Auto merge of #3044 - rust-lang:rustup-2023-08-31, r=RalfJung

Automatic sync from rustc

9 files changed, 42 insertions, 29 deletions

diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
index b6c70c62249..3dc83f50b21 100644
--- a/compiler/rustc_codegen_ssa/messages.ftl
+++ b/compiler/rustc_codegen_ssa/messages.ftl
@@ -35,6 +35,8 @@ codegen_ssa_extract_bundled_libs_parse_archive = failed to parse archive '{$rlib
 codegen_ssa_extract_bundled_libs_read_entry = failed to read entry '{$rlib}': {$error}
 codegen_ssa_extract_bundled_libs_write_file = failed to write file '{$rlib}': {$error}
 
+codegen_ssa_failed_to_get_layout = failed to get layout for {$ty}: {$err}
+
 codegen_ssa_failed_to_write = failed to write {$path}: {$error}
 
 codegen_ssa_ignoring_emit_path = ignoring emit path because multiple .{$extension} files were produced
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index 4c854740753..c6f4bd35e29 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -226,9 +226,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
 
     let mut file = write::Object::new(binary_format, architecture, endianness);
     if sess.target.is_like_osx {
-        if let Some(build_version) = macho_object_build_version_for_target(&sess.target) {
-            file.set_macho_build_version(build_version)
-        }
+        file.set_macho_build_version(macho_object_build_version_for_target(&sess.target))
     }
     let e_flags = match architecture {
         Architecture::Mips => {
@@ -334,31 +332,28 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
     Some(file)
 }
 
-/// Apple's LD, when linking for Mac Catalyst, requires object files to
-/// contain information about what they were built for (LC_BUILD_VERSION):
-/// the platform (macOS/watchOS etc), minimum OS version, and SDK version.
-/// This returns a `MachOBuildVersion` if necessary for the target.
-fn macho_object_build_version_for_target(
-    target: &Target,
-) -> Option<object::write::MachOBuildVersion> {
-    if !target.llvm_target.ends_with("-macabi") {
-        return None;
-    }
+/// Since Xcode 15 Apple's LD requires object files to contain information about what they were
+/// built for (LC_BUILD_VERSION): the platform (macOS/watchOS etc), minimum OS version, and SDK
+/// version. This returns a `MachOBuildVersion` for the target.
+fn macho_object_build_version_for_target(target: &Target) -> object::write::MachOBuildVersion {
     /// The `object` crate demands "X.Y.Z encoded in nibbles as xxxx.yy.zz"
     /// e.g. minOS 14.0 = 0x000E0000, or SDK 16.2 = 0x00100200
     fn pack_version((major, minor): (u32, u32)) -> u32 {
         (major << 16) | (minor << 8)
     }
 
-    let platform = object::macho::PLATFORM_MACCATALYST;
-    let min_os = (14, 0);
-    let sdk = (16, 2);
+    let platform =
+        rustc_target::spec::current_apple_platform(target).expect("unknown Apple target OS");
+    let min_os = rustc_target::spec::current_apple_deployment_target(target)
+        .expect("unknown Apple target OS");
+    let sdk =
+        rustc_target::spec::current_apple_sdk_version(platform).expect("unknown Apple target OS");
 
     let mut build_version = object::write::MachOBuildVersion::default();
     build_version.platform = platform;
     build_version.minos = pack_version(min_os);
     build_version.sdk = pack_version(sdk);
-    Some(build_version)
+    build_version
 }
 
 pub enum MetadataPosition {
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index aa003e4e898..cd19885faa0 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -202,7 +202,7 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             (src, unsized_info(bx, a, b, old_info))
         }
         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
-            assert_eq!(def_a, def_b);
+            assert_eq!(def_a, def_b); // implies same number of fields
             let src_layout = bx.cx().layout_of(src_ty);
             let dst_layout = bx.cx().layout_of(dst_ty);
             if src_ty == dst_ty {
@@ -211,7 +211,8 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             let mut result = None;
             for i in 0..src_layout.fields.count() {
                 let src_f = src_layout.field(bx.cx(), i);
-                if src_f.is_zst() {
+                if src_f.is_1zst() {
+                    // We are looking for the one non-1-ZST field; this is not it.
                     continue;
                 }
 
@@ -272,13 +273,14 @@ pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         }
 
         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
-            assert_eq!(def_a, def_b);
+            assert_eq!(def_a, def_b); // implies same number of fields
 
             for i in def_a.variant(FIRST_VARIANT).fields.indices() {
                 let src_f = src.project_field(bx, i.as_usize());
                 let dst_f = dst.project_field(bx, i.as_usize());
 
                 if dst_f.layout.is_zst() {
+                    // No data here, nothing to copy/coerce.
                     continue;
                 }
 
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index b7d8b9b45bf..41602321ded 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -7,6 +7,7 @@ use rustc_errors::{
     IntoDiagnosticArg,
 };
 use rustc_macros::Diagnostic;
+use rustc_middle::ty::layout::LayoutError;
 use rustc_middle::ty::Ty;
 use rustc_span::{Span, Symbol};
 use rustc_type_ir::FloatTy;
@@ -1031,6 +1032,15 @@ pub struct TargetFeatureSafeTrait {
 }
 
 #[derive(Diagnostic)]
+#[diag(codegen_ssa_failed_to_get_layout)]
+pub struct FailedToGetLayout<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub ty: Ty<'tcx>,
+    pub err: LayoutError<'tcx>,
+}
+
+#[derive(Diagnostic)]
 #[diag(codegen_ssa_error_creating_remark_dir)]
 pub struct ErrorCreatingRemarkDir {
     pub error: std::io::Error,
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 6aef1664394..d78a0c49107 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -933,8 +933,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         {
                             for i in 0..op.layout.fields.count() {
                                 let field = op.extract_field(bx, i);
-                                if !field.layout.is_zst() {
-                                    // we found the one non-zero-sized field that is allowed
+                                if !field.layout.is_1zst() {
+                                    // we found the one non-1-ZST field that is allowed
                                     // now find *its* non-zero-sized field, or stop if it's a
                                     // pointer
                                     op = field;
@@ -975,10 +975,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         {
                             for i in 0..op.layout.fields.count() {
                                 let field = op.extract_field(bx, i);
-                                if !field.layout.is_zst() {
-                                    // we found the one non-zero-sized field that is allowed
-                                    // now find *its* non-zero-sized field, or stop if it's a
-                                    // pointer
+                                if !field.layout.is_1zst() {
+                                    // We found the one non-1-ZST field that is allowed. (The rules
+                                    // for `DispatchFromDyn` ensure there's exactly one such field.)
+                                    // Now find *its* non-zero-sized field, or stop if it's a
+                                    // pointer.
                                     op = field;
                                     continue 'descend_newtypes;
                                 }
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 3d0c17e9cfb..bf937c2fc7c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -145,7 +145,7 @@ impl<'tcx, V: CodegenObject> LocalRef<'tcx, V> {
         if layout.is_zst() {
             // Zero-size temporaries aren't always initialized, which
             // doesn't matter because they don't contain data, but
-            // we need something in the operand.
+            // we need something sufficiently aligned in the operand.
             LocalRef::Operand(OperandRef::zero_sized(layout))
         } else {
             LocalRef::PendingOperand
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index f90d1a0fc9c..ef66aa6ce1c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -50,7 +50,8 @@ pub enum OperandValue<V> {
     /// from [`ConstMethods::const_poison`].
     ///
     /// An `OperandValue` *must* be this variant for any type for which
-    /// `is_zst` on its `Layout` returns `true`.
+    /// `is_zst` on its `Layout` returns `true`. Note however that
+    /// these values can still require alignment.
     ZeroSized,
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs
index e7c3906d977..a9ecbdc5f35 100644
--- a/compiler/rustc_codegen_ssa/src/mir/place.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/place.rs
@@ -114,7 +114,8 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
                     bx.struct_gep(ty, self.llval, 1)
                 }
                 Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. } if field.is_zst() => {
-                    // ZST fields are not included in Scalar, ScalarPair, and Vector layouts, so manually offset the pointer.
+                    // ZST fields (even some that require alignment) are not included in Scalar,
+                    // ScalarPair, and Vector layouts, so manually offset the pointer.
                     bx.gep(bx.cx().type_i8(), self.llval, &[bx.const_usize(offset.bytes())])
                 }
                 Abi::Scalar(_) | Abi::ScalarPair(..) => {
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index 07c61df2140..fc8d3389102 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -1004,6 +1004,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             mir::Rvalue::Aggregate(..) => {
                 let ty = rvalue.ty(self.mir, self.cx.tcx());
                 let ty = self.monomorphize(ty);
+                // For ZST this can be `OperandValueKind::ZeroSized`.
                 self.cx.spanned_layout_of(ty, span).is_zst()
             }
         }