rust/src/diagnostics.rs
2021-07-16 10:10:12 +02:00

345 lines
13 KiB
Rust

use std::cell::RefCell;
use std::fmt;
use std::num::NonZeroU64;
use log::trace;
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::{source_map::DUMMY_SP, Span, SpanData, Symbol};
use crate::*;
/// Details of premature program termination.
pub enum TerminationInfo {
Exit(i64),
Abort(String),
UnsupportedInIsolation(String),
ExperimentalUb {
msg: String,
url: String,
},
Deadlock,
MultipleSymbolDefinitions {
link_name: Symbol,
first: SpanData,
first_crate: Symbol,
second: SpanData,
second_crate: Symbol,
},
SymbolShimClashing {
link_name: Symbol,
span: SpanData,
},
}
impl fmt::Display for TerminationInfo {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use TerminationInfo::*;
match self {
Exit(code) => write!(f, "the evaluated program completed with exit code {}", code),
Abort(msg) => write!(f, "{}", msg),
UnsupportedInIsolation(msg) => write!(f, "{}", msg),
ExperimentalUb { msg, .. } => write!(f, "{}", msg),
Deadlock => write!(f, "the evaluated program deadlocked"),
MultipleSymbolDefinitions { link_name, .. } =>
write!(f, "multiple definitions of symbol `{}`", link_name),
SymbolShimClashing { link_name, .. } =>
write!(
f,
"found `{}` symbol definition that clashes with a built-in shim",
link_name
),
}
}
}
impl MachineStopType for TerminationInfo {}
/// Miri specific diagnostics
pub enum NonHaltingDiagnostic {
CreatedPointerTag(NonZeroU64),
PoppedPointerTag(Item),
CreatedCallId(CallId),
CreatedAlloc(AllocId),
FreedAlloc(AllocId),
RejectedIsolatedOp(String),
}
/// Level of Miri specific diagnostics
enum DiagLevel {
Error,
Warning,
Note,
}
/// Emit a custom diagnostic without going through the miri-engine machinery
pub fn report_error<'tcx, 'mir>(
ecx: &InterpCx<'mir, 'tcx, Evaluator<'mir, 'tcx>>,
e: InterpErrorInfo<'tcx>,
) -> Option<i64> {
use InterpError::*;
let (title, helps) = match &e.kind() {
MachineStop(info) => {
let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
use TerminationInfo::*;
let title = match info {
Exit(code) => return Some(*code),
Abort(_) => Some("abnormal termination"),
UnsupportedInIsolation(_) => Some("unsupported operation"),
ExperimentalUb { .. } => Some("Undefined Behavior"),
Deadlock => Some("deadlock"),
MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
};
#[rustfmt::skip]
let helps = match info {
UnsupportedInIsolation(_) =>
vec![
(None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
(None, format!("or pass `-Zmiri-isolation-error=warn to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning")),
],
ExperimentalUb { url, .. } =>
vec![
(None, format!("this indicates a potential bug in the program: it performed an invalid operation, but the rules it violated are still experimental")),
(None, format!("see {} for further information", url)),
],
MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
vec![
(Some(*first), format!("it's first defined here, in crate `{}`", first_crate)),
(Some(*second), format!("then it's defined here again, in crate `{}`", second_crate)),
],
SymbolShimClashing { link_name, span } =>
vec![(Some(*span), format!("the `{}` symbol is defined here", link_name))],
_ => vec![],
};
(title, helps)
}
_ => {
#[rustfmt::skip]
let title = match e.kind() {
Unsupported(_) =>
"unsupported operation",
UndefinedBehavior(_) =>
"Undefined Behavior",
ResourceExhaustion(_) =>
"resource exhaustion",
InvalidProgram(InvalidProgramInfo::ReferencedConstant) =>
"post-monomorphization error",
InvalidProgram(InvalidProgramInfo::AlreadyReported(_)) =>
"error occurred",
kind =>
bug!("This error should be impossible in Miri: {:?}", kind),
};
#[rustfmt::skip]
let helps = match e.kind() {
Unsupported(UnsupportedOpInfo::NoMirFor(..)) =>
vec![(None, format!("make sure to use a Miri sysroot, which you can prepare with `cargo miri setup`"))],
Unsupported(UnsupportedOpInfo::ThreadLocalStatic(_) | UnsupportedOpInfo::ReadExternStatic(_)) =>
panic!("Error should never be raised by Miri: {:?}", e.kind()),
Unsupported(_) =>
vec![(None, format!("this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support"))],
UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })
if ecx.memory.extra.check_alignment == AlignmentCheck::Symbolic
=>
vec![
(None, format!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior")),
(None, format!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives")),
],
UndefinedBehavior(_) =>
vec![
(None, format!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior")),
(None, format!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information")),
],
_ => vec![],
};
(Some(title), helps)
}
};
e.print_backtrace();
let msg = e.to_string();
report_msg(
*ecx.tcx,
DiagLevel::Error,
&if let Some(title) = title { format!("{}: {}", title, msg) } else { msg.clone() },
msg,
helps,
&ecx.generate_stacktrace(),
);
// Debug-dump all locals.
for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
trace!("-------------------");
trace!("Frame {}", i);
trace!(" return: {:?}", frame.return_place.map(|p| *p));
for (i, local) in frame.locals.iter().enumerate() {
trace!(" local {}: {:?}", i, local.value);
}
}
// Extra output to help debug specific issues.
match e.kind() {
UndefinedBehavior(UndefinedBehaviorInfo::InvalidUninitBytes(Some((alloc_id, access)))) => {
eprintln!(
"Uninitialized read occurred at offsets 0x{:x}..0x{:x} into this allocation:",
access.uninit_offset.bytes(),
access.uninit_offset.bytes() + access.uninit_size.bytes(),
);
eprintln!("{:?}", ecx.memory.dump_alloc(*alloc_id));
}
_ => {}
}
None
}
/// Report an error or note (depending on the `error` argument) with the given stacktrace.
/// Also emits a full stacktrace of the interpreter stack.
fn report_msg<'tcx>(
tcx: TyCtxt<'tcx>,
diag_level: DiagLevel,
title: &str,
span_msg: String,
mut helps: Vec<(Option<SpanData>, String)>,
stacktrace: &[FrameInfo<'tcx>],
) {
let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
let mut err = match diag_level {
DiagLevel::Error => tcx.sess.struct_span_err(span, title),
DiagLevel::Warning => tcx.sess.struct_span_warn(span, title),
DiagLevel::Note => tcx.sess.diagnostic().span_note_diag(span, title),
};
// Show main message.
if span != DUMMY_SP {
err.span_label(span, span_msg);
} else {
// Make sure we show the message even when it is a dummy span.
err.note(&span_msg);
err.note("(no span available)");
}
// Show help messages.
if !helps.is_empty() {
// Add visual separator before backtrace.
helps.last_mut().unwrap().1.push_str("\n");
for (span_data, help) in helps {
if let Some(span_data) = span_data {
err.span_help(span_data.span(), &help);
} else {
err.help(&help);
}
}
}
// Add backtrace
for (idx, frame_info) in stacktrace.iter().enumerate() {
let is_local = frame_info.instance.def_id().is_local();
// No span for non-local frames and the first frame (which is the error site).
if is_local && idx > 0 {
err.span_note(frame_info.span, &frame_info.to_string());
} else {
err.note(&frame_info.to_string());
}
}
err.emit();
}
thread_local! {
static DIAGNOSTICS: RefCell<Vec<NonHaltingDiagnostic>> = RefCell::new(Vec::new());
}
/// Schedule a diagnostic for emitting. This function works even if you have no `InterpCx` available.
/// The diagnostic will be emitted after the current interpreter step is finished.
pub fn register_diagnostic(e: NonHaltingDiagnostic) {
DIAGNOSTICS.with(|diagnostics| diagnostics.borrow_mut().push(e));
}
/// Remember enough about the topmost frame so that we can restore the stack
/// after a step was taken.
pub struct TopFrameInfo<'tcx> {
stack_size: usize,
instance: Option<ty::Instance<'tcx>>,
span: Span,
}
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
fn preprocess_diagnostics(&self) -> TopFrameInfo<'tcx> {
// Ensure we have no lingering diagnostics.
DIAGNOSTICS.with(|diagnostics| assert!(diagnostics.borrow().is_empty()));
let this = self.eval_context_ref();
if this.active_thread_stack().is_empty() {
// Diagnostics can happen even with the empty stack (e.g. deallocation of thread-local statics).
return TopFrameInfo { stack_size: 0, instance: None, span: DUMMY_SP };
}
let frame = this.frame();
TopFrameInfo {
stack_size: this.active_thread_stack().len(),
instance: Some(frame.instance),
span: frame.current_span(),
}
}
/// Emit all diagnostics that were registed with `register_diagnostics`
fn process_diagnostics(&self, info: TopFrameInfo<'tcx>) {
let this = self.eval_context_ref();
DIAGNOSTICS.with(|diagnostics| {
let mut diagnostics = diagnostics.borrow_mut();
if diagnostics.is_empty() {
return;
}
// We need to fix up the stack trace, because the machine has already
// stepped to the next statement.
let mut stacktrace = this.generate_stacktrace();
// Remove newly pushed frames.
while stacktrace.len() > info.stack_size {
stacktrace.remove(0);
}
// Add popped frame back.
if stacktrace.len() < info.stack_size {
assert!(
stacktrace.len() == info.stack_size - 1,
"we should never pop more than one frame at once"
);
let frame_info = FrameInfo {
instance: info.instance.unwrap(),
span: info.span,
lint_root: None,
};
stacktrace.insert(0, frame_info);
} else if let Some(instance) = info.instance {
// Adjust topmost frame.
stacktrace[0].span = info.span;
assert_eq!(
stacktrace[0].instance, instance,
"we should not pop and push a frame in one step"
);
}
// Show diagnostics.
for e in diagnostics.drain(..) {
use NonHaltingDiagnostic::*;
let msg = match e {
CreatedPointerTag(tag) => format!("created tag {:?}", tag),
PoppedPointerTag(item) => format!("popped tracked tag for item {:?}", item),
CreatedCallId(id) => format!("function call with id {}", id),
CreatedAlloc(AllocId(id)) => format!("created allocation with id {}", id),
FreedAlloc(AllocId(id)) => format!("freed allocation with id {}", id),
RejectedIsolatedOp(ref op) =>
format!("`{}` was made to return an error due to isolation", op),
};
let (title, diag_level) = match e {
RejectedIsolatedOp(_) =>
("operation rejected by isolation", DiagLevel::Warning),
_ => ("tracking was triggered", DiagLevel::Note),
};
report_msg(*this.tcx, diag_level, title, msg, vec![], &stacktrace);
}
});
}
}