Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 957 insertions, 0 deletions

diff --git a/rust/syn/pat.rs b/rust/syn/pat.rs
new file mode 100644
index 000000000..46edd63d5
--- /dev/null
+++ b/rust/syn/pat.rs
@@ -0,0 +1,957 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Member;
+use crate::ident::Ident;
+use crate::path::{Path, QSelf};
+use crate::punctuated::Punctuated;
+use crate::token;
+use crate::ty::Type;
+use proc_macro2::TokenStream;
+
+pub use crate::expr::{
+    ExprConst as PatConst, ExprLit as PatLit, ExprMacro as PatMacro, ExprPath as PatPath,
+    ExprRange as PatRange,
+};
+
+ast_enum_of_structs! {
+    /// A pattern in a local binding, function signature, match expression, or
+    /// various other places.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum Pat {
+        /// A const block: `const { ... }`.
+        Const(PatConst),
+
+        /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+        Ident(PatIdent),
+
+        /// A literal pattern: `0`.
+        Lit(PatLit),
+
+        /// A macro in pattern position.
+        Macro(PatMacro),
+
+        /// A pattern that matches any one of a set of cases.
+        Or(PatOr),
+
+        /// A parenthesized pattern: `(A | B)`.
+        Paren(PatParen),
+
+        /// A path pattern like `Color::Red`, optionally qualified with a
+        /// self-type.
+        ///
+        /// Unqualified path patterns can legally refer to variants, structs,
+        /// constants or associated constants. Qualified path patterns like
+        /// `<A>::B::C` and `<A as Trait>::B::C` can only legally refer to
+        /// associated constants.
+        Path(PatPath),
+
+        /// A range pattern: `1..=2`.
+        Range(PatRange),
+
+        /// A reference pattern: `&mut var`.
+        Reference(PatReference),
+
+        /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+        Rest(PatRest),
+
+        /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+        Slice(PatSlice),
+
+        /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+        Struct(PatStruct),
+
+        /// A tuple pattern: `(a, b)`.
+        Tuple(PatTuple),
+
+        /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+        TupleStruct(PatTupleStruct),
+
+        /// A type ascription pattern: `foo: f64`.
+        Type(PatType),
+
+        /// Tokens in pattern position not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        /// A pattern that matches any value: `_`.
+        Wild(PatWild),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match pat {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         Pat::Box(pat) => {...}
+        //         Pat::Ident(pat) => {...}
+        //         ...
+        //         Pat::Wild(pat) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+    ///
+    /// It may also be a unit struct or struct variant (e.g. `None`), or a
+    /// constant; these cannot be distinguished syntactically.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatIdent {
+        pub attrs: Vec<Attribute>,
+        pub by_ref: Option<Token![ref]>,
+        pub mutability: Option<Token![mut]>,
+        pub ident: Ident,
+        pub subpat: Option<(Token![@], Box<Pat>)>,
+    }
+}
+
+ast_struct! {
+    /// A pattern that matches any one of a set of cases.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatOr {
+        pub attrs: Vec<Attribute>,
+        pub leading_vert: Option<Token![|]>,
+        pub cases: Punctuated<Pat, Token![|]>,
+    }
+}
+
+ast_struct! {
+    /// A parenthesized pattern: `(A | B)`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatParen {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub pat: Box<Pat>,
+    }
+}
+
+ast_struct! {
+    /// A reference pattern: `&mut var`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatReference {
+        pub attrs: Vec<Attribute>,
+        pub and_token: Token![&],
+        pub mutability: Option<Token![mut]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+ast_struct! {
+    /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatRest {
+        pub attrs: Vec<Attribute>,
+        pub dot2_token: Token![..],
+    }
+}
+
+ast_struct! {
+    /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatSlice {
+        pub attrs: Vec<Attribute>,
+        pub bracket_token: token::Bracket,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatStruct {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+        pub brace_token: token::Brace,
+        pub fields: Punctuated<FieldPat, Token![,]>,
+        pub rest: Option<PatRest>,
+    }
+}
+
+ast_struct! {
+    /// A tuple pattern: `(a, b)`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatTuple {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatTupleStruct {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A type ascription pattern: `foo: f64`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatType {
+        pub attrs: Vec<Attribute>,
+        pub pat: Box<Pat>,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A pattern that matches any value: `_`.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct PatWild {
+        pub attrs: Vec<Attribute>,
+        pub underscore_token: Token![_],
+    }
+}
+
+ast_struct! {
+    /// A single field in a struct pattern.
+    ///
+    /// Patterns like the fields of Foo `{ x, ref y, ref mut z }` are treated
+    /// the same as `x: x, y: ref y, z: ref mut z` but there is no colon token.
+    #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
+    pub struct FieldPat {
+        pub attrs: Vec<Attribute>,
+        pub member: Member,
+        pub colon_token: Option<Token![:]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::{self, Result};
+    use crate::expr::{
+        Expr, ExprConst, ExprLit, ExprMacro, ExprPath, ExprRange, Member, RangeLimits,
+    };
+    use crate::ext::IdentExt as _;
+    use crate::ident::Ident;
+    use crate::lit::Lit;
+    use crate::mac::{self, Macro};
+    use crate::parse::{Parse, ParseBuffer, ParseStream};
+    use crate::pat::{
+        FieldPat, Pat, PatIdent, PatOr, PatParen, PatReference, PatRest, PatSlice, PatStruct,
+        PatTuple, PatTupleStruct, PatType, PatWild,
+    };
+    use crate::path::{self, Path, QSelf};
+    use crate::punctuated::Punctuated;
+    use crate::stmt::Block;
+    use crate::token;
+    use crate::verbatim;
+    use proc_macro2::TokenStream;
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
+    impl Pat {
+        /// Parse a pattern that does _not_ involve `|` at the top level.
+        ///
+        /// This parser matches the behavior of the `$:pat_param` macro_rules
+        /// matcher, and on editions prior to Rust 2021, the behavior of
+        /// `$:pat`.
+        ///
+        /// In Rust syntax, some examples of where this syntax would occur are
+        /// in the argument pattern of functions and closures. Patterns using
+        /// `|` are not allowed to occur in these positions.
+        ///
+        /// ```compile_fail
+        /// fn f(Some(_) | None: Option<T>) {
+        ///     let _ = |Some(_) | None: Option<T>| {};
+        ///     //       ^^^^^^^^^^^^^^^^^^^^^^^^^??? :(
+        /// }
+        /// ```
+        ///
+        /// ```console
+        /// error: top-level or-patterns are not allowed in function parameters
+        ///  --> src/main.rs:1:6
+        ///   |
+        /// 1 | fn f(Some(_) | None: Option<T>) {
+        ///   |      ^^^^^^^^^^^^^^ help: wrap the pattern in parentheses: `(Some(_) | None)`
+        /// ```
+        pub fn parse_single(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Ident)
+                && (input.peek2(Token![::])
+                    || input.peek2(Token![!])
+                    || input.peek2(token::Brace)
+                    || input.peek2(token::Paren)
+                    || input.peek2(Token![..]))
+                || input.peek(Token![self]) && input.peek2(Token![::])
+                || lookahead.peek(Token![::])
+                || lookahead.peek(Token![<])
+                || input.peek(Token![Self])
+                || input.peek(Token![super])
+                || input.peek(Token![crate])
+            {
+                pat_path_or_macro_or_struct_or_range(input)
+            } else if lookahead.peek(Token![_]) {
+                input.call(pat_wild).map(Pat::Wild)
+            } else if input.peek(Token![box]) {
+                pat_box(begin, input)
+            } else if input.peek(Token![-]) || lookahead.peek(Lit) || lookahead.peek(Token![const])
+            {
+                pat_lit_or_range(input)
+            } else if lookahead.peek(Token![ref])
+                || lookahead.peek(Token![mut])
+                || input.peek(Token![self])
+                || input.peek(Ident)
+            {
+                input.call(pat_ident).map(Pat::Ident)
+            } else if lookahead.peek(Token![&]) {
+                input.call(pat_reference).map(Pat::Reference)
+            } else if lookahead.peek(token::Paren) {
+                input.call(pat_paren_or_tuple)
+            } else if lookahead.peek(token::Bracket) {
+                input.call(pat_slice).map(Pat::Slice)
+            } else if lookahead.peek(Token![..]) && !input.peek(Token![...]) {
+                pat_range_half_open(input)
+            } else if lookahead.peek(Token![const]) {
+                input.call(pat_const).map(Pat::Verbatim)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+
+        /// Parse a pattern, possibly involving `|`, but not a leading `|`.
+        pub fn parse_multi(input: ParseStream) -> Result<Self> {
+            multi_pat_impl(input, None)
+        }
+
+        /// Parse a pattern, possibly involving `|`, possibly including a
+        /// leading `|`.
+        ///
+        /// This parser matches the behavior of the Rust 2021 edition's `$:pat`
+        /// macro_rules matcher.
+        ///
+        /// In Rust syntax, an example of where this syntax would occur is in
+        /// the pattern of a `match` arm, where the language permits an optional
+        /// leading `|`, although it is not idiomatic to write one there in
+        /// handwritten code.
+        ///
+        /// ```
+        /// # let wat = None;
+        /// match wat {
+        ///     | None | Some(false) => {}
+        ///     | Some(true) => {}
+        /// }
+        /// ```
+        ///
+        /// The compiler accepts it only to facilitate some situations in
+        /// macro-generated code where a macro author might need to write:
+        ///
+        /// ```
+        /// # macro_rules! doc {
+        /// #     ($value:expr, ($($conditions1:pat),*), ($($conditions2:pat),*), $then:expr) => {
+        /// match $value {
+        ///     $(| $conditions1)* $(| $conditions2)* => $then
+        /// }
+        /// #     };
+        /// # }
+        /// #
+        /// # doc!(true, (true), (false), {});
+        /// # doc!(true, (), (true, false), {});
+        /// # doc!(true, (true, false), (), {});
+        /// ```
+        ///
+        /// Expressing the same thing correctly in the case that either one (but
+        /// not both) of `$conditions1` and `$conditions2` might be empty,
+        /// without leading `|`, is complex.
+        ///
+        /// Use [`Pat::parse_multi`] instead if you are not intending to support
+        /// macro-generated macro input.
+        pub fn parse_multi_with_leading_vert(input: ParseStream) -> Result<Self> {
+            let leading_vert: Option<Token![|]> = input.parse()?;
+            multi_pat_impl(input, leading_vert)
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
+    impl Parse for PatType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(PatType {
+                attrs: Vec::new(),
+                pat: Box::new(Pat::parse_single(input)?),
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+            })
+        }
+    }
+
+    fn multi_pat_impl(input: ParseStream, leading_vert: Option<Token![|]>) -> Result<Pat> {
+        let mut pat = Pat::parse_single(input)?;
+        if leading_vert.is_some()
+            || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
+        {
+            let mut cases = Punctuated::new();
+            cases.push_value(pat);
+            while input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=]) {
+                let punct = input.parse()?;
+                cases.push_punct(punct);
+                let pat = Pat::parse_single(input)?;
+                cases.push_value(pat);
+            }
+            pat = Pat::Or(PatOr {
+                attrs: Vec::new(),
+                leading_vert,
+                cases,
+            });
+        }
+        Ok(pat)
+    }
+
+    fn pat_path_or_macro_or_struct_or_range(input: ParseStream) -> Result<Pat> {
+        let expr_style = true;
+        let (qself, path) = path::parsing::qpath(input, expr_style)?;
+
+        if qself.is_none()
+            && input.peek(Token![!])
+            && !input.peek(Token![!=])
+            && path.is_mod_style()
+        {
+            let bang_token: Token![!] = input.parse()?;
+            let (delimiter, tokens) = mac::parse_delimiter(input)?;
+            return Ok(Pat::Macro(ExprMacro {
+                attrs: Vec::new(),
+                mac: Macro {
+                    path,
+                    bang_token,
+                    delimiter,
+                    tokens,
+                },
+            }));
+        }
+
+        if input.peek(token::Brace) {
+            pat_struct(input, qself, path).map(Pat::Struct)
+        } else if input.peek(token::Paren) {
+            pat_tuple_struct(input, qself, path).map(Pat::TupleStruct)
+        } else if input.peek(Token![..]) {
+            pat_range(input, qself, path)
+        } else {
+            Ok(Pat::Path(ExprPath {
+                attrs: Vec::new(),
+                qself,
+                path,
+            }))
+        }
+    }
+
+    fn pat_wild(input: ParseStream) -> Result<PatWild> {
+        Ok(PatWild {
+            attrs: Vec::new(),
+            underscore_token: input.parse()?,
+        })
+    }
+
+    fn pat_box(begin: ParseBuffer, input: ParseStream) -> Result<Pat> {
+        input.parse::<Token![box]>()?;
+        Pat::parse_single(input)?;
+        Ok(Pat::Verbatim(verbatim::between(&begin, input)))
+    }
+
+    fn pat_ident(input: ParseStream) -> Result<PatIdent> {
+        Ok(PatIdent {
+            attrs: Vec::new(),
+            by_ref: input.parse()?,
+            mutability: input.parse()?,
+            ident: {
+                if input.peek(Token![self]) {
+                    input.call(Ident::parse_any)?
+                } else {
+                    input.parse()?
+                }
+            },
+            subpat: {
+                if input.peek(Token![@]) {
+                    let at_token: Token![@] = input.parse()?;
+                    let subpat = Pat::parse_single(input)?;
+                    Some((at_token, Box::new(subpat)))
+                } else {
+                    None
+                }
+            },
+        })
+    }
+
+    fn pat_tuple_struct(
+        input: ParseStream,
+        qself: Option<QSelf>,
+        path: Path,
+    ) -> Result<PatTupleStruct> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            elems.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(PatTupleStruct {
+            attrs: Vec::new(),
+            qself,
+            path,
+            paren_token,
+            elems,
+        })
+    }
+
+    fn pat_struct(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<PatStruct> {
+        let content;
+        let brace_token = braced!(content in input);
+
+        let mut fields = Punctuated::new();
+        let mut rest = None;
+        while !content.is_empty() {
+            let attrs = content.call(Attribute::parse_outer)?;
+            if content.peek(Token![..]) {
+                rest = Some(PatRest {
+                    attrs,
+                    dot2_token: content.parse()?,
+                });
+                break;
+            }
+            let mut value = content.call(field_pat)?;
+            value.attrs = attrs;
+            fields.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct: Token![,] = content.parse()?;
+            fields.push_punct(punct);
+        }
+
+        Ok(PatStruct {
+            attrs: Vec::new(),
+            qself,
+            path,
+            brace_token,
+            fields,
+            rest,
+        })
+    }
+
+    fn field_pat(input: ParseStream) -> Result<FieldPat> {
+        let begin = input.fork();
+        let boxed: Option<Token![box]> = input.parse()?;
+        let by_ref: Option<Token![ref]> = input.parse()?;
+        let mutability: Option<Token![mut]> = input.parse()?;
+
+        let member = if boxed.is_some() || by_ref.is_some() || mutability.is_some() {
+            input.parse().map(Member::Named)
+        } else {
+            input.parse()
+        }?;
+
+        if boxed.is_none() && by_ref.is_none() && mutability.is_none() && input.peek(Token![:])
+            || !member.is_named()
+        {
+            return Ok(FieldPat {
+                attrs: Vec::new(),
+                member,
+                colon_token: Some(input.parse()?),
+                pat: Box::new(Pat::parse_multi_with_leading_vert(input)?),
+            });
+        }
+
+        let ident = match member {
+            Member::Named(ident) => ident,
+            Member::Unnamed(_) => unreachable!(),
+        };
+
+        let pat = if boxed.is_some() {
+            Pat::Verbatim(verbatim::between(&begin, input))
+        } else {
+            Pat::Ident(PatIdent {
+                attrs: Vec::new(),
+                by_ref,
+                mutability,
+                ident: ident.clone(),
+                subpat: None,
+            })
+        };
+
+        Ok(FieldPat {
+            attrs: Vec::new(),
+            member: Member::Named(ident),
+            colon_token: None,
+            pat: Box::new(pat),
+        })
+    }
+
+    fn pat_range(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<Pat> {
+        let limits = RangeLimits::parse_obsolete(input)?;
+        let end = input.call(pat_range_bound)?;
+        if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+            return Err(input.error("expected range upper bound"));
+        }
+        Ok(Pat::Range(ExprRange {
+            attrs: Vec::new(),
+            start: Some(Box::new(Expr::Path(ExprPath {
+                attrs: Vec::new(),
+                qself,
+                path,
+            }))),
+            limits,
+            end: end.map(PatRangeBound::into_expr),
+        }))
+    }
+
+    fn pat_range_half_open(input: ParseStream) -> Result<Pat> {
+        let limits: RangeLimits = input.parse()?;
+        let end = input.call(pat_range_bound)?;
+        if end.is_some() {
+            Ok(Pat::Range(ExprRange {
+                attrs: Vec::new(),
+                start: None,
+                limits,
+                end: end.map(PatRangeBound::into_expr),
+            }))
+        } else {
+            match limits {
+                RangeLimits::HalfOpen(dot2_token) => Ok(Pat::Rest(PatRest {
+                    attrs: Vec::new(),
+                    dot2_token,
+                })),
+                RangeLimits::Closed(_) => Err(input.error("expected range upper bound")),
+            }
+        }
+    }
+
+    fn pat_paren_or_tuple(input: ParseStream) -> Result<Pat> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            if content.is_empty() {
+                if elems.is_empty() && !matches!(value, Pat::Rest(_)) {
+                    return Ok(Pat::Paren(PatParen {
+                        attrs: Vec::new(),
+                        paren_token,
+                        pat: Box::new(value),
+                    }));
+                }
+                elems.push_value(value);
+                break;
+            }
+            elems.push_value(value);
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(Pat::Tuple(PatTuple {
+            attrs: Vec::new(),
+            paren_token,
+            elems,
+        }))
+    }
+
+    fn pat_reference(input: ParseStream) -> Result<PatReference> {
+        Ok(PatReference {
+            attrs: Vec::new(),
+            and_token: input.parse()?,
+            mutability: input.parse()?,
+            pat: Box::new(Pat::parse_single(input)?),
+        })
+    }
+
+    fn pat_lit_or_range(input: ParseStream) -> Result<Pat> {
+        let start = input.call(pat_range_bound)?.unwrap();
+        if input.peek(Token![..]) {
+            let limits = RangeLimits::parse_obsolete(input)?;
+            let end = input.call(pat_range_bound)?;
+            if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+                return Err(input.error("expected range upper bound"));
+            }
+            Ok(Pat::Range(ExprRange {
+                attrs: Vec::new(),
+                start: Some(start.into_expr()),
+                limits,
+                end: end.map(PatRangeBound::into_expr),
+            }))
+        } else {
+            Ok(start.into_pat())
+        }
+    }
+
+    // Patterns that can appear on either side of a range pattern.
+    enum PatRangeBound {
+        Const(ExprConst),
+        Lit(ExprLit),
+        Path(ExprPath),
+    }
+
+    impl PatRangeBound {
+        fn into_expr(self) -> Box<Expr> {
+            Box::new(match self {
+                PatRangeBound::Const(pat) => Expr::Const(pat),
+                PatRangeBound::Lit(pat) => Expr::Lit(pat),
+                PatRangeBound::Path(pat) => Expr::Path(pat),
+            })
+        }
+
+        fn into_pat(self) -> Pat {
+            match self {
+                PatRangeBound::Const(pat) => Pat::Const(pat),
+                PatRangeBound::Lit(pat) => Pat::Lit(pat),
+                PatRangeBound::Path(pat) => Pat::Path(pat),
+            }
+        }
+    }
+
+    fn pat_range_bound(input: ParseStream) -> Result<Option<PatRangeBound>> {
+        if input.is_empty()
+            || input.peek(Token![|])
+            || input.peek(Token![=])
+            || input.peek(Token![:]) && !input.peek(Token![::])
+            || input.peek(Token![,])
+            || input.peek(Token![;])
+            || input.peek(Token![if])
+        {
+            return Ok(None);
+        }
+
+        let lookahead = input.lookahead1();
+        let expr = if lookahead.peek(Lit) {
+            PatRangeBound::Lit(input.parse()?)
+        } else if lookahead.peek(Ident)
+            || lookahead.peek(Token![::])
+            || lookahead.peek(Token![<])
+            || lookahead.peek(Token![self])
+            || lookahead.peek(Token![Self])
+            || lookahead.peek(Token![super])
+            || lookahead.peek(Token![crate])
+        {
+            PatRangeBound::Path(input.parse()?)
+        } else if lookahead.peek(Token![const]) {
+            PatRangeBound::Const(input.parse()?)
+        } else {
+            return Err(lookahead.error());
+        };
+
+        Ok(Some(expr))
+    }
+
+    fn pat_slice(input: ParseStream) -> Result<PatSlice> {
+        let content;
+        let bracket_token = bracketed!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            match value {
+                Pat::Range(pat) if pat.start.is_none() || pat.end.is_none() => {
+                    let (start, end) = match pat.limits {
+                        RangeLimits::HalfOpen(dot_dot) => (dot_dot.spans[0], dot_dot.spans[1]),
+                        RangeLimits::Closed(dot_dot_eq) => {
+                            (dot_dot_eq.spans[0], dot_dot_eq.spans[2])
+                        }
+                    };
+                    let msg = "range pattern is not allowed unparenthesized inside slice pattern";
+                    return Err(error::new2(start, end, msg));
+                }
+                _ => {}
+            }
+            elems.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(PatSlice {
+            attrs: Vec::new(),
+            bracket_token,
+            elems,
+        })
+    }
+
+    fn pat_const(input: ParseStream) -> Result<TokenStream> {
+        let begin = input.fork();
+        input.parse::<Token![const]>()?;
+
+        let content;
+        braced!(content in input);
+        content.call(Attribute::parse_inner)?;
+        content.call(Block::parse_within)?;
+
+        Ok(verbatim::between(&begin, input))
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::pat::{
+        FieldPat, Pat, PatIdent, PatOr, PatParen, PatReference, PatRest, PatSlice, PatStruct,
+        PatTuple, PatTupleStruct, PatType, PatWild,
+    };
+    use crate::path;
+    use crate::path::printing::PathStyle;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatIdent {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.by_ref.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((at_token, subpat)) = &self.subpat {
+                at_token.to_tokens(tokens);
+                subpat.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatOr {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.leading_vert.to_tokens(tokens);
+            self.cases.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatParen {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.paren_token.surround(tokens, |tokens| {
+                self.pat.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatReference {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.and_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatRest {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.dot2_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatSlice {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.bracket_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            path::printing::print_qpath(tokens, &self.qself, &self.path, PathStyle::Expr);
+            self.brace_token.surround(tokens, |tokens| {
+                self.fields.to_tokens(tokens);
+                // NOTE: We need a comma before the dot2 token if it is present.
+                if !self.fields.empty_or_trailing() && self.rest.is_some() {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+                self.rest.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatTuple {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+                // If there is only one element, a trailing comma is needed to
+                // distinguish PatTuple from PatParen, unless this is `(..)`
+                // which is a tuple pattern even without comma.
+                if self.elems.len() == 1
+                    && !self.elems.trailing_punct()
+                    && !matches!(self.elems[0], Pat::Rest { .. })
+                {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+            });
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatTupleStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            path::printing::print_qpath(tokens, &self.qself, &self.path, PathStyle::Expr);
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.pat.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatWild {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.underscore_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for FieldPat {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some(colon_token) = &self.colon_token {
+                self.member.to_tokens(tokens);
+                colon_token.to_tokens(tokens);
+            }
+            self.pat.to_tokens(tokens);
+        }
+    }
+}