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Auto merge of #29547 - arielb1:speculative-upvar, r=eddyb
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`resolve_identifier` used to mark a variable as an upvar when used within a closure. However, the function is also used for the "unnecessary qualification" lint, which would mark paths whose last component had the same name as a local as upvars.

Fixes #29522 

r? @eddyb
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@bors
bors committed Nov 4, 2015
2 parents 708e319 + ca04855 commit c340ea1
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Showing 3 changed files with 194 additions and 151 deletions.
300 changes: 149 additions & 151 deletions src/librustc_resolve/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ use rustc::front::map as hir_map;
use rustc::session::Session;
use rustc::lint;
use rustc::metadata::csearch;
use rustc::metadata::decoder::{DefLike, DlDef, DlField, DlImpl};
use rustc::metadata::decoder::{DefLike, DlDef};
use rustc::middle::def::*;
use rustc::middle::def_id::DefId;
use rustc::middle::pat_util::pat_bindings_hygienic;
Expand Down Expand Up @@ -652,6 +652,21 @@ impl Rib {
}
}

/// A definition along with the index of the rib it was found on
struct LocalDef {
ribs: Option<(Namespace, usize)>,
def: Def
}

impl LocalDef {
fn from_def(def: Def) -> Self {
LocalDef {
ribs: None,
def: def
}
}
}

/// The link from a module up to its nearest parent node.
#[derive(Clone,Debug)]
enum ParentLink {
Expand Down Expand Up @@ -1954,116 +1969,6 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
self.current_module = orig_module;
}

/// Wraps the given definition in the appropriate number of `DefUpvar`
/// wrappers.
fn upvarify(&self,
ribs: &[Rib],
def_like: DefLike,
span: Span)
-> Option<DefLike> {
let mut def = match def_like {
DlDef(def) => def,
_ => return Some(def_like)
};
match def {
DefUpvar(..) => {
self.session.span_bug(span,
&format!("unexpected {:?} in bindings", def))
}
DefLocal(_, node_id) => {
for rib in ribs {
match rib.kind {
NormalRibKind => {
// Nothing to do. Continue.
}
ClosureRibKind(function_id) => {
let prev_def = def;
let node_def_id = self.ast_map.local_def_id(node_id);

let mut seen = self.freevars_seen.borrow_mut();
let seen = seen.entry(function_id).or_insert_with(|| NodeMap());
if let Some(&index) = seen.get(&node_id) {
def = DefUpvar(node_def_id, node_id, index, function_id);
continue;
}
let mut freevars = self.freevars.borrow_mut();
let vec = freevars.entry(function_id)
.or_insert_with(|| vec![]);
let depth = vec.len();
vec.push(Freevar { def: prev_def, span: span });

def = DefUpvar(node_def_id, node_id, depth, function_id);
seen.insert(node_id, depth);
}
ItemRibKind | MethodRibKind => {
// This was an attempt to access an upvar inside a
// named function item. This is not allowed, so we
// report an error.
resolve_error(
self,
span,
ResolutionError::CannotCaptureDynamicEnvironmentInFnItem
);
return None;
}
ConstantItemRibKind => {
// Still doesn't deal with upvars
resolve_error(
self,
span,
ResolutionError::AttemptToUseNonConstantValueInConstant
);
return None;
}
}
}
}
DefTyParam(..) | DefSelfTy(..) => {
for rib in ribs {
match rib.kind {
NormalRibKind | MethodRibKind | ClosureRibKind(..) => {
// Nothing to do. Continue.
}
ItemRibKind => {
// This was an attempt to use a type parameter outside
// its scope.

resolve_error(self,
span,
ResolutionError::TypeParametersFromOuterFunction);
return None;
}
ConstantItemRibKind => {
// see #9186
resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
return None;
}
}
}
}
_ => {}
}
Some(DlDef(def))
}

/// Searches the current set of local scopes and
/// applies translations for closures.
fn search_ribs(&self,
ribs: &[Rib],
name: Name,
span: Span)
-> Option<DefLike> {
// FIXME #4950: Try caching?

for (i, rib) in ribs.iter().enumerate().rev() {
if let Some(def_like) = rib.bindings.get(&name).cloned() {
return self.upvarify(&ribs[i + 1..], def_like, span);
}
}

None
}

/// Searches the current set of local scopes for labels.
/// Stops after meeting a closure.
fn search_label(&self, name: Name) -> Option<DefLike> {
Expand Down Expand Up @@ -3123,19 +3028,21 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
}

// Try to find a path to an item in a module.
let unqualified_def =
self.resolve_identifier(segments.last().unwrap().identifier,
namespace,
check_ribs,
span);
let unqualified_def = self.resolve_identifier(
segments.last().unwrap().identifier,
namespace, check_ribs);

if segments.len() <= 1 {
return unqualified_def.map(mk_res);
return unqualified_def
.and_then(|def| self.adjust_local_def(def, span))
.map(|def| {
PathResolution::new(def, LastMod(AllPublic), path_depth)
});
}

let def = self.resolve_module_relative_path(span, segments, namespace);
match (def, unqualified_def) {
(Some((ref d, _)), Some((ref ud, _))) if *d == *ud => {
(Some((ref d, _)), Some(ref ud)) if *d == ud.def => {
self.session
.add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
id, span,
Expand All @@ -3147,31 +3054,119 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
def.map(mk_res)
}

// Resolve a single identifier.
// Resolve a single identifier
fn resolve_identifier(&mut self,
identifier: Ident,
namespace: Namespace,
check_ribs: bool,
span: Span)
-> Option<(Def, LastPrivate)> {
check_ribs: bool)
-> Option<LocalDef> {
// First, check to see whether the name is a primitive type.
if namespace == TypeNS {
if let Some(&prim_ty) = self.primitive_type_table
.primitive_types
.get(&identifier.name) {
return Some((DefPrimTy(prim_ty), LastMod(AllPublic)));
return Some(LocalDef::from_def(DefPrimTy(prim_ty)));
}
}

if check_ribs {
if let Some(def) = self.resolve_identifier_in_local_ribs(identifier,
namespace,
span) {
return Some((def, LastMod(AllPublic)));
namespace) {
return Some(def);
}
}

self.resolve_item_by_name_in_lexical_scope(identifier.name, namespace)
.map(LocalDef::from_def)
}

// Resolve a local definition, potentially adjusting for closures.
fn adjust_local_def(&self, local_def: LocalDef, span: Span) -> Option<Def> {
let ribs = match local_def.ribs {
Some((TypeNS, i)) => &self.type_ribs[i+1..],
Some((ValueNS, i)) => &self.value_ribs[i+1..],
_ => &[] as &[_]
};
let mut def = local_def.def;
match def {
DefUpvar(..) => {
self.session.span_bug(span,
&format!("unexpected {:?} in bindings", def))
}
DefLocal(_, node_id) => {
for rib in ribs {
match rib.kind {
NormalRibKind => {
// Nothing to do. Continue.
}
ClosureRibKind(function_id) => {
let prev_def = def;
let node_def_id = self.ast_map.local_def_id(node_id);

let mut seen = self.freevars_seen.borrow_mut();
let seen = seen.entry(function_id).or_insert_with(|| NodeMap());
if let Some(&index) = seen.get(&node_id) {
def = DefUpvar(node_def_id, node_id, index, function_id);
continue;
}
let mut freevars = self.freevars.borrow_mut();
let vec = freevars.entry(function_id)
.or_insert_with(|| vec![]);
let depth = vec.len();
vec.push(Freevar { def: prev_def, span: span });

def = DefUpvar(node_def_id, node_id, depth, function_id);
seen.insert(node_id, depth);
}
ItemRibKind | MethodRibKind => {
// This was an attempt to access an upvar inside a
// named function item. This is not allowed, so we
// report an error.
resolve_error(
self,
span,
ResolutionError::CannotCaptureDynamicEnvironmentInFnItem
);
return None;
}
ConstantItemRibKind => {
// Still doesn't deal with upvars
resolve_error(
self,
span,
ResolutionError::AttemptToUseNonConstantValueInConstant
);
return None;
}
}
}
}
DefTyParam(..) | DefSelfTy(..) => {
for rib in ribs {
match rib.kind {
NormalRibKind | MethodRibKind | ClosureRibKind(..) => {
// Nothing to do. Continue.
}
ItemRibKind => {
// This was an attempt to use a type parameter outside
// its scope.

resolve_error(self,
span,
ResolutionError::TypeParametersFromOuterFunction);
return None;
}
ConstantItemRibKind => {
// see #9186
resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
return None;
}
}
}
}
_ => {}
}
return Some(def);
}

// FIXME #4952: Merge me with resolve_name_in_module?
Expand Down Expand Up @@ -3364,38 +3359,41 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {

fn resolve_identifier_in_local_ribs(&mut self,
ident: Ident,
namespace: Namespace,
span: Span)
-> Option<Def> {
namespace: Namespace)
-> Option<LocalDef> {
// Check the local set of ribs.
let search_result = match namespace {
ValueNS => {
let renamed = mtwt::resolve(ident);
self.search_ribs(&self.value_ribs, renamed, span)
}
TypeNS => {
let name = ident.name;
self.search_ribs(&self.type_ribs, name, span)
}
let (name, ribs) = match namespace {
ValueNS => (mtwt::resolve(ident), &self.value_ribs),
TypeNS => (ident.name, &self.type_ribs)
};

match search_result {
Some(DlDef(def)) => {
debug!("(resolving path in local ribs) resolved `{}` to local: {:?}",
ident,
def);
Some(def)
}
Some(DlField) | Some(DlImpl(_)) | None => {
None
for (i, rib) in ribs.iter().enumerate().rev() {
if let Some(def_like) = rib.bindings.get(&name).cloned() {
match def_like {
DlDef(def) => {
debug!("(resolving path in local ribs) resolved `{}` to {:?} at {}",
name, def, i);
return Some(LocalDef {
ribs: Some((namespace, i)),
def: def
});
}
def_like => {
debug!("(resolving path in local ribs) resolved `{}` to pseudo-def {:?}",
name, def_like);
return None;
}
}
}
}

None
}

fn resolve_item_by_name_in_lexical_scope(&mut self,
name: Name,
namespace: Namespace)
-> Option<(Def, LastPrivate)> {
-> Option<Def> {
// Check the items.
let module = self.current_module.clone();
match self.resolve_item_in_lexical_scope(module,
Expand All @@ -3409,7 +3407,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
debug!("(resolving item path by identifier in lexical \
scope) failed to resolve {} after success...",
name);
return None;
None
}
Some(def) => {
debug!("(resolving item path in lexical scope) \
Expand All @@ -3418,7 +3416,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
// This lookup is "all public" because it only searched
// for one identifier in the current module (couldn't
// have passed through reexports or anything like that.
return Some((def, LastMod(AllPublic)));
Some(def)
}
}
}
Expand All @@ -3433,7 +3431,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
resolve_error(self, span, ResolutionError::FailedToResolve(&*msg))
}

return None;
None
}
}
}
Expand Down
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