Auto merge of #1987 - saethlin:short-backtraces, r=oli-obk

bors · bors · commit 144d56532c75 · 2022-02-26T08:56:02.000Z
Prune stacktraces for tag-tracking diagnostics too In #1977 we forgot to use the pruning logic when printing tag-tracking messages. I just saw this output before this PR which is very silly: ``` test sanity ... note: tracking was triggered --> src/lib.rs:110:21 | 110 | unsafe { &*(&self.value[range] as *const [T] as *const Aligned<A, [T]>) } | ^^^^^^^^^^^^^^^^^^ created tag 160954 | = note: inside `<Aligned<A4, [u8]> as std::ops::Index<std::ops::RangeTo<usize>>>::index` at src/lib.rs:110:21 note: inside `sanity` at src/lib.rs:261:30 --> src/lib.rs:261:30 | 261 | let y: &Aligned<_, _> = &y[..2]; | ^^^^^^ note: inside closure at src/lib.rs:229:1 --> src/lib.rs:229:1 | 228 | #[test] | ------- in this procedural macro expansion 229 | / fn sanity() { 230 | | use core::mem; 231 | | 232 | | let x: Aligned<A2, _> = Aligned([0u8; 3]); ... | 284 | | let _: &[u8] = y; 285 | | } | |_^ = note: inside `<[closure@src/lib.rs:229:1: 285:2] as std::ops::FnOnce<()>>::call_once - shim` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5 = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5 = note: inside `test::__rust_begin_short_backtrace::<fn()>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:575:5 = note: inside closure at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:566:30 = note: inside `<[closure@test::run_test::{closure#1}] as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5 = note: inside `<std::boxed::Box<dyn std::ops::FnOnce() + std::marker::Send> as std::ops::FnOnce<()>>::call_once` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1854:9 = note: inside `<std::panic::AssertUnwindSafe<std::boxed::Box<dyn std::ops::FnOnce() + std::marker::Send>> as std::ops::FnOnce<()>>::call_once` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:271:9 = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<std::boxed::Box<dyn std::ops::FnOnce() + std::marker::Send>>, ()>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:492:40 = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<std::boxed::Box<dyn std::ops::FnOnce() + std::marker::Send>>>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:456:19 = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<std::boxed::Box<dyn std::ops::FnOnce() + std::marker::Send>>, ()>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panic.rs:137:14 = note: inside `test::run_test_in_process` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:598:18 = note: inside closure at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:492:39 = note: inside `test::run_test::run_test_inner` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:530:13 = note: inside `test::run_test` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:562:28 = note: inside `test::run_tests::<[closure@test::run_tests_console::{closure#2}]>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:305:17 = note: inside `test::run_tests_console` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/console.rs:286:5 = note: inside `test::test_main` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:116:15 = note: inside `test::test_main_static` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/test/src/lib.rs:135:5 = note: inside `main` = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5 = note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:122:18 = note: inside closure at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:145:18 = note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ops/function.rs:259:13 = note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:492:40 = note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:456:19 = note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panic.rs:137:14 = note: inside closure at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:128:48 = note: inside `std::panicking::r#try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:492:40 = note: inside `std::panicking::r#try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:456:19 = note: inside `std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panic.rs:137:14 = note: inside `std::rt::lang_start_internal` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:128:20 = note: inside `std::rt::lang_start::<()>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/rt.rs:144:17 = note: this note originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info) error: Undefined Behavior: trying to reborrow for SharedReadOnly at alloc61593+0x2, but parent tag <160954> does not have an appropriate item in the borrow stack --> src/lib.rs:261:30 | 261 | let y: &Aligned<_, _> = &y[..2]; | ^^^^^^ trying to reborrow for SharedReadOnly at alloc61593+0x2, but parent tag <160954> does not have an appropriate item in the borrow stack | = help: this indicates a potential bug in the program: it performed an invalid operation, but the rules it violated are still experimental = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information = note: inside `sanity` at src/lib.rs:261:30 note: inside closure at src/lib.rs:229:1 --> src/lib.rs:229:1 | 228 | #[test] | ------- in this procedural macro expansion 229 | / fn sanity() { 230 | | use core::mem; 231 | | 232 | | let x: Aligned<A2, _> = Aligned([0u8; 3]); ... | 284 | | let _: &[u8] = y; 285 | | } | |_^ = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info) note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace error: aborting due to previous error error: test failed, to rerun pass '--lib' ```
diff --git a/src/diagnostics.rs b/src/diagnostics.rs
@@ -75,6 +75,54 @@ enum DiagLevel {
     Note,
 }
 
+fn has_local_frame(stacktrace: &[FrameInfo<'_>]) -> bool {
+    stacktrace.iter().any(|frame| frame.instance.def_id().is_local())
+}
+
+fn prune_stacktrace<'mir, 'tcx>(
+    ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
+    mut stacktrace: Vec<FrameInfo<'tcx>>,
+) -> Vec<FrameInfo<'tcx>> {
+    match ecx.machine.backtrace_style {
+        BacktraceStyle::Off => {
+            // Retain one frame so that we can print a span for the error itself
+            stacktrace.truncate(1);
+        }
+        BacktraceStyle::Short => {
+            // Only prune frames if there is at least one local frame. This check ensures that if
+            // we get a backtrace that never makes it to the user code because it has detected a
+            // bug in the Rust runtime, we don't prune away every frame.
+            if has_local_frame(&stacktrace) {
+                // This is part of the logic that `std` uses to select the relevant part of a
+                // backtrace. But here, we only look for __rust_begin_short_backtrace, not
+                // __rust_end_short_backtrace because the end symbol comes from a call to the default
+                // panic handler.
+                stacktrace = stacktrace
+                    .into_iter()
+                    .take_while(|frame| {
+                        let def_id = frame.instance.def_id();
+                        let path = ecx.tcx.tcx.def_path_str(def_id);
+                        !path.contains("__rust_begin_short_backtrace")
+                    })
+                    .collect::<Vec<_>>();
+
+                // After we prune frames from the bottom, there are a few left that are part of the
+                // Rust runtime. So we remove frames until we get to a local symbol, which should be
+                // main or a test.
+                // This len check ensures that we don't somehow remove every frame, as doing so breaks
+                // the primary error message.
+                while stacktrace.len() > 1
+                    && stacktrace.last().map_or(false, |e| !e.instance.def_id().is_local())
+                {
+                    stacktrace.pop();
+                }
+            }
+        }
+        BacktraceStyle::Full => {}
+    }
+    stacktrace
+}
+
 /// Emit a custom diagnostic without going through the miri-engine machinery
 pub fn report_error<'tcx, 'mir>(
     ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
@@ -157,46 +205,8 @@ pub fn report_error<'tcx, 'mir>(
         }
     };
 
-    let mut stacktrace = ecx.generate_stacktrace();
-    let has_local_frame = stacktrace.iter().any(|frame| frame.instance.def_id().is_local());
-    match ecx.machine.backtrace_style {
-        BacktraceStyle::Off => {
-            // Retain one frame so that we can print a span for the error itself
-            stacktrace.truncate(1);
-        }
-        BacktraceStyle::Short => {
-            // Only prune frames if there is at least one local frame. This check ensures that if
-            // we get a backtrace that never makes it to the user code because it has detected a
-            // bug in the Rust runtime, we don't prune away every frame.
-            if has_local_frame {
-                // This is part of the logic that `std` uses to select the relevant part of a
-                // backtrace. But here, we only look for __rust_begin_short_backtrace, not
-                // __rust_end_short_backtrace because the end symbol comes from a call to the default
-                // panic handler.
-                stacktrace = stacktrace
-                    .into_iter()
-                    .take_while(|frame| {
-                        let def_id = frame.instance.def_id();
-                        let path = ecx.tcx.tcx.def_path_str(def_id);
-                        !path.contains("__rust_begin_short_backtrace")
-                    })
-                    .collect::<Vec<_>>();
-
-                // After we prune frames from the bottom, there are a few left that are part of the
-                // Rust runtime. So we remove frames until we get to a local symbol, which should be
-                // main or a test.
-                // This len check ensures that we don't somehow remove every frame, as doing so breaks
-                // the primary error message.
-                while stacktrace.len() > 1
-                    && stacktrace.last().map_or(false, |e| !e.instance.def_id().is_local())
-                {
-                    stacktrace.pop();
-                }
-            }
-        }
-        BacktraceStyle::Full => {}
-    }
-
+    let stacktrace = ecx.generate_stacktrace();
+    let stacktrace = prune_stacktrace(ecx, stacktrace);
     e.print_backtrace();
     let msg = e.to_string();
     report_msg(
@@ -210,7 +220,7 @@ pub fn report_error<'tcx, 'mir>(
 
     // Include a note like `std` does for short backtraces, but since we are opt-out not opt-in, we
     // do not include a note when backtraces are off.
-    if ecx.machine.backtrace_style == BacktraceStyle::Short && has_local_frame {
+    if ecx.machine.backtrace_style == BacktraceStyle::Short && has_local_frame(&stacktrace) {
         ecx.tcx.sess.diagnostic().note_without_error(
             "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
         );
@@ -367,6 +377,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 );
             }
 
+            let stacktrace = prune_stacktrace(this, stacktrace);
+
             // Show diagnostics.
             for e in diagnostics.drain(..) {
                 use NonHaltingDiagnostic::*;
