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resolve: account for general or-patterns in consistency checking.

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This commit is contained in:
Mazdak Farrokhzad 2019-09-01 22:52:02 +02:00
parent 498ec59520
commit 896a1c7fcd
3 changed files with 91 additions and 47 deletions
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123
src/librustc_resolve/late.rs
View file

@ -1112,6 +1112,7 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
let mut bindings = smallvec![(false, <_>::default())];
for Param { pat, ty, .. } in params {
self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
self.check_consistent_bindings_top(pat);
self.visit_ty(ty);
debug!("(resolving function / closure) recorded parameter");
}
@ -1128,69 +1129,90 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
self.resolve_pattern_top(&local.pat, PatternSource::Let);
}
// build a map from pattern identifiers to binding-info's.
// this is done hygienically. This could arise for a macro
// that expands into an or-pattern where one 'x' was from the
// user and one 'x' came from the macro.
/// build a map from pattern identifiers to binding-info's.
/// this is done hygienically. This could arise for a macro
/// that expands into an or-pattern where one 'x' was from the
/// user and one 'x' came from the macro.
fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
let mut binding_map = FxHashMap::default();
pat.walk(&mut |pat| {
if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
if sub_pat.is_some() || match self.r.partial_res_map.get(&pat.id)
.map(|res| res.base_res()) {
Some(Res::Local(..)) => true,
_ => false,
} {
let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
binding_map.insert(ident, binding_info);
match pat.node {
PatKind::Ident(binding_mode, ident, ref sub_pat)
if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
{
binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
}
PatKind::Or(ref ps) => {
// Check the consistency of this or-pattern and
// then add all bindings to the larger map.
for bm in self.check_consistent_bindings(ps) {
binding_map.extend(bm);
}
return false;
}
_ => {}
}
true
});
binding_map
}
// Checks that all of the arms in an or-pattern have exactly the
// same set of bindings, with the same binding modes for each.
fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) {
fn is_base_res_local(&self, nid: NodeId) -> bool {
match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
Some(Res::Local(..)) => true,
_ => false,
}
}
/// Checks that all of the arms in an or-pattern have exactly the
/// same set of bindings, with the same binding modes for each.
fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
let mut missing_vars = FxHashMap::default();
let mut inconsistent_vars = FxHashMap::default();
for pat_outer in pats.iter() {
let map_outer = self.binding_mode_map(&pat_outer);
// 1) Compute the binding maps of all arms.
let maps = pats.iter()
.map(|pat| self.binding_mode_map(pat))
.collect::<Vec<_>>();
for pat_inner in pats.iter().filter(|pat| pat.id != pat_outer.id) {
let map_inner = self.binding_mode_map(&pat_inner);
// 2) Record any missing bindings or binding mode inconsistencies.
for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
// Check against all arms except for the same pattern which is always self-consistent.
let inners = pats.iter().enumerate()
.filter(|(_, pat)| pat.id != pat_outer.id)
.flat_map(|(idx, _)| maps[idx].iter())
.map(|(key, binding)| (key.name, map_outer.get(&key), binding));
for (&key_inner, &binding_inner) in map_inner.iter() {
match map_outer.get(&key_inner) {
None => { // missing binding
let binding_error = missing_vars
.entry(key_inner.name)
.or_insert(BindingError {
name: key_inner.name,
origin: BTreeSet::new(),
target: BTreeSet::new(),
could_be_path:
key_inner.name.as_str().starts_with(char::is_uppercase)
});
binding_error.origin.insert(binding_inner.span);
binding_error.target.insert(pat_outer.span);
}
Some(binding_outer) => { // check consistent binding
if binding_outer.binding_mode != binding_inner.binding_mode {
inconsistent_vars
.entry(key_inner.name)
.or_insert((binding_inner.span, binding_outer.span));
}
for (name, info, &binding_inner) in inners {
match info {
None => { // The inner binding is missing in the outer.
let binding_error = missing_vars
.entry(name)
.or_insert_with(|| BindingError {
name,
origin: BTreeSet::new(),
target: BTreeSet::new(),
could_be_path: name.as_str().starts_with(char::is_uppercase),
});
binding_error.origin.insert(binding_inner.span);
binding_error.target.insert(pat_outer.span);
}
Some(binding_outer) => {
if binding_outer.binding_mode != binding_inner.binding_mode {
// The binding modes in the outer and inner bindings differ.
inconsistent_vars
.entry(name)
.or_insert((binding_inner.span, binding_outer.span));
}
}
}
}
}
// 3) Report all missing variables we found.
let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
missing_vars.sort();
for (name, mut v) in missing_vars {
@ -1202,11 +1224,26 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
ResolutionError::VariableNotBoundInPattern(v));
}
// 4) Report all inconsistencies in binding modes we found.
let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
inconsistent_vars.sort();
for (name, v) in inconsistent_vars {
self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
}
// 5) Finally bubble up all the binding maps.
maps
}
/// Check the consistency of the outermost or-patterns.
fn check_consistent_bindings_top(&mut self, pat: &Pat) {
pat.walk(&mut |pat| match pat.node {
PatKind::Or(ref ps) => {
self.check_consistent_bindings(ps);
false
},
_ => true,
})
}
fn resolve_arm(&mut self, arm: &Arm) {
@ -1227,13 +1264,13 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
bindings.last_mut().unwrap().1.extend(collected);
}
// This has to happen *after* we determine which pat_idents are variants
if pats.len() > 1 {
self.check_consistent_bindings(pats);
}
self.check_consistent_bindings(pats);
}
fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) {
self.resolve_pattern(pat, pat_src, &mut smallvec![(false, <_>::default())]);
// This has to happen *after* we determine which pat_idents are variants:
self.check_consistent_bindings_top(pat);
}
fn resolve_pattern(

1
src/test/ui/or-patterns/already-bound-name.rs
View file

@ -38,6 +38,7 @@ fn main() {
let B(_) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
//~^ ERROR identifier `a` is bound more than once in the same pattern
//~| ERROR identifier `a` is bound more than once in the same pattern
//~| ERROR variable `a` is not bound in all patterns
let B(A(a, _) | B(a)) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
//~^ ERROR identifier `a` is bound more than once in the same pattern

14
src/test/ui/or-patterns/already-bound-name.stderr
View file

@ -64,14 +64,20 @@ error[E0416]: identifier `a` is bound more than once in the same pattern
LL | let B(_) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
| ^ used in a pattern more than once
error[E0408]: variable `a` is not bound in all patterns
--> $DIR/already-bound-name.rs:38:9
|
LL | let B(_) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
| ^^^^ pattern doesn't bind `a` - variable not in all patterns
error[E0416]: identifier `a` is bound more than once in the same pattern
--> $DIR/already-bound-name.rs:42:49
--> $DIR/already-bound-name.rs:43:49
|
LL | let B(A(a, _) | B(a)) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
| ^ used in a pattern more than once
error[E0416]: identifier `a` is bound more than once in the same pattern
--> $DIR/already-bound-name.rs:42:59
--> $DIR/already-bound-name.rs:43:59
|
LL | let B(A(a, _) | B(a)) | A(A(a, _) | B(a), A(a, _) | B(a)) = B(B(1));
| ^ used in a pattern more than once
@ -85,7 +91,7 @@ LL | let B(A(a, _) | B(a)) | A(a, A(a, _) | B(a)) = B(B(1));
= note: expected type `{integer}`
found type `E<{integer}>`
error: aborting due to 14 previous errors
error: aborting due to 15 previous errors
Some errors have detailed explanations: E0308, E0416.
Some errors have detailed explanations: E0308, E0408, E0416.
For more information about an error, try `rustc --explain E0308`.