Auto merge of #1538 - RalfJung:rustup, r=RalfJung

rustup: work around rustc optimizations becoming too smart

Author: bors

ci.sh

@@ -25,8 +25,8 @@ function run_tests {
   ./miri test --locked
   if ! [ -n "${MIRI_TEST_TARGET+exists}" ]; then
     # Only for host architecture: tests with MIR optimizations
-    # FIXME:only testing level 1 because of <https://github.com/rust-lang/rust/issues/73223>.
-    MIRI_TEST_FLAGS="-Z mir-opt-level=1" ./miri test --locked
+    # FIXME: only testing level 2 because of <https://github.com/rust-lang/rust/issues/76432>.
+    MIRI_TEST_FLAGS="-Z mir-opt-level=2" ./miri test --locked
   fi
   # "miri test" has built the sysroot for us, now this should pass without
   # any interactive questions.

rust-version

@@ -1 +1 @@
-d2454643e137bde519786ee9e650c455d7ad6f34
+e114d6228b948ce056de0bcdec2603c8e89d3727

tests/compile-fail/invalid_bool.rs

@@ -1,8 +1,9 @@
 // Validation makes this fail in the wrong place
 // Make sure we find these even with many checks disabled.
 // compile-flags: -Zmiri-disable-alignment-check -Zmiri-disable-stacked-borrows -Zmiri-disable-validation
+#![feature(test)]
 
 fn main() {
     let b = unsafe { std::mem::transmute::<u8, bool>(2) };
-    let _x = b == true; //~ ERROR interpreting an invalid 8-bit value as a bool: 0x02
+    let _x = b == std::hint::black_box(true); //~ ERROR interpreting an invalid 8-bit value as a bool: 0x02
 }

tests/compile-fail/unaligned_pointers/unaligned_ptr_zst.rs

@@ -2,8 +2,8 @@
 // compile-flags: -Zmiri-disable-validation
 
 fn main() {
-    for _ in 0..10 { // Try many times as this might work by chance.
-        let x = 2u8;
+    for i in 0..10 { // Try many times as this might work by chance.
+        let x = i as u8;
         let x = &x as *const _ as *const [u32; 0];
         // This must fail because alignment is violated. Test specifically for loading ZST.
         let _x = unsafe { *x }; //~ERROR alignment 4 is required

tests/run-pass/float.rs

@@ -1,5 +1,8 @@
-#![feature(stmt_expr_attributes)]
+// compile-flags: -Zmir-opt-level=0
+// FIXME: Using opt-level 2 here makes the test take forever (https://github.com/rust-lang/rust/issues/76433).
+#![feature(stmt_expr_attributes, test)]
 use std::fmt::Debug;
+use std::hint::black_box;
 
 // Helper function to avoid promotion so that this tests "run-time" casts, not CTFE.
 // Doesn't make a big difference when running this in Miri, but it means we can compare this
@@ -339,10 +342,6 @@ fn ops() {
 /// Tests taken from rustc test suite.
 ///
 
-// Poor-man's black-box
-#[inline(never)]
-fn black_box<T>(x: T) -> T { x }
-
 macro_rules! test {
     ($val:expr, $src_ty:ident -> $dest_ty:ident, $expected:expr) => (
         // black_box disables constant evaluation to test run-time conversions:

tests/run-pass/u128.rs

@@ -1,4 +1,5 @@
-fn b<T>(t: T) -> T { t }
+#![feature(test)]
+use std::hint::black_box as b;
 
 fn main() {
     let x: u128 = 0xFFFF_FFFF_FFFF_FFFF__FFFF_FFFF_FFFF_FFFF;