Rollup merge of #64416 - mark-i-m:region-naming-ctx, r=estebank
Various refactorings to clean up nll diagnostics
- Create ErrorReportingCtx and ErrorConstraintInfo, vasting reducing the
number of arguments passed around everywhere in the error reporting code
- Create RegionErrorNamingCtx, making a given lifetime have consistent
numbering thoughout all error messages for that MIR def.
- Make the error reporting code return the DiagnosticBuilder rather than
directly buffer the Diagnostic. This makes it easier to modify the
diagnostic later, e.g. to add suggestions.
r? @estebank
Split out from https://github.com/rust-lang/rust/pull/58281
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
index efa1858..26a89b4 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
@@ -13,7 +13,7 @@
use rustc::mir::{ConstraintCategory, Location, Body};
use rustc::ty::{self, RegionVid};
use rustc_data_structures::indexed_vec::IndexVec;
-use rustc_errors::{Diagnostic, DiagnosticBuilder};
+use rustc_errors::DiagnosticBuilder;
use std::collections::VecDeque;
use syntax::errors::Applicability;
use syntax::symbol::kw;
@@ -22,7 +22,7 @@
mod region_name;
mod var_name;
-crate use self::region_name::{RegionName, RegionNameSource};
+crate use self::region_name::{RegionName, RegionNameSource, RegionErrorNamingCtx};
impl ConstraintDescription for ConstraintCategory {
fn description(&self) -> &'static str {
@@ -54,6 +54,39 @@
NotVisited,
}
+/// Various pieces of state used when reporting borrow checker errors.
+pub struct ErrorReportingCtx<'a, 'b, 'tcx> {
+ /// The region inference context used for borrow chekcing this MIR body.
+ #[allow(dead_code)] // FIXME(mark-i-m): used by outlives suggestions
+ region_infcx: &'b RegionInferenceContext<'tcx>,
+
+ /// The inference context used for type checking.
+ infcx: &'b InferCtxt<'a, 'tcx>,
+
+ /// The MIR def we are reporting errors on.
+ mir_def_id: DefId,
+
+ /// The MIR body we are reporting errors on (for convenience).
+ body: &'b Body<'tcx>,
+
+ /// Any upvars for the MIR body we have kept track of during borrow checking.
+ upvars: &'b [Upvar],
+}
+
+/// Information about the various region constraints involved in a borrow checker error.
+#[derive(Clone, Debug)]
+pub struct ErrorConstraintInfo {
+ // fr: outlived_fr
+ fr: RegionVid,
+ fr_is_local: bool,
+ outlived_fr: RegionVid,
+ outlived_fr_is_local: bool,
+
+ // Category and span for best blame constraint
+ category: ConstraintCategory,
+ span: Span,
+}
+
impl<'tcx> RegionInferenceContext<'tcx> {
/// Tries to find the best constraint to blame for the fact that
/// `R: from_region`, where `R` is some region that meets
@@ -257,16 +290,16 @@
/// ```
///
/// Here we would be invoked with `fr = 'a` and `outlived_fr = `'b`.
- pub(super) fn report_error(
- &self,
+ pub(super) fn report_error<'a>(
+ &'a self,
body: &Body<'tcx>,
upvars: &[Upvar],
- infcx: &InferCtxt<'_, 'tcx>,
+ infcx: &'a InferCtxt<'a, 'tcx>,
mir_def_id: DefId,
fr: RegionVid,
outlived_fr: RegionVid,
- errors_buffer: &mut Vec<Diagnostic>,
- ) {
+ renctx: &mut RegionErrorNamingCtx,
+ ) -> DiagnosticBuilder<'a> {
debug!("report_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr);
let (category, _, span) = self.best_blame_constraint(body, fr, |r| {
@@ -279,8 +312,7 @@
let tables = infcx.tcx.typeck_tables_of(mir_def_id);
let nice = NiceRegionError::new_from_span(infcx, span, o, f, Some(tables));
if let Some(diag) = nice.try_report_from_nll() {
- diag.buffer(errors_buffer);
- return;
+ return diag;
}
}
@@ -293,45 +325,28 @@
"report_error: fr_is_local={:?} outlived_fr_is_local={:?} category={:?}",
fr_is_local, outlived_fr_is_local, category
);
+
+ let errctx = ErrorReportingCtx {
+ region_infcx: self,
+ infcx,
+ mir_def_id,
+ body,
+ upvars,
+ };
+
+ let errci = ErrorConstraintInfo {
+ fr, outlived_fr, fr_is_local, outlived_fr_is_local, category, span
+ };
+
match (category, fr_is_local, outlived_fr_is_local) {
(ConstraintCategory::Return, true, false) if self.is_closure_fn_mut(infcx, fr) => {
- self.report_fnmut_error(
- body,
- upvars,
- infcx,
- mir_def_id,
- fr,
- outlived_fr,
- span,
- errors_buffer,
- )
+ self.report_fnmut_error(&errctx, &errci, renctx)
}
(ConstraintCategory::Assignment, true, false)
- | (ConstraintCategory::CallArgument, true, false) => self.report_escaping_data_error(
- body,
- upvars,
- infcx,
- mir_def_id,
- fr,
- outlived_fr,
- category,
- span,
- errors_buffer,
- ),
- _ => self.report_general_error(
- body,
- upvars,
- infcx,
- mir_def_id,
- fr,
- fr_is_local,
- outlived_fr,
- outlived_fr_is_local,
- category,
- span,
- errors_buffer,
- ),
- };
+ | (ConstraintCategory::CallArgument, true, false) =>
+ self.report_escaping_data_error(&errctx, &errci, renctx),
+ _ => self.report_general_error(&errctx, &errci, renctx),
+ }
}
/// We have a constraint `fr1: fr2` that is not satisfied, where
@@ -379,19 +394,19 @@
/// ```
fn report_fnmut_error(
&self,
- body: &Body<'tcx>,
- upvars: &[Upvar],
- infcx: &InferCtxt<'_, 'tcx>,
- mir_def_id: DefId,
- _fr: RegionVid,
- outlived_fr: RegionVid,
- span: Span,
- errors_buffer: &mut Vec<Diagnostic>,
- ) {
- let mut diag = infcx
+ errctx: &ErrorReportingCtx<'_, '_, 'tcx>,
+ errci: &ErrorConstraintInfo,
+ renctx: &mut RegionErrorNamingCtx,
+ ) -> DiagnosticBuilder<'_> {
+ let ErrorConstraintInfo {
+ outlived_fr, span, ..
+ } = errci;
+
+ let mut diag = errctx
+ .infcx
.tcx
.sess
- .struct_span_err(span, "captured variable cannot escape `FnMut` closure body");
+ .struct_span_err(*span, "captured variable cannot escape `FnMut` closure body");
// We should check if the return type of this closure is in fact a closure - in that
// case, we can special case the error further.
@@ -403,11 +418,9 @@
"returns a reference to a captured variable which escapes the closure body"
};
- diag.span_label(span, message);
+ diag.span_label(*span, message);
- match self.give_region_a_name(infcx, body, upvars, mir_def_id, outlived_fr, &mut 1)
- .unwrap().source
- {
+ match self.give_region_a_name(errctx, renctx, *outlived_fr).unwrap().source {
RegionNameSource::NamedEarlyBoundRegion(fr_span)
| RegionNameSource::NamedFreeRegion(fr_span)
| RegionNameSource::SynthesizedFreeEnvRegion(fr_span, _)
@@ -427,7 +440,7 @@
);
diag.note("...therefore, they cannot allow references to captured variables to escape");
- diag.buffer(errors_buffer);
+ diag
}
/// Reports a error specifically for when data is escaping a closure.
@@ -444,20 +457,22 @@
/// ```
fn report_escaping_data_error(
&self,
- body: &Body<'tcx>,
- upvars: &[Upvar],
- infcx: &InferCtxt<'_, 'tcx>,
- mir_def_id: DefId,
- fr: RegionVid,
- outlived_fr: RegionVid,
- category: ConstraintCategory,
- span: Span,
- errors_buffer: &mut Vec<Diagnostic>,
- ) {
+ errctx: &ErrorReportingCtx<'_, '_, 'tcx>,
+ errci: &ErrorConstraintInfo,
+ renctx: &mut RegionErrorNamingCtx,
+ ) -> DiagnosticBuilder<'_> {
+ let ErrorReportingCtx {
+ infcx, body, upvars, ..
+ } = errctx;
+
+ let ErrorConstraintInfo {
+ span, category, ..
+ } = errci;
+
let fr_name_and_span =
- self.get_var_name_and_span_for_region(infcx.tcx, body, upvars, fr);
+ self.get_var_name_and_span_for_region(infcx.tcx, body, upvars, errci.fr);
let outlived_fr_name_and_span =
- self.get_var_name_and_span_for_region(infcx.tcx, body, upvars, outlived_fr);
+ self.get_var_name_and_span_for_region(infcx.tcx, body, upvars, errci.outlived_fr);
let escapes_from = match self.universal_regions.defining_ty {
DefiningTy::Closure(..) => "closure",
@@ -469,27 +484,23 @@
// Revert to the normal error in these cases.
// Assignments aren't "escapes" in function items.
if (fr_name_and_span.is_none() && outlived_fr_name_and_span.is_none())
- || (category == ConstraintCategory::Assignment && escapes_from == "function")
+ || (*category == ConstraintCategory::Assignment && escapes_from == "function")
|| escapes_from == "const"
{
return self.report_general_error(
- body,
- upvars,
- infcx,
- mir_def_id,
- fr,
- true,
- outlived_fr,
- false,
- category,
- span,
- errors_buffer,
+ errctx,
+ &ErrorConstraintInfo {
+ fr_is_local: true,
+ outlived_fr_is_local: false,
+ .. *errci
+ },
+ renctx,
);
}
let mut diag = borrowck_errors::borrowed_data_escapes_closure(
infcx.tcx,
- span,
+ *span,
escapes_from,
);
@@ -513,12 +524,12 @@
);
diag.span_label(
- span,
+ *span,
format!("`{}` escapes the {} body here", fr_name, escapes_from),
);
}
- diag.buffer(errors_buffer);
+ diag
}
/// Reports a region inference error for the general case with named/synthesized lifetimes to
@@ -538,41 +549,37 @@
/// ```
fn report_general_error(
&self,
- body: &Body<'tcx>,
- upvars: &[Upvar],
- infcx: &InferCtxt<'_, 'tcx>,
- mir_def_id: DefId,
- fr: RegionVid,
- fr_is_local: bool,
- outlived_fr: RegionVid,
- outlived_fr_is_local: bool,
- category: ConstraintCategory,
- span: Span,
- errors_buffer: &mut Vec<Diagnostic>,
- ) {
+ errctx: &ErrorReportingCtx<'_, '_, 'tcx>,
+ errci: &ErrorConstraintInfo,
+ renctx: &mut RegionErrorNamingCtx,
+ ) -> DiagnosticBuilder<'_> {
+ let ErrorReportingCtx {
+ infcx, mir_def_id, ..
+ } = errctx;
+ let ErrorConstraintInfo {
+ fr, fr_is_local, outlived_fr, outlived_fr_is_local, span, category, ..
+ } = errci;
+
let mut diag = infcx.tcx.sess.struct_span_err(
- span,
+ *span,
"lifetime may not live long enough"
);
- let counter = &mut 1;
- let fr_name = self.give_region_a_name(
- infcx, body, upvars, mir_def_id, fr, counter).unwrap();
- fr_name.highlight_region_name(&mut diag);
- let outlived_fr_name =
- self.give_region_a_name(infcx, body, upvars, mir_def_id, outlived_fr, counter).unwrap();
- outlived_fr_name.highlight_region_name(&mut diag);
-
- let mir_def_name = if infcx.tcx.is_closure(mir_def_id) {
+ let mir_def_name = if infcx.tcx.is_closure(*mir_def_id) {
"closure"
} else {
"function"
};
+ let fr_name = self.give_region_a_name(errctx, renctx, *fr).unwrap();
+ fr_name.highlight_region_name(&mut diag);
+ let outlived_fr_name = self.give_region_a_name(errctx, renctx, *outlived_fr).unwrap();
+ outlived_fr_name.highlight_region_name(&mut diag);
+
match (category, outlived_fr_is_local, fr_is_local) {
(ConstraintCategory::Return, true, _) => {
diag.span_label(
- span,
+ *span,
format!(
"{} was supposed to return data with lifetime `{}` but it is returning \
data with lifetime `{}`",
@@ -582,7 +589,7 @@
}
_ => {
diag.span_label(
- span,
+ *span,
format!(
"{}requires that `{}` must outlive `{}`",
category.description(),
@@ -593,9 +600,9 @@
}
}
- self.add_static_impl_trait_suggestion(infcx, &mut diag, fr, fr_name, outlived_fr);
+ self.add_static_impl_trait_suggestion(infcx, &mut diag, *fr, fr_name, *outlived_fr);
- diag.buffer(errors_buffer);
+ diag
}
/// Adds a suggestion to errors where a `impl Trait` is returned.
@@ -704,8 +711,14 @@
borrow_region,
|r| self.provides_universal_region(r, borrow_region, outlived_region)
);
- let outlived_fr_name =
- self.give_region_a_name(infcx, body, upvars, mir_def_id, outlived_region, &mut 1);
+
+ let mut renctx = RegionErrorNamingCtx::new();
+ let errctx = ErrorReportingCtx {
+ infcx, body, upvars, mir_def_id,
+ region_infcx: self,
+ };
+ let outlived_fr_name = self.give_region_a_name(&errctx, &mut renctx, outlived_region);
+
(category, from_closure, span, outlived_fr_name)
}
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/region_name.rs b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/region_name.rs
index 75a3162..6fa9426 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/region_name.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/region_name.rs
@@ -1,5 +1,9 @@
use std::fmt::{self, Display};
-use crate::borrow_check::nll::region_infer::RegionInferenceContext;
+
+use crate::borrow_check::nll::region_infer::{
+ RegionInferenceContext,
+ error_reporting::ErrorReportingCtx,
+};
use crate::borrow_check::nll::universal_regions::DefiningTy;
use crate::borrow_check::nll::ToRegionVid;
use crate::borrow_check::Upvar;
@@ -13,29 +17,75 @@
use rustc::ty::print::RegionHighlightMode;
use rustc_errors::DiagnosticBuilder;
use syntax::symbol::kw;
-use syntax_pos::Span;
-use syntax_pos::symbol::InternedString;
+use rustc_data_structures::fx::FxHashMap;
+use syntax_pos::{Span, symbol::InternedString};
-#[derive(Debug)]
+/// A name for a particular region used in emitting diagnostics. This name could be a generated
+/// name like `'1`, a name used by the user like `'a`, or a name like `'static`.
+#[derive(Debug, Clone)]
crate struct RegionName {
+ /// The name of the region (interned).
crate name: InternedString,
+ /// Where the region comes from.
crate source: RegionNameSource,
}
-#[derive(Debug)]
+/// Denotes the source of a region that is named by a `RegionName`. For example, a free region that
+/// was named by the user would get `NamedFreeRegion` and `'static` lifetime would get `Static`.
+/// This helps to print the right kinds of diagnostics.
+#[derive(Debug, Clone)]
crate enum RegionNameSource {
+ /// A bound (not free) region that was substituted at the def site (not an HRTB).
NamedEarlyBoundRegion(Span),
+ /// A free region that the user has a name (`'a`) for.
NamedFreeRegion(Span),
+ /// The `'static` region.
Static,
+ /// The free region corresponding to the environment of a closure.
SynthesizedFreeEnvRegion(Span, String),
+ /// The region name corresponds to a region where the type annotation is completely missing
+ /// from the code, e.g. in a closure arguments `|x| { ... }`, where `x` is a reference.
CannotMatchHirTy(Span, String),
+ /// The region name corresponds a reference that was found by traversing the type in the HIR.
MatchedHirTy(Span),
+ /// A region name from the generics list of a struct/enum/union.
MatchedAdtAndSegment(Span),
+ /// The region corresponding to a closure upvar.
AnonRegionFromUpvar(Span, String),
+ /// The region corresponding to the return type of a closure.
AnonRegionFromOutput(Span, String, String),
AnonRegionFromYieldTy(Span, String),
}
+/// Records region names that have been assigned before so that we can use the same ones in later
+/// diagnostics.
+#[derive(Debug, Clone)]
+crate struct RegionErrorNamingCtx {
+ /// Record the region names generated for each region in the given
+ /// MIR def so that we can reuse them later in help/error messages.
+ renctx: FxHashMap<RegionVid, RegionName>,
+
+ /// The counter for generating new region names.
+ counter: usize,
+}
+
+impl RegionErrorNamingCtx {
+ crate fn new() -> Self {
+ Self {
+ counter: 1,
+ renctx: FxHashMap::default(),
+ }
+ }
+
+ crate fn get(&self, region: &RegionVid) -> Option<&RegionName> {
+ self.renctx.get(region)
+ }
+
+ crate fn insert(&mut self, region: RegionVid, name: RegionName) {
+ self.renctx.insert(region, name);
+ }
+}
+
impl RegionName {
#[allow(dead_code)]
crate fn was_named(&self) -> bool {
@@ -63,43 +113,40 @@
self.name
}
- crate fn highlight_region_name(
- &self,
- diag: &mut DiagnosticBuilder<'_>
- ) {
+ crate fn highlight_region_name(&self, diag: &mut DiagnosticBuilder<'_>) {
match &self.source {
- RegionNameSource::NamedFreeRegion(span) |
- RegionNameSource::NamedEarlyBoundRegion(span) => {
- diag.span_label(
- *span,
- format!("lifetime `{}` defined here", self),
- );
- },
+ RegionNameSource::NamedFreeRegion(span)
+ | RegionNameSource::NamedEarlyBoundRegion(span) => {
+ diag.span_label(*span, format!("lifetime `{}` defined here", self));
+ }
RegionNameSource::SynthesizedFreeEnvRegion(span, note) => {
diag.span_label(
*span,
format!("lifetime `{}` represents this closure's body", self),
);
diag.note(¬e);
- },
+ }
RegionNameSource::CannotMatchHirTy(span, type_name) => {
diag.span_label(*span, format!("has type `{}`", type_name));
- },
+ }
RegionNameSource::MatchedHirTy(span) => {
diag.span_label(
*span,
format!("let's call the lifetime of this reference `{}`", self),
);
- },
+ }
RegionNameSource::MatchedAdtAndSegment(span) => {
diag.span_label(*span, format!("let's call this `{}`", self));
- },
+ }
RegionNameSource::AnonRegionFromUpvar(span, upvar_name) => {
diag.span_label(
*span,
- format!("lifetime `{}` appears in the type of `{}`", self, upvar_name),
+ format!(
+ "lifetime `{}` appears in the type of `{}`",
+ self, upvar_name
+ ),
);
- },
+ }
RegionNameSource::AnonRegionFromOutput(span, mir_description, type_name) => {
diag.span_label(
*span,
@@ -151,39 +198,49 @@
/// and then return the name `'1` for us to use.
crate fn give_region_a_name(
&self,
- infcx: &InferCtxt<'_, 'tcx>,
- body: &Body<'tcx>,
- upvars: &[Upvar],
- mir_def_id: DefId,
+ errctx: &ErrorReportingCtx<'_, '_, 'tcx>,
+ renctx: &mut RegionErrorNamingCtx,
fr: RegionVid,
- counter: &mut usize,
) -> Option<RegionName> {
- debug!("give_region_a_name(fr={:?}, counter={})", fr, counter);
+ let ErrorReportingCtx {
+ infcx, body, mir_def_id, upvars, ..
+ } = errctx;
+
+ debug!("give_region_a_name(fr={:?}, counter={:?})", fr, renctx.counter);
assert!(self.universal_regions.is_universal_region(fr));
- let value = self.give_name_from_error_region(infcx.tcx, mir_def_id, fr, counter)
+ if let Some(value) = renctx.get(&fr) {
+ return Some(value.clone());
+ }
+
+ let value = self
+ .give_name_from_error_region(infcx.tcx, *mir_def_id, fr, renctx)
.or_else(|| {
self.give_name_if_anonymous_region_appears_in_arguments(
- infcx, body, mir_def_id, fr, counter,
+ infcx, body, *mir_def_id, fr, renctx,
)
})
.or_else(|| {
self.give_name_if_anonymous_region_appears_in_upvars(
- infcx.tcx, upvars, fr, counter,
+ infcx.tcx, upvars, fr, renctx
)
})
.or_else(|| {
self.give_name_if_anonymous_region_appears_in_output(
- infcx, body, mir_def_id, fr, counter,
+ infcx, body, *mir_def_id, fr, renctx,
)
})
.or_else(|| {
self.give_name_if_anonymous_region_appears_in_yield_ty(
- infcx, body, mir_def_id, fr, counter,
+ infcx, body, *mir_def_id, fr, renctx,
)
});
+ if let Some(ref value) = value {
+ renctx.insert(fr, value.clone());
+ }
+
debug!("give_region_a_name: gave name {:?}", value);
value
}
@@ -197,7 +254,7 @@
tcx: TyCtxt<'tcx>,
mir_def_id: DefId,
fr: RegionVid,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let error_region = self.to_error_region(fr)?;
@@ -208,7 +265,7 @@
let span = self.get_named_span(tcx, error_region, ebr.name);
Some(RegionName {
name: ebr.name,
- source: RegionNameSource::NamedEarlyBoundRegion(span)
+ source: RegionNameSource::NamedEarlyBoundRegion(span),
})
} else {
None
@@ -227,12 +284,10 @@
name,
source: RegionNameSource::NamedFreeRegion(span),
})
- },
+ }
ty::BoundRegion::BrEnv => {
- let mir_hir_id = tcx.hir()
- .as_local_hir_id(mir_def_id)
- .expect("non-local mir");
+ let mir_hir_id = tcx.hir().as_local_hir_id(mir_def_id).expect("non-local mir");
let def_ty = self.universal_regions.defining_ty;
if let DefiningTy::Closure(def_id, substs) = def_ty {
@@ -243,7 +298,7 @@
} else {
bug!("Closure is not defined by a closure expr");
};
- let region_name = self.synthesize_region_name(counter);
+ let region_name = self.synthesize_region_name(renctx);
let closure_kind_ty = substs.closure_kind_ty(def_id, tcx);
let note = match closure_kind_ty.to_opt_closure_kind() {
@@ -265,7 +320,7 @@
name: region_name,
source: RegionNameSource::SynthesizedFreeEnvRegion(
args_span,
- note.to_string()
+ note.to_string(),
),
})
} else {
@@ -335,7 +390,7 @@
body: &Body<'tcx>,
mir_def_id: DefId,
fr: RegionVid,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let implicit_inputs = self.universal_regions.defining_ty.implicit_inputs();
let argument_index = self.get_argument_index_for_region(infcx.tcx, fr)?;
@@ -349,12 +404,12 @@
fr,
arg_ty,
argument_index,
- counter,
+ renctx,
) {
return Some(region_name);
}
- self.give_name_if_we_cannot_match_hir_ty(infcx, body, fr, arg_ty, counter)
+ self.give_name_if_we_cannot_match_hir_ty(infcx, body, fr, arg_ty, renctx)
}
fn give_name_if_we_can_match_hir_ty_from_argument(
@@ -365,7 +420,7 @@
needle_fr: RegionVid,
argument_ty: Ty<'tcx>,
argument_index: usize,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let mir_hir_id = infcx.tcx.hir().as_local_hir_id(mir_def_id)?;
let fn_decl = infcx.tcx.hir().fn_decl_by_hir_id(mir_hir_id)?;
@@ -379,7 +434,7 @@
body,
needle_fr,
argument_ty,
- counter,
+ renctx,
),
_ => self.give_name_if_we_can_match_hir_ty(
@@ -387,7 +442,7 @@
needle_fr,
argument_ty,
argument_hir_ty,
- counter,
+ renctx,
),
}
}
@@ -409,10 +464,11 @@
body: &Body<'tcx>,
needle_fr: RegionVid,
argument_ty: Ty<'tcx>,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
+ let counter = renctx.counter;
let mut highlight = RegionHighlightMode::default();
- highlight.highlighting_region_vid(needle_fr, *counter);
+ highlight.highlighting_region_vid(needle_fr, counter);
let type_name = infcx.extract_type_name(&argument_ty, Some(highlight)).0;
debug!(
@@ -428,7 +484,7 @@
// This counter value will already have been used, so this function will increment
// it so the next value will be used next and return the region name that would
// have been used.
- name: self.synthesize_region_name(counter),
+ name: self.synthesize_region_name(renctx),
source: RegionNameSource::CannotMatchHirTy(span, type_name),
})
} else {
@@ -455,7 +511,7 @@
/// type. Once we find that, we can use the span of the `hir::Ty`
/// to add the highlight.
///
- /// This is a somewhat imperfect process, so long the way we also
+ /// This is a somewhat imperfect process, so along the way we also
/// keep track of the **closest** type we've found. If we fail to
/// find the exact `&` or `'_` to highlight, then we may fall back
/// to highlighting that closest type instead.
@@ -465,7 +521,7 @@
needle_fr: RegionVid,
argument_ty: Ty<'tcx>,
argument_hir_ty: &hir::Ty,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let search_stack: &mut Vec<(Ty<'tcx>, &hir::Ty)> =
&mut vec![(argument_ty, argument_hir_ty)];
@@ -483,7 +539,7 @@
hir::TyKind::Rptr(_lifetime, referent_hir_ty),
) => {
if region.to_region_vid() == needle_fr {
- let region_name = self.synthesize_region_name(counter);
+ let region_name = self.synthesize_region_name(renctx);
// Just grab the first character, the `&`.
let source_map = tcx.sess.source_map();
@@ -515,7 +571,7 @@
substs,
needle_fr,
last_segment,
- counter,
+ renctx,
search_stack,
) {
return Some(name);
@@ -559,18 +615,19 @@
substs: SubstsRef<'tcx>,
needle_fr: RegionVid,
last_segment: &'hir hir::PathSegment,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
search_stack: &mut Vec<(Ty<'tcx>, &'hir hir::Ty)>,
) -> Option<RegionName> {
// Did the user give explicit arguments? (e.g., `Foo<..>`)
let args = last_segment.args.as_ref()?;
- let lifetime = self.try_match_adt_and_generic_args(substs, needle_fr, args, search_stack)?;
+ let lifetime =
+ self.try_match_adt_and_generic_args(substs, needle_fr, args, search_stack)?;
match lifetime.name {
hir::LifetimeName::Param(_)
| hir::LifetimeName::Error
| hir::LifetimeName::Static
| hir::LifetimeName::Underscore => {
- let region_name = self.synthesize_region_name(counter);
+ let region_name = self.synthesize_region_name(renctx);
let ampersand_span = lifetime.span;
Some(RegionName {
name: region_name,
@@ -657,12 +714,12 @@
tcx: TyCtxt<'tcx>,
upvars: &[Upvar],
fr: RegionVid,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let upvar_index = self.get_upvar_index_for_region(tcx, fr)?;
let (upvar_name, upvar_span) =
self.get_upvar_name_and_span_for_region(tcx, upvars, upvar_index);
- let region_name = self.synthesize_region_name(counter);
+ let region_name = self.synthesize_region_name(renctx);
Some(RegionName {
name: region_name,
@@ -680,7 +737,7 @@
body: &Body<'tcx>,
mir_def_id: DefId,
fr: RegionVid,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
let tcx = infcx.tcx;
@@ -694,7 +751,7 @@
}
let mut highlight = RegionHighlightMode::default();
- highlight.highlighting_region_vid(fr, *counter);
+ highlight.highlighting_region_vid(fr, renctx.counter);
let type_name = infcx.extract_type_name(&return_ty, Some(highlight)).0;
let mir_hir_id = tcx.hir().as_local_hir_id(mir_def_id).expect("non-local mir");
@@ -725,11 +782,11 @@
// This counter value will already have been used, so this function will increment it
// so the next value will be used next and return the region name that would have been
// used.
- name: self.synthesize_region_name(counter),
+ name: self.synthesize_region_name(renctx),
source: RegionNameSource::AnonRegionFromOutput(
return_span,
mir_description.to_string(),
- type_name
+ type_name,
),
})
}
@@ -740,7 +797,7 @@
body: &Body<'tcx>,
mir_def_id: DefId,
fr: RegionVid,
- counter: &mut usize,
+ renctx: &mut RegionErrorNamingCtx,
) -> Option<RegionName> {
// Note: generators from `async fn` yield `()`, so we don't have to
// worry about them here.
@@ -757,7 +814,7 @@
}
let mut highlight = RegionHighlightMode::default();
- highlight.highlighting_region_vid(fr, *counter);
+ highlight.highlighting_region_vid(fr, renctx.counter);
let type_name = infcx.extract_type_name(&yield_ty, Some(highlight)).0;
let mir_hir_id = tcx.hir().as_local_hir_id(mir_def_id).expect("non-local mir");
@@ -780,16 +837,15 @@
);
Some(RegionName {
- name: self.synthesize_region_name(counter),
+ name: self.synthesize_region_name(renctx),
source: RegionNameSource::AnonRegionFromYieldTy(yield_span, type_name),
})
}
- /// Creates a synthetic region named `'1`, incrementing the
- /// counter.
- fn synthesize_region_name(&self, counter: &mut usize) -> InternedString {
- let c = *counter;
- *counter += 1;
+ /// Creates a synthetic region named `'1`, incrementing the counter.
+ fn synthesize_region_name(&self, renctx: &mut RegionErrorNamingCtx) -> InternedString {
+ let c = renctx.counter;
+ renctx.counter += 1;
InternedString::intern(&format!("'{:?}", c))
}
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
index 4038872..78e7943 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
@@ -1,15 +1,20 @@
-use super::universal_regions::UniversalRegions;
-use crate::borrow_check::nll::constraints::graph::NormalConstraintGraph;
-use crate::borrow_check::nll::constraints::{
- ConstraintSccIndex, OutlivesConstraint, OutlivesConstraintSet,
+use std::rc::Rc;
+
+use crate::borrow_check::nll::{
+ constraints::{
+ graph::NormalConstraintGraph,
+ ConstraintSccIndex,
+ OutlivesConstraint,
+ OutlivesConstraintSet,
+ },
+ member_constraints::{MemberConstraintSet, NllMemberConstraintIndex},
+ region_infer::values::{
+ PlaceholderIndices, RegionElement, ToElementIndex
+ },
+ type_check::{free_region_relations::UniversalRegionRelations, Locations},
};
-use crate::borrow_check::nll::member_constraints::{MemberConstraintSet, NllMemberConstraintIndex};
-use crate::borrow_check::nll::region_infer::values::{
- PlaceholderIndices, RegionElement, ToElementIndex,
-};
-use crate::borrow_check::nll::type_check::free_region_relations::UniversalRegionRelations;
-use crate::borrow_check::nll::type_check::Locations;
use crate::borrow_check::Upvar;
+
use rustc::hir::def_id::DefId;
use rustc::infer::canonical::QueryOutlivesConstraint;
use rustc::infer::opaque_types;
@@ -31,16 +36,16 @@
use rustc_errors::{Diagnostic, DiagnosticBuilder};
use syntax_pos::Span;
-use std::rc::Rc;
+crate use self::error_reporting::{RegionName, RegionNameSource, RegionErrorNamingCtx};
+use self::values::{LivenessValues, RegionValueElements, RegionValues};
+use super::universal_regions::UniversalRegions;
+use super::ToRegionVid;
mod dump_mir;
mod error_reporting;
-crate use self::error_reporting::{RegionName, RegionNameSource};
mod graphviz;
-pub mod values;
-use self::values::{LivenessValues, RegionValueElements, RegionValues};
-use super::ToRegionVid;
+pub mod values;
pub struct RegionInferenceContext<'tcx> {
/// Contains the definition for every region variable. Region
@@ -487,6 +492,12 @@
errors_buffer,
);
+ // If we produce any errors, we keep track of the names of all regions, so that we can use
+ // the same error names in any suggestions we produce. Note that we need names to be unique
+ // across different errors for the same MIR def so that we can make suggestions that fix
+ // multiple problems.
+ let mut region_naming = RegionErrorNamingCtx::new();
+
self.check_universal_regions(
infcx,
body,
@@ -494,6 +505,7 @@
mir_def_id,
outlives_requirements.as_mut(),
errors_buffer,
+ &mut region_naming,
);
self.check_member_constraints(infcx, mir_def_id, errors_buffer);
@@ -1312,6 +1324,7 @@
mir_def_id: DefId,
mut propagated_outlives_requirements: Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
errors_buffer: &mut Vec<Diagnostic>,
+ region_naming: &mut RegionErrorNamingCtx,
) {
for (fr, fr_definition) in self.definitions.iter_enumerated() {
match fr_definition.origin {
@@ -1327,6 +1340,7 @@
fr,
&mut propagated_outlives_requirements,
errors_buffer,
+ region_naming,
);
}
@@ -1358,6 +1372,7 @@
longer_fr: RegionVid,
propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
errors_buffer: &mut Vec<Diagnostic>,
+ region_naming: &mut RegionErrorNamingCtx,
) {
debug!("check_universal_region(fr={:?})", longer_fr);
@@ -1385,6 +1400,7 @@
mir_def_id,
propagated_outlives_requirements,
errors_buffer,
+ region_naming,
);
return;
}
@@ -1401,8 +1417,13 @@
mir_def_id,
propagated_outlives_requirements,
errors_buffer,
+ region_naming,
) {
// continuing to iterate just reports more errors than necessary
+ //
+ // FIXME It would also allow us to report more Outlives Suggestions, though, so
+ // it's not clear that that's a bad thing. Somebody should try commenting out this
+ // line and see it is actually a regression.
return;
}
}
@@ -1418,6 +1439,7 @@
mir_def_id: DefId,
propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
errors_buffer: &mut Vec<Diagnostic>,
+ region_naming: &mut RegionErrorNamingCtx,
) -> Option<ErrorReported> {
// If it is known that `fr: o`, carry on.
if self.universal_region_relations.outlives(longer_fr, shorter_fr) {
@@ -1466,7 +1488,18 @@
//
// Note: in this case, we use the unapproximated regions to report the
// error. This gives better error messages in some cases.
- self.report_error(body, upvars, infcx, mir_def_id, longer_fr, shorter_fr, errors_buffer);
+ let db = self.report_error(
+ body,
+ upvars,
+ infcx,
+ mir_def_id,
+ longer_fr,
+ shorter_fr,
+ region_naming,
+ );
+
+ db.buffer(errors_buffer);
+
Some(ErrorReported)
}
diff --git a/src/test/ui/c-variadic/variadic-ffi-4.nll.stderr b/src/test/ui/c-variadic/variadic-ffi-4.nll.stderr
index 4947d6e..ab8398e 100644
--- a/src/test/ui/c-variadic/variadic-ffi-4.nll.stderr
+++ b/src/test/ui/c-variadic/variadic-ffi-4.nll.stderr
@@ -37,11 +37,11 @@
--> $DIR/variadic-ffi-4.rs:20:5
|
LL | pub unsafe extern "C" fn no_escape3(_: usize, mut ap0: &mut VaListImpl, mut ap1: ...) {
- | ------- ------- has type `core::ffi::VaListImpl<'1>`
+ | ------- ------- has type `core::ffi::VaListImpl<'2>`
| |
- | has type `&mut core::ffi::VaListImpl<'2>`
+ | has type `&mut core::ffi::VaListImpl<'1>`
LL | *ap0 = ap1;
- | ^^^^ assignment requires that `'1` must outlive `'2`
+ | ^^^^ assignment requires that `'2` must outlive `'1`
error: lifetime may not live long enough
--> $DIR/variadic-ffi-4.rs:25:5
@@ -57,11 +57,11 @@
--> $DIR/variadic-ffi-4.rs:25:5
|
LL | pub unsafe extern "C" fn no_escape4(_: usize, ap0: &mut VaListImpl, mut ap1: ...) {
- | --- ------- has type `core::ffi::VaListImpl<'1>`
+ | --- ------- has type `core::ffi::VaListImpl<'2>`
| |
- | has type `&mut core::ffi::VaListImpl<'2>`
+ | has type `&mut core::ffi::VaListImpl<'1>`
LL | ap0 = &mut ap1;
- | ^^^^^^^^^^^^^^ assignment requires that `'1` must outlive `'2`
+ | ^^^^^^^^^^^^^^ assignment requires that `'2` must outlive `'1`
error[E0384]: cannot assign to immutable argument `ap0`
--> $DIR/variadic-ffi-4.rs:25:5
@@ -99,11 +99,11 @@
--> $DIR/variadic-ffi-4.rs:33:12
|
LL | pub unsafe extern "C" fn no_escape5(_: usize, mut ap0: &mut VaListImpl, mut ap1: ...) {
- | ------- ------- has type `core::ffi::VaListImpl<'1>`
+ | ------- ------- has type `core::ffi::VaListImpl<'2>`
| |
- | has type `&mut core::ffi::VaListImpl<'2>`
+ | has type `&mut core::ffi::VaListImpl<'1>`
LL | *ap0 = ap1.clone();
- | ^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
+ | ^^^^^^^^^^^ argument requires that `'2` must outlive `'1`
error: aborting due to 11 previous errors
diff --git a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-3.nll.stderr b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-3.nll.stderr
index 779e2eb..2ed4d6d 100644
--- a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-3.nll.stderr
+++ b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-3.nll.stderr
@@ -12,11 +12,11 @@
--> $DIR/ex3-both-anon-regions-3.rs:2:5
|
LL | fn foo(z: &mut Vec<(&u8,&u8)>, (x, y): (&u8, &u8)) {
- | - - let's call the lifetime of this reference `'1`
+ | - - let's call the lifetime of this reference `'3`
| |
- | let's call the lifetime of this reference `'2`
+ | let's call the lifetime of this reference `'4`
LL | z.push((x,y));
- | ^^^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
+ | ^^^^^^^^^^^^^ argument requires that `'3` must outlive `'4`
error: aborting due to 2 previous errors
