Backport #46428 and #46253

src/librustc/ty/layout.rs

@@ -1083,7 +1083,9 @@ impl<'a, 'tcx> LayoutDetails {
                         // We have exactly one non-ZST field.
                         (Some((i, field)), None, None) => {
                             // Field fills the struct and it has a scalar or scalar pair ABI.
-                            if offsets[i].bytes() == 0 && size == field.size {
+                            if offsets[i].bytes() == 0 &&
+                               align.abi() == field.align.abi() &&
+                               size == field.size {
                                 match field.abi {
                                     // For plain scalars we can't unpack newtypes
                                     // for `#[repr(C)]`, as that affects C ABIs.

src/librustc_trans/abi.rs

@@ -792,7 +792,8 @@ impl<'a, 'tcx> FnType<'tcx> {
                     // dependencies rather than pointer equality
                     let no_alias = match kind {
                         PointerKind::Shared => false,
-                        PointerKind::Frozen | PointerKind::UniqueOwned => true,
+                        PointerKind::UniqueOwned => true,
+                        PointerKind::Frozen |
                         PointerKind::UniqueBorrowed => !is_return
                     };
                     if no_alias {

src/librustc_trans/mir/lvalue.rs

@@ -359,14 +359,12 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
     /// Set the discriminant for a new value of the given case of the given
     /// representation.
     pub fn trans_set_discr(&self, bcx: &Builder<'a, 'tcx>, variant_index: usize) {
-        match self.layout.variants {
+            if self.layout.for_variant(bcx.ccx, variant_index).abi == layout::Abi::Uninhabited {
+                return;
+            }
+            match self.layout.variants {
             layout::Variants::Single { index } => {
-                if index != variant_index {
-                    // If the layout of an enum is `Single`, all
-                    // other variants are necessarily uninhabited.
-                    assert_eq!(self.layout.for_variant(bcx.ccx, variant_index).abi,
-                               layout::Abi::Uninhabited);
-                }
+                assert_eq!(index, variant_index);
             }
             layout::Variants::Tagged { .. } => {
                 let ptr = self.project_field(bcx, 0);

src/test/codegen/packed.rs

@@ -57,3 +57,14 @@ pub fn pkd_pair(pair1: &mut PackedPair, pair2: &mut PackedPair) {
 // CHECK: call void @llvm.memcpy.{{.*}}(i8* %{{.*}}, i8* %{{.*}}, i{{[0-9]+}} 5, i32 1, i1 false)
     *pair2 = *pair1;
 }
+
+#[repr(packed)]
+#[derive(Copy, Clone)]
+pub struct PackedNestedPair((u32, u32));
+
+// CHECK-LABEL: @pkd_nested_pair
+#[no_mangle]
+pub fn pkd_nested_pair(pair1: &mut PackedNestedPair, pair2: &mut PackedNestedPair) {
+// CHECK: call void @llvm.memcpy.{{.*}}(i8* %{{.*}}, i8* %{{.*}}, i{{[0-9]+}} 8, i32 1, i1 false)
+    *pair2 = *pair1;
+}

src/test/run-make/issue-46239/Makefile

@@ -0,0 +1,5 @@
+-include ../tools.mk
+
+all:
+	$(RUSTC) main.rs -C opt-level=1
+	$(call RUN,main)

src/test/run-make/issue-46239/main.rs

@@ -0,0 +1,18 @@
+// Copyright 2017 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.
+
+fn project<T>(x: &(T,)) -> &T { &x.0 }
+
+fn dummy() {}
+
+fn main() {
+    let f = (dummy as fn(),);
+    (*project(&f))();
+}

src/test/run-pass/issue-46519.rs

@@ -0,0 +1,37 @@
+// Copyright 2017 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.
+
+// compile-flags:--test -O
+
+#[test]
+#[should_panic(expected = "creating inhabited type")]
+fn test() {
+    FontLanguageOverride::system_font(SystemFont::new());
+}
+
+pub enum FontLanguageOverride {
+    Normal,
+    Override(&'static str),
+    System(SystemFont)
+}
+
+pub enum SystemFont {}
+
+impl FontLanguageOverride {
+    fn system_font(f: SystemFont) -> Self {
+        FontLanguageOverride::System(f)
+    }
+}
+
+impl SystemFont {
+    fn new() -> Self {
+        panic!("creating inhabited type")
+    }
+}