chore: add vendor directory

2 files changed, 951 insertions, 0 deletions

diff --git a/vendor/prettyplease/tests/test.rs b/vendor/prettyplease/tests/test.rs
new file mode 100644
index 00000000..aa6b849f
--- /dev/null
+++ b/vendor/prettyplease/tests/test.rs
@@ -0,0 +1,51 @@
+use indoc::indoc;
+use proc_macro2::{Delimiter, Group, TokenStream};
+use quote::quote;
+
+#[track_caller]
+fn test(tokens: TokenStream, expected: &str) {
+    let syntax_tree: syn::File = syn::parse2(tokens).unwrap();
+    let pretty = prettyplease::unparse(&syntax_tree);
+    assert_eq!(pretty, expected);
+}
+
+#[test]
+fn test_parenthesize_cond() {
+    let s = Group::new(Delimiter::None, quote!(Struct {}));
+    test(
+        quote! {
+            fn main() {
+                if #s == #s {}
+            }
+        },
+        indoc! {"
+            fn main() {
+                if (Struct {}) == (Struct {}) {}
+            }
+        "},
+    );
+}
+
+#[test]
+fn test_parenthesize_match_guard() {
+    let expr_struct = Group::new(Delimiter::None, quote!(Struct {}));
+    let expr_binary = Group::new(Delimiter::None, quote!(true && false));
+    test(
+        quote! {
+            fn main() {
+                match () {
+                    () if let _ = #expr_struct => {}
+                    () if let _ = #expr_binary => {}
+                }
+            }
+        },
+        indoc! {"
+            fn main() {
+                match () {
+                    () if let _ = Struct {} => {}
+                    () if let _ = (true && false) => {}
+                }
+            }
+        "},
+    );
+}
diff --git a/vendor/prettyplease/tests/test_precedence.rs b/vendor/prettyplease/tests/test_precedence.rs
new file mode 100644
index 00000000..f1eec232
--- /dev/null
+++ b/vendor/prettyplease/tests/test_precedence.rs
@@ -0,0 +1,900 @@
+use proc_macro2::{Ident, Span, TokenStream};
+use quote::ToTokens as _;
+use std::mem;
+use std::process::ExitCode;
+use syn::punctuated::Punctuated;
+use syn::visit_mut::{self, VisitMut};
+use syn::{
+    token, AngleBracketedGenericArguments, Arm, BinOp, Block, Expr, ExprArray, ExprAssign,
+    ExprAsync, ExprAwait, ExprBinary, ExprBlock, ExprBreak, ExprCall, ExprCast, ExprClosure,
+    ExprConst, ExprContinue, ExprField, ExprForLoop, ExprIf, ExprIndex, ExprLet, ExprLit, ExprLoop,
+    ExprMacro, ExprMatch, ExprMethodCall, ExprPath, ExprRange, ExprRawAddr, ExprReference,
+    ExprReturn, ExprStruct, ExprTry, ExprTryBlock, ExprUnary, ExprUnsafe, ExprWhile, ExprYield,
+    File, GenericArgument, Generics, Item, ItemConst, Label, Lifetime, LifetimeParam, Lit, LitInt,
+    Macro, MacroDelimiter, Member, Pat, PatWild, Path, PathArguments, PathSegment,
+    PointerMutability, QSelf, RangeLimits, ReturnType, Stmt, StmtMacro, Token, Type, TypeInfer,
+    TypeParam, TypePath, UnOp, Visibility,
+};
+
+struct FlattenParens;
+
+impl VisitMut for FlattenParens {
+    fn visit_expr_mut(&mut self, e: &mut Expr) {
+        while let Expr::Paren(paren) = e {
+            *e = mem::replace(&mut *paren.expr, Expr::PLACEHOLDER);
+        }
+        visit_mut::visit_expr_mut(self, e);
+    }
+}
+
+struct AsIfPrinted;
+
+impl VisitMut for AsIfPrinted {
+    fn visit_generics_mut(&mut self, generics: &mut Generics) {
+        if generics.params.is_empty() {
+            generics.lt_token = None;
+            generics.gt_token = None;
+        }
+        if let Some(where_clause) = &generics.where_clause {
+            if where_clause.predicates.is_empty() {
+                generics.where_clause = None;
+            }
+        }
+        visit_mut::visit_generics_mut(self, generics);
+    }
+
+    fn visit_lifetime_param_mut(&mut self, param: &mut LifetimeParam) {
+        if param.bounds.is_empty() {
+            param.colon_token = None;
+        }
+        visit_mut::visit_lifetime_param_mut(self, param);
+    }
+
+    fn visit_stmt_mut(&mut self, stmt: &mut Stmt) {
+        if let Stmt::Expr(expr, semi) = stmt {
+            if let Expr::Macro(e) = expr {
+                if match e.mac.delimiter {
+                    MacroDelimiter::Brace(_) => true,
+                    MacroDelimiter::Paren(_) | MacroDelimiter::Bracket(_) => semi.is_some(),
+                } {
+                    let expr = match mem::replace(expr, Expr::PLACEHOLDER) {
+                        Expr::Macro(expr) => expr,
+                        _ => unreachable!(),
+                    };
+                    *stmt = Stmt::Macro(StmtMacro {
+                        attrs: expr.attrs,
+                        mac: expr.mac,
+                        semi_token: *semi,
+                    });
+                }
+            }
+        }
+        visit_mut::visit_stmt_mut(self, stmt);
+    }
+
+    fn visit_type_param_mut(&mut self, param: &mut TypeParam) {
+        if param.bounds.is_empty() {
+            param.colon_token = None;
+        }
+        visit_mut::visit_type_param_mut(self, param);
+    }
+}
+
+#[test]
+fn test_permutations() -> ExitCode {
+    fn iter(depth: usize, f: &mut dyn FnMut(Expr)) {
+        let span = Span::call_site();
+
+        // Expr::Path
+        f(Expr::Path(ExprPath {
+            // `x`
+            attrs: Vec::new(),
+            qself: None,
+            path: Path::from(Ident::new("x", span)),
+        }));
+        if false {
+            f(Expr::Path(ExprPath {
+                // `x::<T>`
+                attrs: Vec::new(),
+                qself: None,
+                path: Path {
+                    leading_colon: None,
+                    segments: Punctuated::from_iter([PathSegment {
+                        ident: Ident::new("x", span),
+                        arguments: PathArguments::AngleBracketed(AngleBracketedGenericArguments {
+                            colon2_token: Some(Token![::](span)),
+                            lt_token: Token![<](span),
+                            args: Punctuated::from_iter([GenericArgument::Type(Type::Path(
+                                TypePath {
+                                    qself: None,
+                                    path: Path::from(Ident::new("T", span)),
+                                },
+                            ))]),
+                            gt_token: Token![>](span),
+                        }),
+                    }]),
+                },
+            }));
+            f(Expr::Path(ExprPath {
+                // `<T as Trait>::CONST`
+                attrs: Vec::new(),
+                qself: Some(QSelf {
+                    lt_token: Token![<](span),
+                    ty: Box::new(Type::Path(TypePath {
+                        qself: None,
+                        path: Path::from(Ident::new("T", span)),
+                    })),
+                    position: 1,
+                    as_token: Some(Token![as](span)),
+                    gt_token: Token![>](span),
+                }),
+                path: Path {
+                    leading_colon: None,
+                    segments: Punctuated::from_iter([
+                        PathSegment::from(Ident::new("Trait", span)),
+                        PathSegment::from(Ident::new("CONST", span)),
+                    ]),
+                },
+            }));
+        }
+
+        let depth = match depth.checked_sub(1) {
+            Some(depth) => depth,
+            None => return,
+        };
+
+        // Expr::Assign
+        iter(depth, &mut |expr| {
+            iter(0, &mut |simple| {
+                f(Expr::Assign(ExprAssign {
+                    // `x = $expr`
+                    attrs: Vec::new(),
+                    left: Box::new(simple.clone()),
+                    eq_token: Token![=](span),
+                    right: Box::new(expr.clone()),
+                }));
+                f(Expr::Assign(ExprAssign {
+                    // `$expr = x`
+                    attrs: Vec::new(),
+                    left: Box::new(expr.clone()),
+                    eq_token: Token![=](span),
+                    right: Box::new(simple),
+                }));
+            });
+        });
+
+        // Expr::Binary
+        iter(depth, &mut |expr| {
+            iter(0, &mut |simple| {
+                for op in [
+                    BinOp::Add(Token![+](span)),
+                    //BinOp::Sub(Token![-](span)),
+                    //BinOp::Mul(Token![*](span)),
+                    //BinOp::Div(Token![/](span)),
+                    //BinOp::Rem(Token![%](span)),
+                    //BinOp::And(Token![&&](span)),
+                    //BinOp::Or(Token![||](span)),
+                    //BinOp::BitXor(Token![^](span)),
+                    //BinOp::BitAnd(Token![&](span)),
+                    //BinOp::BitOr(Token![|](span)),
+                    //BinOp::Shl(Token![<<](span)),
+                    //BinOp::Shr(Token![>>](span)),
+                    //BinOp::Eq(Token![==](span)),
+                    BinOp::Lt(Token![<](span)),
+                    //BinOp::Le(Token![<=](span)),
+                    //BinOp::Ne(Token![!=](span)),
+                    //BinOp::Ge(Token![>=](span)),
+                    //BinOp::Gt(Token![>](span)),
+                    BinOp::ShlAssign(Token![<<=](span)),
+                ] {
+                    f(Expr::Binary(ExprBinary {
+                        // `x + $expr`
+                        attrs: Vec::new(),
+                        left: Box::new(simple.clone()),
+                        op,
+                        right: Box::new(expr.clone()),
+                    }));
+                    f(Expr::Binary(ExprBinary {
+                        // `$expr + x`
+                        attrs: Vec::new(),
+                        left: Box::new(expr.clone()),
+                        op,
+                        right: Box::new(simple.clone()),
+                    }));
+                }
+            });
+        });
+
+        // Expr::Block
+        f(Expr::Block(ExprBlock {
+            // `{}`
+            attrs: Vec::new(),
+            label: None,
+            block: Block {
+                brace_token: token::Brace(span),
+                stmts: Vec::new(),
+            },
+        }));
+
+        // Expr::Break
+        f(Expr::Break(ExprBreak {
+            // `break`
+            attrs: Vec::new(),
+            break_token: Token![break](span),
+            label: None,
+            expr: None,
+        }));
+        iter(depth, &mut |expr| {
+            f(Expr::Break(ExprBreak {
+                // `break $expr`
+                attrs: Vec::new(),
+                break_token: Token![break](span),
+                label: None,
+                expr: Some(Box::new(expr)),
+            }));
+        });
+
+        // Expr::Call
+        iter(depth, &mut |expr| {
+            f(Expr::Call(ExprCall {
+                // `$expr()`
+                attrs: Vec::new(),
+                func: Box::new(expr),
+                paren_token: token::Paren(span),
+                args: Punctuated::new(),
+            }));
+        });
+
+        // Expr::Cast
+        iter(depth, &mut |expr| {
+            f(Expr::Cast(ExprCast {
+                // `$expr as T`
+                attrs: Vec::new(),
+                expr: Box::new(expr),
+                as_token: Token![as](span),
+                ty: Box::new(Type::Path(TypePath {
+                    qself: None,
+                    path: Path::from(Ident::new("T", span)),
+                })),
+            }));
+        });
+
+        // Expr::Closure
+        iter(depth, &mut |expr| {
+            f(Expr::Closure(ExprClosure {
+                // `|| $expr`
+                attrs: Vec::new(),
+                lifetimes: None,
+                constness: None,
+                movability: None,
+                asyncness: None,
+                capture: None,
+                or1_token: Token![|](span),
+                inputs: Punctuated::new(),
+                or2_token: Token![|](span),
+                output: ReturnType::Default,
+                body: Box::new(expr),
+            }));
+        });
+
+        // Expr::Field
+        iter(depth, &mut |expr| {
+            f(Expr::Field(ExprField {
+                // `$expr.field`
+                attrs: Vec::new(),
+                base: Box::new(expr),
+                dot_token: Token![.](span),
+                member: Member::Named(Ident::new("field", span)),
+            }));
+        });
+
+        // Expr::If
+        iter(depth, &mut |expr| {
+            f(Expr::If(ExprIf {
+                // `if $expr {}`
+                attrs: Vec::new(),
+                if_token: Token![if](span),
+                cond: Box::new(expr),
+                then_branch: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+                else_branch: None,
+            }));
+        });
+
+        // Expr::Let
+        iter(depth, &mut |expr| {
+            f(Expr::Let(ExprLet {
+                attrs: Vec::new(),
+                let_token: Token![let](span),
+                pat: Box::new(Pat::Wild(PatWild {
+                    attrs: Vec::new(),
+                    underscore_token: Token![_](span),
+                })),
+                eq_token: Token![=](span),
+                expr: Box::new(expr),
+            }));
+        });
+
+        // Expr::Range
+        f(Expr::Range(ExprRange {
+            // `..`
+            attrs: Vec::new(),
+            start: None,
+            limits: RangeLimits::HalfOpen(Token![..](span)),
+            end: None,
+        }));
+        iter(depth, &mut |expr| {
+            f(Expr::Range(ExprRange {
+                // `..$expr`
+                attrs: Vec::new(),
+                start: None,
+                limits: RangeLimits::HalfOpen(Token![..](span)),
+                end: Some(Box::new(expr.clone())),
+            }));
+            f(Expr::Range(ExprRange {
+                // `$expr..`
+                attrs: Vec::new(),
+                start: Some(Box::new(expr)),
+                limits: RangeLimits::HalfOpen(Token![..](span)),
+                end: None,
+            }));
+        });
+
+        // Expr::Reference
+        iter(depth, &mut |expr| {
+            f(Expr::Reference(ExprReference {
+                // `&$expr`
+                attrs: Vec::new(),
+                and_token: Token![&](span),
+                mutability: None,
+                expr: Box::new(expr),
+            }));
+        });
+
+        // Expr::Return
+        f(Expr::Return(ExprReturn {
+            // `return`
+            attrs: Vec::new(),
+            return_token: Token![return](span),
+            expr: None,
+        }));
+        iter(depth, &mut |expr| {
+            f(Expr::Return(ExprReturn {
+                // `return $expr`
+                attrs: Vec::new(),
+                return_token: Token![return](span),
+                expr: Some(Box::new(expr)),
+            }));
+        });
+
+        // Expr::Try
+        iter(depth, &mut |expr| {
+            f(Expr::Try(ExprTry {
+                // `$expr?`
+                attrs: Vec::new(),
+                expr: Box::new(expr),
+                question_token: Token![?](span),
+            }));
+        });
+
+        // Expr::Unary
+        iter(depth, &mut |expr| {
+            for op in [
+                UnOp::Deref(Token![*](span)),
+                //UnOp::Not(Token![!](span)),
+                //UnOp::Neg(Token![-](span)),
+            ] {
+                f(Expr::Unary(ExprUnary {
+                    // `*$expr`
+                    attrs: Vec::new(),
+                    op,
+                    expr: Box::new(expr.clone()),
+                }));
+            }
+        });
+
+        if false {
+            // Expr::Array
+            f(Expr::Array(ExprArray {
+                // `[]`
+                attrs: Vec::new(),
+                bracket_token: token::Bracket(span),
+                elems: Punctuated::new(),
+            }));
+
+            // Expr::Async
+            f(Expr::Async(ExprAsync {
+                // `async {}`
+                attrs: Vec::new(),
+                async_token: Token![async](span),
+                capture: None,
+                block: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+
+            // Expr::Await
+            iter(depth, &mut |expr| {
+                f(Expr::Await(ExprAwait {
+                    // `$expr.await`
+                    attrs: Vec::new(),
+                    base: Box::new(expr),
+                    dot_token: Token![.](span),
+                    await_token: Token![await](span),
+                }));
+            });
+
+            // Expr::Block
+            f(Expr::Block(ExprBlock {
+                // `'a: {}`
+                attrs: Vec::new(),
+                label: Some(Label {
+                    name: Lifetime::new("'a", span),
+                    colon_token: Token![:](span),
+                }),
+                block: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+            iter(depth, &mut |expr| {
+                f(Expr::Block(ExprBlock {
+                    // `{ $expr }`
+                    attrs: Vec::new(),
+                    label: None,
+                    block: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::from([Stmt::Expr(expr.clone(), None)]),
+                    },
+                }));
+                f(Expr::Block(ExprBlock {
+                    // `{ $expr; }`
+                    attrs: Vec::new(),
+                    label: None,
+                    block: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::from([Stmt::Expr(expr, Some(Token![;](span)))]),
+                    },
+                }));
+            });
+
+            // Expr::Break
+            f(Expr::Break(ExprBreak {
+                // `break 'a`
+                attrs: Vec::new(),
+                break_token: Token![break](span),
+                label: Some(Lifetime::new("'a", span)),
+                expr: None,
+            }));
+            iter(depth, &mut |expr| {
+                f(Expr::Break(ExprBreak {
+                    // `break 'a $expr`
+                    attrs: Vec::new(),
+                    break_token: Token![break](span),
+                    label: Some(Lifetime::new("'a", span)),
+                    expr: Some(Box::new(expr)),
+                }));
+            });
+
+            // Expr::Closure
+            f(Expr::Closure(ExprClosure {
+                // `|| -> T {}`
+                attrs: Vec::new(),
+                lifetimes: None,
+                constness: None,
+                movability: None,
+                asyncness: None,
+                capture: None,
+                or1_token: Token![|](span),
+                inputs: Punctuated::new(),
+                or2_token: Token![|](span),
+                output: ReturnType::Type(
+                    Token![->](span),
+                    Box::new(Type::Path(TypePath {
+                        qself: None,
+                        path: Path::from(Ident::new("T", span)),
+                    })),
+                ),
+                body: Box::new(Expr::Block(ExprBlock {
+                    attrs: Vec::new(),
+                    label: None,
+                    block: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::new(),
+                    },
+                })),
+            }));
+
+            // Expr::Const
+            f(Expr::Const(ExprConst {
+                // `const {}`
+                attrs: Vec::new(),
+                const_token: Token![const](span),
+                block: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+
+            // Expr::Continue
+            f(Expr::Continue(ExprContinue {
+                // `continue`
+                attrs: Vec::new(),
+                continue_token: Token![continue](span),
+                label: None,
+            }));
+            f(Expr::Continue(ExprContinue {
+                // `continue 'a`
+                attrs: Vec::new(),
+                continue_token: Token![continue](span),
+                label: Some(Lifetime::new("'a", span)),
+            }));
+
+            // Expr::ForLoop
+            iter(depth, &mut |expr| {
+                f(Expr::ForLoop(ExprForLoop {
+                    // `for _ in $expr {}`
+                    attrs: Vec::new(),
+                    label: None,
+                    for_token: Token![for](span),
+                    pat: Box::new(Pat::Wild(PatWild {
+                        attrs: Vec::new(),
+                        underscore_token: Token![_](span),
+                    })),
+                    in_token: Token![in](span),
+                    expr: Box::new(expr.clone()),
+                    body: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::new(),
+                    },
+                }));
+                f(Expr::ForLoop(ExprForLoop {
+                    // `'a: for _ in $expr {}`
+                    attrs: Vec::new(),
+                    label: Some(Label {
+                        name: Lifetime::new("'a", span),
+                        colon_token: Token![:](span),
+                    }),
+                    for_token: Token![for](span),
+                    pat: Box::new(Pat::Wild(PatWild {
+                        attrs: Vec::new(),
+                        underscore_token: Token![_](span),
+                    })),
+                    in_token: Token![in](span),
+                    expr: Box::new(expr),
+                    body: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::new(),
+                    },
+                }));
+            });
+
+            // Expr::Index
+            iter(depth, &mut |expr| {
+                f(Expr::Index(ExprIndex {
+                    // `$expr[0]`
+                    attrs: Vec::new(),
+                    expr: Box::new(expr),
+                    bracket_token: token::Bracket(span),
+                    index: Box::new(Expr::Lit(ExprLit {
+                        attrs: Vec::new(),
+                        lit: Lit::Int(LitInt::new("0", span)),
+                    })),
+                }));
+            });
+
+            // Expr::Loop
+            f(Expr::Loop(ExprLoop {
+                // `loop {}`
+                attrs: Vec::new(),
+                label: None,
+                loop_token: Token![loop](span),
+                body: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+            f(Expr::Loop(ExprLoop {
+                // `'a: loop {}`
+                attrs: Vec::new(),
+                label: Some(Label {
+                    name: Lifetime::new("'a", span),
+                    colon_token: Token![:](span),
+                }),
+                loop_token: Token![loop](span),
+                body: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+
+            // Expr::Macro
+            f(Expr::Macro(ExprMacro {
+                // `m!()`
+                attrs: Vec::new(),
+                mac: Macro {
+                    path: Path::from(Ident::new("m", span)),
+                    bang_token: Token![!](span),
+                    delimiter: MacroDelimiter::Paren(token::Paren(span)),
+                    tokens: TokenStream::new(),
+                },
+            }));
+            f(Expr::Macro(ExprMacro {
+                // `m! {}`
+                attrs: Vec::new(),
+                mac: Macro {
+                    path: Path::from(Ident::new("m", span)),
+                    bang_token: Token![!](span),
+                    delimiter: MacroDelimiter::Brace(token::Brace(span)),
+                    tokens: TokenStream::new(),
+                },
+            }));
+
+            // Expr::Match
+            iter(depth, &mut |expr| {
+                f(Expr::Match(ExprMatch {
+                    // `match $expr {}`
+                    attrs: Vec::new(),
+                    match_token: Token![match](span),
+                    expr: Box::new(expr.clone()),
+                    brace_token: token::Brace(span),
+                    arms: Vec::new(),
+                }));
+                f(Expr::Match(ExprMatch {
+                    // `match x { _ => $expr }`
+                    attrs: Vec::new(),
+                    match_token: Token![match](span),
+                    expr: Box::new(Expr::Path(ExprPath {
+                        attrs: Vec::new(),
+                        qself: None,
+                        path: Path::from(Ident::new("x", span)),
+                    })),
+                    brace_token: token::Brace(span),
+                    arms: Vec::from([Arm {
+                        attrs: Vec::new(),
+                        pat: Pat::Wild(PatWild {
+                            attrs: Vec::new(),
+                            underscore_token: Token![_](span),
+                        }),
+                        guard: None,
+                        fat_arrow_token: Token![=>](span),
+                        body: Box::new(expr.clone()),
+                        comma: None,
+                    }]),
+                }));
+                f(Expr::Match(ExprMatch {
+                    // `match x { _ if $expr => {} }`
+                    attrs: Vec::new(),
+                    match_token: Token![match](span),
+                    expr: Box::new(Expr::Path(ExprPath {
+                        attrs: Vec::new(),
+                        qself: None,
+                        path: Path::from(Ident::new("x", span)),
+                    })),
+                    brace_token: token::Brace(span),
+                    arms: Vec::from([Arm {
+                        attrs: Vec::new(),
+                        pat: Pat::Wild(PatWild {
+                            attrs: Vec::new(),
+                            underscore_token: Token![_](span),
+                        }),
+                        guard: Some((Token![if](span), Box::new(expr))),
+                        fat_arrow_token: Token![=>](span),
+                        body: Box::new(Expr::Block(ExprBlock {
+                            attrs: Vec::new(),
+                            label: None,
+                            block: Block {
+                                brace_token: token::Brace(span),
+                                stmts: Vec::new(),
+                            },
+                        })),
+                        comma: None,
+                    }]),
+                }));
+            });
+
+            // Expr::MethodCall
+            iter(depth, &mut |expr| {
+                f(Expr::MethodCall(ExprMethodCall {
+                    // `$expr.method()`
+                    attrs: Vec::new(),
+                    receiver: Box::new(expr.clone()),
+                    dot_token: Token![.](span),
+                    method: Ident::new("method", span),
+                    turbofish: None,
+                    paren_token: token::Paren(span),
+                    args: Punctuated::new(),
+                }));
+                f(Expr::MethodCall(ExprMethodCall {
+                    // `$expr.method::<T>()`
+                    attrs: Vec::new(),
+                    receiver: Box::new(expr),
+                    dot_token: Token![.](span),
+                    method: Ident::new("method", span),
+                    turbofish: Some(AngleBracketedGenericArguments {
+                        colon2_token: Some(Token![::](span)),
+                        lt_token: Token![<](span),
+                        args: Punctuated::from_iter([GenericArgument::Type(Type::Path(
+                            TypePath {
+                                qself: None,
+                                path: Path::from(Ident::new("T", span)),
+                            },
+                        ))]),
+                        gt_token: Token![>](span),
+                    }),
+                    paren_token: token::Paren(span),
+                    args: Punctuated::new(),
+                }));
+            });
+
+            // Expr::RawAddr
+            iter(depth, &mut |expr| {
+                f(Expr::RawAddr(ExprRawAddr {
+                    // `&raw const $expr`
+                    attrs: Vec::new(),
+                    and_token: Token![&](span),
+                    raw: Token![raw](span),
+                    mutability: PointerMutability::Const(Token![const](span)),
+                    expr: Box::new(expr),
+                }));
+            });
+
+            // Expr::Struct
+            f(Expr::Struct(ExprStruct {
+                // `Struct {}`
+                attrs: Vec::new(),
+                qself: None,
+                path: Path::from(Ident::new("Struct", span)),
+                brace_token: token::Brace(span),
+                fields: Punctuated::new(),
+                dot2_token: None,
+                rest: None,
+            }));
+
+            // Expr::TryBlock
+            f(Expr::TryBlock(ExprTryBlock {
+                // `try {}`
+                attrs: Vec::new(),
+                try_token: Token![try](span),
+                block: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+
+            // Expr::Unsafe
+            f(Expr::Unsafe(ExprUnsafe {
+                // `unsafe {}`
+                attrs: Vec::new(),
+                unsafe_token: Token![unsafe](span),
+                block: Block {
+                    brace_token: token::Brace(span),
+                    stmts: Vec::new(),
+                },
+            }));
+
+            // Expr::While
+            iter(depth, &mut |expr| {
+                f(Expr::While(ExprWhile {
+                    // `while $expr {}`
+                    attrs: Vec::new(),
+                    label: None,
+                    while_token: Token![while](span),
+                    cond: Box::new(expr.clone()),
+                    body: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::new(),
+                    },
+                }));
+                f(Expr::While(ExprWhile {
+                    // `'a: while $expr {}`
+                    attrs: Vec::new(),
+                    label: Some(Label {
+                        name: Lifetime::new("'a", span),
+                        colon_token: Token![:](span),
+                    }),
+                    while_token: Token![while](span),
+                    cond: Box::new(expr),
+                    body: Block {
+                        brace_token: token::Brace(span),
+                        stmts: Vec::new(),
+                    },
+                }));
+            });
+
+            // Expr::Yield
+            f(Expr::Yield(ExprYield {
+                // `yield`
+                attrs: Vec::new(),
+                yield_token: Token![yield](span),
+                expr: None,
+            }));
+            iter(depth, &mut |expr| {
+                f(Expr::Yield(ExprYield {
+                    // `yield $expr`
+                    attrs: Vec::new(),
+                    yield_token: Token![yield](span),
+                    expr: Some(Box::new(expr)),
+                }));
+            });
+        }
+    }
+
+    let mut failures = 0;
+    macro_rules! fail {
+        ($($message:tt)*) => {{
+            eprintln!($($message)*);
+            failures += 1;
+            return;
+        }};
+    }
+    let mut assert = |mut original: Expr| {
+        let span = Span::call_site();
+        // `const _: () = $expr;`
+        let pretty = prettyplease::unparse(&File {
+            shebang: None,
+            attrs: Vec::new(),
+            items: Vec::from([Item::Const(ItemConst {
+                attrs: Vec::new(),
+                vis: Visibility::Inherited,
+                const_token: Token![const](span),
+                ident: Ident::from(Token![_](span)),
+                generics: Generics::default(),
+                colon_token: Token![:](span),
+                ty: Box::new(Type::Infer(TypeInfer {
+                    underscore_token: Token![_](span),
+                })),
+                eq_token: Token![=](span),
+                expr: Box::new(original.clone()),
+                semi_token: Token![;](span),
+            })]),
+        });
+        let mut parsed = match syn::parse_file(&pretty) {
+            Ok(parsed) => parsed,
+            _ => fail!("failed to parse: {pretty}{original:#?}"),
+        };
+        let item = match parsed.items.as_mut_slice() {
+            [Item::Const(item)] => item,
+            _ => unreachable!(),
+        };
+        let mut parsed = mem::replace(&mut *item.expr, Expr::PLACEHOLDER);
+        AsIfPrinted.visit_expr_mut(&mut original);
+        FlattenParens.visit_expr_mut(&mut parsed);
+        if original != parsed {
+            fail!(
+                "before: {}\n{:#?}\nafter: {}\n{:#?}",
+                original.to_token_stream(),
+                original,
+                parsed.to_token_stream(),
+                parsed,
+            );
+        }
+        if pretty.contains("(||") {
+            // https://github.com/dtolnay/prettyplease/issues/99
+            return;
+        }
+        let no_paren = pretty.replace(['(', ')'], "");
+        if pretty != no_paren {
+            if let Ok(mut parsed2) = syn::parse_file(&no_paren) {
+                let item = match parsed2.items.as_mut_slice() {
+                    [Item::Const(item)] => item,
+                    _ => unreachable!(),
+                };
+                if original == *item.expr {
+                    fail!("redundant parens: {}", pretty);
+                }
+            }
+        }
+    };
+
+    iter(if cfg!(debug_assertions) { 3 } else { 4 }, &mut assert);
+    if failures > 0 {
+        eprintln!("FAILURES: {failures}");
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
+    }
+}