1934 lines
76 KiB
Rust
1934 lines
76 KiB
Rust
// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Error Reporting Code for the inference engine
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//!
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//! Because of the way inference, and in particular region inference,
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//! works, it often happens that errors are not detected until far after
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//! the relevant line of code has been type-checked. Therefore, there is
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//! an elaborate system to track why a particular constraint in the
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//! inference graph arose so that we can explain to the user what gave
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//! rise to a particular error.
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//!
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//! The basis of the system are the "origin" types. An "origin" is the
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//! reason that a constraint or inference variable arose. There are
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//! different "origin" enums for different kinds of constraints/variables
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//! (e.g., `TypeOrigin`, `RegionVariableOrigin`). An origin always has
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//! a span, but also more information so that we can generate a meaningful
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//! error message.
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//!
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//! Having a catalogue of all the different reasons an error can arise is
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//! also useful for other reasons, like cross-referencing FAQs etc, though
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//! we are not really taking advantage of this yet.
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//!
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//! # Region Inference
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//!
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//! Region inference is particularly tricky because it always succeeds "in
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//! the moment" and simply registers a constraint. Then, at the end, we
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//! can compute the full graph and report errors, so we need to be able to
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//! store and later report what gave rise to the conflicting constraints.
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//!
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//! # Subtype Trace
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//!
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//! Determining whether `T1 <: T2` often involves a number of subtypes and
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//! subconstraints along the way. A "TypeTrace" is an extended version
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//! of an origin that traces the types and other values that were being
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//! compared. It is not necessarily comprehensive (in fact, at the time of
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//! this writing it only tracks the root values being compared) but I'd
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//! like to extend it to include significant "waypoints". For example, if
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//! you are comparing `(T1, T2) <: (T3, T4)`, and the problem is that `T2
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//! <: T4` fails, I'd like the trace to include enough information to say
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//! "in the 2nd element of the tuple". Similarly, failures when comparing
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//! arguments or return types in fn types should be able to cite the
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//! specific position, etc.
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//!
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//! # Reality vs plan
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//!
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//! Of course, there is still a LOT of code in typeck that has yet to be
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//! ported to this system, and which relies on string concatenation at the
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//! time of error detection.
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use self::FreshOrKept::*;
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use super::InferCtxt;
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use super::TypeTrace;
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use super::SubregionOrigin;
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use super::RegionVariableOrigin;
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use super::ValuePairs;
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use super::region_inference::RegionResolutionError;
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use super::region_inference::ConcreteFailure;
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use super::region_inference::SubSupConflict;
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use super::region_inference::SupSupConflict;
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use super::region_inference::GenericBoundFailure;
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use super::region_inference::GenericKind;
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use super::region_inference::ProcessedErrors;
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use super::region_inference::SameRegions;
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use std::collections::HashSet;
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use ast_map;
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use middle::def;
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use middle::infer;
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use middle::region;
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use middle::subst;
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use middle::ty::{self, Ty, TypeError, HasTypeFlags};
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use middle::ty::{Region, ReFree};
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use std::cell::{Cell, RefCell};
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use std::char::from_u32;
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use std::fmt;
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use syntax::ast;
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use syntax::ast_util::name_to_dummy_lifetime;
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use syntax::owned_slice::OwnedSlice;
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use syntax::codemap::{Pos, Span};
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use syntax::parse::token;
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use syntax::print::pprust;
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use syntax::ptr::P;
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impl<'tcx> ty::ctxt<'tcx> {
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pub fn note_and_explain_region(&self,
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prefix: &str,
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region: ty::Region,
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suffix: &str) {
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fn item_scope_tag(item: &ast::Item) -> &'static str {
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match item.node {
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ast::ItemImpl(..) => "impl",
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ast::ItemStruct(..) => "struct",
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ast::ItemEnum(..) => "enum",
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ast::ItemTrait(..) => "trait",
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ast::ItemFn(..) => "function body",
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_ => "item"
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}
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}
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fn explain_span(tcx: &ty::ctxt, heading: &str, span: Span)
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-> (String, Option<Span>) {
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let lo = tcx.sess.codemap().lookup_char_pos_adj(span.lo);
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(format!("the {} at {}:{}", heading, lo.line, lo.col.to_usize()),
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Some(span))
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}
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let (description, span) = match region {
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ty::ReScope(scope) => {
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let new_string;
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let unknown_scope = || {
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format!("{}unknown scope: {:?}{}. Please report a bug.",
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prefix, scope, suffix)
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};
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let span = match scope.span(&self.map) {
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Some(s) => s,
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None => return self.sess.note(&unknown_scope())
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};
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let tag = match self.map.find(scope.node_id()) {
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Some(ast_map::NodeBlock(_)) => "block",
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Some(ast_map::NodeExpr(expr)) => match expr.node {
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ast::ExprCall(..) => "call",
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ast::ExprMethodCall(..) => "method call",
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ast::ExprMatch(_, _, ast::MatchSource::IfLetDesugar { .. }) => "if let",
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ast::ExprMatch(_, _, ast::MatchSource::WhileLetDesugar) => "while let",
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ast::ExprMatch(_, _, ast::MatchSource::ForLoopDesugar) => "for",
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ast::ExprMatch(..) => "match",
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_ => "expression",
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},
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Some(ast_map::NodeStmt(_)) => "statement",
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Some(ast_map::NodeItem(it)) => item_scope_tag(&*it),
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Some(_) | None => {
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return self.sess.span_note(span, &unknown_scope());
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}
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};
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let scope_decorated_tag = match scope {
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region::CodeExtent::Misc(_) => tag,
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region::CodeExtent::ParameterScope { .. } => {
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"scope of parameters for function"
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}
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region::CodeExtent::DestructionScope(_) => {
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new_string = format!("destruction scope surrounding {}", tag);
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&new_string[..]
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}
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region::CodeExtent::Remainder(r) => {
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new_string = format!("block suffix following statement {}",
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r.first_statement_index);
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&new_string[..]
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}
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};
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explain_span(self, scope_decorated_tag, span)
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}
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ty::ReFree(ref fr) => {
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let prefix = match fr.bound_region {
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ty::BrAnon(idx) => {
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format!("the anonymous lifetime #{} defined on", idx + 1)
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}
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ty::BrFresh(_) => "an anonymous lifetime defined on".to_owned(),
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_ => {
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format!("the lifetime {} as defined on",
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fr.bound_region)
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}
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};
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match self.map.find(fr.scope.node_id) {
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Some(ast_map::NodeBlock(ref blk)) => {
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let (msg, opt_span) = explain_span(self, "block", blk.span);
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(format!("{} {}", prefix, msg), opt_span)
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}
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Some(ast_map::NodeItem(it)) => {
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let tag = item_scope_tag(&*it);
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let (msg, opt_span) = explain_span(self, tag, it.span);
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(format!("{} {}", prefix, msg), opt_span)
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}
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Some(_) | None => {
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// this really should not happen
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(format!("{} unknown free region bounded by scope {:?}",
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prefix, fr.scope), None)
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}
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}
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}
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ty::ReStatic => ("the static lifetime".to_owned(), None),
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ty::ReEmpty => ("the empty lifetime".to_owned(), None),
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ty::ReEarlyBound(ref data) => (data.name.to_string(), None),
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// I believe these cases should not occur (except when debugging,
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// perhaps)
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ty::ReInfer(_) | ty::ReLateBound(..) => {
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(format!("lifetime {:?}", region), None)
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}
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};
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let message = format!("{}{}{}", prefix, description, suffix);
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if let Some(span) = span {
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self.sess.span_note(span, &message);
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} else {
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self.sess.note(&message);
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}
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}
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}
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pub trait ErrorReporting<'tcx> {
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fn report_region_errors(&self,
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errors: &Vec<RegionResolutionError<'tcx>>);
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fn process_errors(&self, errors: &Vec<RegionResolutionError<'tcx>>)
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-> Vec<RegionResolutionError<'tcx>>;
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fn report_type_error(&self, trace: TypeTrace<'tcx>, terr: &ty::TypeError<'tcx>);
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fn report_and_explain_type_error(&self,
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trace: TypeTrace<'tcx>,
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terr: &ty::TypeError<'tcx>);
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fn values_str(&self, values: &ValuePairs<'tcx>) -> Option<String>;
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fn expected_found_str<T: fmt::Display + Resolvable<'tcx> + HasTypeFlags>(
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&self,
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exp_found: &ty::ExpectedFound<T>)
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-> Option<String>;
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fn report_concrete_failure(&self,
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origin: SubregionOrigin<'tcx>,
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sub: Region,
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sup: Region);
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fn report_generic_bound_failure(&self,
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origin: SubregionOrigin<'tcx>,
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kind: GenericKind<'tcx>,
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sub: Region);
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fn report_sub_sup_conflict(&self,
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var_origin: RegionVariableOrigin,
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sub_origin: SubregionOrigin<'tcx>,
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sub_region: Region,
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sup_origin: SubregionOrigin<'tcx>,
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sup_region: Region);
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fn report_sup_sup_conflict(&self,
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var_origin: RegionVariableOrigin,
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origin1: SubregionOrigin<'tcx>,
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region1: Region,
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origin2: SubregionOrigin<'tcx>,
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region2: Region);
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fn report_processed_errors(&self,
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var_origin: &[RegionVariableOrigin],
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trace_origin: &[(TypeTrace<'tcx>, ty::TypeError<'tcx>)],
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same_regions: &[SameRegions]);
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fn give_suggestion(&self, same_regions: &[SameRegions]);
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}
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trait ErrorReportingHelpers<'tcx> {
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fn report_inference_failure(&self,
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var_origin: RegionVariableOrigin);
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fn note_region_origin(&self,
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origin: &SubregionOrigin<'tcx>);
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fn give_expl_lifetime_param(&self,
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decl: &ast::FnDecl,
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unsafety: ast::Unsafety,
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constness: ast::Constness,
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ident: ast::Ident,
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opt_explicit_self: Option<&ast::ExplicitSelf_>,
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generics: &ast::Generics,
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span: Span);
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}
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impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
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fn report_region_errors(&self,
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errors: &Vec<RegionResolutionError<'tcx>>) {
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let p_errors = self.process_errors(errors);
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let errors = if p_errors.is_empty() { errors } else { &p_errors };
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for error in errors {
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match error.clone() {
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ConcreteFailure(origin, sub, sup) => {
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self.report_concrete_failure(origin, sub, sup);
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}
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GenericBoundFailure(kind, param_ty, sub) => {
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self.report_generic_bound_failure(kind, param_ty, sub);
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}
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SubSupConflict(var_origin,
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sub_origin, sub_r,
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sup_origin, sup_r) => {
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self.report_sub_sup_conflict(var_origin,
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sub_origin, sub_r,
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sup_origin, sup_r);
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}
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SupSupConflict(var_origin,
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origin1, r1,
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origin2, r2) => {
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self.report_sup_sup_conflict(var_origin,
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origin1, r1,
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origin2, r2);
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}
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ProcessedErrors(ref var_origins,
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ref trace_origins,
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ref same_regions) => {
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if !same_regions.is_empty() {
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self.report_processed_errors(&var_origins[..],
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&trace_origins[..],
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&same_regions[..]);
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}
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}
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}
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}
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}
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// This method goes through all the errors and try to group certain types
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// of error together, for the purpose of suggesting explicit lifetime
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// parameters to the user. This is done so that we can have a more
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// complete view of what lifetimes should be the same.
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// If the return value is an empty vector, it means that processing
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// failed (so the return value of this method should not be used)
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fn process_errors(&self, errors: &Vec<RegionResolutionError<'tcx>>)
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-> Vec<RegionResolutionError<'tcx>> {
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debug!("process_errors()");
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let mut var_origins = Vec::new();
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let mut trace_origins = Vec::new();
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let mut same_regions = Vec::new();
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let mut processed_errors = Vec::new();
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for error in errors {
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match error.clone() {
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ConcreteFailure(origin, sub, sup) => {
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debug!("processing ConcreteFailure");
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let trace = match origin {
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infer::Subtype(trace) => Some(trace),
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_ => None,
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};
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match free_regions_from_same_fn(self.tcx, sub, sup) {
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Some(ref same_frs) if trace.is_some() => {
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let trace = trace.unwrap();
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let terr = TypeError::RegionsDoesNotOutlive(sup,
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sub);
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trace_origins.push((trace, terr));
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append_to_same_regions(&mut same_regions, same_frs);
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}
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_ => processed_errors.push((*error).clone()),
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}
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}
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SubSupConflict(var_origin, _, sub_r, _, sup_r) => {
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debug!("processing SubSupConflict sub: {:?} sup: {:?}", sub_r, sup_r);
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match free_regions_from_same_fn(self.tcx, sub_r, sup_r) {
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Some(ref same_frs) => {
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var_origins.push(var_origin);
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append_to_same_regions(&mut same_regions, same_frs);
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}
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None => processed_errors.push((*error).clone()),
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}
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}
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SupSupConflict(..) => processed_errors.push((*error).clone()),
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_ => () // This shouldn't happen
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}
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}
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if !same_regions.is_empty() {
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let common_scope_id = same_regions[0].scope_id;
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for sr in &same_regions {
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// Since ProcessedErrors is used to reconstruct the function
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// declaration, we want to make sure that they are, in fact,
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// from the same scope
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if sr.scope_id != common_scope_id {
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debug!("returning empty result from process_errors because
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{} != {}", sr.scope_id, common_scope_id);
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return vec!();
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}
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}
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let pe = ProcessedErrors(var_origins, trace_origins, same_regions);
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debug!("errors processed: {:?}", pe);
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processed_errors.push(pe);
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}
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return processed_errors;
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struct FreeRegionsFromSameFn {
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sub_fr: ty::FreeRegion,
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sup_fr: ty::FreeRegion,
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scope_id: ast::NodeId
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}
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impl FreeRegionsFromSameFn {
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fn new(sub_fr: ty::FreeRegion,
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sup_fr: ty::FreeRegion,
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scope_id: ast::NodeId)
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-> FreeRegionsFromSameFn {
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FreeRegionsFromSameFn {
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sub_fr: sub_fr,
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sup_fr: sup_fr,
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scope_id: scope_id
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}
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}
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}
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fn free_regions_from_same_fn(tcx: &ty::ctxt,
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sub: Region,
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sup: Region)
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-> Option<FreeRegionsFromSameFn> {
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debug!("free_regions_from_same_fn(sub={:?}, sup={:?})", sub, sup);
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let (scope_id, fr1, fr2) = match (sub, sup) {
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(ReFree(fr1), ReFree(fr2)) => {
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if fr1.scope != fr2.scope {
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return None
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}
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assert!(fr1.scope == fr2.scope);
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(fr1.scope.node_id, fr1, fr2)
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},
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_ => return None
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};
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let parent = tcx.map.get_parent(scope_id);
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let parent_node = tcx.map.find(parent);
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match parent_node {
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Some(node) => match node {
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ast_map::NodeItem(item) => match item.node {
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ast::ItemFn(..) => {
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Some(FreeRegionsFromSameFn::new(fr1, fr2, scope_id))
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},
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_ => None
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},
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ast_map::NodeImplItem(..) |
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ast_map::NodeTraitItem(..) => {
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Some(FreeRegionsFromSameFn::new(fr1, fr2, scope_id))
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},
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_ => None
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},
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None => {
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debug!("no parent node of scope_id {}", scope_id);
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None
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}
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}
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}
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fn append_to_same_regions(same_regions: &mut Vec<SameRegions>,
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same_frs: &FreeRegionsFromSameFn) {
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let scope_id = same_frs.scope_id;
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let (sub_fr, sup_fr) = (same_frs.sub_fr, same_frs.sup_fr);
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for sr in &mut *same_regions {
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if sr.contains(&sup_fr.bound_region)
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&& scope_id == sr.scope_id {
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sr.push(sub_fr.bound_region);
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return
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}
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}
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same_regions.push(SameRegions {
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scope_id: scope_id,
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regions: vec!(sub_fr.bound_region, sup_fr.bound_region)
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})
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}
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}
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fn report_type_error(&self, trace: TypeTrace<'tcx>, terr: &ty::TypeError<'tcx>) {
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let expected_found_str = match self.values_str(&trace.values) {
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Some(v) => v,
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None => {
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return; /* derived error */
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}
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};
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span_err!(self.tcx.sess, trace.origin.span(), E0308,
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"{}: {} ({})",
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trace.origin,
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expected_found_str,
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terr);
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match trace.origin {
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infer::MatchExpressionArm(_, arm_span) =>
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self.tcx.sess.span_note(arm_span, "match arm with an incompatible type"),
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_ => ()
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}
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}
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fn report_and_explain_type_error(&self,
|
|
trace: TypeTrace<'tcx>,
|
|
terr: &ty::TypeError<'tcx>) {
|
|
let span = trace.origin.span();
|
|
self.report_type_error(trace, terr);
|
|
self.tcx.note_and_explain_type_err(terr, span);
|
|
}
|
|
|
|
/// Returns a string of the form "expected `{}`, found `{}`", or None if this is a derived
|
|
/// error.
|
|
fn values_str(&self, values: &ValuePairs<'tcx>) -> Option<String> {
|
|
match *values {
|
|
infer::Types(ref exp_found) => self.expected_found_str(exp_found),
|
|
infer::TraitRefs(ref exp_found) => self.expected_found_str(exp_found),
|
|
infer::PolyTraitRefs(ref exp_found) => self.expected_found_str(exp_found)
|
|
}
|
|
}
|
|
|
|
fn expected_found_str<T: fmt::Display + Resolvable<'tcx> + HasTypeFlags>(
|
|
&self,
|
|
exp_found: &ty::ExpectedFound<T>)
|
|
-> Option<String>
|
|
{
|
|
let expected = exp_found.expected.resolve(self);
|
|
if expected.references_error() {
|
|
return None;
|
|
}
|
|
|
|
let found = exp_found.found.resolve(self);
|
|
if found.references_error() {
|
|
return None;
|
|
}
|
|
|
|
Some(format!("expected `{}`, found `{}`",
|
|
expected,
|
|
found))
|
|
}
|
|
|
|
fn report_generic_bound_failure(&self,
|
|
origin: SubregionOrigin<'tcx>,
|
|
bound_kind: GenericKind<'tcx>,
|
|
sub: Region)
|
|
{
|
|
// FIXME: it would be better to report the first error message
|
|
// with the span of the parameter itself, rather than the span
|
|
// where the error was detected. But that span is not readily
|
|
// accessible.
|
|
|
|
let is_warning = match origin {
|
|
infer::RFC1214Subregion(_) => true,
|
|
_ => false,
|
|
};
|
|
|
|
let labeled_user_string = match bound_kind {
|
|
GenericKind::Param(ref p) =>
|
|
format!("the parameter type `{}`", p),
|
|
GenericKind::Projection(ref p) =>
|
|
format!("the associated type `{}`", p),
|
|
};
|
|
|
|
match sub {
|
|
ty::ReFree(ty::FreeRegion {bound_region: ty::BrNamed(..), ..}) => {
|
|
// Does the required lifetime have a nice name we can print?
|
|
span_err_or_warn!(
|
|
is_warning, self.tcx.sess, origin.span(), E0309,
|
|
"{} may not live long enough", labeled_user_string);
|
|
self.tcx.sess.fileline_help(
|
|
origin.span(),
|
|
&format!(
|
|
"consider adding an explicit lifetime bound `{}: {}`...",
|
|
bound_kind,
|
|
sub));
|
|
}
|
|
|
|
ty::ReStatic => {
|
|
// Does the required lifetime have a nice name we can print?
|
|
span_err_or_warn!(
|
|
is_warning, self.tcx.sess, origin.span(), E0310,
|
|
"{} may not live long enough", labeled_user_string);
|
|
self.tcx.sess.fileline_help(
|
|
origin.span(),
|
|
&format!(
|
|
"consider adding an explicit lifetime bound `{}: 'static`...",
|
|
bound_kind));
|
|
}
|
|
|
|
_ => {
|
|
// If not, be less specific.
|
|
span_err_or_warn!(
|
|
is_warning, self.tcx.sess, origin.span(), E0311,
|
|
"{} may not live long enough",
|
|
labeled_user_string);
|
|
self.tcx.sess.fileline_help(
|
|
origin.span(),
|
|
&format!(
|
|
"consider adding an explicit lifetime bound for `{}`",
|
|
bound_kind));
|
|
self.tcx.note_and_explain_region(
|
|
&format!("{} must be valid for ", labeled_user_string),
|
|
sub,
|
|
"...");
|
|
}
|
|
}
|
|
|
|
if is_warning {
|
|
self.tcx.sess.note_rfc_1214(origin.span());
|
|
}
|
|
|
|
self.note_region_origin(&origin);
|
|
}
|
|
|
|
fn report_concrete_failure(&self,
|
|
origin: SubregionOrigin<'tcx>,
|
|
sub: Region,
|
|
sup: Region) {
|
|
match origin {
|
|
infer::RFC1214Subregion(ref suborigin) => {
|
|
// Ideally, this would be a warning, but it doesn't
|
|
// seem to come up in practice, since the changes from
|
|
// RFC1214 mostly trigger errors in type definitions
|
|
// that don't wind up coming down this path.
|
|
self.report_concrete_failure((**suborigin).clone(), sub, sup);
|
|
}
|
|
infer::Subtype(trace) => {
|
|
let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
|
|
self.report_and_explain_type_error(trace, &terr);
|
|
}
|
|
infer::Reborrow(span) => {
|
|
span_err!(self.tcx.sess, span, E0312,
|
|
"lifetime of reference outlines \
|
|
lifetime of borrowed content...");
|
|
self.tcx.note_and_explain_region(
|
|
"...the reference is valid for ",
|
|
sub,
|
|
"...");
|
|
self.tcx.note_and_explain_region(
|
|
"...but the borrowed content is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::ReborrowUpvar(span, ref upvar_id) => {
|
|
span_err!(self.tcx.sess, span, E0313,
|
|
"lifetime of borrowed pointer outlives \
|
|
lifetime of captured variable `{}`...",
|
|
self.tcx.local_var_name_str(upvar_id.var_id));
|
|
self.tcx.note_and_explain_region(
|
|
"...the borrowed pointer is valid for ",
|
|
sub,
|
|
"...");
|
|
self.tcx.note_and_explain_region(
|
|
&format!("...but `{}` is only valid for ",
|
|
self.tcx.local_var_name_str(upvar_id.var_id)),
|
|
sup,
|
|
"");
|
|
}
|
|
infer::InfStackClosure(span) => {
|
|
span_err!(self.tcx.sess, span, E0314,
|
|
"closure outlives stack frame");
|
|
self.tcx.note_and_explain_region(
|
|
"...the closure must be valid for ",
|
|
sub,
|
|
"...");
|
|
self.tcx.note_and_explain_region(
|
|
"...but the closure's stack frame is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::InvokeClosure(span) => {
|
|
span_err!(self.tcx.sess, span, E0315,
|
|
"cannot invoke closure outside of its lifetime");
|
|
self.tcx.note_and_explain_region(
|
|
"the closure is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::DerefPointer(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"dereference of reference outside its lifetime");
|
|
self.tcx.note_and_explain_region(
|
|
"the reference is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::FreeVariable(span, id) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("captured variable `{}` does not \
|
|
outlive the enclosing closure",
|
|
self.tcx.local_var_name_str(id)));
|
|
self.tcx.note_and_explain_region(
|
|
"captured variable is valid for ",
|
|
sup,
|
|
"");
|
|
self.tcx.note_and_explain_region(
|
|
"closure is valid for ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::IndexSlice(span) => {
|
|
self.tcx.sess.span_err(span,
|
|
"index of slice outside its lifetime");
|
|
self.tcx.note_and_explain_region(
|
|
"the slice is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::RelateObjectBound(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of the source pointer does not outlive \
|
|
lifetime bound of the object type");
|
|
self.tcx.note_and_explain_region(
|
|
"object type is valid for ",
|
|
sub,
|
|
"");
|
|
self.tcx.note_and_explain_region(
|
|
"source pointer is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::RelateParamBound(span, ty) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("the type `{}` does not fulfill the \
|
|
required lifetime",
|
|
self.ty_to_string(ty)));
|
|
self.tcx.note_and_explain_region(
|
|
"type must outlive ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::RelateRegionParamBound(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime bound not satisfied");
|
|
self.tcx.note_and_explain_region(
|
|
"lifetime parameter instantiated with ",
|
|
sup,
|
|
"");
|
|
self.tcx.note_and_explain_region(
|
|
"but lifetime parameter must outlive ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::RelateDefaultParamBound(span, ty) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("the type `{}` (provided as the value of \
|
|
a type parameter) is not valid at this point",
|
|
self.ty_to_string(ty)));
|
|
self.tcx.note_and_explain_region(
|
|
"type must outlive ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::CallRcvr(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of method receiver does not outlive \
|
|
the method call");
|
|
self.tcx.note_and_explain_region(
|
|
"the receiver is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::CallArg(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of function argument does not outlive \
|
|
the function call");
|
|
self.tcx.note_and_explain_region(
|
|
"the function argument is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::CallReturn(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of return value does not outlive \
|
|
the function call");
|
|
self.tcx.note_and_explain_region(
|
|
"the return value is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::Operand(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of operand does not outlive \
|
|
the operation");
|
|
self.tcx.note_and_explain_region(
|
|
"the operand is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::AddrOf(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"reference is not valid \
|
|
at the time of borrow");
|
|
self.tcx.note_and_explain_region(
|
|
"the borrow is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::AutoBorrow(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"automatically reference is not valid \
|
|
at the time of borrow");
|
|
self.tcx.note_and_explain_region(
|
|
"the automatic borrow is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::ExprTypeIsNotInScope(t, span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("type of expression contains references \
|
|
that are not valid during the expression: `{}`",
|
|
self.ty_to_string(t)));
|
|
self.tcx.note_and_explain_region(
|
|
"type is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::SafeDestructor(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"unsafe use of destructor: destructor might be called \
|
|
while references are dead");
|
|
// FIXME (22171): terms "super/subregion" are suboptimal
|
|
self.tcx.note_and_explain_region(
|
|
"superregion: ",
|
|
sup,
|
|
"");
|
|
self.tcx.note_and_explain_region(
|
|
"subregion: ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::BindingTypeIsNotValidAtDecl(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"lifetime of variable does not enclose its declaration");
|
|
self.tcx.note_and_explain_region(
|
|
"the variable is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
infer::ParameterInScope(_, span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("type/lifetime parameter not in scope here"));
|
|
self.tcx.note_and_explain_region(
|
|
"the parameter is only valid for ",
|
|
sub,
|
|
"");
|
|
}
|
|
infer::DataBorrowed(ty, span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("a value of type `{}` is borrowed for too long",
|
|
self.ty_to_string(ty)));
|
|
self.tcx.note_and_explain_region("the type is valid for ", sub, "");
|
|
self.tcx.note_and_explain_region("but the borrow lasts for ", sup, "");
|
|
}
|
|
infer::ReferenceOutlivesReferent(ty, span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
&format!("in type `{}`, reference has a longer lifetime \
|
|
than the data it references",
|
|
self.ty_to_string(ty)));
|
|
self.tcx.note_and_explain_region(
|
|
"the pointer is valid for ",
|
|
sub,
|
|
"");
|
|
self.tcx.note_and_explain_region(
|
|
"but the referenced data is only valid for ",
|
|
sup,
|
|
"");
|
|
}
|
|
}
|
|
}
|
|
|
|
fn report_sub_sup_conflict(&self,
|
|
var_origin: RegionVariableOrigin,
|
|
sub_origin: SubregionOrigin<'tcx>,
|
|
sub_region: Region,
|
|
sup_origin: SubregionOrigin<'tcx>,
|
|
sup_region: Region) {
|
|
self.report_inference_failure(var_origin);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
"first, the lifetime cannot outlive ",
|
|
sup_region,
|
|
"...");
|
|
|
|
self.note_region_origin(&sup_origin);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
"but, the lifetime must be valid for ",
|
|
sub_region,
|
|
"...");
|
|
|
|
self.note_region_origin(&sub_origin);
|
|
}
|
|
|
|
fn report_sup_sup_conflict(&self,
|
|
var_origin: RegionVariableOrigin,
|
|
origin1: SubregionOrigin<'tcx>,
|
|
region1: Region,
|
|
origin2: SubregionOrigin<'tcx>,
|
|
region2: Region) {
|
|
self.report_inference_failure(var_origin);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
"first, the lifetime must be contained by ",
|
|
region1,
|
|
"...");
|
|
|
|
self.note_region_origin(&origin1);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
"but, the lifetime must also be contained by ",
|
|
region2,
|
|
"...");
|
|
|
|
self.note_region_origin(&origin2);
|
|
}
|
|
|
|
fn report_processed_errors(&self,
|
|
var_origins: &[RegionVariableOrigin],
|
|
trace_origins: &[(TypeTrace<'tcx>, ty::TypeError<'tcx>)],
|
|
same_regions: &[SameRegions]) {
|
|
for vo in var_origins {
|
|
self.report_inference_failure(vo.clone());
|
|
}
|
|
self.give_suggestion(same_regions);
|
|
for &(ref trace, ref terr) in trace_origins {
|
|
self.report_and_explain_type_error(trace.clone(), terr);
|
|
}
|
|
}
|
|
|
|
fn give_suggestion(&self, same_regions: &[SameRegions]) {
|
|
let scope_id = same_regions[0].scope_id;
|
|
let parent = self.tcx.map.get_parent(scope_id);
|
|
let parent_node = self.tcx.map.find(parent);
|
|
let taken = lifetimes_in_scope(self.tcx, scope_id);
|
|
let life_giver = LifeGiver::with_taken(&taken[..]);
|
|
let node_inner = match parent_node {
|
|
Some(ref node) => match *node {
|
|
ast_map::NodeItem(ref item) => {
|
|
match item.node {
|
|
ast::ItemFn(ref fn_decl, unsafety, constness, _, ref gen, _) => {
|
|
Some((fn_decl, gen, unsafety, constness,
|
|
item.ident, None, item.span))
|
|
},
|
|
_ => None
|
|
}
|
|
}
|
|
ast_map::NodeImplItem(item) => {
|
|
match item.node {
|
|
ast::MethodImplItem(ref sig, _) => {
|
|
Some((&sig.decl,
|
|
&sig.generics,
|
|
sig.unsafety,
|
|
sig.constness,
|
|
item.ident,
|
|
Some(&sig.explicit_self.node),
|
|
item.span))
|
|
}
|
|
ast::MacImplItem(_) => self.tcx.sess.bug("unexpanded macro"),
|
|
_ => None,
|
|
}
|
|
},
|
|
ast_map::NodeTraitItem(item) => {
|
|
match item.node {
|
|
ast::MethodTraitItem(ref sig, Some(_)) => {
|
|
Some((&sig.decl,
|
|
&sig.generics,
|
|
sig.unsafety,
|
|
sig.constness,
|
|
item.ident,
|
|
Some(&sig.explicit_self.node),
|
|
item.span))
|
|
}
|
|
_ => None
|
|
}
|
|
}
|
|
_ => None
|
|
},
|
|
None => None
|
|
};
|
|
let (fn_decl, generics, unsafety, constness, ident, expl_self, span)
|
|
= node_inner.expect("expect item fn");
|
|
let rebuilder = Rebuilder::new(self.tcx, fn_decl, expl_self,
|
|
generics, same_regions, &life_giver);
|
|
let (fn_decl, expl_self, generics) = rebuilder.rebuild();
|
|
self.give_expl_lifetime_param(&fn_decl, unsafety, constness, ident,
|
|
expl_self.as_ref(), &generics, span);
|
|
}
|
|
}
|
|
|
|
struct RebuildPathInfo<'a> {
|
|
path: &'a ast::Path,
|
|
// indexes to insert lifetime on path.lifetimes
|
|
indexes: Vec<u32>,
|
|
// number of lifetimes we expect to see on the type referred by `path`
|
|
// (e.g., expected=1 for struct Foo<'a>)
|
|
expected: u32,
|
|
anon_nums: &'a HashSet<u32>,
|
|
region_names: &'a HashSet<ast::Name>
|
|
}
|
|
|
|
struct Rebuilder<'a, 'tcx: 'a> {
|
|
tcx: &'a ty::ctxt<'tcx>,
|
|
fn_decl: &'a ast::FnDecl,
|
|
expl_self_opt: Option<&'a ast::ExplicitSelf_>,
|
|
generics: &'a ast::Generics,
|
|
same_regions: &'a [SameRegions],
|
|
life_giver: &'a LifeGiver,
|
|
cur_anon: Cell<u32>,
|
|
inserted_anons: RefCell<HashSet<u32>>,
|
|
}
|
|
|
|
enum FreshOrKept {
|
|
Fresh,
|
|
Kept
|
|
}
|
|
|
|
impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
|
|
fn new(tcx: &'a ty::ctxt<'tcx>,
|
|
fn_decl: &'a ast::FnDecl,
|
|
expl_self_opt: Option<&'a ast::ExplicitSelf_>,
|
|
generics: &'a ast::Generics,
|
|
same_regions: &'a [SameRegions],
|
|
life_giver: &'a LifeGiver)
|
|
-> Rebuilder<'a, 'tcx> {
|
|
Rebuilder {
|
|
tcx: tcx,
|
|
fn_decl: fn_decl,
|
|
expl_self_opt: expl_self_opt,
|
|
generics: generics,
|
|
same_regions: same_regions,
|
|
life_giver: life_giver,
|
|
cur_anon: Cell::new(0),
|
|
inserted_anons: RefCell::new(HashSet::new()),
|
|
}
|
|
}
|
|
|
|
fn rebuild(&self)
|
|
-> (ast::FnDecl, Option<ast::ExplicitSelf_>, ast::Generics) {
|
|
let mut expl_self_opt = self.expl_self_opt.cloned();
|
|
let mut inputs = self.fn_decl.inputs.clone();
|
|
let mut output = self.fn_decl.output.clone();
|
|
let mut ty_params = self.generics.ty_params.clone();
|
|
let where_clause = self.generics.where_clause.clone();
|
|
let mut kept_lifetimes = HashSet::new();
|
|
for sr in self.same_regions {
|
|
self.cur_anon.set(0);
|
|
self.offset_cur_anon();
|
|
let (anon_nums, region_names) =
|
|
self.extract_anon_nums_and_names(sr);
|
|
let (lifetime, fresh_or_kept) = self.pick_lifetime(®ion_names);
|
|
match fresh_or_kept {
|
|
Kept => { kept_lifetimes.insert(lifetime.name); }
|
|
_ => ()
|
|
}
|
|
expl_self_opt = self.rebuild_expl_self(expl_self_opt, lifetime,
|
|
&anon_nums, ®ion_names);
|
|
inputs = self.rebuild_args_ty(&inputs[..], lifetime,
|
|
&anon_nums, ®ion_names);
|
|
output = self.rebuild_output(&output, lifetime, &anon_nums, ®ion_names);
|
|
ty_params = self.rebuild_ty_params(ty_params, lifetime,
|
|
®ion_names);
|
|
}
|
|
let fresh_lifetimes = self.life_giver.get_generated_lifetimes();
|
|
let all_region_names = self.extract_all_region_names();
|
|
let generics = self.rebuild_generics(self.generics,
|
|
&fresh_lifetimes,
|
|
&kept_lifetimes,
|
|
&all_region_names,
|
|
ty_params,
|
|
where_clause);
|
|
let new_fn_decl = ast::FnDecl {
|
|
inputs: inputs,
|
|
output: output,
|
|
variadic: self.fn_decl.variadic
|
|
};
|
|
(new_fn_decl, expl_self_opt, generics)
|
|
}
|
|
|
|
fn pick_lifetime(&self,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> (ast::Lifetime, FreshOrKept) {
|
|
if !region_names.is_empty() {
|
|
// It's not necessary to convert the set of region names to a
|
|
// vector of string and then sort them. However, it makes the
|
|
// choice of lifetime name deterministic and thus easier to test.
|
|
let mut names = Vec::new();
|
|
for rn in region_names {
|
|
let lt_name = rn.to_string();
|
|
names.push(lt_name);
|
|
}
|
|
names.sort();
|
|
let name = token::str_to_ident(&names[0]).name;
|
|
return (name_to_dummy_lifetime(name), Kept);
|
|
}
|
|
return (self.life_giver.give_lifetime(), Fresh);
|
|
}
|
|
|
|
fn extract_anon_nums_and_names(&self, same_regions: &SameRegions)
|
|
-> (HashSet<u32>, HashSet<ast::Name>) {
|
|
let mut anon_nums = HashSet::new();
|
|
let mut region_names = HashSet::new();
|
|
for br in &same_regions.regions {
|
|
match *br {
|
|
ty::BrAnon(i) => {
|
|
anon_nums.insert(i);
|
|
}
|
|
ty::BrNamed(_, name) => {
|
|
region_names.insert(name);
|
|
}
|
|
_ => ()
|
|
}
|
|
}
|
|
(anon_nums, region_names)
|
|
}
|
|
|
|
fn extract_all_region_names(&self) -> HashSet<ast::Name> {
|
|
let mut all_region_names = HashSet::new();
|
|
for sr in self.same_regions {
|
|
for br in &sr.regions {
|
|
match *br {
|
|
ty::BrNamed(_, name) => {
|
|
all_region_names.insert(name);
|
|
}
|
|
_ => ()
|
|
}
|
|
}
|
|
}
|
|
all_region_names
|
|
}
|
|
|
|
fn inc_cur_anon(&self, n: u32) {
|
|
let anon = self.cur_anon.get();
|
|
self.cur_anon.set(anon+n);
|
|
}
|
|
|
|
fn offset_cur_anon(&self) {
|
|
let mut anon = self.cur_anon.get();
|
|
while self.inserted_anons.borrow().contains(&anon) {
|
|
anon += 1;
|
|
}
|
|
self.cur_anon.set(anon);
|
|
}
|
|
|
|
fn inc_and_offset_cur_anon(&self, n: u32) {
|
|
self.inc_cur_anon(n);
|
|
self.offset_cur_anon();
|
|
}
|
|
|
|
fn track_anon(&self, anon: u32) {
|
|
self.inserted_anons.borrow_mut().insert(anon);
|
|
}
|
|
|
|
fn rebuild_ty_params(&self,
|
|
ty_params: OwnedSlice<ast::TyParam>,
|
|
lifetime: ast::Lifetime,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> OwnedSlice<ast::TyParam> {
|
|
ty_params.map(|ty_param| {
|
|
let bounds = self.rebuild_ty_param_bounds(ty_param.bounds.clone(),
|
|
lifetime,
|
|
region_names);
|
|
ast::TyParam {
|
|
ident: ty_param.ident,
|
|
id: ty_param.id,
|
|
bounds: bounds,
|
|
default: ty_param.default.clone(),
|
|
span: ty_param.span,
|
|
}
|
|
})
|
|
}
|
|
|
|
fn rebuild_ty_param_bounds(&self,
|
|
ty_param_bounds: OwnedSlice<ast::TyParamBound>,
|
|
lifetime: ast::Lifetime,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> OwnedSlice<ast::TyParamBound> {
|
|
ty_param_bounds.map(|tpb| {
|
|
match tpb {
|
|
&ast::RegionTyParamBound(lt) => {
|
|
// FIXME -- it's unclear whether I'm supposed to
|
|
// substitute lifetime here. I suspect we need to
|
|
// be passing down a map.
|
|
ast::RegionTyParamBound(lt)
|
|
}
|
|
&ast::TraitTyParamBound(ref poly_tr, modifier) => {
|
|
let tr = &poly_tr.trait_ref;
|
|
let last_seg = tr.path.segments.last().unwrap();
|
|
let mut insert = Vec::new();
|
|
let lifetimes = last_seg.parameters.lifetimes();
|
|
for (i, lt) in lifetimes.iter().enumerate() {
|
|
if region_names.contains(<.name) {
|
|
insert.push(i as u32);
|
|
}
|
|
}
|
|
let rebuild_info = RebuildPathInfo {
|
|
path: &tr.path,
|
|
indexes: insert,
|
|
expected: lifetimes.len() as u32,
|
|
anon_nums: &HashSet::new(),
|
|
region_names: region_names
|
|
};
|
|
let new_path = self.rebuild_path(rebuild_info, lifetime);
|
|
ast::TraitTyParamBound(ast::PolyTraitRef {
|
|
bound_lifetimes: poly_tr.bound_lifetimes.clone(),
|
|
trait_ref: ast::TraitRef {
|
|
path: new_path,
|
|
ref_id: tr.ref_id,
|
|
},
|
|
span: poly_tr.span,
|
|
}, modifier)
|
|
}
|
|
}
|
|
})
|
|
}
|
|
|
|
fn rebuild_expl_self(&self,
|
|
expl_self_opt: Option<ast::ExplicitSelf_>,
|
|
lifetime: ast::Lifetime,
|
|
anon_nums: &HashSet<u32>,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> Option<ast::ExplicitSelf_> {
|
|
match expl_self_opt {
|
|
Some(ref expl_self) => match *expl_self {
|
|
ast::SelfRegion(lt_opt, muta, id) => match lt_opt {
|
|
Some(lt) => if region_names.contains(<.name) {
|
|
return Some(ast::SelfRegion(Some(lifetime), muta, id));
|
|
},
|
|
None => {
|
|
let anon = self.cur_anon.get();
|
|
self.inc_and_offset_cur_anon(1);
|
|
if anon_nums.contains(&anon) {
|
|
self.track_anon(anon);
|
|
return Some(ast::SelfRegion(Some(lifetime), muta, id));
|
|
}
|
|
}
|
|
},
|
|
_ => ()
|
|
},
|
|
None => ()
|
|
}
|
|
expl_self_opt
|
|
}
|
|
|
|
fn rebuild_generics(&self,
|
|
generics: &ast::Generics,
|
|
add: &Vec<ast::Lifetime>,
|
|
keep: &HashSet<ast::Name>,
|
|
remove: &HashSet<ast::Name>,
|
|
ty_params: OwnedSlice<ast::TyParam>,
|
|
where_clause: ast::WhereClause)
|
|
-> ast::Generics {
|
|
let mut lifetimes = Vec::new();
|
|
for lt in add {
|
|
lifetimes.push(ast::LifetimeDef { lifetime: *lt,
|
|
bounds: Vec::new() });
|
|
}
|
|
for lt in &generics.lifetimes {
|
|
if keep.contains(<.lifetime.name) ||
|
|
!remove.contains(<.lifetime.name) {
|
|
lifetimes.push((*lt).clone());
|
|
}
|
|
}
|
|
ast::Generics {
|
|
lifetimes: lifetimes,
|
|
ty_params: ty_params,
|
|
where_clause: where_clause,
|
|
}
|
|
}
|
|
|
|
fn rebuild_args_ty(&self,
|
|
inputs: &[ast::Arg],
|
|
lifetime: ast::Lifetime,
|
|
anon_nums: &HashSet<u32>,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> Vec<ast::Arg> {
|
|
let mut new_inputs = Vec::new();
|
|
for arg in inputs {
|
|
let new_ty = self.rebuild_arg_ty_or_output(&*arg.ty, lifetime,
|
|
anon_nums, region_names);
|
|
let possibly_new_arg = ast::Arg {
|
|
ty: new_ty,
|
|
pat: arg.pat.clone(),
|
|
id: arg.id
|
|
};
|
|
new_inputs.push(possibly_new_arg);
|
|
}
|
|
new_inputs
|
|
}
|
|
|
|
fn rebuild_output(&self, ty: &ast::FunctionRetTy,
|
|
lifetime: ast::Lifetime,
|
|
anon_nums: &HashSet<u32>,
|
|
region_names: &HashSet<ast::Name>) -> ast::FunctionRetTy {
|
|
match *ty {
|
|
ast::Return(ref ret_ty) => ast::Return(
|
|
self.rebuild_arg_ty_or_output(&**ret_ty, lifetime, anon_nums, region_names)
|
|
),
|
|
ast::DefaultReturn(span) => ast::DefaultReturn(span),
|
|
ast::NoReturn(span) => ast::NoReturn(span)
|
|
}
|
|
}
|
|
|
|
fn rebuild_arg_ty_or_output(&self,
|
|
ty: &ast::Ty,
|
|
lifetime: ast::Lifetime,
|
|
anon_nums: &HashSet<u32>,
|
|
region_names: &HashSet<ast::Name>)
|
|
-> P<ast::Ty> {
|
|
let mut new_ty = P(ty.clone());
|
|
let mut ty_queue = vec!(ty);
|
|
while !ty_queue.is_empty() {
|
|
let cur_ty = ty_queue.remove(0);
|
|
match cur_ty.node {
|
|
ast::TyRptr(lt_opt, ref mut_ty) => {
|
|
let rebuild = match lt_opt {
|
|
Some(lt) => region_names.contains(<.name),
|
|
None => {
|
|
let anon = self.cur_anon.get();
|
|
let rebuild = anon_nums.contains(&anon);
|
|
if rebuild {
|
|
self.track_anon(anon);
|
|
}
|
|
self.inc_and_offset_cur_anon(1);
|
|
rebuild
|
|
}
|
|
};
|
|
if rebuild {
|
|
let to = ast::Ty {
|
|
id: cur_ty.id,
|
|
node: ast::TyRptr(Some(lifetime), mut_ty.clone()),
|
|
span: cur_ty.span
|
|
};
|
|
new_ty = self.rebuild_ty(new_ty, P(to));
|
|
}
|
|
ty_queue.push(&*mut_ty.ty);
|
|
}
|
|
ast::TyPath(ref maybe_qself, ref path) => {
|
|
let a_def = match self.tcx.def_map.borrow().get(&cur_ty.id) {
|
|
None => {
|
|
self.tcx
|
|
.sess
|
|
.fatal(&format!(
|
|
"unbound path {}",
|
|
pprust::path_to_string(path)))
|
|
}
|
|
Some(d) => d.full_def()
|
|
};
|
|
match a_def {
|
|
def::DefTy(did, _) | def::DefStruct(did) => {
|
|
let generics = self.tcx.lookup_item_type(did).generics;
|
|
|
|
let expected =
|
|
generics.regions.len(subst::TypeSpace) as u32;
|
|
let lifetimes =
|
|
path.segments.last().unwrap().parameters.lifetimes();
|
|
let mut insert = Vec::new();
|
|
if lifetimes.is_empty() {
|
|
let anon = self.cur_anon.get();
|
|
for (i, a) in (anon..anon+expected).enumerate() {
|
|
if anon_nums.contains(&a) {
|
|
insert.push(i as u32);
|
|
}
|
|
self.track_anon(a);
|
|
}
|
|
self.inc_and_offset_cur_anon(expected);
|
|
} else {
|
|
for (i, lt) in lifetimes.iter().enumerate() {
|
|
if region_names.contains(<.name) {
|
|
insert.push(i as u32);
|
|
}
|
|
}
|
|
}
|
|
let rebuild_info = RebuildPathInfo {
|
|
path: path,
|
|
indexes: insert,
|
|
expected: expected,
|
|
anon_nums: anon_nums,
|
|
region_names: region_names
|
|
};
|
|
let new_path = self.rebuild_path(rebuild_info, lifetime);
|
|
let qself = maybe_qself.as_ref().map(|qself| {
|
|
ast::QSelf {
|
|
ty: self.rebuild_arg_ty_or_output(&qself.ty, lifetime,
|
|
anon_nums, region_names),
|
|
position: qself.position
|
|
}
|
|
});
|
|
let to = ast::Ty {
|
|
id: cur_ty.id,
|
|
node: ast::TyPath(qself, new_path),
|
|
span: cur_ty.span
|
|
};
|
|
new_ty = self.rebuild_ty(new_ty, P(to));
|
|
}
|
|
_ => ()
|
|
}
|
|
|
|
}
|
|
|
|
ast::TyPtr(ref mut_ty) => {
|
|
ty_queue.push(&*mut_ty.ty);
|
|
}
|
|
ast::TyVec(ref ty) |
|
|
ast::TyFixedLengthVec(ref ty, _) => {
|
|
ty_queue.push(&**ty);
|
|
}
|
|
ast::TyTup(ref tys) => ty_queue.extend(tys.iter().map(|ty| &**ty)),
|
|
_ => {}
|
|
}
|
|
}
|
|
new_ty
|
|
}
|
|
|
|
fn rebuild_ty(&self,
|
|
from: P<ast::Ty>,
|
|
to: P<ast::Ty>)
|
|
-> P<ast::Ty> {
|
|
|
|
fn build_to(from: P<ast::Ty>,
|
|
to: &mut Option<P<ast::Ty>>)
|
|
-> P<ast::Ty> {
|
|
if Some(from.id) == to.as_ref().map(|ty| ty.id) {
|
|
return to.take().expect("`to` type found more than once during rebuild");
|
|
}
|
|
from.map(|ast::Ty {id, node, span}| {
|
|
let new_node = match node {
|
|
ast::TyRptr(lifetime, mut_ty) => {
|
|
ast::TyRptr(lifetime, ast::MutTy {
|
|
mutbl: mut_ty.mutbl,
|
|
ty: build_to(mut_ty.ty, to),
|
|
})
|
|
}
|
|
ast::TyPtr(mut_ty) => {
|
|
ast::TyPtr(ast::MutTy {
|
|
mutbl: mut_ty.mutbl,
|
|
ty: build_to(mut_ty.ty, to),
|
|
})
|
|
}
|
|
ast::TyVec(ty) => ast::TyVec(build_to(ty, to)),
|
|
ast::TyFixedLengthVec(ty, e) => {
|
|
ast::TyFixedLengthVec(build_to(ty, to), e)
|
|
}
|
|
ast::TyTup(tys) => {
|
|
ast::TyTup(tys.into_iter().map(|ty| build_to(ty, to)).collect())
|
|
}
|
|
ast::TyParen(typ) => ast::TyParen(build_to(typ, to)),
|
|
other => other
|
|
};
|
|
ast::Ty { id: id, node: new_node, span: span }
|
|
})
|
|
}
|
|
|
|
build_to(from, &mut Some(to))
|
|
}
|
|
|
|
fn rebuild_path(&self,
|
|
rebuild_info: RebuildPathInfo,
|
|
lifetime: ast::Lifetime)
|
|
-> ast::Path
|
|
{
|
|
let RebuildPathInfo {
|
|
path,
|
|
indexes,
|
|
expected,
|
|
anon_nums,
|
|
region_names,
|
|
} = rebuild_info;
|
|
|
|
let last_seg = path.segments.last().unwrap();
|
|
let new_parameters = match last_seg.parameters {
|
|
ast::ParenthesizedParameters(..) => {
|
|
last_seg.parameters.clone()
|
|
}
|
|
|
|
ast::AngleBracketedParameters(ref data) => {
|
|
let mut new_lts = Vec::new();
|
|
if data.lifetimes.is_empty() {
|
|
// traverse once to see if there's a need to insert lifetime
|
|
let need_insert = (0..expected).any(|i| {
|
|
indexes.contains(&i)
|
|
});
|
|
if need_insert {
|
|
for i in 0..expected {
|
|
if indexes.contains(&i) {
|
|
new_lts.push(lifetime);
|
|
} else {
|
|
new_lts.push(self.life_giver.give_lifetime());
|
|
}
|
|
}
|
|
}
|
|
} else {
|
|
for (i, lt) in data.lifetimes.iter().enumerate() {
|
|
if indexes.contains(&(i as u32)) {
|
|
new_lts.push(lifetime);
|
|
} else {
|
|
new_lts.push(*lt);
|
|
}
|
|
}
|
|
}
|
|
let new_types = data.types.map(|t| {
|
|
self.rebuild_arg_ty_or_output(&**t, lifetime, anon_nums, region_names)
|
|
});
|
|
let new_bindings = data.bindings.map(|b| {
|
|
P(ast::TypeBinding {
|
|
id: b.id,
|
|
ident: b.ident,
|
|
ty: self.rebuild_arg_ty_or_output(&*b.ty,
|
|
lifetime,
|
|
anon_nums,
|
|
region_names),
|
|
span: b.span
|
|
})
|
|
});
|
|
ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
|
|
lifetimes: new_lts,
|
|
types: new_types,
|
|
bindings: new_bindings,
|
|
})
|
|
}
|
|
};
|
|
let new_seg = ast::PathSegment {
|
|
identifier: last_seg.identifier,
|
|
parameters: new_parameters
|
|
};
|
|
let mut new_segs = Vec::new();
|
|
new_segs.push_all(path.segments.split_last().unwrap().1);
|
|
new_segs.push(new_seg);
|
|
ast::Path {
|
|
span: path.span,
|
|
global: path.global,
|
|
segments: new_segs
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> ErrorReportingHelpers<'tcx> for InferCtxt<'a, 'tcx> {
|
|
fn give_expl_lifetime_param(&self,
|
|
decl: &ast::FnDecl,
|
|
unsafety: ast::Unsafety,
|
|
constness: ast::Constness,
|
|
ident: ast::Ident,
|
|
opt_explicit_self: Option<&ast::ExplicitSelf_>,
|
|
generics: &ast::Generics,
|
|
span: Span) {
|
|
let suggested_fn = pprust::fun_to_string(decl, unsafety, constness, ident,
|
|
opt_explicit_self, generics);
|
|
let msg = format!("consider using an explicit lifetime \
|
|
parameter as shown: {}", suggested_fn);
|
|
self.tcx.sess.span_help(span, &msg[..]);
|
|
}
|
|
|
|
fn report_inference_failure(&self,
|
|
var_origin: RegionVariableOrigin) {
|
|
let br_string = |br: ty::BoundRegion| {
|
|
let mut s = br.to_string();
|
|
if !s.is_empty() {
|
|
s.push_str(" ");
|
|
}
|
|
s
|
|
};
|
|
let var_description = match var_origin {
|
|
infer::MiscVariable(_) => "".to_string(),
|
|
infer::PatternRegion(_) => " for pattern".to_string(),
|
|
infer::AddrOfRegion(_) => " for borrow expression".to_string(),
|
|
infer::Autoref(_) => " for autoref".to_string(),
|
|
infer::Coercion(_) => " for automatic coercion".to_string(),
|
|
infer::LateBoundRegion(_, br, infer::FnCall) => {
|
|
format!(" for lifetime parameter {}in function call",
|
|
br_string(br))
|
|
}
|
|
infer::LateBoundRegion(_, br, infer::HigherRankedType) => {
|
|
format!(" for lifetime parameter {}in generic type", br_string(br))
|
|
}
|
|
infer::LateBoundRegion(_, br, infer::AssocTypeProjection(type_name)) => {
|
|
format!(" for lifetime parameter {}in trait containing associated type `{}`",
|
|
br_string(br), type_name)
|
|
}
|
|
infer::EarlyBoundRegion(_, name) => {
|
|
format!(" for lifetime parameter `{}`",
|
|
name)
|
|
}
|
|
infer::BoundRegionInCoherence(name) => {
|
|
format!(" for lifetime parameter `{}` in coherence check",
|
|
name)
|
|
}
|
|
infer::UpvarRegion(ref upvar_id, _) => {
|
|
format!(" for capture of `{}` by closure",
|
|
self.tcx.local_var_name_str(upvar_id.var_id).to_string())
|
|
}
|
|
};
|
|
|
|
self.tcx.sess.span_err(
|
|
var_origin.span(),
|
|
&format!("cannot infer an appropriate lifetime{} \
|
|
due to conflicting requirements",
|
|
var_description));
|
|
}
|
|
|
|
fn note_region_origin(&self, origin: &SubregionOrigin<'tcx>) {
|
|
match *origin {
|
|
infer::RFC1214Subregion(ref suborigin) => {
|
|
self.note_region_origin(suborigin);
|
|
}
|
|
infer::Subtype(ref trace) => {
|
|
let desc = match trace.origin {
|
|
infer::Misc(_) => {
|
|
"types are compatible"
|
|
}
|
|
infer::MethodCompatCheck(_) => {
|
|
"method type is compatible with trait"
|
|
}
|
|
infer::ExprAssignable(_) => {
|
|
"expression is assignable"
|
|
}
|
|
infer::RelateTraitRefs(_) => {
|
|
"traits are compatible"
|
|
}
|
|
infer::RelateSelfType(_) => {
|
|
"self type matches impl self type"
|
|
}
|
|
infer::RelateOutputImplTypes(_) => {
|
|
"trait type parameters matches those \
|
|
specified on the impl"
|
|
}
|
|
infer::MatchExpressionArm(_, _) => {
|
|
"match arms have compatible types"
|
|
}
|
|
infer::IfExpression(_) => {
|
|
"if and else have compatible types"
|
|
}
|
|
infer::IfExpressionWithNoElse(_) => {
|
|
"if may be missing an else clause"
|
|
}
|
|
infer::RangeExpression(_) => {
|
|
"start and end of range have compatible types"
|
|
}
|
|
infer::EquatePredicate(_) => {
|
|
"equality where clause is satisfied"
|
|
}
|
|
};
|
|
|
|
match self.values_str(&trace.values) {
|
|
Some(values_str) => {
|
|
self.tcx.sess.span_note(
|
|
trace.origin.span(),
|
|
&format!("...so that {} ({})",
|
|
desc, values_str));
|
|
}
|
|
None => {
|
|
// Really should avoid printing this error at
|
|
// all, since it is derived, but that would
|
|
// require more refactoring than I feel like
|
|
// doing right now. - nmatsakis
|
|
self.tcx.sess.span_note(
|
|
trace.origin.span(),
|
|
&format!("...so that {}", desc));
|
|
}
|
|
}
|
|
}
|
|
infer::Reborrow(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that reference does not outlive \
|
|
borrowed content");
|
|
}
|
|
infer::ReborrowUpvar(span, ref upvar_id) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!(
|
|
"...so that closure can access `{}`",
|
|
self.tcx.local_var_name_str(upvar_id.var_id)
|
|
.to_string()))
|
|
}
|
|
infer::InfStackClosure(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that closure does not outlive its stack frame");
|
|
}
|
|
infer::InvokeClosure(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that closure is not invoked outside its lifetime");
|
|
}
|
|
infer::DerefPointer(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that pointer is not dereferenced \
|
|
outside its lifetime");
|
|
}
|
|
infer::FreeVariable(span, id) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that captured variable `{}` \
|
|
does not outlive the enclosing closure",
|
|
self.tcx.local_var_name_str(id)));
|
|
}
|
|
infer::IndexSlice(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that slice is not indexed outside the lifetime");
|
|
}
|
|
infer::RelateObjectBound(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that it can be closed over into an object");
|
|
}
|
|
infer::CallRcvr(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that method receiver is valid for the method call");
|
|
}
|
|
infer::CallArg(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that argument is valid for the call");
|
|
}
|
|
infer::CallReturn(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that return value is valid for the call");
|
|
}
|
|
infer::Operand(span) => {
|
|
self.tcx.sess.span_err(
|
|
span,
|
|
"...so that operand is valid for operation");
|
|
}
|
|
infer::AddrOf(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that reference is valid \
|
|
at the time of borrow");
|
|
}
|
|
infer::AutoBorrow(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that auto-reference is valid \
|
|
at the time of borrow");
|
|
}
|
|
infer::ExprTypeIsNotInScope(t, span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so type `{}` of expression is valid during the \
|
|
expression",
|
|
self.ty_to_string(t)));
|
|
}
|
|
infer::BindingTypeIsNotValidAtDecl(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that variable is valid at time of its declaration");
|
|
}
|
|
infer::ParameterInScope(_, span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that a type/lifetime parameter is in scope here"));
|
|
}
|
|
infer::DataBorrowed(ty, span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that the type `{}` is not borrowed for too long",
|
|
self.ty_to_string(ty)));
|
|
}
|
|
infer::ReferenceOutlivesReferent(ty, span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that the reference type `{}` \
|
|
does not outlive the data it points at",
|
|
self.ty_to_string(ty)));
|
|
}
|
|
infer::RelateParamBound(span, t) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that the type `{}` \
|
|
will meet its required lifetime bounds",
|
|
self.ty_to_string(t)));
|
|
}
|
|
infer::RelateDefaultParamBound(span, t) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
&format!("...so that type parameter \
|
|
instantiated with `{}`, \
|
|
will meet its declared lifetime bounds",
|
|
self.ty_to_string(t)));
|
|
}
|
|
infer::RelateRegionParamBound(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that the declared lifetime parameter bounds \
|
|
are satisfied");
|
|
}
|
|
infer::SafeDestructor(span) => {
|
|
self.tcx.sess.span_note(
|
|
span,
|
|
"...so that references are valid when the destructor \
|
|
runs")
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub trait Resolvable<'tcx> {
|
|
fn resolve<'a>(&self, infcx: &InferCtxt<'a, 'tcx>) -> Self;
|
|
}
|
|
|
|
impl<'tcx> Resolvable<'tcx> for Ty<'tcx> {
|
|
fn resolve<'a>(&self, infcx: &InferCtxt<'a, 'tcx>) -> Ty<'tcx> {
|
|
infcx.resolve_type_vars_if_possible(self)
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Resolvable<'tcx> for ty::TraitRef<'tcx> {
|
|
fn resolve<'a>(&self, infcx: &InferCtxt<'a, 'tcx>)
|
|
-> ty::TraitRef<'tcx> {
|
|
infcx.resolve_type_vars_if_possible(self)
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Resolvable<'tcx> for ty::PolyTraitRef<'tcx> {
|
|
fn resolve<'a>(&self,
|
|
infcx: &InferCtxt<'a, 'tcx>)
|
|
-> ty::PolyTraitRef<'tcx>
|
|
{
|
|
infcx.resolve_type_vars_if_possible(self)
|
|
}
|
|
}
|
|
|
|
fn lifetimes_in_scope(tcx: &ty::ctxt,
|
|
scope_id: ast::NodeId)
|
|
-> Vec<ast::LifetimeDef> {
|
|
let mut taken = Vec::new();
|
|
let parent = tcx.map.get_parent(scope_id);
|
|
let method_id_opt = match tcx.map.find(parent) {
|
|
Some(node) => match node {
|
|
ast_map::NodeItem(item) => match item.node {
|
|
ast::ItemFn(_, _, _, _, ref gen, _) => {
|
|
taken.push_all(&gen.lifetimes);
|
|
None
|
|
},
|
|
_ => None
|
|
},
|
|
ast_map::NodeImplItem(ii) => {
|
|
match ii.node {
|
|
ast::MethodImplItem(ref sig, _) => {
|
|
taken.push_all(&sig.generics.lifetimes);
|
|
Some(ii.id)
|
|
}
|
|
ast::MacImplItem(_) => tcx.sess.bug("unexpanded macro"),
|
|
_ => None,
|
|
}
|
|
}
|
|
_ => None
|
|
},
|
|
None => None
|
|
};
|
|
if method_id_opt.is_some() {
|
|
let method_id = method_id_opt.unwrap();
|
|
let parent = tcx.map.get_parent(method_id);
|
|
match tcx.map.find(parent) {
|
|
Some(node) => match node {
|
|
ast_map::NodeItem(item) => match item.node {
|
|
ast::ItemImpl(_, _, ref gen, _, _, _) => {
|
|
taken.push_all(&gen.lifetimes);
|
|
}
|
|
_ => ()
|
|
},
|
|
_ => ()
|
|
},
|
|
None => ()
|
|
}
|
|
}
|
|
return taken;
|
|
}
|
|
|
|
// LifeGiver is responsible for generating fresh lifetime names
|
|
struct LifeGiver {
|
|
taken: HashSet<String>,
|
|
counter: Cell<usize>,
|
|
generated: RefCell<Vec<ast::Lifetime>>,
|
|
}
|
|
|
|
impl LifeGiver {
|
|
fn with_taken(taken: &[ast::LifetimeDef]) -> LifeGiver {
|
|
let mut taken_ = HashSet::new();
|
|
for lt in taken {
|
|
let lt_name = lt.lifetime.name.to_string();
|
|
taken_.insert(lt_name);
|
|
}
|
|
LifeGiver {
|
|
taken: taken_,
|
|
counter: Cell::new(0),
|
|
generated: RefCell::new(Vec::new()),
|
|
}
|
|
}
|
|
|
|
fn inc_counter(&self) {
|
|
let c = self.counter.get();
|
|
self.counter.set(c+1);
|
|
}
|
|
|
|
fn give_lifetime(&self) -> ast::Lifetime {
|
|
let lifetime;
|
|
loop {
|
|
let mut s = String::from("'");
|
|
s.push_str(&num_to_string(self.counter.get()));
|
|
if !self.taken.contains(&s) {
|
|
lifetime = name_to_dummy_lifetime(
|
|
token::str_to_ident(&s[..]).name);
|
|
self.generated.borrow_mut().push(lifetime);
|
|
break;
|
|
}
|
|
self.inc_counter();
|
|
}
|
|
self.inc_counter();
|
|
return lifetime;
|
|
|
|
// 0 .. 25 generates a .. z, 26 .. 51 generates aa .. zz, and so on
|
|
fn num_to_string(counter: usize) -> String {
|
|
let mut s = String::new();
|
|
let (n, r) = (counter/26 + 1, counter % 26);
|
|
let letter: char = from_u32((r+97) as u32).unwrap();
|
|
for _ in 0..n {
|
|
s.push(letter);
|
|
}
|
|
s
|
|
}
|
|
}
|
|
|
|
fn get_generated_lifetimes(&self) -> Vec<ast::Lifetime> {
|
|
self.generated.borrow().clone()
|
|
}
|
|
}
|