Macro std::assert_matches::debug_assert_matches
source · pub macro debug_assert_matches($($arg:tt)*) { ... }
🔬This is a nightly-only experimental API. (
assert_matches
#82775)Expand description
Asserts that an expression matches any of the given patterns.
Like in a match
expression, the pattern can be optionally followed by if
and a guard expression that has access to names bound by the pattern.
On panic, this macro will print the value of the expression with its debug representation.
Unlike assert_matches!
, debug_assert_matches!
statements are only
enabled in non optimized builds by default. An optimized build will not
execute debug_assert_matches!
statements unless -C debug-assertions
is
passed to the compiler. This makes debug_assert_matches!
useful for
checks that are too expensive to be present in a release build but may be
helpful during development. The result of expanding debug_assert_matches!
is always type checked.
§Examples
#![feature(assert_matches)]
use std::assert_matches::debug_assert_matches;
let a = 1u32.checked_add(2);
let b = 1u32.checked_sub(2);
debug_assert_matches!(a, Some(_));
debug_assert_matches!(b, None);
let c = Ok("abc".to_string());
debug_assert_matches!(c, Ok(x) | Err(x) if x.len() < 100);
Run