data_race: link to docs for 'unusual' race conditions

Author: RalfJung

src/tools/miri/src/diagnostics.rs

@@ -270,7 +270,8 @@ pub fn report_error<'tcx, 'mir>(
             DataRace { op1, extra, .. } => {
                 let mut helps = vec![(Some(op1.span), format!("and (1) occurred earlier here"))];
                 if let Some(extra) = extra {
-                    helps.push((None, format!("{extra}")))
+                    helps.push((None, format!("{extra}")));
+                    helps.push((None, format!("see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model")));
                 }
                 helps.push((None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")));
                 helps.push((None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")));

src/tools/miri/tests/fail/data_race/mixed_size_read.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |             a16.load(Ordering::SeqCst);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: overlapping unsynchronized atomic accesses must use the same access size
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):

src/tools/miri/tests/fail/data_race/mixed_size_write.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |             a16.store(1, Ordering::SeqCst);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: overlapping unsynchronized atomic accesses must use the same access size
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):

src/tools/miri/tests/fail/data_race/read_read_race1.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |             unsafe { ptr.read() };
    |                      ^^^^^^^^^^
    = help: overlapping atomic and non-atomic accesses must be synchronized, even if both are read-only
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):

src/tools/miri/tests/fail/data_race/read_read_race2.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |             a.load(Ordering::SeqCst);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^
    = help: overlapping atomic and non-atomic accesses must be synchronized, even if both are read-only
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):

src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |         x.store(1, Relaxed);
    |         ^^^^^^^^^^^^^^^^^^^
    = help: overlapping unsynchronized atomic accesses must use the same access size
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):

src/tools/miri/tests/fail/weak_memory/racing_mixed_size_read.stderr

@@ -10,6 +10,7 @@ help: and (1) occurred earlier here
 LL |         x.load(Relaxed);
    |         ^^^^^^^^^^^^^^^
    = help: overlapping unsynchronized atomic accesses must use the same access size
+   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE (of the first span):