[beta] Backport union stabilization PRs

src/bootstrap/channel.rs

@@ -28,7 +28,7 @@ pub const CFG_RELEASE_NUM: &'static str = "1.18.0";
 // An optional number to put after the label, e.g. '.2' -> '-beta.2'
 // Be sure to make this starts with a dot to conform to semver pre-release
 // versions (section 9)
-pub const CFG_PRERELEASE_VERSION: &'static str = ".4";
+pub const CFG_PRERELEASE_VERSION: &'static str = ".5";
 
 pub struct GitInfo {
     inner: Option<Info>,

src/libcollections/lib.rs

@@ -64,7 +64,6 @@
 #![feature(trusted_len)]
 #![feature(unicode)]
 #![feature(unique)]
-#![feature(untagged_unions)]
 #![cfg_attr(not(test), feature(str_checked_slicing))]
 #![cfg_attr(test, feature(rand, test))]
 #![feature(offset_to)]

src/librustc/middle/effect.rs

@@ -52,6 +52,7 @@ fn type_is_unsafe_function(ty: Ty) -> bool {
 struct EffectCheckVisitor<'a, 'tcx: 'a> {
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     tables: &'a ty::TypeckTables<'tcx>,
+    body_id: hir::BodyId,
 
     /// Whether we're in an unsafe context.
     unsafe_context: UnsafeContext,
@@ -99,10 +100,13 @@ impl<'a, 'tcx> Visitor<'tcx> for EffectCheckVisitor<'a, 'tcx> {
 
     fn visit_nested_body(&mut self, body: hir::BodyId) {
         let old_tables = self.tables;
+        let old_body_id = self.body_id;
         self.tables = self.tcx.body_tables(body);
+        self.body_id = body;
         let body = self.tcx.hir.body(body);
         self.visit_body(body);
         self.tables = old_tables;
+        self.body_id = old_body_id;
     }
 
     fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, fn_decl: &'tcx hir::FnDecl,
@@ -218,6 +222,25 @@ impl<'a, 'tcx> Visitor<'tcx> for EffectCheckVisitor<'a, 'tcx> {
                     }
                 }
             }
+            hir::ExprAssign(ref lhs, ref rhs) => {
+                if let hir::ExprField(ref base_expr, field) = lhs.node {
+                    if let ty::TyAdt(adt, ..) = self.tables.expr_ty_adjusted(base_expr).sty {
+                        if adt.is_union() {
+                            let field_ty = self.tables.expr_ty_adjusted(lhs);
+                            let owner_id = self.tcx.hir.body_owner(self.body_id);
+                            let param_env = ty::ParameterEnvironment::for_item(self.tcx, owner_id);
+                            if field_ty.moves_by_default(self.tcx, &param_env, field.span) {
+                                self.require_unsafe(field.span,
+                                                    "assignment to non-`Copy` union field");
+                            }
+                            // Do not walk the field expr again.
+                            intravisit::walk_expr(self, base_expr);
+                            intravisit::walk_expr(self, rhs);
+                            return
+                        }
+                    }
+                }
+            }
             _ => {}
         }
 
@@ -243,6 +266,7 @@ pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
     let mut visitor = EffectCheckVisitor {
         tcx: tcx,
         tables: &ty::TypeckTables::empty(),
+        body_id: hir::BodyId { node_id: ast::CRATE_NODE_ID },
         unsafe_context: UnsafeContext::new(SafeContext),
     };
 

src/librustc/middle/stability.rs

@@ -590,6 +590,27 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
                 }
             }
 
+            // There's no good place to insert stability check for non-Copy unions,
+            // so semi-randomly perform it here in stability.rs
+            hir::ItemUnion(..) if !self.tcx.sess.features.borrow().untagged_unions => {
+                let def_id = self.tcx.hir.local_def_id(item.id);
+                let adt_def = self.tcx.lookup_adt_def(def_id);
+                let ty = self.tcx.item_type(def_id);
+
+                if adt_def.has_dtor(self.tcx) {
+                    emit_feature_err(&self.tcx.sess.parse_sess,
+                                     "untagged_unions", item.span, GateIssue::Language,
+                                     "unions with `Drop` implementations are unstable");
+                } else {
+                    let param_env = ty::ParameterEnvironment::for_item(self.tcx, item.id);
+                    if !param_env.can_type_implement_copy(self.tcx, ty, item.span).is_ok() {
+                        emit_feature_err(&self.tcx.sess.parse_sess,
+                                        "untagged_unions", item.span, GateIssue::Language,
+                                        "unions with non-`Copy` fields are unstable");
+                    }
+                }
+            }
+
             _ => (/* pass */)
         }
         intravisit::walk_item(self, item);

src/librustc_data_structures/lib.rs

@@ -32,7 +32,6 @@
 #![feature(staged_api)]
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
-#![feature(untagged_unions)]
 #![feature(associated_consts)]
 #![feature(unsize)]
 #![feature(i128_type)]

src/libsyntax/feature_gate.rs

@@ -1202,12 +1202,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
 
-            ast::ItemKind::Union(..) => {
-                gate_feature_post!(&self, untagged_unions,
-                                   i.span,
-                                   "unions are unstable and possibly buggy");
-            }
-
             ast::ItemKind::DefaultImpl(..) => {
                 gate_feature_post!(&self, optin_builtin_traits,
                                    i.span,

src/test/compile-fail/borrowck/borrowck-union-borrow-nested.rs

@@ -8,10 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// ignore-tidy-linelength
-
-#![feature(untagged_unions)]
-
 #[derive(Clone, Copy)]
 struct S {
     a: u8,

src/test/compile-fail/borrowck/borrowck-union-borrow.rs

@@ -10,8 +10,6 @@
 
 // ignore-tidy-linelength
 
-#![feature(untagged_unions)]
-
 #[derive(Clone, Copy)]
 union U {
     a: u8,

src/test/compile-fail/borrowck/borrowck-union-uninitialized.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 struct S {
     a: u8,
 }

src/test/compile-fail/privacy/union-field-privacy-1.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 mod m {
     pub union U {
         pub a: u8,

src/test/compile-fail/privacy/union-field-privacy-2.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 mod m {
     pub union U {
         pub a: u8,

src/test/compile-fail/union/union-const-eval.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     a: usize,
     b: usize,

src/test/compile-fail/union/union-const-pat.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     a: usize,
     b: usize,

src/test/compile-fail/union/union-derive.rs

@@ -10,8 +10,6 @@
 
 // Most traits cannot be derived for unions.
 
-#![feature(untagged_unions)]
-
 #[derive(
     PartialEq, //~ ERROR this trait cannot be derived for unions
     PartialOrd, //~ ERROR this trait cannot be derived for unions

src/test/compile-fail/union/union-empty.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {} //~ ERROR unions cannot have zero fields
 
 fn main() {}

src/test/compile-fail/union/union-feature-gate.rs

@@ -10,8 +10,28 @@
 
 // gate-test-untagged_unions
 
-union U { //~ ERROR unions are unstable and possibly buggy
+union U1 { // OK
     a: u8,
 }
 
+union U2<T: Copy> { // OK
+    a: T,
+}
+
+union U3 { //~ ERROR unions with non-`Copy` fields are unstable
+    a: String,
+}
+
+union U4<T> { //~ ERROR unions with non-`Copy` fields are unstable
+    a: T,
+}
+
+union U5 { //~ ERROR unions with `Drop` implementations are unstable
+    a: u8,
+}
+
+impl Drop for U5 {
+    fn drop(&mut self) {}
+}
+
 fn main() {}

src/test/compile-fail/union/union-fields.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     a: u8,
     b: u16,

src/test/compile-fail/union/union-generic.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 use std::rc::Rc;
 
 union U<T: Copy> {

src/test/compile-fail/union/union-lint-dead-code.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
 #![deny(dead_code)]
 
 union Foo {

src/test/compile-fail/union/union-repr-c.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
 #![allow(unused)]
 #![deny(improper_ctypes)]
 

src/test/compile-fail/union/union-suggest-field.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     principal: u8,
 }

src/test/compile-fail/union/union-unsafe.rs

@@ -10,15 +10,46 @@
 
 #![feature(untagged_unions)]
 
-union U {
+union U1 {
     a: u8
 }
 
+union U2 {
+    a: String
+}
+
+union U3<T> {
+    a: T
+}
+
+union U4<T: Copy> {
+    a: T
+}
+
+fn generic_noncopy<T: Default>() {
+    let mut u3 = U3 { a: T::default() };
+    u3.a = T::default(); //~ ERROR assignment to non-`Copy` union field requires unsafe
+}
+
+fn generic_copy<T: Copy + Default>() {
+    let mut u3 = U3 { a: T::default() };
+    u3.a = T::default(); // OK
+    let mut u4 = U4 { a: T::default() };
+    u4.a = T::default(); // OK
+}
+
 fn main() {
-    let mut u = U { a: 10 }; // OK
-    let a = u.a; //~ ERROR access to union field requires unsafe function or block
-    u.a = 11; //~ ERROR access to union field requires unsafe function or block
-    let U { a } = u; //~ ERROR matching on union field requires unsafe function or block
-    if let U { a: 12 } = u {} //~ ERROR matching on union field requires unsafe function or block
-    // let U { .. } = u; // OK
+    let mut u1 = U1 { a: 10 }; // OK
+    let a = u1.a; //~ ERROR access to union field requires unsafe
+    u1.a = 11; // OK
+    let U1 { a } = u1; //~ ERROR matching on union field requires unsafe
+    if let U1 { a: 12 } = u1 {} //~ ERROR matching on union field requires unsafe
+    // let U1 { .. } = u1; // OK
+
+    let mut u2 = U2 { a: String::from("old") }; // OK
+    u2.a = String::from("new"); //~ ERROR assignment to non-`Copy` union field requires unsafe
+    let mut u3 = U3 { a: 0 }; // OK
+    u3.a = 1; // OK
+    let mut u3 = U3 { a: String::from("old") }; // OK
+    u3.a = String::from("new"); //~ ERROR assignment to non-`Copy` union field requires unsafe
 }

src/test/debuginfo/union-smoke.rs

@@ -34,7 +34,6 @@
 #![allow(unused)]
 #![feature(omit_gdb_pretty_printer_section)]
 #![omit_gdb_pretty_printer_section]
-#![feature(untagged_unions)]
 
 union U {
     a: (u8, u8),

src/test/run-pass/union/auxiliary/union.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 pub union U {
     pub a: u8,
     pub b: u16,

src/test/run-pass/union/union-backcomp.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 macro_rules! union {
     () => (struct S;)
 }

src/test/run-pass/union/union-basic.rs

@@ -13,8 +13,6 @@
 // FIXME: This test case makes little-endian assumptions.
 // ignore-s390x
 
-#![feature(untagged_unions)]
-
 extern crate union;
 use std::mem::{size_of, align_of, zeroed};
 

src/test/run-pass/union/union-c-interop.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 #[derive(Clone, Copy)]
 #[repr(C)]
 struct LARGE_INTEGER_U {

src/test/run-pass/union/union-const-trans.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     a: u64,
     b: u64,

src/test/run-pass/union/union-inherent-method.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(untagged_unions)]
-
 union U {
     a: u8,
 }