Rollup of 8 pull requests

compiler/rustc_borrowck/src/borrowck_errors.rs

@@ -278,7 +278,7 @@ impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
         move_from_span: Span,
         move_from_desc: &str,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
-        struct_span_err!(self, move_from_span, E0507, "cannot move out of {}", move_from_desc,)
+        struct_span_err!(self, move_from_span, E0507, "cannot move out of {}", move_from_desc)
     }
 
     /// Signal an error due to an attempt to move out of the interior

compiler/rustc_lint_defs/src/builtin.rs

@@ -3464,7 +3464,8 @@ declare_lint! {
     /// out an update in your own time.
     pub LONG_RUNNING_CONST_EVAL,
     Deny,
-    "detects long const eval operations"
+    "detects long const eval operations",
+    report_in_external_macro
 }
 
 declare_lint! {

compiler/rustc_macros/src/diagnostics/error.rs

@@ -54,7 +54,7 @@ fn path_to_string(path: &syn::Path) -> String {
 
 /// Returns an error diagnostic on span `span` with msg `msg`.
 #[must_use]
-pub(crate) fn span_err(span: impl MultiSpan, msg: &str) -> Diagnostic {
+pub(crate) fn span_err<T: Into<String>>(span: impl MultiSpan, msg: T) -> Diagnostic {
     Diagnostic::spanned(span, Level::Error, msg)
 }
 
@@ -77,11 +77,9 @@ pub(crate) fn invalid_attr(attr: &Attribute) -> Diagnostic {
     let span = attr.span().unwrap();
     let path = path_to_string(attr.path());
     match attr.meta {
-        Meta::Path(_) => span_err(span, &format!("`#[{path}]` is not a valid attribute")),
-        Meta::NameValue(_) => {
-            span_err(span, &format!("`#[{path} = ...]` is not a valid attribute"))
-        }
-        Meta::List(_) => span_err(span, &format!("`#[{path}(...)]` is not a valid attribute")),
+        Meta::Path(_) => span_err(span, format!("`#[{path}]` is not a valid attribute")),
+        Meta::NameValue(_) => span_err(span, format!("`#[{path} = ...]` is not a valid attribute")),
+        Meta::List(_) => span_err(span, format!("`#[{path}(...)]` is not a valid attribute")),
     }
 }
 

compiler/rustc_macros/src/diagnostics/subdiagnostic.rs

@@ -200,7 +200,7 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
 
                 throw_span_err!(
                     attr.span().unwrap(),
-                    &format!(
+                    format!(
                         "diagnostic slug must be first argument of a `#[{name}(...)]` attribute"
                     )
                 );

compiler/rustc_macros/src/diagnostics/utils.rs

@@ -347,7 +347,7 @@ pub(crate) trait HasFieldMap {
                 None => {
                     span_err(
                         span.unwrap(),
-                        &format!("`{field}` doesn't refer to a field on this type"),
+                        format!("`{field}` doesn't refer to a field on this type"),
                     )
                     .emit();
                     quote! {

library/core/src/slice/raw.rs

@@ -32,7 +32,8 @@ use crate::ptr;
 /// * The memory referenced by the returned slice must not be mutated for the duration
 ///   of lifetime `'a`, except inside an `UnsafeCell`.
 ///
-/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`.
+/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`,
+///   and adding that size to `data` must not "wrap around" the address space.
 ///   See the safety documentation of [`pointer::offset`].
 ///
 /// # Caveat
@@ -125,7 +126,8 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
 ///   (not derived from the return value) for the duration of lifetime `'a`.
 ///   Both read and write accesses are forbidden.
 ///
-/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`.
+/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`,
+///   and adding that size to `data` must not "wrap around" the address space.
 ///   See the safety documentation of [`pointer::offset`].
 ///
 /// [valid]: ptr#safety
@@ -179,15 +181,16 @@ pub const fn from_mut<T>(s: &mut T) -> &mut [T] {
 ///   the last element, such that the offset from the end to the start pointer is
 ///   the length of the slice.
 ///
-/// * The range must contain `N` consecutive properly initialized values of type `T`:
+/// * The entire memory range of this slice must be contained within a single allocated object!
+///   Slices can never span across multiple allocated objects.
 ///
-///     * The entire memory range of this slice must be contained within a single allocated object!
-///       Slices can never span across multiple allocated objects.
+/// * The range must contain `N` consecutive properly initialized values of type `T`.
 ///
 /// * The memory referenced by the returned slice must not be mutated for the duration
 ///   of lifetime `'a`, except inside an `UnsafeCell`.
 ///
-/// * The total length of the range must be no larger than `isize::MAX`.
+/// * The total length of the range must be no larger than `isize::MAX`,
+///   and adding that size to `data` must not "wrap around" the address space.
 ///   See the safety documentation of [`pointer::offset`].
 ///
 /// Note that a range created from [`slice::as_ptr_range`] fulfills these requirements.
@@ -247,16 +250,17 @@ pub const unsafe fn from_ptr_range<'a, T>(range: Range<*const T>) -> &'a [T] {
 ///   the last element, such that the offset from the end to the start pointer is
 ///   the length of the slice.
 ///
-/// * The range must contain `N` consecutive properly initialized values of type `T`:
+/// * The entire memory range of this slice must be contained within a single allocated object!
+///   Slices can never span across multiple allocated objects.
 ///
-///     * The entire memory range of this slice must be contained within a single allocated object!
-///       Slices can never span across multiple allocated objects.
+/// * The range must contain `N` consecutive properly initialized values of type `T`.
 ///
 /// * The memory referenced by the returned slice must not be accessed through any other pointer
 ///   (not derived from the return value) for the duration of lifetime `'a`.
 ///   Both read and write accesses are forbidden.
 ///
-/// * The total length of the range must be no larger than `isize::MAX`.
+/// * The total length of the range must be no larger than `isize::MAX`,
+///   and adding that size to `data` must not "wrap around" the address space.
 ///   See the safety documentation of [`pointer::offset`].
 ///
 /// Note that a range created from [`slice::as_mut_ptr_range`] fulfills these requirements.

src/doc/style-guide/src/README.md

@@ -16,9 +16,21 @@ Rust code has similar formatting, less mental effort is required to comprehend a
 new project, lowering the barrier to entry for new developers.
 
 Thus, there are productivity benefits to using a formatting tool (such as
-rustfmt), and even larger benefits by using a community-consistent formatting,
-typically by using a formatting tool's default settings.
+`rustfmt`), and even larger benefits by using a community-consistent
+formatting, typically by using a formatting tool's default settings.
 
+## The default Rust style
+
+The Rust Style Guide defines the default Rust style, and *recommends* that
+developers and tools follow the default Rust style. Tools such as `rustfmt` use
+the style guide as a reference for the default style. Everything in this style
+guide, whether or not it uses language such as "must" or the imperative mood
+such as "insert a space ..." or "break the line after ...", refers to the
+default style.
+
+This should not be interpreted as forbidding developers from following a
+non-default style, or forbidding tools from adding any particular configuration
+options.
 
 ## Formatting conventions
 
@@ -28,8 +40,47 @@ typically by using a formatting tool's default settings.
 * Each level of indentation must be four spaces (that is, all indentation
   outside of string literals and comments must be a multiple of four).
 * The maximum width for a line is 100 characters.
-* A tool should be configurable for all three of these variables.
+* A tool may choose to make some of these configurable.
+
+#### Block indent
+
+Prefer block indent over visual indent:
+
+```rust
+// Block indent
+a_function_call(
+    foo,
+    bar,
+);
+
+// Visual indent
+a_function_call(foo,
+                bar);
+```
 
+This makes for smaller diffs (e.g., if `a_function_call` is renamed in the above
+example) and less rightward drift.
+
+### Trailing commas
+
+Lists should have a trailing comma when followed by a newline:
+
+```rust
+function_call(
+    argument,
+    another_argument,
+);
+
+let array = [
+    element,
+    another_element,
+    yet_another_element,
+];
+```
+
+This makes moving code (e.g., by copy and paste) easier, and makes diffs
+smaller, as appending or removing items does not require modifying another line
+to add or remove a comma.
 
 ### Blank lines
 
@@ -48,11 +99,7 @@ fn bar() {}
 fn baz() {}
 ```
 
-Formatting tools should make the bounds on blank lines configurable: there
-should be separate minimum and maximum numbers of newlines between both
-statements and (top-level) items (i.e., four options). As described above, the
-defaults for both statements and items should be minimum: 1, maximum: 2.
-
+Formatting tools may wish to make the bounds on blank lines configurable.
 
 ### [Module-level items](items.md)
 ### [Statements](statements.md)

src/doc/style-guide/src/SUMMARY.md

@@ -2,10 +2,10 @@
 
 [Introduction](README.md)
 
-- [Module-level items](items.md)
+- [Items](items.md)
 - [Statements](statements.md)
 - [Expressions](expressions.md)
-- [Types](types.md)
-- [Non-formatting conventions](advice.md)
+- [Types and Bounds](types.md)
+- [Other style advice](advice.md)
 - [`Cargo.toml` conventions](cargo.md)
-- [Principles used for deciding these guidelines](principles.md)
+- [Guiding principles and rationale](principles.md)

src/doc/style-guide/src/advice.md

@@ -25,9 +25,9 @@ if y {
  * Local variables shall be `snake_case`,
  * Macro names shall be `snake_case`,
  * Constants (`const`s and immutable `static`s) shall be `SCREAMING_SNAKE_CASE`.
- * When a name is forbidden because it is a reserved word (e.g., `crate`), use a
-   trailing underscore to make the name legal (e.g., `crate_`), or use raw
-   identifiers if possible.
+ * When a name is forbidden because it is a reserved word (such as `crate`),
+   either use a raw identifier (`r#crate`) or use a trailing underscore
+   (`crate_`). Don't misspell the word (`krate`).
 
 ### Modules
 

src/doc/style-guide/src/cargo.md

@@ -1,4 +1,4 @@
-# Cargo.toml conventions
+# `Cargo.toml` conventions
 
 ## Formatting conventions
 
@@ -25,16 +25,17 @@ not indent any key names; start all key names at the start of a line.
 Use multi-line strings (rather than newline escape sequences) for any string
 values that include multiple lines, such as the crate description.
 
-For array values, such as a list of authors, put the entire list on the same
+For array values, such as a list of features, put the entire list on the same
 line as the key, if it fits. Otherwise, use block indentation: put a newline
 after the opening square bracket, indent each item by one indentation level,
 put a comma after each item (including the last), and put the closing square
 bracket at the start of a line by itself after the last item.
 
 ```rust
-authors = [
-    "A Uthor <a.uthor@example.org>",
-    "Another Author <author@example.net>",
+some_feature = [
+    "another_feature",
+    "yet_another_feature",
+    "some_dependency?/some_feature",
 ]
 ```
 
@@ -54,11 +55,11 @@ version = "4.5.6"
 
 ## Metadata conventions
 
-The authors list should consist of strings that each contain an author name
-followed by an email address in angle brackets: `Full Name <email@address>`.
-It should not contain bare email addresses, or names without email addresses.
-(The authors list may also include a mailing list address without an associated
-name.)
+The authors list, if present, should consist of strings that each contain an
+author name followed by an email address in angle brackets: `Full Name
+<email@address>`. It should not contain bare email addresses, or names without
+email addresses. (The authors list may also include a mailing list address
+without an associated name.)
 
 The license field must contain a valid [SPDX
 expression](https://spdx.org/spdx-specification-21-web-version#h.jxpfx0ykyb60),

src/doc/style-guide/src/expressions.md

@@ -690,7 +690,7 @@ Where it is possible to use a block form on the right-hand side and avoid
 breaking the left-hand side, do that. E.g.
 
 ```rust
-    // Assuming the following line does done fit in the max width
+    // Assuming the following line does not fit in the max width
     a_very_long_pattern | another_pattern => ALongStructName {
         ...
     },

src/doc/style-guide/src/items.md

@@ -1,5 +1,10 @@
 ## Items
 
+Items consist of the set of things permitted at the top level of a module.
+However, Rust also allows some items to appear within some other types of
+items, such as within a function. The same formatting conventions apply whether
+an item appears at module level or within another item.
+
 `extern crate` statements must be first in a file. They must be ordered
 alphabetically.
 
@@ -15,8 +20,8 @@ Tools should make the above ordering optional.
 
 ### Function definitions
 
-In Rust, one finds functions by searching for `fn [function-name]`; It's
-important that you style your code so that it's very searchable in this way.
+In Rust, people often find functions by searching for `fn [function-name]`, so
+the formatting of function definitions shold enable this.
 
 The proper ordering and spacing is:
 
@@ -63,8 +68,9 @@ let y = (11, 22, 33);
 
 In the declaration, put each variant on its own line, block indented.
 
-Format each variant accordingly as either a struct, tuple struct, or identifier,
-which doesn't require special formatting (but without the `struct` keyword.
+Format each variant accordingly as either a struct (but without the `struct`
+keyword), a tuple struct, or an identifier (which doesn't require special
+formatting):
 
 ```rust
 enum FooBar {
@@ -139,7 +145,7 @@ union Foo {
 
 Put the whole struct on one line if possible. Types in the parentheses should be
 separated by a comma and space with no trailing comma. No spaces around the
-parentheses or semi-colon:
+parentheses or semicolon:
 
 ```rust
 pub struct Foo(String, u8);
@@ -230,7 +236,7 @@ impl Bar
 
 `extern crate foo;`
 
-Use spaces around keywords, no spaces around the semi-colon.
+Use spaces around keywords, no spaces around the semicolon.
 
 
 ### Modules
@@ -245,7 +251,7 @@ mod foo;
 ```
 
 Use spaces around keywords and before the opening brace, no spaces around the
-semi-colon.
+semicolon.
 
 ### macro\_rules!
 
@@ -478,8 +484,8 @@ foo::{
 A *group* of imports is a set of imports on the same or sequential lines. One or
 more blank lines or other items (e.g., a function) separate groups of imports.
 
-Within a group of imports, imports must be sorted ascii-betically. Groups of
-imports must not be merged or re-ordered.
+Within a group of imports, imports must be sorted ASCIIbetically (uppercase
+before lowercase). Groups of imports must not be merged or re-ordered.
 
 
 E.g., input:
@@ -505,13 +511,9 @@ use b;
 Because of `macro_use`, attributes must also start a new group and prevent
 re-ordering.
 
-Note that tools which only have access to syntax (such as Rustfmt) cannot tell
-which imports are from an external crate or the std lib, etc.
-
-
 #### Ordering list import
 
-Names in a list import must be sorted ascii-betically, but with `self` and
+Names in a list import must be sorted ASCIIbetically, but with `self` and
 `super` first, and groups and glob imports last. This applies recursively. For
 example, `a::*` comes before `b::a` but `a::b` comes before `a::*`. E.g.,
 `use foo::bar::{a, b::c, b::d, b::d::{x, y, z}, b::{self, r, s}};`.