From 2358e3eff604a770d5dabab9680d81148106fd68 Mon Sep 17 00:00:00 2001
From: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
Date: Wed, 7 Aug 2019 13:19:07 +0900
Subject: [PATCH] Revert "Rollup merge of #62150 - alex:mem-uninit-refactor,
r=RalfJung"
This reverts commit 1d45156866b54c3fc36edfdfcdd8149ad9cb5711, reversing
changes made to 0f92eb8a4a7d8715381f5b5d748d22315f6ff9c7.
---
src/libcore/intrinsics.rs | 19 +++++++++++++++++--
src/libcore/mem/mod.rs | 10 ++++++++--
src/librustc_codegen_llvm/intrinsic.rs | 2 +-
src/librustc_typeck/check/intrinsic.rs | 1 +
src/test/ui/intrinsics/intrinsic-uninit.rs | 13 +++++++++++++
5 files changed, 40 insertions(+), 5 deletions(-)
create mode 100644 src/test/ui/intrinsics/intrinsic-uninit.rs
diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 56e45c3695f61..ceaa870d2b3f7 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -707,11 +707,26 @@ extern "rust-intrinsic" {
they should be used through stabilized interfaces \
in the rest of the standard library",
issue = "0")]
- #[rustc_deprecated(reason = "no longer used by rustc, will be removed - use MaybeUninit \
- instead",
+ #[rustc_deprecated(reason = "superseded by MaybeUninit, removal planned",
since = "1.38.0")]
pub fn init<T>() -> T;
+ /// Creates an uninitialized value.
+ ///
+ /// `uninit` is unsafe because there is no guarantee of what its
+ /// contents are. In particular its drop-flag may be set to any
+ /// state, which means it may claim either dropped or
+ /// undropped. In the general case one must use `ptr::write` to
+ /// initialize memory previous set to the result of `uninit`.
+ #[unstable(feature = "core_intrinsics",
+ reason = "intrinsics are unlikely to ever be stabilized, instead \
+ they should be used through stabilized interfaces \
+ in the rest of the standard library",
+ issue = "0")]
+ #[rustc_deprecated(reason = "superseded by MaybeUninit, removal planned",
+ since = "1.38.0")]
+ pub fn uninit<T>() -> T;
+
/// Moves a value out of scope without running drop glue.
pub fn forget<T: ?Sized>(_: T);
diff --git a/src/libcore/mem/mod.rs b/src/libcore/mem/mod.rs
index 86dae985fdb00..2b462f08d42dc 100644
--- a/src/libcore/mem/mod.rs
+++ b/src/libcore/mem/mod.rs
@@ -452,8 +452,11 @@ pub const fn needs_drop<T>() -> bool {
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(bootstrap, allow(deprecated_in_future))]
+#[allow(deprecated)]
pub unsafe fn zeroed<T>() -> T {
- MaybeUninit::zeroed().assume_init()
+ intrinsics::panic_if_uninhabited::<T>();
+ intrinsics::init()
}
/// Bypasses Rust's normal memory-initialization checks by pretending to
@@ -477,8 +480,11 @@ pub unsafe fn zeroed<T>() -> T {
#[inline]
#[rustc_deprecated(since = "1.39.0", reason = "use `mem::MaybeUninit` instead")]
#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(bootstrap, allow(deprecated_in_future))]
+#[allow(deprecated)]
pub unsafe fn uninitialized<T>() -> T {
- MaybeUninit::uninit().assume_init()
+ intrinsics::panic_if_uninhabited::<T>();
+ intrinsics::uninit()
}
/// Swaps the values at two mutable locations, without deinitializing either one.
diff --git a/src/librustc_codegen_llvm/intrinsic.rs b/src/librustc_codegen_llvm/intrinsic.rs
index 199170182e4b4..a9b8962f45b1b 100644
--- a/src/librustc_codegen_llvm/intrinsic.rs
+++ b/src/librustc_codegen_llvm/intrinsic.rs
@@ -232,7 +232,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
return;
}
// Effectively no-ops
- "forget" => {
+ "uninit" | "forget" => {
return;
}
"needs_drop" => {
diff --git a/src/librustc_typeck/check/intrinsic.rs b/src/librustc_typeck/check/intrinsic.rs
index 4d8f564123634..8bb24eef5e94c 100644
--- a/src/librustc_typeck/check/intrinsic.rs
+++ b/src/librustc_typeck/check/intrinsic.rs
@@ -145,6 +145,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem) {
"rustc_peek" => (1, vec![param(0)], param(0)),
"panic_if_uninhabited" => (1, Vec::new(), tcx.mk_unit()),
"init" => (1, Vec::new(), param(0)),
+ "uninit" => (1, Vec::new(), param(0)),
"forget" => (1, vec![param(0)], tcx.mk_unit()),
"transmute" => (2, vec![ param(0) ], param(1)),
"move_val_init" => {
diff --git a/src/test/ui/intrinsics/intrinsic-uninit.rs b/src/test/ui/intrinsics/intrinsic-uninit.rs
new file mode 100644
index 0000000000000..9555efb639b50
--- /dev/null
+++ b/src/test/ui/intrinsics/intrinsic-uninit.rs
@@ -0,0 +1,13 @@
+// run-pass
+// pretty-expanded FIXME #23616
+
+#![feature(intrinsics)]
+
+mod rusti {
+ extern "rust-intrinsic" {
+ pub fn uninit<T>() -> T;
+ }
+}
+pub fn main() {
+ let _a : isize = unsafe {rusti::uninit()};
+}