Rollup merge of rust-lang#119169 - fmease:pretty-yeet-syntactic-cruft, r=compiler-errors

Rid the AST & HIR pretty printer of cruft

Found while working on rust-lang#119163.

For `trait Trait: ?Sized {}` (semantically malformed), we currently output `trait Trait for ? Sized {}` (sic!) / `trait Trait for ? Sized { }` (sic!) if `-Zunpretty=expanded` / `-Zunpretty=hir` is passed.

`trait Tr for Sized? {}` (rust-lang#15521) and later also `trait Tr for ?Sized {}` (I guess, rust-lang#20194) is former Rust syntax. Hence I'm removing these outdated branches.

~~This will conflict with rust-lang#119163, therefore marking this PR as blocked.~~ Rebased

Author: matthiaskrgr

compiler/rustc_ast_pretty/src/pprust/state/item.rs

@@ -5,7 +5,6 @@ use crate::pprust::state::{AnnNode, PrintState, State, INDENT_UNIT};
 use ast::StaticItem;
 use itertools::{Itertools, Position};
 use rustc_ast as ast;
-use rustc_ast::GenericBound;
 use rustc_ast::ModKind;
 use rustc_span::symbol::Ident;
 
@@ -338,21 +337,9 @@ impl<'a> State<'a> {
                 self.word_nbsp("trait");
                 self.print_ident(item.ident);
                 self.print_generic_params(&generics.params);
-                let mut real_bounds = Vec::with_capacity(bounds.len());
-                for bound in bounds.iter() {
-                    if let GenericBound::Trait(ptr, modifiers) = bound
-                        && let ast::BoundPolarity::Maybe(_) = modifiers.polarity
-                    {
-                        self.space();
-                        self.word_space("for ?");
-                        self.print_trait_ref(&ptr.trait_ref);
-                    } else {
-                        real_bounds.push(bound.clone());
-                    }
-                }
-                if !real_bounds.is_empty() {
+                if !bounds.is_empty() {
                     self.word_nbsp(":");
-                    self.print_type_bounds(&real_bounds);
+                    self.print_type_bounds(bounds);
                 }
                 self.print_where_clause(&generics.where_clause);
                 self.word(" ");

compiler/rustc_hir_pretty/src/lib.rs

@@ -553,17 +553,7 @@ impl<'a> State<'a> {
             }
             hir::ItemKind::OpaqueTy(opaque_ty) => {
                 self.print_item_type(item, opaque_ty.generics, |state| {
-                    let mut real_bounds = Vec::with_capacity(opaque_ty.bounds.len());
-                    for b in opaque_ty.bounds {
-                        if let GenericBound::Trait(ptr, hir::TraitBoundModifier::Maybe) = b {
-                            state.space();
-                            state.word_space("for ?");
-                            state.print_trait_ref(&ptr.trait_ref);
-                        } else {
-                            real_bounds.push(b);
-                        }
-                    }
-                    state.print_bounds("= impl", real_bounds);
+                    state.print_bounds("= impl", opaque_ty.bounds)
                 });
             }
             hir::ItemKind::Enum(ref enum_definition, params) => {
@@ -625,17 +615,7 @@ impl<'a> State<'a> {
                 self.word_nbsp("trait");
                 self.print_ident(item.ident);
                 self.print_generic_params(generics.params);
-                let mut real_bounds = Vec::with_capacity(bounds.len());
-                for b in bounds {
-                    if let GenericBound::Trait(ptr, hir::TraitBoundModifier::Maybe) = b {
-                        self.space();
-                        self.word_space("for ?");
-                        self.print_trait_ref(&ptr.trait_ref);
-                    } else {
-                        real_bounds.push(b);
-                    }
-                }
-                self.print_bounds(":", real_bounds);
+                self.print_bounds(":", bounds);
                 self.print_where_clause(generics);
                 self.word(" ");
                 self.bopen();