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Rollup merge of rust-lang#55970 - RalfJung:miri-backtrace, r=@oli-obk
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Miri backtrace improvements

Nicer pretty-printing of the `RUST_CTFE_BACKTRACE`-backtraces:
```
  0: backtrace::backtrace::libunwind::trace::hc410fcb66fe85b11
           at /home/r/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.9/src/backtrace/libunwind.rs:53
     backtrace::backtrace::trace::h2106294a22648407
           at /home/r/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.9/src/backtrace/mod.rs:42
  1: backtrace::capture::Backtrace::new_unresolved::h5d8d98b993d092ba
           at /home/r/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.9/src/capture.rs:88
  2: <rustc::mir::interpret::error::EvalError<'tcx> as core::convert::From<rustc::mir::interpret::error::EvalErrorKind<'tcx, u64>>>::from::h6355269b2a661412
           at librustc/mir/interpret/error.rs:236
  3: <T as core::convert::Into<U>>::into::h70fcb917509539bd
           at /home/r/src/rust/rustc.2/src/libcore/convert.rs:455
  4: <rustc_mir::interpret::eval_context::EvalContext<'a, 'mir, 'tcx, miri::Evaluator<'tcx>> as miri::fn_call::EvalContextExt<'tcx, 'mir>>::emulate_foreign_item::h9cde0e3ce7455a4a
           at src/fn_call.rs:292
  5: <rustc_mir::interpret::eval_context::EvalContext<'a, 'mir, 'tcx, miri::Evaluator<'tcx>> as miri::fn_call::EvalContextExt<'tcx, 'mir>>::find_fn::h83f89524b9d1a49a
           at src/fn_call.rs:74
  6: <miri::Evaluator<'tcx> as rustc_mir::interpret::machine::Machine<'a, 'mir, 'tcx>>::find_fn::hf9980473c4775f0c
           at src/lib.rs:345
     rustc_mir::interpret::terminator::<impl rustc_mir::interpret::eval_context::EvalContext<'a, 'mir, 'tcx, M>>::eval_fn_call::h401dec4a687f96e9
           at /home/r/src/rust/rustc.2/src/librustc_mir/interpret/terminator.rs:285
```
Indentation is now consistent with `RUST_BACKTRACE`, and the frame number is not repeated when there are multiple symbols for a frame.

Also preserve the `ty::Instance` for the internal backtrace (showing which frames in the user code where on the interpreter stack when the error happened), used by miri to avoid printing spans for libstd internals:
```
error[E0080]: constant evaluation error: the evaluated program panicked
   --> /home/r/src/rust/rustc.2/src/libstd/panicking.rs:525:9
    |
525 |         __rust_start_panic(obj as usize)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked
    |
    = note: inside call to `std::panicking::rust_panic` at /home/r/src/rust/rustc.2/src/libstd/panicking.rs:496:5
    = note: inside call to `std::panicking::rust_panic_with_hook` at /home/r/src/rust/rustc.2/src/libstd/panicking.rs:390:5
    = note: inside call to `std::panicking::continue_panic_fmt` at /home/r/src/rust/rustc.2/src/libstd/panicking.rs:345:5
note: inside call to `std::rt::begin_panic_fmt` at <::std::macros::panic macros>:8:1
   --> tests/compile-fail/panic.rs:4:5
    |
4   |     assert_eq!(5, 6);
    |     ^^^^^^^^^^^^^^^^^
    = note: inside call to `main` at /home/r/src/rust/rustc.2/src/libstd/rt.rs:74:34
    = note: inside call to closure at /home/r/src/rust/rustc.2/src/libstd/rt.rs:59:75
    = note: inside call to closure at /home/r/src/rust/rustc.2/src/libstd/sys_common/backtrace.rs:136:5
    = note: inside call to `std::sys_common::backtrace::__rust_begin_short_backtrace::<[closure@DefId(1/1:1913 ~ std[78f0]::rt[0]::lang_start_internal[0]::{{closure}}[0]::{{closure}}[0]) 0:&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe], i32>` at /home/r/src/rust/rustc.2/src/libstd/rt.rs:59:13
    = note: inside call to closure at /home/r/src/rust/rustc.2/src/libstd/panicking.rs:310:40
    = note: inside call to `std::panicking::try::do_call::<[closure@DefId(1/1:1912 ~ std[78f0]::rt[0]::lang_start_internal[0]::{{closure}}[0]) 0:&&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe], i32>` at /home/r/src/rust/rustc.2/src/libstd/panicking.rs:306:5
    = note: inside call to `std::panicking::try::<i32, [closure@DefId(1/1:1912 ~ std[78f0]::rt[0]::lang_start_internal[0]::{{closure}}[0]) 0:&&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe]>` at /home/r/src/rust/rustc.2/src/libstd/panic.rs:398:9
    = note: inside call to `std::panic::catch_unwind::<[closure@DefId(1/1:1912 ~ std[78f0]::rt[0]::lang_start_internal[0]::{{closure}}[0]) 0:&&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe], i32>` at /home/r/src/rust/rustc.2/src/libstd/rt.rs:58:25
    = note: inside call to `std::rt::lang_start_internal` at /home/r/src/rust/rustc.2/src/libstd/rt.rs:74:5
    = note: inside call to `std::rt::lang_start::<()>`
```
Also notice that we show filenames and line numbers here now.

r? @oli-obk
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@pietroalbini
pietroalbini committed Nov 18, 2018
2 parents 00a84e3 + 62cf9ab commit 34ab7ce
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Showing 4 changed files with 100 additions and 78 deletions.
6 changes: 3 additions & 3 deletions src/librustc/ich/impls_ty.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -389,10 +389,10 @@ impl_stable_hash_for!(enum mir::interpret::ErrorHandled {
TooGeneric
});

impl_stable_hash_for!(struct mir::interpret::FrameInfo {
span,
impl_stable_hash_for!(struct mir::interpret::FrameInfo<'tcx> {
call_site,
lint_root,
location
instance
});

impl_stable_hash_for!(struct ty::ClosureSubsts<'tcx> { substs });
Expand Down
55 changes: 43 additions & 12 deletions src/librustc/mir/interpret/error.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,20 +10,20 @@

use std::{fmt, env};

use hir::map::definitions::DefPathData;
use mir;
use ty::{Ty, layout};
use ty::{self, Ty, layout};
use ty::layout::{Size, Align, LayoutError};
use rustc_target::spec::abi::Abi;

use super::{Pointer, InboundsCheck, ScalarMaybeUndef};

use backtrace::Backtrace;

use ty;
use ty::query::TyCtxtAt;
use errors::DiagnosticBuilder;

use syntax_pos::Span;
use syntax_pos::{Pos, Span};
use syntax::ast;
use syntax::symbol::Symbol;

Expand Down Expand Up @@ -52,16 +52,35 @@ pub type ConstEvalResult<'tcx> = Result<&'tcx ty::Const<'tcx>, ErrorHandled>;
pub struct ConstEvalErr<'tcx> {
pub span: Span,
pub error: ::mir::interpret::EvalErrorKind<'tcx, u64>,
pub stacktrace: Vec<FrameInfo>,
pub stacktrace: Vec<FrameInfo<'tcx>>,
}

#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct FrameInfo {
pub span: Span,
pub location: String,
pub struct FrameInfo<'tcx> {
pub call_site: Span, // this span is in the caller!
pub instance: ty::Instance<'tcx>,
pub lint_root: Option<ast::NodeId>,
}

impl<'tcx> fmt::Display for FrameInfo<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
ty::tls::with(|tcx| {
if tcx.def_key(self.instance.def_id()).disambiguated_data.data
== DefPathData::ClosureExpr
{
write!(f, "inside call to closure")?;
} else {
write!(f, "inside call to `{}`", self.instance)?;
}
if !self.call_site.is_dummy() {
let lo = tcx.sess.source_map().lookup_char_pos_adj(self.call_site.lo());
write!(f, " at {}:{}:{}", lo.filename, lo.line, lo.col.to_usize() + 1)?;
}
Ok(())
})
}
}

impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
pub fn struct_error(&self,
tcx: TyCtxtAt<'a, 'gcx, 'tcx>,
Expand Down Expand Up @@ -135,8 +154,13 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
struct_error(tcx, message)
};
err.span_label(self.span, self.error.to_string());
for FrameInfo { span, location, .. } in &self.stacktrace {
err.span_label(*span, format!("inside call to `{}`", location));
// Skip the last, which is just the environment of the constant. The stacktrace
// is sometimes empty because we create "fake" eval contexts in CTFE to do work
// on constant values.
if self.stacktrace.len() > 0 {
for frame_info in &self.stacktrace[..self.stacktrace.len()-1] {
err.span_label(frame_info.call_site, frame_info.to_string());
}
}
Ok(err)
}
Expand Down Expand Up @@ -172,16 +196,23 @@ fn print_backtrace(backtrace: &mut Backtrace) -> String {
write!(trace_text, "backtrace frames: {}\n", backtrace.frames().len()).unwrap();
'frames: for (i, frame) in backtrace.frames().iter().enumerate() {
if frame.symbols().is_empty() {
write!(trace_text, "{}: no symbols\n", i).unwrap();
write!(trace_text, " {}: no symbols\n", i).unwrap();
}
let mut first = true;
for symbol in frame.symbols() {
write!(trace_text, "{}: ", i).unwrap();
if first {
write!(trace_text, " {}: ", i).unwrap();
first = false;
} else {
let len = i.to_string().len();
write!(trace_text, " {} ", " ".repeat(len)).unwrap();
}
if let Some(name) = symbol.name() {
write!(trace_text, "{}\n", name).unwrap();
} else {
write!(trace_text, "<unknown>\n").unwrap();
}
write!(trace_text, "\tat ").unwrap();
write!(trace_text, " at ").unwrap();
if let Some(file_path) = symbol.filename() {
write!(trace_text, "{}", file_path.display()).unwrap();
} else {
Expand Down
15 changes: 3 additions & 12 deletions src/librustc_mir/interpret/eval_context.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@ use std::mem;
use syntax::source_map::{self, Span, DUMMY_SP};
use rustc::hir::def_id::DefId;
use rustc::hir::def::Def;
use rustc::hir::map::definitions::DefPathData;
use rustc::mir;
use rustc::ty::layout::{
self, Size, Align, HasDataLayout, LayoutOf, TyLayout
Expand Down Expand Up @@ -654,11 +653,10 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
}
}

pub fn generate_stacktrace(&self, explicit_span: Option<Span>) -> Vec<FrameInfo> {
pub fn generate_stacktrace(&self, explicit_span: Option<Span>) -> Vec<FrameInfo<'tcx>> {
let mut last_span = None;
let mut frames = Vec::new();
// skip 1 because the last frame is just the environment of the constant
for &Frame { instance, span, mir, block, stmt, .. } in self.stack().iter().skip(1).rev() {
for &Frame { instance, span, mir, block, stmt, .. } in self.stack().iter().rev() {
// make sure we don't emit frames that are duplicates of the previous
if explicit_span == Some(span) {
last_span = Some(span);
Expand All @@ -671,13 +669,6 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
} else {
last_span = Some(span);
}
let location = if self.tcx.def_key(instance.def_id()).disambiguated_data.data
== DefPathData::ClosureExpr
{
"closure".to_owned()
} else {
instance.to_string()
};
let block = &mir.basic_blocks()[block];
let source_info = if stmt < block.statements.len() {
block.statements[stmt].source_info
Expand All @@ -688,7 +679,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
mir::ClearCrossCrate::Set(ref ivs) => Some(ivs[source_info.scope].lint_root),
mir::ClearCrossCrate::Clear => None,
};
frames.push(FrameInfo { span, location, lint_root });
frames.push(FrameInfo { call_site: span, instance, lint_root });
}
trace!("generate stacktrace: {:#?}, {:?}", frames, explicit_span);
frames
Expand Down
102 changes: 51 additions & 51 deletions src/test/ui/infinite/infinite-recursion-const-fn.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,61 +5,61 @@ LL | const fn a() -> usize { b() } //~ ERROR evaluation of constant value failed
| ^^^
| |
| reached the configured maximum number of stack frames
| inside call to `b`
| inside call to `b` at $DIR/infinite-recursion-const-fn.rs:13:25
LL | const fn b() -> usize { a() }
| ---
| |
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a`
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
| inside call to `a` at $DIR/infinite-recursion-const-fn.rs:14:25
LL | const ARR: [i32; a()] = [5; 6];
| --- inside call to `a`
| --- inside call to `a` at $DIR/infinite-recursion-const-fn.rs:15:18

error: aborting due to previous error

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