Replace pretty-printer Box<dyn Write> with &mut Vec<u8>

Author: Mark-Simulacrum

src/librustc/hir/print.rs

@@ -17,7 +17,7 @@ use crate::hir::{GenericParam, GenericParamKind, GenericArg};
 
 use std::borrow::Cow;
 use std::cell::Cell;
-use std::io::{self, Write, Read};
+use std::io::{self, Read};
 use std::vec;
 
 pub enum AnnNode<'a> {
@@ -112,7 +112,7 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
                        krate: &hir::Crate,
                        filename: FileName,
                        input: &mut dyn Read,
-                       out: Box<dyn Write + 'a>,
+                       out: &'a mut Vec<u8>,
                        ann: &'a dyn PpAnn)
                        -> io::Result<()> {
     let mut s = State::new_from_input(cm, sess, filename, input, out, ann);
@@ -130,15 +130,15 @@ impl<'a> State<'a> {
                           sess: &ParseSess,
                           filename: FileName,
                           input: &mut dyn Read,
-                          out: Box<dyn Write + 'a>,
+                          out: &'a mut Vec<u8>,
                           ann: &'a dyn PpAnn)
                           -> State<'a> {
         let comments = comments::gather_comments(sess, filename, input);
         State::new(cm, out, ann, Some(comments))
     }
 
     pub fn new(cm: &'a SourceMap,
-               out: Box<dyn Write + 'a>,
+               out: &'a mut Vec<u8>,
                ann: &'a dyn PpAnn,
                comments: Option<Vec<comments::Comment>>)
                -> State<'a> {
@@ -159,7 +159,7 @@ pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
     let mut wr = Vec::new();
     {
         let mut printer = State {
-            s: pp::mk_printer(Box::new(&mut wr), default_columns),
+            s: pp::mk_printer(&mut wr, default_columns),
             cm: None,
             comments: None,
             cur_cmnt: 0,

src/librustc_driver/pretty.rs

@@ -733,7 +733,7 @@ pub fn print_after_parsing(sess: &Session,
 
     if let PpmSource(s) = ppm {
         // Silently ignores an identified node.
-        let out: &mut dyn Write = &mut out;
+        let out = &mut out;
         s.call_with_pp_support(sess, None, move |annotation| {
             debug!("pretty printing source code {:?}", s);
             let sess = annotation.sess();
@@ -742,7 +742,7 @@ pub fn print_after_parsing(sess: &Session,
                                 krate,
                                 src_name,
                                 &mut rdr,
-                                box out,
+                                out,
                                 annotation.pp_ann(),
                                 false)
         }).unwrap()
@@ -779,7 +779,7 @@ pub fn print_after_hir_lowering<'tcx>(
     match (ppm, opt_uii) {
             (PpmSource(s), _) => {
                 // Silently ignores an identified node.
-                let out: &mut dyn Write = &mut out;
+                let out = &mut out;
                 s.call_with_pp_support(tcx.sess, Some(tcx), move |annotation| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -788,14 +788,14 @@ pub fn print_after_hir_lowering<'tcx>(
                                         krate,
                                         src_name,
                                         &mut rdr,
-                                        box out,
+                                        out,
                                         annotation.pp_ann(),
                                         true)
                 })
             }
 
             (PpmHir(s), None) => {
-                let out: &mut dyn Write = &mut out;
+                let out = &mut out;
                 s.call_with_pp_support_hir(tcx, move |annotation, krate| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -804,21 +804,21 @@ pub fn print_after_hir_lowering<'tcx>(
                                             krate,
                                             src_name,
                                             &mut rdr,
-                                            box out,
+                                            out,
                                             annotation.pp_ann())
                 })
             }
 
             (PpmHirTree(s), None) => {
-                let out: &mut dyn Write = &mut out;
+                let out = &mut out;
                 s.call_with_pp_support_hir(tcx, move |_annotation, krate| {
                     debug!("pretty printing source code {:?}", s);
                     write!(out, "{:#?}", krate)
                 })
             }
 
             (PpmHir(s), Some(uii)) => {
-                let out: &mut dyn Write = &mut out;
+                let out = &mut out;
                 s.call_with_pp_support_hir(tcx, move |annotation, _| {
                     debug!("pretty printing source code {:?}", s);
                     let sess = annotation.sess();
@@ -827,7 +827,7 @@ pub fn print_after_hir_lowering<'tcx>(
                                                                          &sess.parse_sess,
                                                                          src_name,
                                                                          &mut rdr,
-                                                                         box out,
+                                                                         out,
                                                                          annotation.pp_ann());
                     for node_id in uii.all_matching_node_ids(hir_map) {
                         let hir_id = tcx.hir().node_to_hir_id(node_id);

src/libsyntax/print/pp.rs

@@ -136,7 +136,7 @@
 
 use std::collections::VecDeque;
 use std::fmt;
-use std::io;
+use std::io::{self, Write};
 use std::borrow::Cow;
 use log::debug;
 
@@ -236,7 +236,7 @@ crate struct PrintStackElem {
 
 const SIZE_INFINITY: isize = 0xffff;
 
-pub fn mk_printer<'a>(out: Box<dyn io::Write+'a>, linewidth: usize) -> Printer<'a> {
+pub fn mk_printer(out: &mut Vec<u8>, linewidth: usize) -> Printer<'_> {
     // Yes 55, it makes the ring buffers big enough to never fall behind.
     let n: usize = 55 * linewidth;
     debug!("mk_printer {}", linewidth);
@@ -259,7 +259,7 @@ pub fn mk_printer<'a>(out: Box<dyn io::Write+'a>, linewidth: usize) -> Printer<'
 }
 
 pub struct Printer<'a> {
-    out: Box<dyn io::Write+'a>,
+    out: &'a mut Vec<u8>,
     buf_max_len: usize,
     /// Width of lines we're constrained to
     margin: isize,

src/libsyntax/print/pprust.rs

@@ -21,7 +21,7 @@ use syntax_pos::{self, BytePos};
 use syntax_pos::{DUMMY_SP, FileName};
 
 use std::borrow::Cow;
-use std::io::{self, Write, Read};
+use std::io::{self, Read};
 use std::vec;
 
 pub enum AnnNode<'a> {
@@ -54,7 +54,7 @@ pub struct State<'a> {
     is_expanded: bool
 }
 
-fn rust_printer<'a>(writer: Box<dyn Write+'a>, ann: &'a dyn PpAnn) -> State<'a> {
+fn rust_printer<'a>(writer: &'a mut Vec<u8>, ann: &'a dyn PpAnn) -> State<'a> {
     State {
         s: pp::mk_printer(writer, DEFAULT_COLUMNS),
         cm: None,
@@ -77,7 +77,7 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
                        krate: &ast::Crate,
                        filename: FileName,
                        input: &mut dyn Read,
-                       out: Box<dyn Write+'a>,
+                       out: &mut Vec<u8>,
                        ann: &'a dyn PpAnn,
                        is_expanded: bool) -> io::Result<()> {
     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
@@ -111,15 +111,15 @@ impl<'a> State<'a> {
                           sess: &ParseSess,
                           filename: FileName,
                           input: &mut dyn Read,
-                          out: Box<dyn Write+'a>,
+                          out: &'a mut Vec<u8>,
                           ann: &'a dyn PpAnn,
                           is_expanded: bool) -> State<'a> {
         let comments = comments::gather_comments(sess, filename, input);
         State::new(cm, out, ann, Some(comments), is_expanded)
     }
 
     pub fn new(cm: &'a SourceMap,
-               out: Box<dyn Write+'a>,
+               out: &'a mut Vec<u8>,
                ann: &'a dyn PpAnn,
                comments: Option<Vec<comments::Comment>>,
                is_expanded: bool) -> State<'a> {
@@ -141,7 +141,7 @@ pub fn to_string<F>(f: F) -> String where
     let mut wr = Vec::new();
     {
         let ann = NoAnn;
-        let mut printer = rust_printer(Box::new(&mut wr), &ann);
+        let mut printer = rust_printer(&mut wr, &ann);
         f(&mut printer).unwrap();
         printer.s.eof().unwrap();
     }