From 5187ad143975ca082d7e4780967783cfc33de565 Mon Sep 17 00:00:00 2001 From: David Wood Date: Mon, 6 Aug 2018 21:15:15 +0200 Subject: [PATCH 1/2] Correctly identify named early bound regions. --- .../nice_region_error/named_anon_conflict.rs | 2 +- src/librustc/ty/mod.rs | 8 ++++- .../error_reporting/region_name.rs | 8 +++-- src/test/ui/nll/issue-52742.rs | 30 +++++++++++++++++++ src/test/ui/nll/issue-52742.stderr | 12 ++++++++ 5 files changed, 56 insertions(+), 4 deletions(-) create mode 100644 src/test/ui/nll/issue-52742.rs create mode 100644 src/test/ui/nll/issue-52742.stderr diff --git a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs index 51abfa2505ab5..457e20eddf7c5 100644 --- a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs +++ b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs @@ -127,7 +127,7 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> { ty::BrNamed(..) => true, _ => false, }, - ty::ReEarlyBound(_) => true, + ty::ReEarlyBound(ebr) => ebr.has_name(), _ => false, } } diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs index 4fda3bdca3dfc..d7e30b0ca7143 100644 --- a/src/librustc/ty/mod.rs +++ b/src/librustc/ty/mod.rs @@ -51,7 +51,7 @@ use std::{mem, ptr}; use syntax::ast::{self, DUMMY_NODE_ID, Name, Ident, NodeId}; use syntax::attr; use syntax::ext::hygiene::Mark; -use syntax::symbol::{Symbol, LocalInternedString, InternedString}; +use syntax::symbol::{keywords, Symbol, LocalInternedString, InternedString}; use syntax_pos::{DUMMY_SP, Span}; use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter; @@ -824,6 +824,12 @@ impl ty::EarlyBoundRegion { pub fn to_bound_region(&self) -> ty::BoundRegion { ty::BoundRegion::BrNamed(self.def_id, self.name) } + + /// Does this early bound region have a name? Early bound regions normally + /// always have names except when using anonymous lifetimes (`'_`). + pub fn has_name(&self) -> bool { + self.name != keywords::UnderscoreLifetime.name().as_interned_str() + } } #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] 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 79165276430d3..e2937e3048ccc 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 @@ -94,8 +94,12 @@ impl<'tcx> RegionInferenceContext<'tcx> { debug!("give_region_a_name: error_region = {:?}", error_region); match error_region { ty::ReEarlyBound(ebr) => { - self.highlight_named_span(tcx, error_region, &ebr.name, diag); - Some(ebr.name) + if ebr.has_name() { + self.highlight_named_span(tcx, error_region, &ebr.name, diag); + Some(ebr.name) + } else { + None + } }, ty::ReStatic => Some(keywords::StaticLifetime.name().as_interned_str()), diff --git a/src/test/ui/nll/issue-52742.rs b/src/test/ui/nll/issue-52742.rs new file mode 100644 index 0000000000000..84d06a1d20aac --- /dev/null +++ b/src/test/ui/nll/issue-52742.rs @@ -0,0 +1,30 @@ +// Copyright 2012 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(nll)] +#![feature(in_band_lifetimes)] + +struct Foo<'a, 'b> { + x: &'a u32, + y: &'b u32, +} + +struct Bar<'b> { + z: &'b u32 +} + +impl Foo<'_, '_> { + fn take_bar(&mut self, b: Bar<'_>) { + self.y = b.z + //~^ ERROR unsatisfied lifetime constraints + } +} + +fn main() { } diff --git a/src/test/ui/nll/issue-52742.stderr b/src/test/ui/nll/issue-52742.stderr new file mode 100644 index 0000000000000..89c235c4e8f9e --- /dev/null +++ b/src/test/ui/nll/issue-52742.stderr @@ -0,0 +1,12 @@ +error: unsatisfied lifetime constraints + --> $DIR/issue-52742.rs:25:9 + | +LL | fn take_bar(&mut self, b: Bar<'_>) { + | --------- -- let's call this `'1` + | | + | lifetime `'2` appears in this type +LL | self.y = b.z + | ^^^^^^^^^^^^ requires that `'1` must outlive `'2` + +error: aborting due to previous error + From 12037ff14869ae3631f9fa7777c081fda8edbf0c Mon Sep 17 00:00:00 2001 From: David Wood Date: Mon, 6 Aug 2018 23:09:36 +0200 Subject: [PATCH 2/2] Fallback to 'has type' error messages rather than 'lifetime appears in type'. --- .../error_reporting/region_name.rs | 34 +++++-------------- src/test/ui/nll/issue-52742.stderr | 2 +- 2 files changed, 10 insertions(+), 26 deletions(-) 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 e2937e3048ccc..7ccea451c501b 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 @@ -208,17 +208,14 @@ impl<'tcx> RegionInferenceContext<'tcx> { return Some(region_name); } - let (_argument_name, argument_span) = self.get_argument_name_and_span_for_region( - mir, argument_index); - - let region_name = self.synthesize_region_name(counter); - - diag.span_label( - argument_span, - format!("lifetime `{}` appears in this argument", region_name,), - ); - - Some(region_name) + self.give_name_if_we_cannot_match_hir_ty( + infcx, + mir, + fr, + arg_ty, + counter, + diag, + ) } fn give_name_if_we_can_match_hir_ty_from_argument( @@ -336,14 +333,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { search_stack.push((argument_ty, argument_hir_ty)); - let mut closest_match: &hir::Ty = argument_hir_ty; - while let Some((ty, hir_ty)) = search_stack.pop() { - // While we search, also track the closet match. - if tcx.any_free_region_meets(&ty, |r| r.to_region_vid() == needle_fr) { - closest_match = hir_ty; - } - match (&ty.sty, &hir_ty.node) { // Check if the `argument_ty` is `&'X ..` where `'X` // is the region we are looking for -- if so, and we have a `&T` @@ -418,13 +408,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { } } - let region_name = self.synthesize_region_name(counter); - diag.span_label( - closest_match.span, - format!("lifetime `{}` appears in this type", region_name), - ); - - return Some(region_name); + return None; } /// We've found an enum/struct/union type with the substitutions diff --git a/src/test/ui/nll/issue-52742.stderr b/src/test/ui/nll/issue-52742.stderr index 89c235c4e8f9e..d1b830b9dfc29 100644 --- a/src/test/ui/nll/issue-52742.stderr +++ b/src/test/ui/nll/issue-52742.stderr @@ -4,7 +4,7 @@ error: unsatisfied lifetime constraints LL | fn take_bar(&mut self, b: Bar<'_>) { | --------- -- let's call this `'1` | | - | lifetime `'2` appears in this type + | has type `&mut Foo<'_, '2>` LL | self.y = b.z | ^^^^^^^^^^^^ requires that `'1` must outlive `'2`