Auto merge of rust-lang#128278 - tgross35:rollup-zv7q0h5, r=tgross35

Rollup of 8 pull requests

Successful merges:

 - rust-lang#125897 (from_ref, from_mut: clarify documentation)
 - rust-lang#128207 (improve error message when `global_asm!` uses `asm!` options)
 - rust-lang#128241 (Remove logic to suggest clone of function output)
 - rust-lang#128259 ([illumos/solaris] set MSG_NOSIGNAL while writing to sockets)
 - rust-lang#128262 (Delete `SimplifyArmIdentity` and `SimplifyBranchSame` tests)
 - rust-lang#128266 (update `rust.channel` default value documentation)
 - rust-lang#128267 (Add rustdoc GUI test to check title with and without search)
 - rust-lang#128271 (Disable jump threading of float equality)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Diff for: compiler/rustc_ast/src/ast.rs

@@ -2266,6 +2266,11 @@ bitflags::bitflags! {
 }
 
 impl InlineAsmOptions {
+    pub const COUNT: usize = Self::all().bits().count_ones() as usize;
+
+    pub const GLOBAL_OPTIONS: Self = Self::ATT_SYNTAX.union(Self::RAW);
+    pub const NAKED_OPTIONS: Self = Self::ATT_SYNTAX.union(Self::RAW).union(Self::NORETURN);
+
     pub fn human_readable_names(&self) -> Vec<&'static str> {
         let mut options = vec![];
 

Diff for: compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1306,37 +1306,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
                     // result of `foo(...)` won't help.
                     break 'outer;
                 }
-
-                // We're suggesting `.clone()` on an borrowed value. See if the expression we have
-                // is an argument to a function or method call, and try to suggest cloning the
-                // *result* of the call, instead of the argument. This is closest to what people
-                // would actually be looking for in most cases, with maybe the exception of things
-                // like `fn(T) -> T`, but even then it is reasonable.
-                let typeck_results = self.infcx.tcx.typeck(self.mir_def_id());
-                let mut prev = expr;
-                while let hir::Node::Expr(parent) = self.infcx.tcx.parent_hir_node(prev.hir_id) {
-                    if let hir::ExprKind::Call(..) | hir::ExprKind::MethodCall(..) = parent.kind
-                        && let Some(call_ty) = typeck_results.node_type_opt(parent.hir_id)
-                        && let call_ty = call_ty.peel_refs()
-                        && (!call_ty
-                            .walk()
-                            .any(|t| matches!(t.unpack(), ty::GenericArgKind::Lifetime(_)))
-                            || if let ty::Alias(ty::Projection, _) = call_ty.kind() {
-                                // FIXME: this isn't quite right with lifetimes on assoc types,
-                                // but ignore for now. We will only suggest cloning if
-                                // `<Ty as Trait>::Assoc: Clone`, which should keep false positives
-                                // down to a managable ammount.
-                                true
-                            } else {
-                                false
-                            })
-                        && self.implements_clone(call_ty)
-                        && self.suggest_cloning_inner(err, call_ty, parent)
-                    {
-                        return;
-                    }
-                    prev = parent;
-                }
             }
         }
         let ty = ty.peel_refs();

Diff for: compiler/rustc_builtin_macros/messages.ftl

@@ -199,6 +199,10 @@ builtin_macros_format_use_positional = consider using a positional formatting ar
 
 builtin_macros_global_asm_clobber_abi = `clobber_abi` cannot be used with `global_asm!`
 
+builtin_macros_global_asm_unsupported_option = the `{$symbol}` option cannot be used with `global_asm!`
+    .label = the `{$symbol}` option is not meaningful for global-scoped inline assembly
+    .suggestion = remove this option
+
 builtin_macros_invalid_crate_attribute = invalid crate attribute
 
 builtin_macros_multiple_default_attrs = multiple `#[default]` attributes

Diff for: compiler/rustc_builtin_macros/src/asm.rs

@@ -310,6 +310,16 @@ fn err_duplicate_option(p: &Parser<'_>, symbol: Symbol, span: Span) {
     p.dcx().emit_err(errors::AsmOptAlreadyprovided { span, symbol, full_span });
 }
 
+/// Report an invalid option error.
+///
+/// This function must be called immediately after the option token is parsed.
+/// Otherwise, the suggestion will be incorrect.
+fn err_unsupported_option(p: &Parser<'_>, symbol: Symbol, span: Span) {
+    // Tool-only output
+    let full_span = if p.token.kind == token::Comma { span.to(p.token.span) } else { span };
+    p.dcx().emit_err(errors::GlobalAsmUnsupportedOption { span, symbol, full_span });
+}
+
 /// Try to set the provided option in the provided `AsmArgs`.
 /// If it is already set, report a duplicate option error.
 ///
@@ -318,13 +328,16 @@ fn err_duplicate_option(p: &Parser<'_>, symbol: Symbol, span: Span) {
 fn try_set_option<'a>(
     p: &Parser<'a>,
     args: &mut AsmArgs,
+    is_global_asm: bool,
     symbol: Symbol,
     option: ast::InlineAsmOptions,
 ) {
-    if !args.options.contains(option) {
-        args.options |= option;
-    } else {
+    if is_global_asm && !ast::InlineAsmOptions::GLOBAL_OPTIONS.contains(option) {
+        err_unsupported_option(p, symbol, p.prev_token.span);
+    } else if args.options.contains(option) {
         err_duplicate_option(p, symbol, p.prev_token.span);
+    } else {
+        args.options |= option;
     }
 }
 
@@ -338,25 +351,33 @@ fn parse_options<'a>(
     p.expect(&token::OpenDelim(Delimiter::Parenthesis))?;
 
     while !p.eat(&token::CloseDelim(Delimiter::Parenthesis)) {
-        if !is_global_asm && p.eat_keyword(sym::pure) {
-            try_set_option(p, args, sym::pure, ast::InlineAsmOptions::PURE);
-        } else if !is_global_asm && p.eat_keyword(sym::nomem) {
-            try_set_option(p, args, sym::nomem, ast::InlineAsmOptions::NOMEM);
-        } else if !is_global_asm && p.eat_keyword(sym::readonly) {
-            try_set_option(p, args, sym::readonly, ast::InlineAsmOptions::READONLY);
-        } else if !is_global_asm && p.eat_keyword(sym::preserves_flags) {
-            try_set_option(p, args, sym::preserves_flags, ast::InlineAsmOptions::PRESERVES_FLAGS);
-        } else if !is_global_asm && p.eat_keyword(sym::noreturn) {
-            try_set_option(p, args, sym::noreturn, ast::InlineAsmOptions::NORETURN);
-        } else if !is_global_asm && p.eat_keyword(sym::nostack) {
-            try_set_option(p, args, sym::nostack, ast::InlineAsmOptions::NOSTACK);
-        } else if !is_global_asm && p.eat_keyword(sym::may_unwind) {
-            try_set_option(p, args, kw::Raw, ast::InlineAsmOptions::MAY_UNWIND);
-        } else if p.eat_keyword(sym::att_syntax) {
-            try_set_option(p, args, sym::att_syntax, ast::InlineAsmOptions::ATT_SYNTAX);
-        } else if p.eat_keyword(kw::Raw) {
-            try_set_option(p, args, kw::Raw, ast::InlineAsmOptions::RAW);
-        } else {
+        const OPTIONS: [(Symbol, ast::InlineAsmOptions); ast::InlineAsmOptions::COUNT] = [
+            (sym::pure, ast::InlineAsmOptions::PURE),
+            (sym::nomem, ast::InlineAsmOptions::NOMEM),
+            (sym::readonly, ast::InlineAsmOptions::READONLY),
+            (sym::preserves_flags, ast::InlineAsmOptions::PRESERVES_FLAGS),
+            (sym::noreturn, ast::InlineAsmOptions::NORETURN),
+            (sym::nostack, ast::InlineAsmOptions::NOSTACK),
+            (sym::may_unwind, ast::InlineAsmOptions::MAY_UNWIND),
+            (sym::att_syntax, ast::InlineAsmOptions::ATT_SYNTAX),
+            (kw::Raw, ast::InlineAsmOptions::RAW),
+        ];
+
+        'blk: {
+            for (symbol, option) in OPTIONS {
+                let kw_matched =
+                    if !is_global_asm || ast::InlineAsmOptions::GLOBAL_OPTIONS.contains(option) {
+                        p.eat_keyword(symbol)
+                    } else {
+                        p.eat_keyword_noexpect(symbol)
+                    };
+
+                if kw_matched {
+                    try_set_option(p, args, is_global_asm, symbol, option);
+                    break 'blk;
+                }
+            }
+
             return p.unexpected();
         }
 

Diff for: compiler/rustc_builtin_macros/src/errors.rs

@@ -845,6 +845,17 @@ pub(crate) struct AsmOptAlreadyprovided {
     pub(crate) full_span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(builtin_macros_global_asm_unsupported_option)]
+pub(crate) struct GlobalAsmUnsupportedOption {
+    #[primary_span]
+    #[label]
+    pub(crate) span: Span,
+    pub(crate) symbol: Symbol,
+    #[suggestion(code = "", applicability = "machine-applicable", style = "tool-only")]
+    pub(crate) full_span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(builtin_macros_test_runner_invalid)]
 pub(crate) struct TestRunnerInvalid {

Diff for: compiler/rustc_mir_transform/src/jump_threading.rs

@@ -509,6 +509,13 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
                     BinOp::Ne => ScalarInt::FALSE,
                     _ => return None,
                 };
+                if value.const_.ty().is_floating_point() {
+                    // Floating point equality does not follow bit-patterns.
+                    // -0.0 and NaN both have special rules for equality,
+                    // and therefore we cannot use integer comparisons for them.
+                    // Avoid handling them, though this could be extended in the future.
+                    return None;
+                }
                 let value = value.const_.normalize(self.tcx, self.param_env).try_to_scalar_int()?;
                 let conds = conditions.map(self.arena, |c| Condition {
                     value,

Diff for: compiler/rustc_parse/src/parser/mod.rs

@@ -599,7 +599,7 @@ impl<'a> Parser<'a> {
 
     /// If the next token is the given keyword, eats it and returns `true`.
     /// Otherwise, returns `false`. An expectation is also added for diagnostics purposes.
-    // Public for rustfmt usage.
+    // Public for rustc_builtin_macros and rustfmt usage.
     #[inline]
     pub fn eat_keyword(&mut self, kw: Symbol) -> bool {
         if self.check_keyword(kw) {
@@ -631,8 +631,11 @@ impl<'a> Parser<'a> {
         false
     }
 
+    /// If the next token is the given keyword, eats it and returns `true`.
+    /// Otherwise, returns `false`. No expectation is added.
+    // Public for rustc_builtin_macros usage.
     #[inline]
-    fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
+    pub fn eat_keyword_noexpect(&mut self, kw: Symbol) -> bool {
         if self.token.is_keyword(kw) {
             self.bump();
             true

Diff for: compiler/rustc_passes/src/naked_functions.rs

@@ -244,10 +244,7 @@ impl<'tcx> CheckInlineAssembly<'tcx> {
             self.tcx.dcx().emit_err(NakedFunctionsOperands { unsupported_operands });
         }
 
-        let supported_options =
-            InlineAsmOptions::RAW | InlineAsmOptions::NORETURN | InlineAsmOptions::ATT_SYNTAX;
-        let unsupported_options = asm.options.difference(supported_options);
-
+        let unsupported_options = asm.options.difference(InlineAsmOptions::NAKED_OPTIONS);
         if !unsupported_options.is_empty() {
             self.tcx.dcx().emit_err(NakedFunctionsAsmOptions {
                 span,

Diff for: config.example.toml

@@ -578,7 +578,10 @@
 # The "channel" for the Rust build to produce. The stable/beta channels only
 # allow using stable features, whereas the nightly and dev channels allow using
 # nightly features
-#channel = "dev"
+#
+# If using tarball sources, default value for `channel` is taken from the `src/ci/channel` file;
+# otherwise, it's "dev".
+#channel = if "is a tarball source" { content of `src/ci/channel` file } else { "dev" }
 
 # A descriptive string to be appended to `rustc --version` output, which is
 # also used in places like debuginfo `DW_AT_producer`. This may be useful for

Diff for: library/alloc/src/vec/mod.rs

@@ -1277,7 +1277,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// valid for zero sized reads if the vector didn't allocate.
     ///
     /// The caller must ensure that the vector outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
+    /// function returns, or else it will end up dangling.
     /// Modifying the vector may cause its buffer to be reallocated,
     /// which would also make any pointers to it invalid.
     ///
@@ -1337,7 +1337,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// raw pointer valid for zero sized reads if the vector didn't allocate.
     ///
     /// The caller must ensure that the vector outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
+    /// function returns, or else it will end up dangling.
     /// Modifying the vector may cause its buffer to be reallocated,
     /// which would also make any pointers to it invalid.
     ///

Diff for: library/core/src/ptr/mod.rs

@@ -777,8 +777,51 @@ where
 
 /// Convert a reference to a raw pointer.
 ///
-/// This is equivalent to `r as *const T`, but is a bit safer since it will never silently change
-/// type or mutability, in particular if the code is refactored.
+/// For `r: &T`, `from_ref(r)` is equivalent to `r as *const T` (except for the caveat noted below),
+/// but is a bit safer since it will never silently change type or mutability, in particular if the
+/// code is refactored.
+///
+/// The caller must ensure that the pointee outlives the pointer this function returns, or else it
+/// will end up dangling.
+///
+/// The caller must also ensure that the memory the pointer (non-transitively) points to is never
+/// written to (except inside an `UnsafeCell`) using this pointer or any pointer derived from it. If
+/// you need to mutate the pointee, use [`from_mut`]`. Specifically, to turn a mutable reference `m:
+/// &mut T` into `*const T`, prefer `from_mut(m).cast_const()` to obtain a pointer that can later be
+/// used for mutation.
+///
+/// ## Interaction with lifetime extension
+///
+/// Note that this has subtle interactions with the rules for lifetime extension of temporaries in
+/// tail expressions. This code is valid, albeit in a non-obvious way:
+/// ```rust
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// // The temporary holding the return value of `foo` has its lifetime extended,
+/// // because the surrounding expression involves no function call.
+/// let p = &foo() as *const T;
+/// unsafe { p.read() };
+/// ```
+/// Naively replacing the cast with `from_ref` is not valid:
+/// ```rust,no_run
+/// # use std::ptr;
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// // The temporary holding the return value of `foo` does *not* have its lifetime extended,
+/// // because the surrounding expression involves no function call.
+/// let p = ptr::from_ref(&foo());
+/// unsafe { p.read() }; // UB! Reading from a dangling pointer ⚠️
+/// ```
+/// The recommended way to write this code is to avoid relying on lifetime extension
+/// when raw pointers are involved:
+/// ```rust
+/// # use std::ptr;
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// let x = foo();
+/// let p = ptr::from_ref(&x);
+/// unsafe { p.read() };
+/// ```
 #[inline(always)]
 #[must_use]
 #[stable(feature = "ptr_from_ref", since = "1.76.0")]
@@ -791,8 +834,45 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
 
 /// Convert a mutable reference to a raw pointer.
 ///
-/// This is equivalent to `r as *mut T`, but is a bit safer since it will never silently change
-/// type or mutability, in particular if the code is refactored.
+/// For `r: &mut T`, `from_mut(r)` is equivalent to `r as *mut T` (except for the caveat noted
+/// below), but is a bit safer since it will never silently change type or mutability, in particular
+/// if the code is refactored.
+///
+/// The caller must ensure that the pointee outlives the pointer this function returns, or else it
+/// will end up dangling.
+///
+/// ## Interaction with lifetime extension
+///
+/// Note that this has subtle interactions with the rules for lifetime extension of temporaries in
+/// tail expressions. This code is valid, albeit in a non-obvious way:
+/// ```rust
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// // The temporary holding the return value of `foo` has its lifetime extended,
+/// // because the surrounding expression involves no function call.
+/// let p = &mut foo() as *mut T;
+/// unsafe { p.write(T::default()) };
+/// ```
+/// Naively replacing the cast with `from_mut` is not valid:
+/// ```rust,no_run
+/// # use std::ptr;
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// // The temporary holding the return value of `foo` does *not* have its lifetime extended,
+/// // because the surrounding expression involves no function call.
+/// let p = ptr::from_mut(&mut foo());
+/// unsafe { p.write(T::default()) }; // UB! Writing to a dangling pointer ⚠️
+/// ```
+/// The recommended way to write this code is to avoid relying on lifetime extension
+/// when raw pointers are involved:
+/// ```rust
+/// # use std::ptr;
+/// # type T = i32;
+/// # fn foo() -> T { 42 }
+/// let mut x = foo();
+/// let p = ptr::from_mut(&mut x);
+/// unsafe { p.write(T::default()) };
+/// ```
 #[inline(always)]
 #[must_use]
 #[stable(feature = "ptr_from_ref", since = "1.76.0")]

Diff for: library/core/src/slice/mod.rs

@@ -726,7 +726,7 @@ impl<T> [T] {
     /// Returns a raw pointer to the slice's buffer.
     ///
     /// The caller must ensure that the slice outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
+    /// function returns, or else it will end up dangling.
     ///
     /// The caller must also ensure that the memory the pointer (non-transitively) points to
     /// is never written to (except inside an `UnsafeCell`) using this pointer or any pointer
@@ -761,7 +761,7 @@ impl<T> [T] {
     /// Returns an unsafe mutable pointer to the slice's buffer.
     ///
     /// The caller must ensure that the slice outlives the pointer this
-    /// function returns, or else it will end up pointing to garbage.
+    /// function returns, or else it will end up dangling.
     ///
     /// Modifying the container referenced by this slice may cause its buffer
     /// to be reallocated, which would also make any pointers to it invalid.

Diff for: library/std/src/os/unix/net/datagram.rs

@@ -20,6 +20,8 @@ use crate::{fmt, io};
     target_os = "freebsd",
     target_os = "openbsd",
     target_os = "netbsd",
+    target_os = "solaris",
+    target_os = "illumos",
     target_os = "haiku",
     target_os = "nto",
 ))]
@@ -31,6 +33,8 @@ use libc::MSG_NOSIGNAL;
     target_os = "freebsd",
     target_os = "openbsd",
     target_os = "netbsd",
+    target_os = "solaris",
+    target_os = "illumos",
     target_os = "haiku",
     target_os = "nto",
 )))]

Diff for: library/std/src/sys_common/net.rs

@@ -42,6 +42,7 @@ cfg_if::cfg_if! {
         target_os = "hurd",
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "openbsd", target_os = "netbsd",
+        target_os = "solaris", target_os = "illumos",
         target_os = "haiku", target_os = "nto"))] {
         use libc::MSG_NOSIGNAL;
     } else {