Rollup merge of rust-lang#73812 - petrochenkov:prettyref, r=varkor

ast_pretty: Pass some token streams and trees by reference

Salvaged from an intermediate version of rust-lang#73345.

Author: Manishearth

src/librustc_ast_pretty/pprust.rs

@@ -9,7 +9,7 @@ use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_ast::attr;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, BinOpToken, DelimToken, Nonterminal, Token, TokenKind};
-use rustc_ast::tokenstream::{self, TokenStream, TokenTree};
+use rustc_ast::tokenstream::{TokenStream, TokenTree};
 use rustc_ast::util::parser::{self, AssocOp, Fixity};
 use rustc_ast::util::{classify, comments};
 use rustc_span::edition::Edition;
@@ -293,7 +293,7 @@ pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
         token::NtIdent(e, is_raw) => IdentPrinter::for_ast_ident(e, is_raw).to_string(),
         token::NtLifetime(e) => e.to_string(),
         token::NtLiteral(ref e) => expr_to_string(e),
-        token::NtTT(ref tree) => tt_to_string(tree.clone()),
+        token::NtTT(ref tree) => tt_to_string(tree),
         token::NtVis(ref e) => vis_to_string(e),
     }
 }
@@ -314,11 +314,11 @@ pub fn expr_to_string(e: &ast::Expr) -> String {
     to_string(|s| s.print_expr(e))
 }
 
-pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
+pub fn tt_to_string(tt: &TokenTree) -> String {
     to_string(|s| s.print_tt(tt, false))
 }
 
-pub fn tts_to_string(tokens: TokenStream) -> String {
+pub fn tts_to_string(tokens: &TokenStream) -> String {
     to_string(|s| s.print_tts(tokens, false))
 }
 
@@ -585,7 +585,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                 false,
                 None,
                 delim.to_token(),
-                tokens.clone(),
+                tokens,
                 true,
                 span,
             ),
@@ -594,7 +594,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                 if let MacArgs::Eq(_, tokens) = &item.args {
                     self.space();
                     self.word_space("=");
-                    self.print_tts(tokens.clone(), true);
+                    self.print_tts(tokens, true);
                 }
             }
         }
@@ -635,9 +635,9 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     /// appropriate macro, transcribe back into the grammar we just parsed from,
     /// and then pretty-print the resulting AST nodes (so, e.g., we print
     /// expression arguments as expressions). It can be done! I think.
-    fn print_tt(&mut self, tt: tokenstream::TokenTree, convert_dollar_crate: bool) {
+    fn print_tt(&mut self, tt: &TokenTree, convert_dollar_crate: bool) {
         match tt {
-            TokenTree::Token(ref token) => {
+            TokenTree::Token(token) => {
                 self.word(token_to_string_ext(&token, convert_dollar_crate));
                 if let token::DocComment(..) = token.kind {
                     self.hardbreak()
@@ -648,7 +648,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                     None,
                     false,
                     None,
-                    delim,
+                    *delim,
                     tts,
                     convert_dollar_crate,
                     dspan.entire(),
@@ -657,14 +657,14 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         }
     }
 
-    fn print_tts(&mut self, tts: tokenstream::TokenStream, convert_dollar_crate: bool) {
-        let mut iter = tts.into_trees().peekable();
+    fn print_tts(&mut self, tts: &TokenStream, convert_dollar_crate: bool) {
+        let mut iter = tts.trees().peekable();
         while let Some(tt) = iter.next() {
-            let show_space =
-                if let Some(next) = iter.peek() { tt_prepend_space(next, &tt) } else { false };
-            self.print_tt(tt, convert_dollar_crate);
-            if show_space {
-                self.space();
+            self.print_tt(&tt, convert_dollar_crate);
+            if let Some(next) = iter.peek() {
+                if tt_prepend_space(next, &tt) {
+                    self.space();
+                }
             }
         }
     }
@@ -675,7 +675,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         has_bang: bool,
         ident: Option<Ident>,
         delim: DelimToken,
-        tts: TokenStream,
+        tts: &TokenStream,
         convert_dollar_crate: bool,
         span: Span,
     ) {
@@ -1253,7 +1253,7 @@ impl<'a> State<'a> {
                     has_bang,
                     Some(item.ident),
                     macro_def.body.delim(),
-                    macro_def.body.inner_tokens(),
+                    &macro_def.body.inner_tokens(),
                     true,
                     item.span,
                 );
@@ -1577,7 +1577,7 @@ impl<'a> State<'a> {
             true,
             None,
             m.args.delim(),
-            m.args.inner_tokens(),
+            &m.args.inner_tokens(),
             true,
             m.span(),
         );

src/librustc_builtin_macros/log_syntax.rs

@@ -7,7 +7,7 @@ pub fn expand_log_syntax<'cx>(
     sp: rustc_span::Span,
     tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'cx> {
-    println!("{}", pprust::tts_to_string(tts));
+    println!("{}", pprust::tts_to_string(&tts));
 
     // any so that `log_syntax` can be invoked as an expression and item.
     base::DummyResult::any_valid(sp)

src/librustc_builtin_macros/source_util.rs

@@ -71,7 +71,7 @@ pub fn expand_stringify(
     tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'static> {
     let sp = cx.with_def_site_ctxt(sp);
-    let s = pprust::tts_to_string(tts);
+    let s = pprust::tts_to_string(&tts);
     base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&s)))
 }
 

src/librustc_expand/mbe/macro_rules.rs

@@ -224,7 +224,7 @@ fn generic_extension<'cx>(
     let sess = cx.parse_sess;
 
     if cx.trace_macros() {
-        let msg = format!("expanding `{}! {{ {} }}`", name, pprust::tts_to_string(arg.clone()));
+        let msg = format!("expanding `{}! {{ {} }}`", name, pprust::tts_to_string(&arg));
         trace_macros_note(&mut cx.expansions, sp, msg);
     }
 
@@ -300,7 +300,7 @@ fn generic_extension<'cx>(
                 }
 
                 if cx.trace_macros() {
-                    let msg = format!("to `{}`", pprust::tts_to_string(tts.clone()));
+                    let msg = format!("to `{}`", pprust::tts_to_string(&tts));
                     trace_macros_note(&mut cx.expansions, sp, msg);
                 }
 

src/librustc_expand/proc_macro_server.rs

@@ -413,7 +413,7 @@ impl server::TokenStream for Rustc<'_> {
         )
     }
     fn to_string(&mut self, stream: &Self::TokenStream) -> String {
-        pprust::tts_to_string(stream.clone())
+        pprust::tts_to_string(stream)
     }
     fn from_token_tree(
         &mut self,