Rollup merge of #67119 - RalfJung:miri-test-libstd, r=alexcrichton

libstd miri tests: avoid warnings

Ignore tests in a way that all the code still gets compiled, to get rid of all the "unused" warnings that otherwise show up when running the test suite in Miri.

16 files changed, 48 insertions, 42 deletions

diff --git a/src/liballoc/alloc/tests.rs b/src/liballoc/alloc/tests.rs
index 956298d7836..c902971638b 100644
--- a/src/liballoc/alloc/tests.rs
+++ b/src/liballoc/alloc/tests.rs
@@ -22,7 +22,7 @@ fn allocate_zeroed() {
 }
 
 #[bench]
-#[cfg(not(miri))] // Miri does not support benchmarks
+#[cfg_attr(miri, ignore)] // Miri does not support benchmarks
 fn alloc_owned_small(b: &mut Bencher) {
     b.iter(|| {
         let _: Box<_> = box 10;
diff --git a/src/liballoc/collections/linked_list/tests.rs b/src/liballoc/collections/linked_list/tests.rs
index 94b92df1294..1b1d8eab39b 100644
--- a/src/liballoc/collections/linked_list/tests.rs
+++ b/src/liballoc/collections/linked_list/tests.rs
@@ -182,7 +182,7 @@ fn test_insert_prev() {
 
 #[test]
 #[cfg_attr(target_os = "emscripten", ignore)]
-#[cfg(not(miri))] // Miri does not support threads
+#[cfg_attr(miri, ignore)] // Miri does not support threads
 fn test_send() {
     let n = list_from(&[1, 2, 3]);
     thread::spawn(move || {
diff --git a/src/liballoc/collections/vec_deque/tests.rs b/src/liballoc/collections/vec_deque/tests.rs
index 8dc097cc088..f2ce5b1d15d 100644
--- a/src/liballoc/collections/vec_deque/tests.rs
+++ b/src/liballoc/collections/vec_deque/tests.rs
@@ -3,7 +3,7 @@ use super::*;
 use ::test;
 
 #[bench]
-#[cfg(not(miri))] // Miri does not support benchmarks
+#[cfg_attr(miri, ignore)] // Miri does not support benchmarks
 fn bench_push_back_100(b: &mut test::Bencher) {
     let mut deq = VecDeque::with_capacity(101);
     b.iter(|| {
@@ -16,7 +16,7 @@ fn bench_push_back_100(b: &mut test::Bencher) {
 }
 
 #[bench]
-#[cfg(not(miri))] // Miri does not support benchmarks
+#[cfg_attr(miri, ignore)] // Miri does not support benchmarks
 fn bench_push_front_100(b: &mut test::Bencher) {
     let mut deq = VecDeque::with_capacity(101);
     b.iter(|| {
@@ -29,7 +29,7 @@ fn bench_push_front_100(b: &mut test::Bencher) {
 }
 
 #[bench]
-#[cfg(not(miri))] // Miri does not support benchmarks
+#[cfg_attr(miri, ignore)] // Miri does not support benchmarks
 fn bench_pop_back_100(b: &mut test::Bencher) {
     let mut deq = VecDeque::<i32>::with_capacity(101);
 
@@ -43,7 +43,7 @@ fn bench_pop_back_100(b: &mut test::Bencher) {
 }
 
 #[bench]
-#[cfg(not(miri))] // Miri does not support benchmarks
+#[cfg_attr(miri, ignore)] // Miri does not support benchmarks
 fn bench_pop_front_100(b: &mut test::Bencher) {
     let mut deq = VecDeque::<i32>::with_capacity(101);
 
diff --git a/src/liballoc/sync/tests.rs b/src/liballoc/sync/tests.rs
index 9220f5e0333..9ddba495b7e 100644
--- a/src/liballoc/sync/tests.rs
+++ b/src/liballoc/sync/tests.rs
@@ -29,7 +29,7 @@ impl Drop for Canary {
 
 #[test]
 #[cfg_attr(target_os = "emscripten", ignore)]
-#[cfg(not(miri))] // Miri does not support threads
+#[cfg_attr(miri, ignore)] // Miri does not support threads
 fn manually_share_arc() {
     let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
     let arc_v = Arc::new(v);
@@ -334,7 +334,7 @@ fn test_ptr_eq() {
 
 #[test]
 #[cfg_attr(target_os = "emscripten", ignore)]
-#[cfg(not(miri))] // Miri does not support threads
+#[cfg_attr(miri, ignore)] // Miri does not support threads
 fn test_weak_count_locked() {
     let mut a = Arc::new(atomic::AtomicBool::new(false));
     let a2 = a.clone();
diff --git a/src/liballoc/tests/slice.rs b/src/liballoc/tests/slice.rs
index d9707b95740..ec45de7c79e 100644
--- a/src/liballoc/tests/slice.rs
+++ b/src/liballoc/tests/slice.rs
@@ -388,7 +388,7 @@ fn test_reverse() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn test_sort() {
     let mut rng = thread_rng();
 
@@ -1610,7 +1610,7 @@ fn panic_safe() {
     let moduli = &[5, 20, 50];
 
     #[cfg(miri)]
-    let lens = (1..13);
+    let lens = 1..13;
     #[cfg(miri)]
     let moduli = &[10];
 
diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index cb73c7c179c..1b011242d01 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -166,7 +166,7 @@ fn test_join_for_different_lengths_with_long_separator() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn test_unsafe_slice() {
     assert_eq!("ab", unsafe {"abc".get_unchecked(0..2)});
     assert_eq!("bc", unsafe {"abc".get_unchecked(1..3)});
@@ -483,8 +483,8 @@ mod slice_index {
     }
 
     #[test]
-    #[cfg(not(target_os = "emscripten"))] // hits an OOM
-    #[cfg(not(miri))] // Miri is too slow
+    #[cfg_attr(target_os = "emscripten", ignore)] // hits an OOM
+    #[cfg_attr(miri, ignore)] // Miri is too slow
     fn simple_big() {
         fn a_million_letter_x() -> String {
             let mut i = 0;
@@ -1069,7 +1069,7 @@ fn test_rev_iterator() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn test_chars_decoding() {
     let mut bytes = [0; 4];
     for c in (0..0x110000).filter_map(std::char::from_u32) {
@@ -1081,7 +1081,7 @@ fn test_chars_decoding() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn test_chars_rev_decoding() {
     let mut bytes = [0; 4];
     for c in (0..0x110000).filter_map(std::char::from_u32) {
@@ -1380,7 +1380,6 @@ fn test_bool_from_str() {
     assert_eq!("not even a boolean".parse::<bool>().ok(), None);
 }
 
-#[cfg(not(miri))] // Miri is too slow
 fn check_contains_all_substrings(s: &str) {
     assert!(s.contains(""));
     for i in 0..s.len() {
@@ -1391,7 +1390,7 @@ fn check_contains_all_substrings(s: &str) {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn strslice_issue_16589() {
     assert!("bananas".contains("nana"));
 
@@ -1408,7 +1407,7 @@ fn strslice_issue_16878() {
 
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn test_strslice_contains() {
     let x = "There are moments, Jeeves, when one asks oneself, 'Do trousers matter?'";
     check_contains_all_substrings(x);
diff --git a/src/liballoc/tests/string.rs b/src/liballoc/tests/string.rs
index 55edf56345b..fe7b4ff24b8 100644
--- a/src/liballoc/tests/string.rs
+++ b/src/liballoc/tests/string.rs
@@ -523,7 +523,7 @@ fn test_reserve_exact() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve() {
 
     // These are the interesting cases:
@@ -601,7 +601,7 @@ fn test_try_reserve() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve_exact() {
 
     // This is exactly the same as test_try_reserve with the method changed.
diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index 9ee254f99ac..5e788d61f84 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -1080,7 +1080,7 @@ fn test_reserve_exact() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve() {
 
     // These are the interesting cases:
@@ -1183,7 +1183,7 @@ fn test_try_reserve() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve_exact() {
 
     // This is exactly the same as test_try_reserve with the method changed.
diff --git a/src/liballoc/tests/vec_deque.rs b/src/liballoc/tests/vec_deque.rs
index 5a0162a5361..ebcc8320171 100644
--- a/src/liballoc/tests/vec_deque.rs
+++ b/src/liballoc/tests/vec_deque.rs
@@ -1100,7 +1100,7 @@ fn test_reserve_exact_2() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve() {
     // These are the interesting cases:
     // * exactly isize::MAX should never trigger a CapacityOverflow (can be OOM)
@@ -1214,7 +1214,7 @@ fn test_try_reserve() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not support signalling OOM
+#[cfg_attr(miri, ignore)] // Miri does not support signalling OOM
 fn test_try_reserve_exact() {
     // This is exactly the same as test_try_reserve with the method changed.
     // See that test for comments.
diff --git a/src/libcore/tests/hash/mod.rs b/src/libcore/tests/hash/mod.rs
index 348245e24f6..ba0220f0d92 100644
--- a/src/libcore/tests/hash/mod.rs
+++ b/src/libcore/tests/hash/mod.rs
@@ -71,14 +71,16 @@ fn test_writer_hasher() {
     let ptr = 5_usize as *mut i32;
     assert_eq!(hash(&ptr), 5);
 
+    if cfg!(miri) { // Miri cannot hash pointers
+        return;
+    }
+
     let cs: &mut [u8] = &mut [1, 2, 3];
     let ptr = cs.as_ptr();
     let slice_ptr = cs as *const [u8];
-    #[cfg(not(miri))] // Miri cannot hash pointers
     assert_eq!(hash(&slice_ptr), hash(&ptr) + cs.len() as u64);
 
     let slice_ptr = cs as *mut [u8];
-    #[cfg(not(miri))] // Miri cannot hash pointers
     assert_eq!(hash(&slice_ptr), hash(&ptr) + cs.len() as u64);
 }
 
diff --git a/src/libcore/tests/num/dec2flt/mod.rs b/src/libcore/tests/num/dec2flt/mod.rs
index 4b772e12b6c..6bb348fd752 100644
--- a/src/libcore/tests/num/dec2flt/mod.rs
+++ b/src/libcore/tests/num/dec2flt/mod.rs
@@ -31,7 +31,11 @@ fn ordinary() {
     test_literal!(0.1);
     test_literal!(12345.);
     test_literal!(0.9999999);
-    #[cfg(not(miri))] // Miri is too slow
+
+    if cfg!(miri) { // Miri is too slow
+        return;
+    }
+
     test_literal!(2.2250738585072014e-308);
 }
 
@@ -53,7 +57,7 @@ fn large() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn subnormals() {
     test_literal!(5e-324);
     test_literal!(91e-324);
@@ -65,7 +69,7 @@ fn subnormals() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn infinity() {
     test_literal!(1e400);
     test_literal!(1e309);
@@ -77,9 +81,12 @@ fn infinity() {
 fn zero() {
     test_literal!(0.0);
     test_literal!(1e-325);
-    #[cfg(not(miri))] // Miri is too slow
+
+    if cfg!(miri) { // Miri is too slow
+        return;
+    }
+
     test_literal!(1e-326);
-    #[cfg(not(miri))] // Miri is too slow
     test_literal!(1e-500);
 }
 
diff --git a/src/libcore/tests/num/flt2dec/mod.rs b/src/libcore/tests/num/flt2dec/mod.rs
index f85369ce40b..2f94ea2fc4b 100644
--- a/src/libcore/tests/num/flt2dec/mod.rs
+++ b/src/libcore/tests/num/flt2dec/mod.rs
@@ -256,7 +256,6 @@ pub fn f32_shortest_sanity_test<F>(mut f: F) where F: FnMut(&Decoded, &mut [u8])
     check_shortest!(f(minf32) => b"1", -44);
 }
 
-#[cfg(not(miri))] // Miri is too slow
 pub fn f32_exact_sanity_test<F>(mut f: F)
         where F: FnMut(&Decoded, &mut [u8], i16) -> (usize, i16) {
     let minf32 = ldexp_f32(1.0, -149);
@@ -362,7 +361,6 @@ pub fn f64_shortest_sanity_test<F>(mut f: F) where F: FnMut(&Decoded, &mut [u8])
     check_shortest!(f(minf64) => b"5", -323);
 }
 
-#[cfg(not(miri))] // Miri is too slow
 pub fn f64_exact_sanity_test<F>(mut f: F)
         where F: FnMut(&Decoded, &mut [u8], i16) -> (usize, i16) {
     let minf64 = ldexp_f64(1.0, -1074);
diff --git a/src/libcore/tests/num/flt2dec/strategy/dragon.rs b/src/libcore/tests/num/flt2dec/strategy/dragon.rs
index 0c545b4d887..3d985c6796b 100644
--- a/src/libcore/tests/num/flt2dec/strategy/dragon.rs
+++ b/src/libcore/tests/num/flt2dec/strategy/dragon.rs
@@ -22,7 +22,7 @@ fn shortest_sanity_test() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn exact_sanity_test() {
     // This test ends up running what I can only assume is some corner-ish case
     // of the `exp2` library function, defined in whatever C runtime we're
diff --git a/src/libcore/tests/num/flt2dec/strategy/grisu.rs b/src/libcore/tests/num/flt2dec/strategy/grisu.rs
index 13396646463..ff8373c6455 100644
--- a/src/libcore/tests/num/flt2dec/strategy/grisu.rs
+++ b/src/libcore/tests/num/flt2dec/strategy/grisu.rs
@@ -41,7 +41,7 @@ fn shortest_sanity_test() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn exact_sanity_test() {
     // See comments in dragon.rs's exact_sanity_test for why this test is
     // ignored on MSVC
diff --git a/src/libcore/tests/ptr.rs b/src/libcore/tests/ptr.rs
index 4f5a9be579e..eea736bc88f 100644
--- a/src/libcore/tests/ptr.rs
+++ b/src/libcore/tests/ptr.rs
@@ -289,7 +289,7 @@ fn write_unaligned_drop() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not compute a maximal `mid` for `align_offset`
+#[cfg_attr(miri, ignore)] // Miri does not compute a maximal `mid` for `align_offset`
 fn align_offset_zst() {
     // For pointers of stride = 0, the pointer is already aligned or it cannot be aligned at
     // all, because no amount of elements will align the pointer.
@@ -304,7 +304,7 @@ fn align_offset_zst() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not compute a maximal `mid` for `align_offset`
+#[cfg_attr(miri, ignore)] // Miri does not compute a maximal `mid` for `align_offset`
 fn align_offset_stride1() {
     // For pointers of stride = 1, the pointer can always be aligned. The offset is equal to
     // number of bytes.
@@ -326,7 +326,7 @@ fn align_offset_stride1() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn align_offset_weird_strides() {
     #[repr(packed)]
     struct A3(u16, u8);
diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index eac18e93ab6..cc274b4aecf 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -1183,7 +1183,7 @@ fn test_rotate_right() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn brute_force_rotate_test_0() {
     // In case of edge cases involving multiple algorithms
     let n = 300;
@@ -1302,7 +1302,7 @@ fn sort_unstable() {
 
 #[test]
 #[cfg(not(target_arch = "wasm32"))]
-#[cfg(not(miri))] // Miri is too slow
+#[cfg_attr(miri, ignore)] // Miri is too slow
 fn partition_at_index() {
     use core::cmp::Ordering::{Equal, Greater, Less};
     use rand::rngs::StdRng;
@@ -1505,7 +1505,7 @@ pub mod memchr {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not compute a maximal `mid` for `align_offset`
+#[cfg_attr(miri, ignore)] // Miri does not compute a maximal `mid` for `align_offset`
 fn test_align_to_simple() {
     let bytes = [1u8, 2, 3, 4, 5, 6, 7];
     let (prefix, aligned, suffix) = unsafe { bytes.align_to::<u16>() };
@@ -1535,7 +1535,7 @@ fn test_align_to_zst() {
 }
 
 #[test]
-#[cfg(not(miri))] // Miri does not compute a maximal `mid` for `align_offset`
+#[cfg_attr(miri, ignore)] // Miri does not compute a maximal `mid` for `align_offset`
 fn test_align_to_non_trivial() {
     #[repr(align(8))]
     struct U64(u64, u64);