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move const_eval error reporting logic into rustc_mir::const_eval::error
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@RalfJung
RalfJung committed Aug 9, 2020
1 parent 8e73853 commit bff69c9
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Showing 7 changed files with 201 additions and 194 deletions.
169 changes: 2 additions & 167 deletions src/librustc_middle/mir/interpret/error.rs
View file
@@ -1,17 +1,13 @@
use super::{AllocId, Pointer, RawConst, Scalar};

use crate::mir::interpret::ConstValue;
use crate::ty::layout::LayoutError;
use crate::ty::query::TyCtxtAt;
use crate::ty::{self, layout, tls, FnSig, Ty};
use crate::ty::{layout, query::TyCtxtAt, tls, FnSig, Ty};

use rustc_data_structures::sync::Lock;
use rustc_errors::{pluralize, struct_span_err, DiagnosticBuilder, ErrorReported};
use rustc_hir as hir;
use rustc_hir::definitions::DefPathData;
use rustc_macros::HashStable;
use rustc_session::CtfeBacktrace;
use rustc_span::{def_id::DefId, Pos, Span};
use rustc_span::def_id::DefId;
use rustc_target::abi::{Align, Size};
use std::{any::Any, backtrace::Backtrace, fmt, mem};

Expand All @@ -34,167 +30,6 @@ CloneTypeFoldableAndLiftImpls! {
pub type ConstEvalRawResult<'tcx> = Result<RawConst<'tcx>, ErrorHandled>;
pub type ConstEvalResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;

#[derive(Debug)]
pub struct ConstEvalErr<'tcx> {
pub span: Span,
pub error: crate::mir::interpret::InterpError<'tcx>,
pub stacktrace: Vec<FrameInfo<'tcx>>,
}

#[derive(Debug)]
pub struct FrameInfo<'tcx> {
pub instance: ty::Instance<'tcx>,
pub span: Span,
pub lint_root: Option<hir::HirId>,
}

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 closure")?;
} else {
write!(f, "inside `{}`", self.instance)?;
}
if !self.span.is_dummy() {
let lo = tcx.sess.source_map().lookup_char_pos(self.span.lo());
write!(f, " at {}:{}:{}", lo.file.name, lo.line, lo.col.to_usize() + 1)?;
}
Ok(())
})
}
}

impl<'tcx> ConstEvalErr<'tcx> {
pub fn struct_error(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
emit: impl FnOnce(DiagnosticBuilder<'_>),
) -> ErrorHandled {
self.struct_generic(tcx, message, emit, None)
}

pub fn report_as_error(&self, tcx: TyCtxtAt<'tcx>, message: &str) -> ErrorHandled {
self.struct_error(tcx, message, |mut e| e.emit())
}

pub fn report_as_lint(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
lint_root: hir::HirId,
span: Option<Span>,
) -> ErrorHandled {
self.struct_generic(
tcx,
message,
|mut lint: DiagnosticBuilder<'_>| {
// Apply the span.
if let Some(span) = span {
let primary_spans = lint.span.primary_spans().to_vec();
// point at the actual error as the primary span
lint.replace_span_with(span);
// point to the `const` statement as a secondary span
// they don't have any label
for sp in primary_spans {
if sp != span {
lint.span_label(sp, "");
}
}
}
lint.emit();
},
Some(lint_root),
)
}

/// Create a diagnostic for this const eval error.
///
/// Sets the message passed in via `message` and adds span labels with detailed error
/// information before handing control back to `emit` to do any final processing.
/// It's the caller's responsibility to call emit(), stash(), etc. within the `emit`
/// function to dispose of the diagnostic properly.
///
/// If `lint_root.is_some()` report it as a lint, else report it as a hard error.
/// (Except that for some errors, we ignore all that -- see `must_error` below.)
fn struct_generic(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
emit: impl FnOnce(DiagnosticBuilder<'_>),
lint_root: Option<hir::HirId>,
) -> ErrorHandled {
let must_error = match self.error {
err_inval!(Layout(LayoutError::Unknown(_))) | err_inval!(TooGeneric) => {
return ErrorHandled::TooGeneric;
}
err_inval!(TypeckError(error_reported)) => {
return ErrorHandled::Reported(error_reported);
}
// We must *always* hard error on these, even if the caller wants just a lint.
err_inval!(Layout(LayoutError::SizeOverflow(_))) => true,
_ => false,
};
trace!("reporting const eval failure at {:?}", self.span);

let err_msg = match &self.error {
InterpError::MachineStop(msg) => {
// A custom error (`ConstEvalErrKind` in `librustc_mir/interp/const_eval/error.rs`).
// Should be turned into a string by now.
msg.downcast_ref::<String>().expect("invalid MachineStop payload").clone()
}
err => err.to_string(),
};

let finish = |mut err: DiagnosticBuilder<'_>, span_msg: Option<String>| {
if let Some(span_msg) = span_msg {
err.span_label(self.span, span_msg);
}
// Add spans for the stacktrace. Don't print a single-line backtrace though.
if self.stacktrace.len() > 1 {
for frame_info in &self.stacktrace {
err.span_label(frame_info.span, frame_info.to_string());
}
}
// Let the caller finish the job.
emit(err)
};

if must_error {
// The `message` makes little sense here, this is a more serious error than the
// caller thinks anyway.
// See <https://github.com/rust-lang/rust/pull/63152>.
finish(struct_error(tcx, &err_msg), None);
ErrorHandled::Reported(ErrorReported)
} else {
// Regular case.
if let Some(lint_root) = lint_root {
// Report as lint.
let hir_id = self
.stacktrace
.iter()
.rev()
.find_map(|frame| frame.lint_root)
.unwrap_or(lint_root);
tcx.struct_span_lint_hir(
rustc_session::lint::builtin::CONST_ERR,
hir_id,
tcx.span,
|lint| finish(lint.build(message), Some(err_msg)),
);
ErrorHandled::Linted
} else {
// Report as hard error.
finish(struct_error(tcx, message), Some(err_msg));
ErrorHandled::Reported(ErrorReported)
}
}
}
}

pub fn struct_error<'tcx>(tcx: TyCtxtAt<'tcx>, msg: &str) -> DiagnosticBuilder<'tcx> {
struct_span_err!(tcx.sess, tcx.span, E0080, "{}", msg)
}
Expand Down
6 changes: 3 additions & 3 deletions src/librustc_middle/mir/interpret/mod.rs
View file
Expand Up @@ -117,9 +117,9 @@ use crate::ty::subst::GenericArgKind;
use crate::ty::{self, Instance, Ty, TyCtxt};

pub use self::error::{
struct_error, CheckInAllocMsg, ConstEvalErr, ConstEvalRawResult, ConstEvalResult, ErrorHandled,
FrameInfo, InterpError, InterpErrorInfo, InterpResult, InvalidProgramInfo, MachineStopType,
ResourceExhaustionInfo, UndefinedBehaviorInfo, UninitBytesAccess, UnsupportedOpInfo,
struct_error, CheckInAllocMsg, ConstEvalRawResult, ConstEvalResult, ErrorHandled, InterpError,
InterpErrorInfo, InterpResult, InvalidProgramInfo, MachineStopType, ResourceExhaustionInfo,
UndefinedBehaviorInfo, UninitBytesAccess, UnsupportedOpInfo,
};

pub use self::value::{get_slice_bytes, ConstValue, RawConst, Scalar, ScalarMaybeUninit};
Expand Down
170 changes: 157 additions & 13 deletions src/librustc_mir/const_eval/error.rs
View file
@@ -1,12 +1,16 @@
use std::error::Error;
use std::fmt;

use rustc_errors::{DiagnosticBuilder, ErrorReported};
use rustc_hir as hir;
use rustc_middle::mir::AssertKind;
use rustc_middle::ty::ConstInt;
use rustc_middle::ty::{layout::LayoutError, query::TyCtxtAt, ConstInt};
use rustc_span::{Span, Symbol};

use super::InterpCx;
use crate::interpret::{ConstEvalErr, InterpErrorInfo, Machine};
use crate::interpret::{
struct_error, ErrorHandled, FrameInfo, InterpError, InterpErrorInfo, Machine,
};

/// The CTFE machine has some custom error kinds.
#[derive(Clone, Debug)]
Expand Down Expand Up @@ -48,15 +52,155 @@ impl fmt::Display for ConstEvalErrKind {

impl Error for ConstEvalErrKind {}

/// Turn an interpreter error into something to report to the user.
/// As a side-effect, if RUSTC_CTFE_BACKTRACE is set, this prints the backtrace.
/// Should be called only if the error is actually going to to be reported!
pub fn error_to_const_error<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>(
ecx: &InterpCx<'mir, 'tcx, M>,
error: InterpErrorInfo<'tcx>,
span: Option<Span>,
) -> ConstEvalErr<'tcx> {
error.print_backtrace();
let stacktrace = ecx.generate_stacktrace();
ConstEvalErr { error: error.kind, stacktrace, span: span.unwrap_or_else(|| ecx.cur_span()) }
/// When const-evaluation errors, this type is constructed with the resulting information,
/// and then used to emit the error as a lint or hard error.
#[derive(Debug)]
pub struct ConstEvalErr<'tcx> {
pub span: Span,
pub error: InterpError<'tcx>,
pub stacktrace: Vec<FrameInfo<'tcx>>,
}

impl<'tcx> ConstEvalErr<'tcx> {
/// Turn an interpreter error into something to report to the user.
/// As a side-effect, if RUSTC_CTFE_BACKTRACE is set, this prints the backtrace.
/// Should be called only if the error is actually going to to be reported!
pub fn new<'mir, M: Machine<'mir, 'tcx>>(
ecx: &InterpCx<'mir, 'tcx, M>,
error: InterpErrorInfo<'tcx>,
span: Option<Span>,
) -> ConstEvalErr<'tcx>
where
'tcx: 'mir,
{
error.print_backtrace();
let stacktrace = ecx.generate_stacktrace();
ConstEvalErr { error: error.kind, stacktrace, span: span.unwrap_or_else(|| ecx.cur_span()) }
}

pub fn struct_error(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
emit: impl FnOnce(DiagnosticBuilder<'_>),
) -> ErrorHandled {
self.struct_generic(tcx, message, emit, None)
}

pub fn report_as_error(&self, tcx: TyCtxtAt<'tcx>, message: &str) -> ErrorHandled {
self.struct_error(tcx, message, |mut e| e.emit())
}

pub fn report_as_lint(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
lint_root: hir::HirId,
span: Option<Span>,
) -> ErrorHandled {
self.struct_generic(
tcx,
message,
|mut lint: DiagnosticBuilder<'_>| {
// Apply the span.
if let Some(span) = span {
let primary_spans = lint.span.primary_spans().to_vec();
// point at the actual error as the primary span
lint.replace_span_with(span);
// point to the `const` statement as a secondary span
// they don't have any label
for sp in primary_spans {
if sp != span {
lint.span_label(sp, "");
}
}
}
lint.emit();
},
Some(lint_root),
)
}

/// Create a diagnostic for this const eval error.
///
/// Sets the message passed in via `message` and adds span labels with detailed error
/// information before handing control back to `emit` to do any final processing.
/// It's the caller's responsibility to call emit(), stash(), etc. within the `emit`
/// function to dispose of the diagnostic properly.
///
/// If `lint_root.is_some()` report it as a lint, else report it as a hard error.
/// (Except that for some errors, we ignore all that -- see `must_error` below.)
fn struct_generic(
&self,
tcx: TyCtxtAt<'tcx>,
message: &str,
emit: impl FnOnce(DiagnosticBuilder<'_>),
lint_root: Option<hir::HirId>,
) -> ErrorHandled {
let must_error = match self.error {
err_inval!(Layout(LayoutError::Unknown(_))) | err_inval!(TooGeneric) => {
return ErrorHandled::TooGeneric;
}
err_inval!(TypeckError(error_reported)) => {
return ErrorHandled::Reported(error_reported);
}
// We must *always* hard error on these, even if the caller wants just a lint.
err_inval!(Layout(LayoutError::SizeOverflow(_))) => true,
_ => false,
};
trace!("reporting const eval failure at {:?}", self.span);

let err_msg = match &self.error {
InterpError::MachineStop(msg) => {
// A custom error (`ConstEvalErrKind` in `librustc_mir/interp/const_eval/error.rs`).
// Should be turned into a string by now.
msg.downcast_ref::<String>().expect("invalid MachineStop payload").clone()
}
err => err.to_string(),
};

let finish = |mut err: DiagnosticBuilder<'_>, span_msg: Option<String>| {
if let Some(span_msg) = span_msg {
err.span_label(self.span, span_msg);
}
// Add spans for the stacktrace. Don't print a single-line backtrace though.
if self.stacktrace.len() > 1 {
for frame_info in &self.stacktrace {
err.span_label(frame_info.span, frame_info.to_string());
}
}
// Let the caller finish the job.
emit(err)
};

if must_error {
// The `message` makes little sense here, this is a more serious error than the
// caller thinks anyway.
// See <https://github.com/rust-lang/rust/pull/63152>.
finish(struct_error(tcx, &err_msg), None);
ErrorHandled::Reported(ErrorReported)
} else {
// Regular case.
if let Some(lint_root) = lint_root {
// Report as lint.
let hir_id = self
.stacktrace
.iter()
.rev()
.find_map(|frame| frame.lint_root)
.unwrap_or(lint_root);
tcx.struct_span_lint_hir(
rustc_session::lint::builtin::CONST_ERR,
hir_id,
tcx.span,
|lint| finish(lint.build(message), Some(err_msg)),
);
ErrorHandled::Linted
} else {
// Report as hard error.
finish(struct_error(tcx, message), Some(err_msg));
ErrorHandled::Reported(ErrorReported)
}
}
}
}

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