Add a LocalDrop trait and a derive proc macro for it

Author: Zoxc

Cargo.lock

@@ -609,7 +609,7 @@ version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.15.21 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -734,7 +734,7 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1341,7 +1341,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "num-traits 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1677,7 +1677,7 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "0.6.8"
+version = "0.6.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2239,6 +2239,7 @@ dependencies = [
  "rustc-rayon 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-rayon-core 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_cratesio_shim 0.0.0",
+ "rustc_local_drop_derive 0.1.0",
  "serialize 0.0.0",
  "smallvec 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "stable_deref_trait 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2334,6 +2335,15 @@ dependencies = [
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "rustc_local_drop_derive"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "synstructure 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "rustc_lsan"
 version = "0.0.0"
@@ -2664,7 +2674,7 @@ version = "1.0.75"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2801,7 +2811,7 @@ version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2831,7 +2841,7 @@ version = "0.14.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2841,7 +2851,7 @@ version = "0.15.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2859,11 +2869,22 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "synstructure"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 0.4.24 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.21 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "syntax"
 version = "0.0.0"
@@ -3400,7 +3421,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum quine-mc_cluskey 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "07589615d719a60c8dd8a4622e7946465dfef20d1a428f969e3443e7386d5f45"
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
 "checksum quote 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9949cfe66888ffe1d53e6ec9d9f3b70714083854be20fd5e271b232a017401e8"
-"checksum quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)" = "dd636425967c33af890042c483632d33fa7a18f19ad1d7ea72e8998c6ef8dea5"
+"checksum quote 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)" = "53fa22a1994bd0f9372d7a816207d8a2677ad0325b073f5c5332760f0fb62b5c"
 "checksum racer 2.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "344a53b68d889ab5f44d0617f2bbe1f696abe6a730bd41fa619cfc6fa83a6078"
 "checksum rand 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8356f47b32624fef5b3301c1be97e5944ecdd595409cc5da11d05f211db6cfbd"
 "checksum rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e464cd887e869cddcae8792a4ee31d23c7edd516700695608f5b98c67ee0131c"
@@ -3465,6 +3486,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)" = "261ae9ecaa397c42b960649561949d69311f08eeaea86a65696e6e46517cf741"
 "checksum syn 0.15.21 (registry+https://github.com/rust-lang/crates.io-index)" = "816b7af21405b011a23554ea2dc3f6576dc86ca557047c34098c1d741f10f823"
 "checksum synom 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a393066ed9010ebaed60b9eafa373d4b1baac186dd7e008555b0f702b51945b6"
+"checksum synstructure 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "73687139bf99285483c96ac0add482c3776528beac1d97d444f6e91f203a2015"
 "checksum synstructure 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "85bb9b7550d063ea184027c9b8c20ac167cd36d3e06b3a40bceb9d746dc1a7b7"
 "checksum tar 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)" = "69e16840a1e0a1f1a880b739ef1cc6a4b85496c99b8aa786ccffce6e0c15624c"
 "checksum tempfile 3.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "c4b103c6d08d323b92ff42c8ce62abcd83ca8efa7fd5bf7927efefec75f58c76"

src/bootstrap/bin/rustc.rs

@@ -268,13 +268,6 @@ fn main() {
             }
         }
 
-        // Force all crates compiled by this compiler to (a) be unstable and (b)
-        // allow the `rustc_private` feature to link to other unstable crates
-        // also in the sysroot.
-        if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
-            cmd.arg("-Z").arg("force-unstable-if-unmarked");
-        }
-
         if let Ok(map) = env::var("RUSTC_DEBUGINFO_MAP") {
             cmd.arg("--remap-path-prefix").arg(&map);
         }
@@ -294,6 +287,13 @@ fn main() {
         }
     }
 
+    // Force all crates compiled by this compiler to (a) be unstable and (b)
+    // allow the `rustc_private` feature to link to other unstable crates
+    // also in the sysroot.
+    if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
+        cmd.arg("-Z").arg("force-unstable-if-unmarked");
+    }
+
     if env::var_os("RUSTC_PARALLEL_QUERIES").is_some() {
         cmd.arg("--cfg").arg("parallel_queries");
     }

src/bootstrap/compile.rs

@@ -1064,15 +1064,9 @@ pub fn run_cargo(builder: &Builder,
 
             let filename = Path::new(&*filename);
 
-            // If this was an output file in the "host dir" we don't actually
-            // worry about it, it's not relevant for us.
-            if filename.starts_with(&host_root_dir) {
-                continue;
-            }
-
             // If this was output in the `deps` dir then this is a precise file
             // name (hash included) so we start tracking it.
-            if filename.starts_with(&target_deps_dir) {
+            if filename.starts_with(&host_root_dir) || filename.starts_with(&target_deps_dir) {
                 deps.push(filename.to_path_buf());
                 continue;
             }

src/libarena/lib.rs

@@ -35,7 +35,8 @@
 extern crate alloc;
 extern crate rustc_data_structures;
 
-use rustc_data_structures::sync::MTLock;
+use rustc_data_structures::local_drop::LocalDrop;
+use rustc_data_structures::sync::{MTLock, WorkerLocal};
 
 use std::cell::{Cell, RefCell};
 use std::cmp;
@@ -447,12 +448,39 @@ impl<T> SyncTypedArena<T> {
     }
 }
 
-#[derive(Default)]
+struct DropType {
+    drop_fn: unsafe fn(*mut u8),
+    obj: *mut u8,
+}
+
+unsafe fn drop_for_type<T>(to_drop: *mut u8) {
+    std::ptr::drop_in_place(to_drop as *mut T)
+}
+
+impl Drop for DropType {
+    fn drop(&mut self) {
+        unsafe {
+            (self.drop_fn)(self.obj)
+        }
+    }
+}
+
 pub struct SyncDroplessArena {
+    // Ordered so `deferred` gets dropped before the arena
+    // since its destructor can reference memory in the arena
+    deferred: WorkerLocal<RefCell<Vec<DropType>>>,
     lock: MTLock<DroplessArena>,
 }
 
 impl SyncDroplessArena {
+    #[inline]
+    pub fn new() -> Self {
+        SyncDroplessArena {
+            lock: Default::default(),
+            deferred: WorkerLocal::new(|_| Default::default()),
+        }
+    }
+
     #[inline(always)]
     pub fn in_arena<T: ?Sized>(&self, ptr: *const T) -> bool {
         self.lock.lock().in_arena(ptr)
@@ -478,6 +506,26 @@ impl SyncDroplessArena {
         // Extend the lifetime of the result since it's limited to the lock guard
         unsafe { &mut *(self.lock.lock().alloc_slice(slice) as *mut [T]) }
     }
+
+    #[inline]
+    pub fn promote<T: LocalDrop>(&self, object: T) -> &T {
+        // Validate that T is really LocalDrop at runtime
+        T::check();
+
+        let mem = self.alloc_raw(mem::size_of::<T>(), mem::align_of::<T>()) as *mut _ as *mut T;
+        let result = unsafe {
+            // Write into uninitialized memory.
+            ptr::write(mem, object);
+            &mut *mem
+        };
+        // Record the destructor after doing the allocation as that may panic
+        // and would cause `object` destuctor to run twice if it was recorded before
+        self.deferred.borrow_mut().push(DropType {
+            drop_fn: drop_for_type::<T>,
+            obj: result as *mut T as *mut u8,
+        });
+        result
+    }
 }
 
 #[cfg(test)]

src/librustc/infer/mod.rs

@@ -478,7 +478,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'gcx> {
     pub fn infer_ctxt(self) -> InferCtxtBuilder<'a, 'gcx, 'tcx> {
         InferCtxtBuilder {
             global_tcx: self,
-            arena: SyncDroplessArena::default(),
+            arena: SyncDroplessArena::new(),
             fresh_tables: None,
         }
     }

src/librustc/ty/context.rs

@@ -55,6 +55,7 @@ use util::nodemap::{DefIdMap, DefIdSet, ItemLocalMap};
 use util::nodemap::{FxHashMap, FxHashSet};
 use rustc_data_structures::interner::HashInterner;
 use smallvec::SmallVec;
+use rustc_data_structures::local_drop::LocalDrop;
 use rustc_data_structures::stable_hasher::{HashStable, hash_stable_hashmap,
                                            StableHasher, StableHasherResult,
                                            StableVec};
@@ -92,7 +93,7 @@ impl<'tcx> AllArenas<'tcx> {
     pub fn new() -> Self {
         AllArenas {
             global: WorkerLocal::new(|_| GlobalArenas::default()),
-            interner: SyncDroplessArena::default(),
+            interner: SyncDroplessArena::new(),
         }
     }
 }
@@ -971,6 +972,16 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
+    #[inline(always)]
+    pub fn promote<T: LocalDrop>(&self, object: T) -> &'gcx T {
+        self.gcx.global_interners.arena.promote(object)
+    }
+
+    #[inline(always)]
+    pub fn promote_vec<T: LocalDrop>(&self, vec: Vec<T>) -> &'gcx [T] {
+        &self.gcx.global_interners.arena.promote(vec)[..]
+    }
+
     pub fn alloc_generics(self, generics: ty::Generics) -> &'gcx ty::Generics {
         self.global_arenas.generics.alloc(generics)
     }

src/librustc_data_structures/Cargo.toml

@@ -11,6 +11,7 @@ crate-type = ["dylib"]
 [dependencies]
 ena = "0.11"
 log = "0.4"
+rustc_local_drop_derive = { path = "../librustc_local_drop_derive" }
 rustc_cratesio_shim = { path = "../librustc_cratesio_shim" }
 serialize = { path = "../libserialize" }
 graphviz = { path = "../libgraphviz" }

src/librustc_data_structures/lib.rs

@@ -20,6 +20,7 @@
       html_favicon_url = "https://www.rust-lang.org/favicon.ico",
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 
+#![feature(core_intrinsics)]
 #![feature(in_band_lifetimes)]
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
@@ -42,6 +43,7 @@ extern crate serialize as rustc_serialize; // used by deriving
 #[cfg(unix)]
 extern crate libc;
 extern crate parking_lot;
+extern crate rustc_local_drop_derive;
 #[macro_use]
 extern crate cfg_if;
 extern crate stable_deref_trait;
@@ -56,9 +58,14 @@ extern crate smallvec;
 #[allow(unused_extern_crates)]
 extern crate rustc_cratesio_shim;
 
+mod rustc_data_structures {
+      pub use ::*;
+}
+
 pub use rustc_serialize::hex::ToHex;
 
 pub mod macros;
+#[macro_use] pub mod local_drop;
 pub mod svh;
 pub mod base_n;
 pub mod bit_set;