diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs index e3ecaae953a6b..2bbf807807bad 100644 --- a/src/librustc/ich/impls_ty.rs +++ b/src/librustc/ich/impls_ty.rs @@ -514,13 +514,8 @@ impl_stable_hash_for!(enum ty::cast::CastKind { FnPtrAddrCast }); -impl_stable_hash_for!(enum ::middle::region::Scope { - Node(local_id), - Destruction(local_id), - CallSite(local_id), - Arguments(local_id), - Remainder(block_remainder) -}); +impl_stable_hash_for!(struct ::middle::region::FirstStatementIndex { idx }); +impl_stable_hash_for!(struct ::middle::region::Scope { id, code }); impl<'gcx> ToStableHashKey> for region::Scope { type KeyType = region::Scope; diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs index a88e90caee307..ead20b5eb5a3e 100644 --- a/src/librustc/infer/error_reporting/mod.rs +++ b/src/librustc/infer/error_reporting/mod.rs @@ -72,6 +72,8 @@ use syntax::ast::DUMMY_NODE_ID; use syntax_pos::{Pos, Span}; use errors::{DiagnosticBuilder, DiagnosticStyledString}; +use rustc_data_structures::indexed_vec::Idx; + mod note; mod need_type_info; @@ -152,21 +154,21 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { return; } }; - let scope_decorated_tag = match scope { - region::Scope::Node(_) => tag, - region::Scope::CallSite(_) => { + let scope_decorated_tag = match scope.data() { + region::ScopeData::Node(_) => tag, + region::ScopeData::CallSite(_) => { "scope of call-site for function" } - region::Scope::Arguments(_) => { + region::ScopeData::Arguments(_) => { "scope of function body" } - region::Scope::Destruction(_) => { + region::ScopeData::Destruction(_) => { new_string = format!("destruction scope surrounding {}", tag); &new_string[..] } - region::Scope::Remainder(r) => { + region::ScopeData::Remainder(r) => { new_string = format!("block suffix following statement {}", - r.first_statement_index); + r.first_statement_index.index()); &new_string[..] } }; @@ -333,11 +335,20 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { GenericBoundFailure(..) => true, }; - if errors.iter().all(|e| is_bound_failure(e)) { + + let mut errors = if errors.iter().all(|e| is_bound_failure(e)) { errors.clone() } else { errors.iter().filter(|&e| !is_bound_failure(e)).cloned().collect() - } + }; + + // sort the errors by span, for better error message stability. + errors.sort_by_key(|u| match *u { + ConcreteFailure(ref sro, _, _) => sro.span(), + GenericBoundFailure(ref sro, _, _) => sro.span(), + SubSupConflict(ref rvo, _, _, _, _) => rvo.span(), + }); + errors } /// Adds a note if the types come from similarly named crates diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs index 6cce7447669f7..cede0c2b9a2c2 100644 --- a/src/librustc/middle/region.rs +++ b/src/librustc/middle/region.rs @@ -18,6 +18,7 @@ use ich::{StableHashingContext, NodeIdHashingMode}; use util::nodemap::{FxHashMap, FxHashSet}; use ty; +use std::fmt; use std::mem; use std::rc::Rc; use syntax::codemap; @@ -31,6 +32,7 @@ use hir::def_id::DefId; use hir::intravisit::{self, Visitor, NestedVisitorMap}; use hir::{Block, Arm, Pat, PatKind, Stmt, Expr, Local}; use mir::transform::MirSource; +use rustc_data_structures::indexed_vec::Idx; use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult}; @@ -95,8 +97,24 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher, /// placate the same deriving in `ty::FreeRegion`, but we may want to /// actually attach a more meaningful ordering to scopes than the one /// generated via deriving here. +/// +/// Scope is a bit-packed to save space - if `code` is SCOPE_DATA_REMAINDER_MAX +/// or less, it is a `ScopeData::Remainder`, otherwise it is a type specified +/// by the bitpacking. +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Copy, RustcEncodable, RustcDecodable)] +pub struct Scope { + pub(crate) id: hir::ItemLocalId, + pub(crate) code: u32 +} + +const SCOPE_DATA_NODE: u32 = !0; +const SCOPE_DATA_CALLSITE: u32 = !1; +const SCOPE_DATA_ARGUMENTS: u32 = !2; +const SCOPE_DATA_DESTRUCTION: u32 = !3; +const SCOPE_DATA_REMAINDER_MAX: u32 = !4; + #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Debug, Copy, RustcEncodable, RustcDecodable)] -pub enum Scope { +pub enum ScopeData { Node(hir::ItemLocalId), // Scope of the call-site for a function or closure @@ -135,7 +153,90 @@ pub enum Scope { RustcDecodable, Debug, Copy)] pub struct BlockRemainder { pub block: hir::ItemLocalId, - pub first_statement_index: u32, + pub first_statement_index: FirstStatementIndex, +} + +#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, RustcEncodable, + RustcDecodable, Copy)] +pub struct FirstStatementIndex { pub idx: u32 } + +impl Idx for FirstStatementIndex { + fn new(idx: usize) -> Self { + assert!(idx <= SCOPE_DATA_REMAINDER_MAX as usize); + FirstStatementIndex { idx: idx as u32 } + } + + fn index(self) -> usize { + self.idx as usize + } +} + +impl fmt::Debug for FirstStatementIndex { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + fmt::Debug::fmt(&self.index(), formatter) + } +} + +impl From for Scope { + #[inline] + fn from(scope_data: ScopeData) -> Self { + let (id, code) = match scope_data { + ScopeData::Node(id) => (id, SCOPE_DATA_NODE), + ScopeData::CallSite(id) => (id, SCOPE_DATA_CALLSITE), + ScopeData::Arguments(id) => (id, SCOPE_DATA_ARGUMENTS), + ScopeData::Destruction(id) => (id, SCOPE_DATA_DESTRUCTION), + ScopeData::Remainder(r) => (r.block, r.first_statement_index.index() as u32) + }; + Self { id, code } + } +} + +impl fmt::Debug for Scope { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + fmt::Debug::fmt(&self.data(), formatter) + } +} + +#[allow(non_snake_case)] +impl Scope { + #[inline] + pub fn data(self) -> ScopeData { + match self.code { + SCOPE_DATA_NODE => ScopeData::Node(self.id), + SCOPE_DATA_CALLSITE => ScopeData::CallSite(self.id), + SCOPE_DATA_ARGUMENTS => ScopeData::Arguments(self.id), + SCOPE_DATA_DESTRUCTION => ScopeData::Destruction(self.id), + idx => ScopeData::Remainder(BlockRemainder { + block: self.id, + first_statement_index: FirstStatementIndex { idx } + }) + } + } + + #[inline] + pub fn Node(id: hir::ItemLocalId) -> Self { + Self::from(ScopeData::Node(id)) + } + + #[inline] + pub fn CallSite(id: hir::ItemLocalId) -> Self { + Self::from(ScopeData::CallSite(id)) + } + + #[inline] + pub fn Arguments(id: hir::ItemLocalId) -> Self { + Self::from(ScopeData::Arguments(id)) + } + + #[inline] + pub fn Destruction(id: hir::ItemLocalId) -> Self { + Self::from(ScopeData::Destruction(id)) + } + + #[inline] + pub fn Remainder(r: BlockRemainder) -> Self { + Self::from(ScopeData::Remainder(r)) + } } impl Scope { @@ -144,16 +245,7 @@ impl Scope { /// NB: likely to be replaced as API is refined; e.g. pnkfelix /// anticipates `fn entry_node_id` and `fn each_exit_node_id`. pub fn item_local_id(&self) -> hir::ItemLocalId { - match *self { - Scope::Node(id) => id, - - // These cases all return rough approximations to the - // precise scope denoted by `self`. - Scope::Remainder(br) => br.block, - Scope::Destruction(id) | - Scope::CallSite(id) | - Scope::Arguments(id) => id, - } + self.id } pub fn node_id(&self, tcx: TyCtxt, scope_tree: &ScopeTree) -> ast::NodeId { @@ -177,7 +269,7 @@ impl Scope { return DUMMY_SP; } let span = tcx.hir.span(node_id); - if let Scope::Remainder(r) = *self { + if let ScopeData::Remainder(r) = self.data() { if let hir::map::NodeBlock(ref blk) = tcx.hir.get(node_id) { // Want span for scope starting after the // indexed statement and ending at end of @@ -187,7 +279,7 @@ impl Scope { // (This is the special case aluded to in the // doc-comment for this method) - let stmt_span = blk.stmts[r.first_statement_index as usize].span; + let stmt_span = blk.stmts[r.first_statement_index.index()].span; // To avoid issues with macro-generated spans, the span // of the statement must be nested in that of the block. @@ -387,7 +479,7 @@ impl<'tcx> ScopeTree { } // record the destruction scopes for later so we can query them - if let Scope::Destruction(n) = child { + if let ScopeData::Destruction(n) = child.data() { self.destruction_scopes.insert(n, child); } } @@ -482,8 +574,8 @@ impl<'tcx> ScopeTree { let mut id = Scope::Node(expr_id); while let Some(&p) = self.parent_map.get(&id) { - match p { - Scope::Destruction(..) => { + match p.data() { + ScopeData::Destruction(..) => { debug!("temporary_scope({:?}) = {:?} [enclosing]", expr_id, id); return Some(id); @@ -573,9 +665,9 @@ impl<'tcx> ScopeTree { // infer::region_inference for more details. let a_root_scope = a_ancestors[a_index]; let b_root_scope = a_ancestors[a_index]; - return match (a_root_scope, b_root_scope) { - (Scope::Destruction(a_root_id), - Scope::Destruction(b_root_id)) => { + return match (a_root_scope.data(), b_root_scope.data()) { + (ScopeData::Destruction(a_root_id), + ScopeData::Destruction(b_root_id)) => { if self.closure_is_enclosed_by(a_root_id, b_root_id) { // `a` is enclosed by `b`, hence `b` is the ancestor of everything in `a` scope_b @@ -764,7 +856,7 @@ fn resolve_block<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'a, 'tcx>, blk: visitor.enter_scope( Scope::Remainder(BlockRemainder { block: blk.hir_id.local_id, - first_statement_index: i as u32 + first_statement_index: FirstStatementIndex::new(i) }) ); visitor.cx.var_parent = visitor.cx.parent; @@ -915,8 +1007,10 @@ fn resolve_expr<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'a, 'tcx>, expr: // Keep traversing up while we can. match visitor.scope_tree.parent_map.get(&scope) { // Don't cross from closure bodies to their parent. - Some(&Scope::CallSite(_)) => break, - Some(&superscope) => scope = superscope, + Some(&superscope) => match superscope.data() { + ScopeData::CallSite(_) => break, + _ => scope = superscope + }, None => break } } diff --git a/src/librustc/util/ppaux.rs b/src/librustc/util/ppaux.rs index cf7a29d2845ac..f714a5e14c47f 100644 --- a/src/librustc/util/ppaux.rs +++ b/src/librustc/util/ppaux.rs @@ -26,6 +26,7 @@ use std::fmt; use std::usize; use rustc_const_math::ConstInt; +use rustc_data_structures::indexed_vec::Idx; use syntax::abi::Abi; use syntax::ast::CRATE_NODE_ID; use syntax::symbol::Symbol; @@ -530,17 +531,17 @@ impl fmt::Display for ty::RegionKind { write!(f, "{}", br) } ty::ReScope(scope) if identify_regions() => { - match scope { - region::Scope::Node(id) => + match scope.data() { + region::ScopeData::Node(id) => write!(f, "'{}s", id.as_usize()), - region::Scope::CallSite(id) => + region::ScopeData::CallSite(id) => write!(f, "'{}cs", id.as_usize()), - region::Scope::Arguments(id) => + region::ScopeData::Arguments(id) => write!(f, "'{}as", id.as_usize()), - region::Scope::Destruction(id) => + region::ScopeData::Destruction(id) => write!(f, "'{}ds", id.as_usize()), - region::Scope::Remainder(BlockRemainder { block, first_statement_index }) => - write!(f, "'{}_{}rs", block.as_usize(), first_statement_index), + region::ScopeData::Remainder(BlockRemainder { block, first_statement_index }) => + write!(f, "'{}_{}rs", block.as_usize(), first_statement_index.index()), } } ty::ReVar(region_vid) if identify_regions() => { diff --git a/src/librustc_mir/build/scope.rs b/src/librustc_mir/build/scope.rs index bac884b4d01e9..ca460e33cccb5 100644 --- a/src/librustc_mir/build/scope.rs +++ b/src/librustc_mir/build/scope.rs @@ -514,8 +514,8 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { // The outermost scope (`scopes[0]`) will be the `CallSiteScope`. // We want `scopes[1]`, which is the `ParameterScope`. assert!(self.scopes.len() >= 2); - assert!(match self.scopes[1].region_scope { - region::Scope::Arguments(_) => true, + assert!(match self.scopes[1].region_scope.data() { + region::ScopeData::Arguments(_) => true, _ => false, }); self.scopes[1].region_scope diff --git a/src/librustc_mir/hair/cx/block.rs b/src/librustc_mir/hair/cx/block.rs index f6b847d6d6de5..5f43cc4c83b61 100644 --- a/src/librustc_mir/hair/cx/block.rs +++ b/src/librustc_mir/hair/cx/block.rs @@ -14,6 +14,8 @@ use hair::cx::to_ref::ToRef; use rustc::middle::region::{self, BlockRemainder}; use rustc::hir; +use rustc_data_structures::indexed_vec::Idx; + impl<'tcx> Mirror<'tcx> for &'tcx hir::Block { type Output = Block<'tcx>; @@ -61,7 +63,7 @@ fn mirror_stmts<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>, hir::DeclLocal(ref local) => { let remainder_scope = region::Scope::Remainder(BlockRemainder { block: block_id, - first_statement_index: index as u32, + first_statement_index: region::FirstStatementIndex::new(index), }); let pattern = cx.pattern_from_hir(&local.pat); diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs index cfcdbcc11959b..94422f93e5922 100644 --- a/src/librustc_typeck/check/coercion.rs +++ b/src/librustc_typeck/check/coercion.rs @@ -187,7 +187,11 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> { } // Consider coercing the subtype to a DST - let unsize = self.coerce_unsized(a, b); + // + // NOTE: this is wrapped in a `commit_if_ok` because it creates + // a "spurious" type variable, and we don't want to have that + // type variable in memory if the coercion fails. + let unsize = self.commit_if_ok(|_| self.coerce_unsized(a, b)); if unsize.is_ok() { debug!("coerce: unsize successful"); return unsize;