Remove type_needs_unwind_cleanup

After the last @dinosaur went extinct, the check became redundant with
type_needs_drop, except for its bugginess.

Fixes #26655.

Author: Ariel Ben-Yehuda

src/librustc_trans/trans/cleanup.rs

@@ -389,7 +389,6 @@ impl<'blk, 'tcx> CleanupMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx> {
         if !self.type_needs_drop(ty) { return; }
         let drop = box DropValue {
             is_immediate: false,
-            must_unwind: common::type_needs_unwind_cleanup(self.ccx, ty),
             val: val,
             ty: ty,
             fill_on_drop: false,
@@ -415,7 +414,6 @@ impl<'blk, 'tcx> CleanupMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx> {
 
         let drop = box DropValue {
             is_immediate: false,
-            must_unwind: common::type_needs_unwind_cleanup(self.ccx, ty),
             val: val,
             ty: ty,
             fill_on_drop: true,
@@ -447,7 +445,6 @@ impl<'blk, 'tcx> CleanupMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx> {
 
         let drop = box DropValue {
             is_immediate: false,
-            must_unwind: common::type_needs_unwind_cleanup(self.ccx, ty),
             val: val,
             ty: ty,
             fill_on_drop: false,
@@ -473,7 +470,6 @@ impl<'blk, 'tcx> CleanupMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx> {
         if !self.type_needs_drop(ty) { return; }
         let drop = box DropValue {
             is_immediate: true,
-            must_unwind: common::type_needs_unwind_cleanup(self.ccx, ty),
             val: val,
             ty: ty,
             fill_on_drop: false,
@@ -1031,7 +1027,6 @@ impl EarlyExitLabel {
 #[derive(Copy, Clone)]
 pub struct DropValue<'tcx> {
     is_immediate: bool,
-    must_unwind: bool,
     val: ValueRef,
     ty: Ty<'tcx>,
     fill_on_drop: bool,
@@ -1040,11 +1035,11 @@ pub struct DropValue<'tcx> {
 
 impl<'tcx> Cleanup<'tcx> for DropValue<'tcx> {
     fn must_unwind(&self) -> bool {
-        self.must_unwind
+        true
     }
 
     fn clean_on_unwind(&self) -> bool {
-        self.must_unwind
+        true
     }
 
     fn is_lifetime_end(&self) -> bool {

src/librustc_trans/trans/common.rs

@@ -25,7 +25,7 @@ use middle::lang_items::LangItem;
 use middle::mem_categorization as mc;
 use middle::mem_categorization::Typer;
 use middle::region;
-use middle::subst::{self, Subst, Substs};
+use middle::subst::{self, Substs};
 use trans::base;
 use trans::build;
 use trans::cleanup;
@@ -54,8 +54,6 @@ use syntax::ast;
 use syntax::codemap::{DUMMY_SP, Span};
 use syntax::parse::token::InternedString;
 use syntax::parse::token;
-use util::common::memoized;
-use util::nodemap::FnvHashSet;
 
 pub use trans::context::CrateContext;
 
@@ -136,47 +134,6 @@ pub fn type_is_fat_ptr<'tcx>(cx: &ty::ctxt<'tcx>, ty: Ty<'tcx>) -> bool {
     }
 }
 
-// Some things don't need cleanups during unwinding because the
-// thread can free them all at once later. Currently only things
-// that only contain scalars and shared boxes can avoid unwind
-// cleanups.
-pub fn type_needs_unwind_cleanup<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
-    return memoized(ccx.needs_unwind_cleanup_cache(), ty, |ty| {
-        type_needs_unwind_cleanup_(ccx.tcx(), ty, &mut FnvHashSet())
-    });
-
-    fn type_needs_unwind_cleanup_<'tcx>(tcx: &ty::ctxt<'tcx>,
-                                        ty: Ty<'tcx>,
-                                        tycache: &mut FnvHashSet<Ty<'tcx>>)
-                                        -> bool
-    {
-        // Prevent infinite recursion
-        if !tycache.insert(ty) {
-            return false;
-        }
-
-        let mut needs_unwind_cleanup = false;
-        ty.maybe_walk(|ty| {
-            needs_unwind_cleanup |= match ty.sty {
-                ty::TyBool | ty::TyInt(_) | ty::TyUint(_) |
-                ty::TyFloat(_) | ty::TyTuple(_) | ty::TyRawPtr(_) => false,
-
-                ty::TyEnum(did, substs) =>
-                    tcx.enum_variants(did).iter().any(|v|
-                        v.args.iter().any(|&aty| {
-                            let t = aty.subst(tcx, substs);
-                            type_needs_unwind_cleanup_(tcx, t, tycache)
-                        })
-                    ),
-
-                _ => true
-            };
-            !needs_unwind_cleanup
-        });
-        needs_unwind_cleanup
-    }
-}
-
 /// If `type_needs_drop` returns true, then `ty` is definitely
 /// non-copy and *might* have a destructor attached; if it returns
 /// false, then `ty` definitely has no destructor (i.e. no drop glue).

src/test/run-pass/issue-26655.rs

@@ -0,0 +1,34 @@
+// Copyright 2015 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 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(const_fn)]
+
+// Check that the destructors of simple enums are run on unwinding
+
+use std::sync::atomic::{Ordering, AtomicUsize};
+use std::thread;
+
+static LOG: AtomicUsize = AtomicUsize::new(0);
+
+enum WithDtor { Val }
+impl Drop for WithDtor {
+    fn drop(&mut self) {
+        LOG.store(LOG.load(Ordering::SeqCst)+1,Ordering::SeqCst);
+    }
+}
+
+pub fn main() {
+    thread::spawn(move|| {
+        let _e: WithDtor = WithDtor::Val;
+        panic!("fail");
+    }).join().unwrap_err();
+
+    assert_eq!(LOG.load(Ordering::SeqCst), 1);
+}