Rollup merge of rust-lang#89718 - jkugelman:must-use-is_condition-tests, r=joshtriplett

Add #[must_use] to is_condition tests

There's nothing insightful to say about these so I didn't write any extra explanations.

Parent issue: rust-lang#89692

Author: matthiaskrgr

library/alloc/src/collections/btree/set.rs

@@ -534,6 +534,7 @@ impl<T> BTreeSet<T> {
     /// b.insert(1);
     /// assert_eq!(a.is_disjoint(&b), false);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_disjoint(&self, other: &BTreeSet<T>) -> bool
     where
@@ -559,6 +560,7 @@ impl<T> BTreeSet<T> {
     /// set.insert(4);
     /// assert_eq!(set.is_subset(&sup), false);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_subset(&self, other: &BTreeSet<T>) -> bool
     where
@@ -638,6 +640,7 @@ impl<T> BTreeSet<T> {
     /// set.insert(2);
     /// assert_eq!(set.is_superset(&sub), true);
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn is_superset(&self, other: &BTreeSet<T>) -> bool
     where

library/core/src/char/methods.rs

@@ -692,6 +692,7 @@ impl char {
     /// // love is many things, but it is not alphabetic
     /// assert!(!c.is_alphabetic());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_alphabetic(self) -> bool {
@@ -724,6 +725,7 @@ impl char {
     /// assert!(!'中'.is_lowercase());
     /// assert!(!' '.is_lowercase());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_lowercase(self) -> bool {
@@ -756,6 +758,7 @@ impl char {
     /// assert!(!'中'.is_uppercase());
     /// assert!(!' '.is_uppercase());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_uppercase(self) -> bool {
@@ -784,6 +787,7 @@ impl char {
     ///
     /// assert!(!'越'.is_whitespace());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_whitespace(self) -> bool {
@@ -812,6 +816,7 @@ impl char {
     /// assert!('و'.is_alphanumeric());
     /// assert!('藏'.is_alphanumeric());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_alphanumeric(self) -> bool {
@@ -837,6 +842,7 @@ impl char {
     /// assert!('œ'.is_control());
     /// assert!(!'q'.is_control());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_control(self) -> bool {
@@ -852,6 +858,7 @@ impl char {
     /// [uax29]: https://www.unicode.org/reports/tr29/
     /// [ucd]: https://www.unicode.org/reports/tr44/
     /// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
+    #[must_use]
     #[inline]
     pub(crate) fn is_grapheme_extended(self) -> bool {
         unicode::Grapheme_Extend(self)
@@ -881,6 +888,7 @@ impl char {
     /// assert!(!'و'.is_numeric());
     /// assert!(!'藏'.is_numeric());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is_numeric(self) -> bool {
@@ -1060,6 +1068,7 @@ impl char {
     /// assert!(ascii.is_ascii());
     /// assert!(!non_ascii.is_ascii());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.32.0")]
     #[inline]
@@ -1237,6 +1246,7 @@ impl char {
     /// assert!(!lf.is_ascii_alphabetic());
     /// assert!(!esc.is_ascii_alphabetic());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1270,6 +1280,7 @@ impl char {
     /// assert!(!lf.is_ascii_uppercase());
     /// assert!(!esc.is_ascii_uppercase());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1303,6 +1314,7 @@ impl char {
     /// assert!(!lf.is_ascii_lowercase());
     /// assert!(!esc.is_ascii_lowercase());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1339,6 +1351,7 @@ impl char {
     /// assert!(!lf.is_ascii_alphanumeric());
     /// assert!(!esc.is_ascii_alphanumeric());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1372,6 +1385,7 @@ impl char {
     /// assert!(!lf.is_ascii_digit());
     /// assert!(!esc.is_ascii_digit());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1408,6 +1422,7 @@ impl char {
     /// assert!(!lf.is_ascii_hexdigit());
     /// assert!(!esc.is_ascii_hexdigit());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1445,6 +1460,7 @@ impl char {
     /// assert!(!lf.is_ascii_punctuation());
     /// assert!(!esc.is_ascii_punctuation());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1478,6 +1494,7 @@ impl char {
     /// assert!(!lf.is_ascii_graphic());
     /// assert!(!esc.is_ascii_graphic());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1528,6 +1545,7 @@ impl char {
     /// assert!(lf.is_ascii_whitespace());
     /// assert!(!esc.is_ascii_whitespace());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]
@@ -1563,6 +1581,7 @@ impl char {
     /// assert!(lf.is_ascii_control());
     /// assert!(esc.is_ascii_control());
     /// ```
+    #[must_use]
     #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
     #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
     #[inline]

library/core/src/num/f32.rs

@@ -436,6 +436,7 @@ impl f32 {
     /// assert!(nan.is_nan());
     /// assert!(!f.is_nan());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -467,6 +468,7 @@ impl f32 {
     /// assert!(inf.is_infinite());
     /// assert!(neg_inf.is_infinite());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -488,6 +490,7 @@ impl f32 {
     /// assert!(!inf.is_finite());
     /// assert!(!neg_inf.is_finite());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -515,6 +518,7 @@ impl f32 {
     /// assert!(lower_than_min.is_subnormal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
+    #[must_use]
     #[stable(feature = "is_subnormal", since = "1.53.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -541,6 +545,7 @@ impl f32 {
     /// assert!(!lower_than_min.is_normal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -587,6 +592,7 @@ impl f32 {
     /// assert!(f.is_sign_positive());
     /// assert!(!g.is_sign_positive());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -604,6 +610,7 @@ impl f32 {
     /// assert!(!f.is_sign_negative());
     /// assert!(g.is_sign_negative());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]

library/core/src/num/f64.rs

@@ -435,6 +435,7 @@ impl f64 {
     /// assert!(nan.is_nan());
     /// assert!(!f.is_nan());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -466,6 +467,7 @@ impl f64 {
     /// assert!(inf.is_infinite());
     /// assert!(neg_inf.is_infinite());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -487,6 +489,7 @@ impl f64 {
     /// assert!(!inf.is_finite());
     /// assert!(!neg_inf.is_finite());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -514,6 +517,7 @@ impl f64 {
     /// assert!(lower_than_min.is_subnormal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
+    #[must_use]
     #[stable(feature = "is_subnormal", since = "1.53.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -540,6 +544,7 @@ impl f64 {
     /// assert!(!lower_than_min.is_normal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
@@ -586,13 +591,15 @@ impl f64 {
     /// assert!(f.is_sign_positive());
     /// assert!(!g.is_sign_positive());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
     pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
     }
 
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_deprecated(since = "1.0.0", reason = "renamed to is_sign_positive")]
     #[inline]
@@ -611,13 +618,15 @@ impl f64 {
     /// assert!(!f.is_sign_negative());
     /// assert!(g.is_sign_negative());
     /// ```
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
     pub const fn is_sign_negative(self) -> bool {
         self.to_bits() & 0x8000_0000_0000_0000 != 0
     }
 
+    #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_deprecated(since = "1.0.0", reason = "renamed to is_sign_negative")]
     #[inline]

library/core/src/num/int_macros.rs

@@ -2502,6 +2502,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert!(10", stringify!($SelfT), ".is_positive());")]
         #[doc = concat!("assert!(!(-10", stringify!($SelfT), ").is_positive());")]
         /// ```
+        #[must_use]
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[inline(always)]
@@ -2518,6 +2519,7 @@ macro_rules! int_impl {
         #[doc = concat!("assert!((-10", stringify!($SelfT), ").is_negative());")]
         #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_negative());")]
         /// ```
+        #[must_use]
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[inline(always)]