, assert_matches, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, matches,
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r#try, todo, unimplemented, unreachable, write, writeln,
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};
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// Re-export built-in macros defined through libcore.
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