From fa22fc387ad17510d5af9eb16db5e5e01bde38b4 Mon Sep 17 00:00:00 2001 From: Niko Matsakis Date: Mon, 21 Nov 2016 12:17:13 -0500 Subject: [PATCH 1/4] in region, treat current (and future) item-likes alike The `visit_fn` code mutates its surrounding context. Between *items*, this was saved/restored, but between impl items it was not. This meant that we wound up with `CallSiteScope` entries with two parents (or more!). As far as I can tell, this is harmless in actual type-checking, since the regions you interact with are always from at most one of those branches. But it can slow things down. Before, the effect was limited, since it only applied to impl items within an impl. After #37660, impl items are visisted all together at the end, and hence this could create a very messed up hierarchy. Isolating impl item properly solves both issues. I cannot come up with a way to unit-test this; for posterity, however, you can observe the messed up hierarchies with a test as simple as the following, which would create a callsite scope with two parents both before and after ``` struct Foo { } impl Foo { fn bar(&self) -> usize { 22 } fn baz(&self) -> usize { 22 } } fn main() { } ``` Fixes #37864. --- src/librustc/middle/region.rs | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs index 05fa619ce41e4..930c9e284f6f2 100644 --- a/src/librustc/middle/region.rs +++ b/src/librustc/middle/region.rs @@ -1066,7 +1066,9 @@ fn resolve_local<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, } } -fn resolve_item<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, item: &'tcx hir::Item) { +fn resolve_item_like<'a, 'tcx, F>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, id: ast::NodeId, walk: F) + where F: FnOnce(&mut RegionResolutionVisitor<'tcx, 'a>) +{ // Items create a new outer block scope as far as we're concerned. let prev_cx = visitor.cx; let prev_ts = mem::replace(&mut visitor.terminating_scopes, NodeSet()); @@ -1075,8 +1077,8 @@ fn resolve_item<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, item: var_parent: ROOT_CODE_EXTENT, parent: ROOT_CODE_EXTENT }; - intravisit::walk_item(visitor, item); - visitor.create_item_scope_if_needed(item.id); + walk(visitor); + visitor.create_item_scope_if_needed(id); visitor.cx = prev_cx; visitor.terminating_scopes = prev_ts; } @@ -1179,17 +1181,15 @@ impl<'ast, 'a> Visitor<'ast> for RegionResolutionVisitor<'ast, 'a> { } fn visit_item(&mut self, i: &'ast Item) { - resolve_item(self, i); + resolve_item_like(self, i.id, |this| intravisit::walk_item(this, i)); } fn visit_impl_item(&mut self, ii: &'ast hir::ImplItem) { - intravisit::walk_impl_item(self, ii); - self.create_item_scope_if_needed(ii.id); + resolve_item_like(self, ii.id, |this| intravisit::walk_impl_item(this, ii)); } fn visit_trait_item(&mut self, ti: &'ast hir::TraitItem) { - intravisit::walk_trait_item(self, ti); - self.create_item_scope_if_needed(ti.id); + resolve_item_like(self, ti.id, |this| intravisit::walk_trait_item(this, ti)); } fn visit_fn(&mut self, fk: FnKind<'ast>, fd: &'ast FnDecl, From 6fe4bffb406cb13d633730b05e029925cef0deb0 Mon Sep 17 00:00:00 2001 From: Niko Matsakis Date: Tue, 29 Nov 2016 11:51:35 -0500 Subject: [PATCH 2/4] test for #37290 using lint --- .../run-pass/issue-37290/auxiliary/lint.rs | 68 +++++++++++++++++++ src/test/run-pass/issue-37290/main.rs | 30 ++++++++ 2 files changed, 98 insertions(+) create mode 100644 src/test/run-pass/issue-37290/auxiliary/lint.rs create mode 100644 src/test/run-pass/issue-37290/main.rs diff --git a/src/test/run-pass/issue-37290/auxiliary/lint.rs b/src/test/run-pass/issue-37290/auxiliary/lint.rs new file mode 100644 index 0000000000000..33d072eb6a890 --- /dev/null +++ b/src/test/run-pass/issue-37290/auxiliary/lint.rs @@ -0,0 +1,68 @@ +// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// This flag is needed for plugins to work: +// compile-flags: -C prefer-dynamic + +#![feature(plugin_registrar, rustc_private)] +#![crate_type = "dylib"] +#![deny(region_hierarchy)] + +extern crate syntax; +#[macro_use] +extern crate rustc; +extern crate rustc_plugin; + +use rustc::lint::{LateContext, LintPass, LateLintPass, LintArray, LintContext}; +use rustc::hir; +use rustc::hir::intravisit::FnKind; +use rustc::middle::region::CodeExtent; +use rustc::util::nodemap::FxHashMap; + +use syntax::ast::{self, NodeId}; +use syntax::codemap::Span; + +declare_lint!(REGION_HIERARCHY, Warn, "warn about bogus region hierarchy"); + +struct Pass { + map: FxHashMap +} + +impl LintPass for Pass { + fn get_lints(&self) -> LintArray { lint_array!(REGION_HIERARCHY) } +} + +impl LateLintPass for Pass { + fn check_fn(&mut self, cx: &LateContext, + fk: FnKind, _: &hir::FnDecl, expr: &hir::Expr, + span: Span, node: ast::NodeId) + { + if let FnKind::Closure(..) = fk { return } + + let mut extent = cx.tcx.region_maps.node_extent(expr.id); + while let Some(parent) = cx.tcx.region_maps.opt_encl_scope(extent) { + extent = parent; + } + if let Some(other) = self.map.insert(extent, node) { + cx.span_lint(REGION_HIERARCHY, span, &format!( + "different fns {:?}, {:?} with the same root extent {:?}", + cx.tcx.map.local_def_id(other), + cx.tcx.map.local_def_id(node), + extent)); + } + } +} + +#[plugin_registrar] +pub fn plugin_registrar(reg: &mut ::rustc_plugin::Registry) { + reg.register_late_lint_pass(Box::new( + Pass { map: FxHashMap() } + )); +} diff --git a/src/test/run-pass/issue-37290/main.rs b/src/test/run-pass/issue-37290/main.rs new file mode 100644 index 0000000000000..394ad92b1d8c0 --- /dev/null +++ b/src/test/run-pass/issue-37290/main.rs @@ -0,0 +1,30 @@ +// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// aux-build:lint.rs + +#![feature(plugin)] +#![plugin(lint)] + +struct Foo { +} + +impl Foo { + fn bar(&self) -> usize { + 22 + } + + fn baz(&self) -> usize { + 22 + } +} + +fn main() { } + From 0adb1b1b0259ea6cccdf92698eecc83b2ecc8936 Mon Sep 17 00:00:00 2001 From: Niko Matsakis Date: Fri, 2 Dec 2016 14:18:09 -0500 Subject: [PATCH 3/4] pacify the mercilous tidy --- src/librustc/middle/region.rs | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs index 930c9e284f6f2..b1e35e54eb9bb 100644 --- a/src/librustc/middle/region.rs +++ b/src/librustc/middle/region.rs @@ -1066,7 +1066,9 @@ fn resolve_local<'a, 'tcx>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, } } -fn resolve_item_like<'a, 'tcx, F>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, id: ast::NodeId, walk: F) +fn resolve_item_like<'a, 'tcx, F>(visitor: &mut RegionResolutionVisitor<'tcx, 'a>, + id: ast::NodeId, + walk: F) where F: FnOnce(&mut RegionResolutionVisitor<'tcx, 'a>) { // Items create a new outer block scope as far as we're concerned. From f8097066f8d40ef2716b6d679324ef894038b261 Mon Sep 17 00:00:00 2001 From: Niko Matsakis Date: Sat, 3 Dec 2016 14:42:34 -0500 Subject: [PATCH 4/4] move test for #37290 into run-pass-fulldeps --- .../{run-pass => run-pass-fulldeps}/issue-37290/auxiliary/lint.rs | 0 src/test/{run-pass => run-pass-fulldeps}/issue-37290/main.rs | 0 2 files changed, 0 insertions(+), 0 deletions(-) rename src/test/{run-pass => run-pass-fulldeps}/issue-37290/auxiliary/lint.rs (100%) rename src/test/{run-pass => run-pass-fulldeps}/issue-37290/main.rs (100%) diff --git a/src/test/run-pass/issue-37290/auxiliary/lint.rs b/src/test/run-pass-fulldeps/issue-37290/auxiliary/lint.rs similarity index 100% rename from src/test/run-pass/issue-37290/auxiliary/lint.rs rename to src/test/run-pass-fulldeps/issue-37290/auxiliary/lint.rs diff --git a/src/test/run-pass/issue-37290/main.rs b/src/test/run-pass-fulldeps/issue-37290/main.rs similarity index 100% rename from src/test/run-pass/issue-37290/main.rs rename to src/test/run-pass-fulldeps/issue-37290/main.rs