Revert "Allow specifying alignment for functions"

RELEASES.md

@@ -1,3 +1,172 @@
+Version 1.52.1 (2021-05-10)
+============================
+
+This release disables incremental compilation, unless the user has explicitly
+opted in via the newly added RUSTC_FORCE_INCREMENTAL=1 environment variable.
+
+This is due to the widespread, and frequently occuring, breakage encountered by
+Rust users due to newly enabled incremental verification in 1.52.0. Notably,
+Rust users **should** upgrade to 1.52.0 or 1.52.1: the bugs that are detected by
+newly added incremental verification are still present in past stable versions,
+and are not yet fixed on any channel. These bugs can lead to miscompilation of
+Rust binaries.
+
+These problems only affect incremental builds, so release builds with Cargo
+should not be affected unless the user has explicitly opted into incremental.
+Debug and check builds are affected.
+
+See [84970] for more details.
+
+[84970]: https://github.com/rust-lang/rust/issues/84970
+
+Version 1.52.0 (2021-05-06)
+============================
+
+Language
+--------
+- [Added the `unsafe_op_in_unsafe_fn` lint, which checks whether the unsafe code
+  in an `unsafe fn` is wrapped in a `unsafe` block.][79208] This lint
+  is allowed by default, and may become a warning or hard error in a
+  future edition.
+- [You can now cast mutable references to arrays to a pointer of the same type as
+  the element.][81479]
+
+Compiler
+--------
+- [Upgraded the default LLVM to LLVM 12.][81451]
+
+Added tier 3\* support for the following targets.
+
+- [`s390x-unknown-linux-musl`][82166]
+- [`riscv32gc-unknown-linux-musl` & `riscv64gc-unknown-linux-musl`][82202]
+- [`powerpc-unknown-openbsd`][82733]
+
+\* Refer to Rust's [platform support page][platform-support-doc] for more
+information on Rust's tiered platform support.
+
+Libraries
+---------
+- [`OsString` now implements `Extend` and `FromIterator`.][82121]
+- [`cmp::Reverse` now has `#[repr(transparent)]` representation.][81879]
+- [`Arc<impl Error>` now implements `error::Error`.][80553]
+- [All integer division and remainder operations are now `const`.][80962]
+
+Stabilised APIs
+-------------
+- [`Arguments::as_str`]
+- [`char::MAX`]
+- [`char::REPLACEMENT_CHARACTER`]
+- [`char::UNICODE_VERSION`]
+- [`char::decode_utf16`]
+- [`char::from_digit`]
+- [`char::from_u32_unchecked`]
+- [`char::from_u32`]
+- [`slice::partition_point`]
+- [`str::rsplit_once`]
+- [`str::split_once`]
+
+The following previously stable APIs are now `const`.
+
+- [`char::len_utf8`]
+- [`char::len_utf16`]
+- [`char::to_ascii_uppercase`]
+- [`char::to_ascii_lowercase`]
+- [`char::eq_ignore_ascii_case`]
+- [`u8::to_ascii_uppercase`]
+- [`u8::to_ascii_lowercase`]
+- [`u8::eq_ignore_ascii_case`]
+
+Rustdoc
+-------
+- [Rustdoc lints are now treated as a tool lint, meaning that
+  lints are now prefixed with `rustdoc::` (e.g. `#[warn(rustdoc::non_autolinks)]`).][80527]
+  Using the old style is still allowed, and will become a warning in
+  a future release.
+- [Rustdoc now supports argument files.][82261]
+- [Rustdoc now generates smart punctuation for documentation.][79423]
+- [You can now use "task lists" in Rustdoc Markdown.][81766] E.g.
+  ```markdown
+  - [x] Complete
+  - [ ] Todo
+  ```
+
+Misc
+----
+- [You can now pass multiple filters to tests.][81356] E.g.
+  `cargo test -- foo bar` will run all tests that match `foo` and `bar`.
+- [Rustup now distributes PDB symbols for the `std` library on Windows,
+  allowing you to see `std` symbols when debugging.][82218]
+
+Internal Only
+-------------
+These changes provide no direct user facing benefits, but represent significant
+improvements to the internals and overall performance of rustc and
+related tools.
+
+- [Check the result cache before the DepGraph when ensuring queries][81855]
+- [Try fast_reject::simplify_type in coherence before doing full check][81744]
+- [Only store a LocalDefId in some HIR nodes][81611]
+- [Store HIR attributes in a side table][79519]
+
+Compatibility Notes
+-------------------
+- [Cargo build scripts are now forbidden from setting `RUSTC_BOOTSTRAP`.][cargo/9181]
+- [Removed support for the `x86_64-rumprun-netbsd` target.][82594]
+- [Deprecated the `x86_64-sun-solaris` target in favor of `x86_64-pc-solaris`.][82216]
+- [Rustdoc now only accepts `,`, ` `, and `\t` as delimiters for specifying
+  languages in code blocks.][78429]
+- [Rustc now catches more cases of `pub_use_of_private_extern_crate`][80763]
+- [Changes in how proc macros handle whitespace may lead to panics when used
+  with older `proc-macro-hack` versions. A `cargo update` should be sufficient to fix this in all cases.][84136]
+
+[84136]: https://github.com/rust-lang/rust/issues/84136
+[80763]: https://github.com/rust-lang/rust/pull/80763
+[82166]: https://github.com/rust-lang/rust/pull/82166
+[82121]: https://github.com/rust-lang/rust/pull/82121
+[81879]: https://github.com/rust-lang/rust/pull/81879
+[82261]: https://github.com/rust-lang/rust/pull/82261
+[82218]: https://github.com/rust-lang/rust/pull/82218
+[82216]: https://github.com/rust-lang/rust/pull/82216
+[82202]: https://github.com/rust-lang/rust/pull/82202
+[81855]: https://github.com/rust-lang/rust/pull/81855
+[81766]: https://github.com/rust-lang/rust/pull/81766
+[81744]: https://github.com/rust-lang/rust/pull/81744
+[81611]: https://github.com/rust-lang/rust/pull/81611
+[81479]: https://github.com/rust-lang/rust/pull/81479
+[81451]: https://github.com/rust-lang/rust/pull/81451
+[81356]: https://github.com/rust-lang/rust/pull/81356
+[80962]: https://github.com/rust-lang/rust/pull/80962
+[80553]: https://github.com/rust-lang/rust/pull/80553
+[80527]: https://github.com/rust-lang/rust/pull/80527
+[79519]: https://github.com/rust-lang/rust/pull/79519
+[79423]: https://github.com/rust-lang/rust/pull/79423
+[79208]: https://github.com/rust-lang/rust/pull/79208
+[78429]: https://github.com/rust-lang/rust/pull/78429
+[82733]: https://github.com/rust-lang/rust/pull/82733
+[82594]: https://github.com/rust-lang/rust/pull/82594
+[cargo/9181]: https://github.com/rust-lang/cargo/pull/9181
+[`char::MAX`]: https://doc.rust-lang.org/std/primitive.char.html#associatedconstant.MAX
+[`char::REPLACEMENT_CHARACTER`]: https://doc.rust-lang.org/std/primitive.char.html#associatedconstant.REPLACEMENT_CHARACTER
+[`char::UNICODE_VERSION`]: https://doc.rust-lang.org/std/primitive.char.html#associatedconstant.UNICODE_VERSION
+[`char::decode_utf16`]: https://doc.rust-lang.org/std/primitive.char.html#method.decode_utf16
+[`char::from_u32`]: https://doc.rust-lang.org/std/primitive.char.html#method.from_u32
+[`char::from_u32_unchecked`]: https://doc.rust-lang.org/std/primitive.char.html#method.from_u32_unchecked
+[`char::from_digit`]: https://doc.rust-lang.org/std/primitive.char.html#method.from_digit
+[`Peekable::next_if`]: https://doc.rust-lang.org/stable/std/iter/struct.Peekable.html#method.next_if
+[`Peekable::next_if_eq`]: https://doc.rust-lang.org/stable/std/iter/struct.Peekable.html#method.next_if_eq
+[`Arguments::as_str`]: https://doc.rust-lang.org/stable/std/fmt/struct.Arguments.html#method.as_str
+[`str::split_once`]: https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_once
+[`str::rsplit_once`]: https://doc.rust-lang.org/stable/std/primitive.str.html#method.rsplit_once
+[`slice::partition_point`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.partition_point
+[`char::len_utf8`]: https://doc.rust-lang.org/stable/std/primitive.char.html#method.len_utf8
+[`char::len_utf16`]: https://doc.rust-lang.org/stable/std/primitive.char.html#method.len_utf16
+[`char::to_ascii_uppercase`]: https://doc.rust-lang.org/stable/std/primitive.char.html#method.to_ascii_uppercase
+[`char::to_ascii_lowercase`]: https://doc.rust-lang.org/stable/std/primitive.char.html#method.to_ascii_lowercase
+[`char::eq_ignore_ascii_case`]: https://doc.rust-lang.org/stable/std/primitive.char.html#method.eq_ignore_ascii_case
+[`u8::to_ascii_uppercase`]: https://doc.rust-lang.org/stable/std/primitive.u8.html#method.to_ascii_uppercase
+[`u8::to_ascii_lowercase`]: https://doc.rust-lang.org/stable/std/primitive.u8.html#method.to_ascii_lowercase
+[`u8::eq_ignore_ascii_case`]: https://doc.rust-lang.org/stable/std/primitive.u8.html#method.eq_ignore_ascii_case
+
 Version 1.51.0 (2021-03-25)
 ============================
 

compiler/rustc_attr/src/builtin.rs

@@ -862,6 +862,18 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
         if let Some(items) = attr.meta_item_list() {
             sess.mark_attr_used(attr);
             for item in items {
+                if !item.is_meta_item() {
+                    handle_errors(
+                        &sess.parse_sess,
+                        item.span(),
+                        AttrError::UnsupportedLiteral(
+                            "meta item in `repr` must be an identifier",
+                            false,
+                        ),
+                    );
+                    continue;
+                }
+
                 let mut recognised = false;
                 if item.is_word() {
                     let hint = match item.name_or_empty() {
@@ -878,6 +890,23 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                         acc.push(h);
                     }
                 } else if let Some((name, value)) = item.name_value_literal() {
+                    let parse_alignment = |node: &ast::LitKind| -> Result<u32, &'static str> {
+                        if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node {
+                            if literal.is_power_of_two() {
+                                // rustc_middle::ty::layout::Align restricts align to <= 2^29
+                                if *literal <= 1 << 29 {
+                                    Ok(*literal as u32)
+                                } else {
+                                    Err("larger than 2^29")
+                                }
+                            } else {
+                                Err("not a power of two")
+                            }
+                        } else {
+                            Err("not an unsuffixed integer")
+                        }
+                    };
+
                     let mut literal_error = None;
                     if name == sym::align {
                         recognised = true;
@@ -937,7 +966,13 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                 }
                 if !recognised {
                     // Not a word we recognize
-                    diagnostic.delay_span_bug(item.span(), "unrecognized representation hint");
+                    struct_span_err!(
+                        diagnostic,
+                        item.span(),
+                        E0552,
+                        "unrecognized representation hint"
+                    )
+                    .emit();
                 }
             }
         }
@@ -1045,16 +1080,3 @@ fn allow_unstable<'a>(
         name
     })
 }
-
-pub fn parse_alignment(node: &ast::LitKind) -> Result<u32, &'static str> {
-    if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node {
-        if literal.is_power_of_two() {
-            // rustc_middle::ty::layout::Align restricts align to <= 2^29
-            if *literal <= 1 << 29 { Ok(*literal as u32) } else { Err("larger than 2^29") }
-        } else {
-            Err("not a power of two")
-        }
-    } else {
-        Err("not an unsuffixed integer")
-    }
-}

compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs

@@ -15,20 +15,12 @@ pub fn expand_deriving_eq(
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
 ) {
+    let span = cx.with_def_site_ctxt(span);
     let inline = cx.meta_word(span, sym::inline);
-    let no_coverage_ident =
-        rustc_ast::attr::mk_nested_word_item(Ident::new(sym::no_coverage, span));
-    let no_coverage_feature =
-        rustc_ast::attr::mk_list_item(Ident::new(sym::feature, span), vec![no_coverage_ident]);
-    let no_coverage = cx.meta_word(span, sym::no_coverage);
     let hidden = rustc_ast::attr::mk_nested_word_item(Ident::new(sym::hidden, span));
     let doc = rustc_ast::attr::mk_list_item(Ident::new(sym::doc, span), vec![hidden]);
-    let attrs = vec![
-        cx.attribute(inline),
-        cx.attribute(no_coverage_feature),
-        cx.attribute(no_coverage),
-        cx.attribute(doc),
-    ];
+    let no_coverage = cx.meta_word(span, sym::no_coverage);
+    let attrs = vec![cx.attribute(inline), cx.attribute(doc), cx.attribute(no_coverage)];
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),

compiler/rustc_codegen_llvm/src/abi.rs

@@ -1,7 +1,6 @@
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::llvm::{self, AttributePlace};
-use crate::llvm_util;
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -52,15 +51,9 @@ pub trait ArgAttributesExt {
 }
 
 fn should_use_mutable_noalias(cx: &CodegenCx<'_, '_>) -> bool {
-    // LLVM prior to version 12 has known miscompiles in the presence of
-    // noalias attributes (see #54878). Only enable mutable noalias by
-    // default for versions we believe to be safe.
-    cx.tcx
-        .sess
-        .opts
-        .debugging_opts
-        .mutable_noalias
-        .unwrap_or_else(|| llvm_util::get_version() >= (12, 0, 0))
+    // While #84958 has been fixed, mutable noalias is not enabled by default
+    // in Rust 1.53 out of an abundance of caution.
+    cx.tcx.sess.opts.debugging_opts.mutable_noalias.unwrap_or(false)
 }
 
 impl ArgAttributesExt for ArgAttributes {

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -281,9 +281,6 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY) {
         llvm::AddFunctionAttrString(llfn, Function, cstr!("cmse_nonsecure_entry"));
     }
-    if let Some(align) = codegen_fn_attrs.alignment {
-        llvm::set_alignment(llfn, align as usize);
-    }
     sanitize(cx, codegen_fn_attrs.no_sanitize, llfn);
 
     // Always annotate functions with the target-cpu they are compiled for.

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -1,5 +1,5 @@
 use crate::back::write::create_informational_target_machine;
-use crate::llvm;
+use crate::{llvm, llvm_util};
 use libc::c_int;
 use rustc_codegen_ssa::target_features::supported_target_features;
 use rustc_data_structures::fx::FxHashSet;
@@ -84,6 +84,17 @@ unsafe fn configure_llvm(sess: &Session) {
         if !sess.opts.debugging_opts.no_generate_arange_section {
             add("-generate-arange-section", false);
         }
+
+        // FIXME(nagisa): disable the machine outliner by default in LLVM versions 11, where it was
+        // introduced and up.
+        //
+        // This should remain in place until https://reviews.llvm.org/D103167 is fixed. If LLVM
+        // has been upgraded since, consider adjusting the version check below to contain an upper
+        // bound.
+        if llvm_util::get_version() >= (11, 0, 0) {
+            add("-enable-machine-outliner=never", false);
+        }
+
         match sess.opts.debugging_opts.merge_functions.unwrap_or(sess.target.merge_functions) {
             MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
             MergeFunctions::Aliases => {

compiler/rustc_codegen_ssa/src/lib.rs

@@ -1,5 +1,4 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(assert_matches)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(drain_filter)]

compiler/rustc_feature/src/active.rs

@@ -637,9 +637,6 @@ declare_features! (
     /// Allows `extern "C-unwind" fn` to enable unwinding across ABI boundaries.
     (active, c_unwind, "1.52.0", Some(74990), None),
 
-    /// Allows using `#[repr(align(...))]` on function items
-    (active, fn_align, "1.53.0", Some(82232), None),
-
     /// Allows `extern "wasm" fn`
     (active, wasm_abi, "1.53.0", Some(83788), None),
 

compiler/rustc_feature/src/builtin_attrs.rs

@@ -273,13 +273,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         template!(List: "address, memory, thread"),
         experimental!(no_sanitize)
     ),
-    ungated!(
-        // Not exclusively gated at the crate level (though crate-level is
-        // supported). The feature can alternatively be enabled on individual
-        // functions.
-        no_coverage, AssumedUsed,
-        template!(Word),
-    ),
+    gated!(no_coverage, AssumedUsed, template!(Word), experimental!(no_coverage)),
 
     // FIXME: #14408 assume docs are used since rustdoc looks at them.
     ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -406,17 +406,17 @@ impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for ExpnId {
 
 impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for Span {
     fn decode(decoder: &mut DecodeContext<'a, 'tcx>) -> Result<Span, String> {
+        let ctxt = SyntaxContext::decode(decoder)?;
         let tag = u8::decode(decoder)?;
 
-        if tag == TAG_INVALID_SPAN {
-            return Ok(DUMMY_SP);
+        if tag == TAG_PARTIAL_SPAN {
+            return Ok(DUMMY_SP.with_ctxt(ctxt));
         }
 
         debug_assert!(tag == TAG_VALID_SPAN_LOCAL || tag == TAG_VALID_SPAN_FOREIGN);
 
         let lo = BytePos::decode(decoder)?;
         let len = BytePos::decode(decoder)?;
-        let ctxt = SyntaxContext::decode(decoder)?;
         let hi = lo + len;
 
         let sess = if let Some(sess) = decoder.sess {