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Rollup merge of rust-lang#47420 - davidtwco:issue-46885, r=estebank
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Fix off-by-one spans in MIR borrowck errors

Fixes rust-lang#46885.

r? @nikomatsakis
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GuillaumeGomez authored Jan 19, 2018
2 parents df40c4a + a1b72f7 commit ac75587
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Showing 24 changed files with 123 additions and 48 deletions.
3 changes: 2 additions & 1 deletion src/librustc/infer/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -958,7 +958,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
// `sp` only covers `T`, change it so that it covers
// `T:` when appropriate
let sp = if has_lifetimes {
sp.to(sp.next_point().next_point())
sp.to(self.tcx.sess.codemap().next_point(
self.tcx.sess.codemap().next_point(sp)))
} else {
sp
};
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4 changes: 2 additions & 2 deletions src/librustc_borrowck/borrowck/check_loans.rs
Original file line number Diff line number Diff line change
Expand Up @@ -484,8 +484,8 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
// 3. Where does old loan expire.

let previous_end_span =
Some(old_loan.kill_scope.span(self.tcx(), &self.bccx.region_scope_tree)
.end_point());
Some(self.tcx().sess.codemap().end_point(
old_loan.kill_scope.span(self.tcx(), &self.bccx.region_scope_tree)));

let mut err = match (new_loan.kind, old_loan.kind) {
(ty::MutBorrow, ty::MutBorrow) =>
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3 changes: 2 additions & 1 deletion src/librustc_borrowck/borrowck/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1343,7 +1343,8 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
fn region_end_span(&self, region: ty::Region<'tcx>) -> Option<Span> {
match *region {
ty::ReScope(scope) => {
Some(scope.span(self.tcx, &self.region_scope_tree).end_point())
Some(self.tcx.sess.codemap().end_point(
scope.span(self.tcx, &self.region_scope_tree)))
}
_ => None
}
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3 changes: 2 additions & 1 deletion src/librustc_mir/borrow_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1090,10 +1090,11 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
debug!("check_for_invalidation_at_exit({:?}): INVALID", place);
// FIXME: should be talking about the region lifetime instead
// of just a span here.
let span = self.tcx.sess.codemap().end_point(span);
self.report_borrowed_value_does_not_live_long_enough(
context,
borrow,
span.end_point(),
span,
flow_state.borrows.operator(),
)
}
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6 changes: 4 additions & 2 deletions src/librustc_mir/build/scope.rs
Original file line number Diff line number Diff line change
Expand Up @@ -695,10 +695,12 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
if let DropKind::Value { .. } = drop_kind {
scope.needs_cleanup = true;
}

let region_scope_span = region_scope.span(self.hir.tcx(),
&self.hir.region_scope_tree);
// Attribute scope exit drops to scope's closing brace
let scope_end = region_scope_span.with_lo(region_scope_span.hi());
// Attribute scope exit drops to scope's closing brace.
let scope_end = self.hir.tcx().sess.codemap().end_point(region_scope_span);

scope.drops.push(DropData {
span: scope_end,
location: place.clone(),
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4 changes: 2 additions & 2 deletions src/librustc_mir/dataflow/impls/borrows.rs
Original file line number Diff line number Diff line change
Expand Up @@ -537,8 +537,8 @@ impl<'a, 'gcx, 'tcx> ActiveBorrows<'a, 'gcx, 'tcx> {
Some(_) => None,
None => {
match self.0.region_span_map.get(region) {
Some(span) => Some(span.end_point()),
None => Some(self.0.mir.span.end_point())
Some(span) => Some(self.0.tcx.sess.codemap().end_point(*span)),
None => Some(self.0.tcx.sess.codemap().end_point(self.0.mir.span))
}
}
}
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4 changes: 2 additions & 2 deletions src/librustc_resolve/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2791,8 +2791,8 @@ impl<'a> Resolver<'a> {
if let Some(sp) = self.current_type_ascription.last() {
let mut sp = *sp;
loop { // try to find the `:`, bail on first non-':'/non-whitespace
sp = sp.next_point();
if let Ok(snippet) = cm.span_to_snippet(sp.to(sp.next_point())) {
sp = cm.next_point(sp);
if let Ok(snippet) = cm.span_to_snippet(sp.to(cm.next_point(sp))) {
debug!("snippet {:?}", snippet);
let line_sp = cm.lookup_char_pos(sp.hi()).line;
let line_base_sp = cm.lookup_char_pos(base_span.lo()).line;
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12 changes: 6 additions & 6 deletions src/librustc_typeck/check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2410,7 +2410,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
err.span_label(def_s, "defined here");
}
if sugg_unit {
let sugg_span = expr_sp.end_point();
let sugg_span = sess.codemap().end_point(expr_sp);
// remove closing `)` from the span
let sugg_span = sugg_span.with_hi(sugg_span.lo());
err.span_suggestion(
Expand Down Expand Up @@ -4400,10 +4400,10 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
/// statement and the return type has been left as default or has been specified as `()`. If so,
/// it suggests adding a semicolon.
fn suggest_missing_semicolon(&self,
err: &mut DiagnosticBuilder<'tcx>,
expression: &'gcx hir::Expr,
expected: Ty<'tcx>,
cause_span: Span) {
err: &mut DiagnosticBuilder<'tcx>,
expression: &'gcx hir::Expr,
expected: Ty<'tcx>,
cause_span: Span) {
if expected.is_nil() {
// `BlockTailExpression` only relevant if the tail expr would be
// useful on its own.
Expand All @@ -4415,7 +4415,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
hir::ExprLoop(..) |
hir::ExprMatch(..) |
hir::ExprBlock(..) => {
let sp = cause_span.next_point();
let sp = self.tcx.sess.codemap().next_point(cause_span);
err.span_suggestion(sp,
"try adding a semicolon",
";".to_string());
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82 changes: 82 additions & 0 deletions src/libsyntax/codemap.rs
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ pub use self::ExpnFormat::*;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::stable_hasher::StableHasher;
use std::cell::{RefCell, Ref};
use std::cmp;
use std::hash::Hash;
use std::path::{Path, PathBuf};
use std::rc::Rc;
Expand Down Expand Up @@ -607,6 +608,87 @@ impl CodeMap {
self.span_until_char(sp, '{')
}

/// Returns a new span representing just the end-point of this span
pub fn end_point(&self, sp: Span) -> Span {
let pos = sp.hi().0;

let width = self.find_width_of_character_at_span(sp, false);
let corrected_end_position = pos.checked_sub(width).unwrap_or(pos);

let end_point = BytePos(cmp::max(corrected_end_position, sp.lo().0));
sp.with_lo(end_point)
}

/// Returns a new span representing the next character after the end-point of this span
pub fn next_point(&self, sp: Span) -> Span {
let start_of_next_point = sp.hi().0;

let width = self.find_width_of_character_at_span(sp, true);
// If the width is 1, then the next span should point to the same `lo` and `hi`. However,
// in the case of a multibyte character, where the width != 1, the next span should
// span multiple bytes to include the whole character.
let end_of_next_point = start_of_next_point.checked_add(
width - 1).unwrap_or(start_of_next_point);

let end_of_next_point = BytePos(cmp::max(sp.lo().0 + 1, end_of_next_point));
Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt())
}

/// Finds the width of a character, either before or after the provided span.
fn find_width_of_character_at_span(&self, sp: Span, forwards: bool) -> u32 {
// Disregard malformed spans and assume a one-byte wide character.
if sp.lo() >= sp.hi() {
return 1;
}

let local_begin = self.lookup_byte_offset(sp.lo());
let local_end = self.lookup_byte_offset(sp.hi());

let start_index = local_begin.pos.to_usize();
let end_index = local_end.pos.to_usize();

// Disregard indexes that are at the start or end of their spans, they can't fit bigger
// characters.
if (!forwards && end_index == usize::min_value()) ||
(forwards && start_index == usize::max_value()) {
return 1;
}

let source_len = (local_begin.fm.end_pos - local_begin.fm.start_pos).to_usize();
// Ensure indexes are also not malformed.
if start_index > end_index || end_index > source_len {
return 1;
}

// We need to extend the snippet to the end of the src rather than to end_index so when
// searching forwards for boundaries we've got somewhere to search.
let snippet = if let Some(ref src) = local_begin.fm.src {
let len = src.len();
(&src[start_index..len]).to_string()
} else if let Some(src) = local_begin.fm.external_src.borrow().get_source() {
let len = src.len();
(&src[start_index..len]).to_string()
} else {
return 1;
};
debug!("DTW start {:?} end {:?}", start_index, end_index);
debug!("DTW snippet {:?}", snippet);

let mut target = if forwards { end_index + 1 } else { end_index - 1 };
debug!("DTW initial target {:?}", target);
while !snippet.is_char_boundary(target - start_index) {
target = if forwards { target + 1 } else { target - 1 };
debug!("DTW update target {:?}", target);
}
debug!("DTW final target {:?}", target);

if forwards {
(target - end_index) as u32
} else {
(end_index - target) as u32
}
}

pub fn get_filemap(&self, filename: &FileName) -> Option<Rc<FileMap>> {
for fm in self.files.borrow().iter() {
if *filename == fm.name {
Expand Down
8 changes: 5 additions & 3 deletions src/libsyntax/parse/parser.rs
Original file line number Diff line number Diff line change
Expand Up @@ -704,13 +704,15 @@ impl<'a> Parser<'a> {
expect.clone()
};
(format!("expected one of {}, found `{}`", expect, actual),
(self.prev_span.next_point(), format!("expected one of {} here", short_expect)))
(self.sess.codemap().next_point(self.prev_span),
format!("expected one of {} here", short_expect)))
} else if expected.is_empty() {
(format!("unexpected token: `{}`", actual),
(self.prev_span, "unexpected token after this".to_string()))
} else {
(format!("expected {}, found `{}`", expect, actual),
(self.prev_span.next_point(), format!("expected {} here", expect)))
(self.sess.codemap().next_point(self.prev_span),
format!("expected {} here", expect)))
};
let mut err = self.fatal(&msg_exp);
let sp = if self.token == token::Token::Eof {
Expand Down Expand Up @@ -3210,7 +3212,7 @@ impl<'a> Parser<'a> {
// return. This won't catch blocks with an explicit `return`, but that would be caught by
// the dead code lint.
if self.eat_keyword(keywords::Else) || !cond.returns() {
let sp = lo.next_point();
let sp = self.sess.codemap().next_point(lo);
let mut err = self.diagnostic()
.struct_span_err(sp, "missing condition for `if` statemement");
err.span_label(sp, "expected if condition here");
Expand Down
14 changes: 0 additions & 14 deletions src/libsyntax_pos/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -216,20 +216,6 @@ impl Span {
self.data().with_ctxt(ctxt)
}

/// Returns a new span representing just the end-point of this span
pub fn end_point(self) -> Span {
let span = self.data();
let lo = cmp::max(span.hi.0 - 1, span.lo.0);
span.with_lo(BytePos(lo))
}

/// Returns a new span representing the next character after the end-point of this span
pub fn next_point(self) -> Span {
let span = self.data();
let lo = cmp::max(span.hi.0, span.lo.0 + 1);
Span::new(BytePos(lo), BytePos(lo), span.ctxt)
}

/// Returns `self` if `self` is not the dummy span, and `other` otherwise.
pub fn substitute_dummy(self, other: Span) -> Span {
if self.source_equal(&DUMMY_SP) { other } else { self }
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2 changes: 1 addition & 1 deletion src/test/ui/issue-46471-1.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ error[E0597]: `z` does not live long enough (Mir)
16 | &mut z
| ^^^^^^ borrowed value does not live long enough
17 | };
| - `z` dropped here while still borrowed
| - `z` dropped here while still borrowed
...
21 | }
| - borrowed value needs to live until here
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issue-46471.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ error[E0597]: `x` does not live long enough (Mir)
| ^^ borrowed value does not live long enough
...
18 | }
| - borrowed value only lives until here
| - borrowed value only lives until here
|
= note: borrowed value must be valid for the static lifetime...

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/issue-46472.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ error[E0597]: borrowed value does not live long enough (Mir)
| ^ temporary value does not live long enough
...
17 | }
| - temporary value only lives until here
| - temporary value only lives until here
|
note: borrowed value must be valid for the lifetime 'a as defined on the function body at 13:1...
--> $DIR/issue-46472.rs:13:1
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2 changes: 1 addition & 1 deletion src/test/ui/nll/capture-ref-in-struct.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ error[E0597]: `y` does not live long enough
| ^^ borrowed value does not live long enough
...
38 | }
| - borrowed value only lives until here
| - borrowed value only lives until here
39 |
40 | deref(p);
| - borrow later used here
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ error[E0597]: `y` does not live long enough
| ^^ borrowed value does not live long enough
38 | //~^ ERROR `y` does not live long enough [E0597]
39 | }
| - borrowed value only lives until here
| - borrowed value only lives until here
40 |
41 | deref(p);
| - borrow later used here
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@ error[E0597]: `y` does not live long enough
| |_________^ borrowed value does not live long enough
...
36 | }
| - borrowed value only lives until here
| - borrowed value only lives until here
37 |
38 | deref(p);
| - borrow later used here
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ error[E0597]: `y` does not live long enough
| ^^^^^^^^^ borrowed value does not live long enough
...
36 | }
| - borrowed value only lives until here
| - borrowed value only lives until here
37 |
38 | deref(p);
| - borrow later used here
Expand Down
4 changes: 2 additions & 2 deletions src/test/ui/nll/drop-no-may-dangle.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ error[E0506]: cannot assign to `v[..]` because it is borrowed
| ^^^^^^^^^ assignment to borrowed `v[..]` occurs here
...
35 | }
| - borrow later used here, when `p` is dropped
| - borrow later used here, when `p` is dropped

error[E0506]: cannot assign to `v[..]` because it is borrowed
--> $DIR/drop-no-may-dangle.rs:34:5
Expand All @@ -19,7 +19,7 @@ error[E0506]: cannot assign to `v[..]` because it is borrowed
34 | v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
| ^^^^^^^^^ assignment to borrowed `v[..]` occurs here
35 | }
| - borrow later used here, when `p` is dropped
| - borrow later used here, when `p` is dropped

error: aborting due to 2 previous errors

Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ error[E0506]: cannot assign to `x` because it is borrowed
| ^^^^^ assignment to borrowed `x` occurs here
33 | // FIXME ^ Should not error in the future with implicit dtors, only manually implemented ones
34 | }
| - borrow later used here, when `foo` is dropped
| - borrow later used here, when `foo` is dropped

error: aborting due to previous error

Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ error[E0506]: cannot assign to `x` because it is borrowed
31 | x = 1; //~ ERROR cannot assign to `x` because it is borrowed [E0506]
| ^^^^^ assignment to borrowed `x` occurs here
32 | }
| - borrow later used here, when `foo` is dropped
| - borrow later used here, when `foo` is dropped

error: aborting due to previous error

Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ error[E0506]: cannot assign to `x` because it is borrowed
| ^^^^^ assignment to borrowed `x` occurs here
33 | // FIXME ^ This currently errors and it should not.
34 | }
| - borrow later used here, when `foo` is dropped
| - borrow later used here, when `foo` is dropped

error: aborting due to previous error

2 changes: 1 addition & 1 deletion src/test/ui/nll/maybe-initialized-drop.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ error[E0506]: cannot assign to `x` because it is borrowed
26 | x = 1; //~ ERROR cannot assign to `x` because it is borrowed [E0506]
| ^^^^^ assignment to borrowed `x` occurs here
27 | }
| - borrow later used here, when `wrap` is dropped
| - borrow later used here, when `wrap` is dropped

error: aborting due to previous error

2 changes: 1 addition & 1 deletion src/test/ui/nll/return-ref-mut-issue-46557.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ error[E0597]: borrowed value does not live long enough
| ^^^^^^^ temporary value does not live long enough
18 | x
19 | }
| - temporary value only lives until here
| - temporary value only lives until here
|
= note: borrowed value must be valid for lifetime '_#2r...

Expand Down

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