run many-seeds tests at least a few times on all tier 1 targets

Author: RalfJung

Diff for: ci/ci.sh

@@ -128,16 +128,18 @@ function run_tests_minimal {
 ## Main Testing Logic ##
 
 # In particular, fully cover all tier 1 targets.
+# We also want to run the many-seeds tests on all tier 1 targets.
 case $HOST_TARGET in
   x86_64-unknown-linux-gnu)
     # Host
     GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 CARGO_MIRI_ENV=1 run_tests
     # Extra tier 1
-    MIRI_TEST_TARGET=i686-unknown-linux-gnu run_tests
-    MIRI_TEST_TARGET=aarch64-unknown-linux-gnu run_tests
-    MIRI_TEST_TARGET=x86_64-apple-darwin run_tests
-    MIRI_TEST_TARGET=i686-pc-windows-gnu run_tests
-    MIRI_TEST_TARGET=x86_64-pc-windows-gnu run_tests
+    # With reduced many-seed count to avoid spending too much time on that.
+    # (All OSes are run with 64 seeds at least once though via the macOS runner.)
+    MANY_SEEDS=16 MIRI_TEST_TARGET=i686-unknown-linux-gnu run_tests
+    MANY_SEEDS=16 MIRI_TEST_TARGET=aarch64-unknown-linux-gnu run_tests
+    MANY_SEEDS=16 MIRI_TEST_TARGET=x86_64-apple-darwin run_tests
+    MANY_SEEDS=16 MIRI_TEST_TARGET=x86_64-pc-windows-gnu run_tests
     # Extra tier 2
     MIRI_TEST_TARGET=aarch64-apple-darwin run_tests
     MIRI_TEST_TARGET=arm-unknown-linux-gnueabi run_tests
@@ -155,14 +157,15 @@ case $HOST_TARGET in
     # Host (tier 2)
     GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 CARGO_MIRI_ENV=1 run_tests
     # Extra tier 1
-    MIRI_TEST_TARGET=x86_64-pc-windows-msvc CARGO_MIRI_ENV=1 run_tests
+    MANY_SEEDS=64 MIRI_TEST_TARGET=i686-pc-windows-gnu run_tests
+    MANY_SEEDS=64 MIRI_TEST_TARGET=x86_64-pc-windows-msvc CARGO_MIRI_ENV=1 run_tests
     # Extra tier 2
     MIRI_TEST_TARGET=s390x-unknown-linux-gnu run_tests # big-endian architecture
     ;;
   i686-pc-windows-msvc)
     # Host
-    # Only smoke-test `many-seeds`; 64 runs take 15min here!
-    GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=1 TEST_BENCH=1 run_tests
+    # Only smoke-test `many-seeds`; 64 runs of just the scoped-thread-leak test take 15min here!
+    GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=4 TEST_BENCH=1 run_tests
     # Extra tier 1
     # We really want to ensure a Linux target works on a Windows host,
     # and a 64bit target works on a 32bit host.

Diff for: tests/many-seeds/tls-leak.rs

@@ -1,13 +1,26 @@
 //! Regression test for <https://github.com/rust-lang/rust/issues/123583>.
 use std::thread;
 
-pub(crate) fn with_thread_local() {
+fn with_thread_local1() {
     thread_local! { static X: Box<u8> = Box::new(0); }
     X.with(|_x| {})
 }
 
+fn with_thread_local2() {
+    thread_local! { static Y: Box<u8> = Box::new(0); }
+    Y.with(|_y| {})
+}
+
 fn main() {
-    let j2 = thread::spawn(with_thread_local);
-    with_thread_local();
-    j2.join().unwrap();
+    // Here we have two threads racing on initializing the thread-local
+    // and (on Windows without target_thread_local) adding it to the global dtor list.
+    let t = thread::spawn(with_thread_local1);
+    with_thread_local1();
+    t.join().unwrap();
+
+    // Here we have one thread running the destructors racing with another thread initializing a thread-local.
+    // The second thread adds a destructor that could be picked up by the first thread.
+    let t = thread::spawn(|| { /* immediately just run destructors */ });
+    with_thread_local2(); // initialize thread-local
+    t.join().unwrap();
 }