]> git.lizzy.rs Git - rust.git/blobdiff - src/visitor.rs
fix: maintain redundant semis on items in statement pos
[rust.git] / src / visitor.rs
index 3bd5af3112de3dda6a86975d2fd7f078c1ceeade..15055d46d30a5cce90156205e0f0623183fd26d1 100644 (file)
@@ -1,71 +1,92 @@
-use std::cell::RefCell;
+use std::cell::{Cell, RefCell};
+use std::rc::Rc;
 
-use syntax::parse::ParseSess;
-use syntax::source_map::{self, BytePos, Pos, SourceMap, Span};
-use syntax::{ast, visit};
+use rustc_ast::{ast, attr::HasAttrs, token::DelimToken, visit};
+use rustc_span::{symbol, BytePos, Pos, Span, DUMMY_SP};
 
 use crate::attr::*;
-use crate::comment::{CodeCharKind, CommentCodeSlices, FindUncommented};
-use crate::config::{BraceStyle, Config, Version};
-use crate::expr::{format_expr, ExprType};
+use crate::comment::{contains_comment, rewrite_comment, CodeCharKind, CommentCodeSlices};
+use crate::config::Version;
+use crate::config::{BraceStyle, Config};
+use crate::coverage::transform_missing_snippet;
 use crate::items::{
     format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item,
-    rewrite_associated_impl_type, rewrite_associated_type, rewrite_existential_impl_type,
-    rewrite_existential_type, rewrite_extern_crate, rewrite_type_alias, FnSig, StaticParts,
-    StructParts,
+    rewrite_associated_impl_type, rewrite_extern_crate, rewrite_opaque_impl_type,
+    rewrite_opaque_type, rewrite_type_alias, FnBraceStyle, FnSig, StaticParts, StructParts,
 };
-use crate::macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
+use crate::macros::{macro_style, rewrite_macro, rewrite_macro_def, MacroPosition};
+use crate::modules::Module;
 use crate::rewrite::{Rewrite, RewriteContext};
 use crate::shape::{Indent, Shape};
+use crate::skip::{is_skip_attr, SkipContext};
 use crate::source_map::{LineRangeUtils, SpanUtils};
 use crate::spanned::Spanned;
+use crate::stmt::Stmt;
+use crate::syntux::session::ParseSess;
 use crate::utils::{
-    self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec,
-    rewrite_ident, stmt_expr, DEPR_SKIP_ANNOTATION,
+    self, contains_skip, count_newlines, depr_skip_annotation, format_unsafety, inner_attributes,
+    last_line_width, mk_sp, ptr_vec_to_ref_vec, rewrite_ident, starts_with_newline, stmt_expr,
 };
 use crate::{ErrorKind, FormatReport, FormattingError};
 
 /// Creates a string slice corresponding to the specified span.
-pub struct SnippetProvider<'a> {
+pub(crate) struct SnippetProvider {
     /// A pointer to the content of the file we are formatting.
-    big_snippet: &'a str,
+    big_snippet: Rc<String>,
     /// A position of the start of `big_snippet`, used as an offset.
     start_pos: usize,
+    /// A end position of the file that this snippet lives.
+    end_pos: usize,
 }
 
-impl<'a> SnippetProvider<'a> {
-    pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
+impl SnippetProvider {
+    pub(crate) fn span_to_snippet(&self, span: Span) -> Option<&str> {
         let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
         let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
         Some(&self.big_snippet[start_index..end_index])
     }
 
-    pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
+    pub(crate) fn new(start_pos: BytePos, end_pos: BytePos, big_snippet: Rc<String>) -> Self {
         let start_pos = start_pos.to_usize();
+        let end_pos = end_pos.to_usize();
         SnippetProvider {
             big_snippet,
             start_pos,
+            end_pos,
         }
     }
+
+    pub(crate) fn entire_snippet(&self) -> &str {
+        self.big_snippet.as_str()
+    }
+
+    pub(crate) fn start_pos(&self) -> BytePos {
+        BytePos::from_usize(self.start_pos)
+    }
+
+    pub(crate) fn end_pos(&self) -> BytePos {
+        BytePos::from_usize(self.end_pos)
+    }
 }
 
-pub struct FmtVisitor<'a> {
+pub(crate) struct FmtVisitor<'a> {
     parent_context: Option<&'a RewriteContext<'a>>,
-    pub parse_session: &'a ParseSess,
-    pub source_map: &'a SourceMap,
-    pub buffer: String,
-    pub last_pos: BytePos,
+    pub(crate) parse_sess: &'a ParseSess,
+    pub(crate) buffer: String,
+    pub(crate) last_pos: BytePos,
     // FIXME: use an RAII util or closure for indenting
-    pub block_indent: Indent,
-    pub config: &'a Config,
-    pub is_if_else_block: bool,
-    pub snippet_provider: &'a SnippetProvider<'a>,
-    pub line_number: usize,
+    pub(crate) block_indent: Indent,
+    pub(crate) config: &'a Config,
+    pub(crate) is_if_else_block: bool,
+    pub(crate) snippet_provider: &'a SnippetProvider,
+    pub(crate) line_number: usize,
     /// List of 1-based line ranges which were annotated with skip
     /// Both bounds are inclusifs.
-    pub skipped_range: Vec<(usize, usize)>,
-    pub macro_rewrite_failure: bool,
+    pub(crate) skipped_range: Rc<RefCell<Vec<(usize, usize)>>>,
+    pub(crate) macro_rewrite_failure: bool,
     pub(crate) report: FormatReport,
+    pub(crate) skip_context: SkipContext,
+    pub(crate) is_macro_def: bool,
 }
 
 impl<'a> Drop for FmtVisitor<'a> {
@@ -83,70 +104,98 @@ fn set_parent_context(&mut self, context: &'a RewriteContext<'_>) {
         self.parent_context = Some(context);
     }
 
-    pub fn shape(&self) -> Shape {
+    pub(crate) fn shape(&self) -> Shape {
         Shape::indented(self.block_indent, self.config)
     }
 
-    fn visit_stmt(&mut self, stmt: &ast::Stmt) {
+    fn next_span(&self, hi: BytePos) -> Span {
+        mk_sp(self.last_pos, hi)
+    }
+
+    fn visit_stmt(&mut self, stmt: &Stmt<'_>, include_empty_semi: bool) {
         debug!(
-            "visit_stmt: {:?} {:?}",
-            self.source_map.lookup_char_pos(stmt.span.lo()),
-            self.source_map.lookup_char_pos(stmt.span.hi())
+            "visit_stmt: {}",
+            self.parse_sess.span_to_debug_info(stmt.span())
         );
 
-        match stmt.node {
+        if stmt.is_empty() {
+            // If the statement is empty, just skip over it. Before that, make sure any comment
+            // snippet preceding the semicolon is picked up.
+            let snippet = self.snippet(mk_sp(self.last_pos, stmt.span().lo()));
+            let original_starts_with_newline = snippet
+                .find(|c| c != ' ')
+                .map_or(false, |i| starts_with_newline(&snippet[i..]));
+            let snippet = snippet.trim();
+            if !snippet.is_empty() {
+                // FIXME(calebcartwright 2021-01-03) - This exists strictly to maintain legacy
+                // formatting where rustfmt would preserve redundant semicolons on Items in a
+                // statement position.
+                // See comment within `walk_stmts` for more info
+                if include_empty_semi {
+                    self.format_missing(stmt.span().hi());
+                } else {
+                    if original_starts_with_newline {
+                        self.push_str("\n");
+                    }
+
+                    self.push_str(&self.block_indent.to_string(self.config));
+                    self.push_str(snippet);
+                }
+            } else if include_empty_semi {
+                self.push_str(";");
+            }
+            self.last_pos = stmt.span().hi();
+            return;
+        }
+
+        match stmt.as_ast_node().kind {
             ast::StmtKind::Item(ref item) => {
                 self.visit_item(item);
-                // Handle potential `;` after the item.
-                self.format_missing(stmt.span.hi());
+                self.last_pos = stmt.span().hi();
             }
             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
-                let attrs = get_attrs_from_stmt(stmt);
+                let attrs = get_attrs_from_stmt(stmt.as_ast_node());
                 if contains_skip(attrs) {
-                    self.push_skipped_with_span(attrs, stmt.span(), get_span_without_attrs(stmt));
+                    self.push_skipped_with_span(
+                        attrs,
+                        stmt.span(),
+                        get_span_without_attrs(stmt.as_ast_node()),
+                    );
                 } else {
                     let shape = self.shape();
                     let rewrite = self.with_context(|ctx| stmt.rewrite(&ctx, shape));
                     self.push_rewrite(stmt.span(), rewrite)
                 }
             }
-            ast::StmtKind::Mac(ref mac) => {
-                let (ref mac, _macro_style, ref attrs) = **mac;
-                if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
-                    self.push_skipped_with_span(attrs, stmt.span(), get_span_without_attrs(stmt));
+            ast::StmtKind::MacCall(ref mac_stmt) => {
+                if self.visit_attrs(&mac_stmt.attrs, ast::AttrStyle::Outer) {
+                    self.push_skipped_with_span(
+                        &mac_stmt.attrs,
+                        stmt.span(),
+                        get_span_without_attrs(stmt.as_ast_node()),
+                    );
                 } else {
-                    self.visit_mac(mac, None, MacroPosition::Statement);
+                    self.visit_mac(&mac_stmt.mac, None, MacroPosition::Statement);
                 }
-                self.format_missing(stmt.span.hi());
+                self.format_missing(stmt.span().hi());
             }
+            ast::StmtKind::Empty => (),
         }
     }
 
-    pub fn visit_block(
+    /// Remove spaces between the opening brace and the first statement or the inner attribute
+    /// of the block.
+    fn trim_spaces_after_opening_brace(
         &mut self,
         b: &ast::Block,
         inner_attrs: Option<&[ast::Attribute]>,
-        has_braces: bool,
     ) {
-        debug!(
-            "visit_block: {:?} {:?}",
-            self.source_map.lookup_char_pos(b.span.lo()),
-            self.source_map.lookup_char_pos(b.span.hi())
-        );
-
-        // Check if this block has braces.
-        let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
-
-        self.last_pos = self.last_pos + brace_compensation;
-        self.block_indent = self.block_indent.block_indent(self.config);
-        self.push_str("{");
-
         if let Some(first_stmt) = b.stmts.first() {
             let hi = inner_attrs
                 .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
-                .unwrap_or(first_stmt.span().lo());
-
-            let snippet = self.snippet(mk_sp(self.last_pos, hi));
+                .unwrap_or_else(|| first_stmt.span().lo());
+            let missing_span = self.next_span(hi);
+            let snippet = self.snippet(missing_span);
             let len = CommentCodeSlices::new(snippet)
                 .nth(0)
                 .and_then(|(kind, _, s)| {
@@ -160,19 +209,30 @@ pub fn visit_block(
                 self.last_pos = self.last_pos + BytePos::from_usize(len);
             }
         }
+    }
 
-        // Format inner attributes if available.
-        let skip_rewrite = if let Some(attrs) = inner_attrs {
-            self.visit_attrs(attrs, ast::AttrStyle::Inner)
-        } else {
-            false
-        };
+    pub(crate) fn visit_block(
+        &mut self,
+        b: &ast::Block,
+        inner_attrs: Option<&[ast::Attribute]>,
+        has_braces: bool,
+    ) {
+        debug!(
+            "visit_block: {}",
+            self.parse_sess.span_to_debug_info(b.span),
+        );
 
-        if skip_rewrite {
-            self.push_rewrite(b.span, None);
-            self.close_block(false);
-            self.last_pos = source!(self, b.span).hi();
-            return;
+        // Check if this block has braces.
+        let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
+
+        self.last_pos = self.last_pos + brace_compensation;
+        self.block_indent = self.block_indent.block_indent(self.config);
+        self.push_str("{");
+        self.trim_spaces_after_opening_brace(b, inner_attrs);
+
+        // Format inner attributes if available.
+        if let Some(attrs) = inner_attrs {
+            self.visit_attrs(attrs, ast::AttrStyle::Inner);
         }
 
         self.walk_block_stmts(b);
@@ -185,66 +245,141 @@ pub fn visit_block(
             }
         }
 
-        let mut remove_len = BytePos(0);
-        if let Some(stmt) = b.stmts.last() {
-            let snippet = self.snippet(mk_sp(
-                stmt.span.hi(),
-                source!(self, b.span).hi() - brace_compensation,
-            ));
-            let len = CommentCodeSlices::new(snippet)
-                .last()
-                .and_then(|(kind, _, s)| {
-                    if kind == CodeCharKind::Normal && s.trim().is_empty() {
-                        Some(s.len())
-                    } else {
-                        None
-                    }
-                });
-            if let Some(len) = len {
-                remove_len = BytePos::from_usize(len);
-            }
-        }
-
-        let unindent_comment = self.is_if_else_block && !b.stmts.is_empty() && {
-            let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
-            let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
-            snippet.contains("//") || snippet.contains("/*")
-        };
-        // FIXME: we should compress any newlines here to just one
-        if unindent_comment {
+        let rest_span = self.next_span(b.span.hi());
+        if out_of_file_lines_range!(self, rest_span) {
+            self.push_str(self.snippet(rest_span));
             self.block_indent = self.block_indent.block_unindent(self.config);
+        } else {
+            // Ignore the closing brace.
+            let missing_span = self.next_span(b.span.hi() - brace_compensation);
+            self.close_block(missing_span, self.unindent_comment_on_closing_brace(b));
         }
-        self.format_missing_with_indent(
-            source!(self, b.span).hi() - brace_compensation - remove_len,
-        );
-        if unindent_comment {
-            self.block_indent = self.block_indent.block_indent(self.config);
-        }
-        self.close_block(unindent_comment);
         self.last_pos = source!(self, b.span).hi();
     }
 
-    // FIXME: this is a terrible hack to indent the comments between the last
-    // item in the block and the closing brace to the block's level.
-    // The closing brace itself, however, should be indented at a shallower
-    // level.
-    fn close_block(&mut self, unindent_comment: bool) {
-        let total_len = self.buffer.len();
-        let chars_too_many = if unindent_comment {
-            0
-        } else if self.config.hard_tabs() {
-            1
+    fn close_block(&mut self, span: Span, unindent_comment: bool) {
+        let config = self.config;
+
+        let mut last_hi = span.lo();
+        let mut unindented = false;
+        let mut prev_ends_with_newline = false;
+        let mut extra_newline = false;
+
+        let skip_normal = |s: &str| {
+            let trimmed = s.trim();
+            trimmed.is_empty() || trimmed.chars().all(|c| c == ';')
+        };
+
+        let comment_snippet = self.snippet(span);
+
+        let align_to_right = if unindent_comment && contains_comment(&comment_snippet) {
+            let first_lines = comment_snippet.splitn(2, '/').next().unwrap_or("");
+            last_line_width(first_lines) > last_line_width(&comment_snippet)
         } else {
-            self.config.tab_spaces()
+            false
         };
-        self.buffer.truncate(total_len - chars_too_many);
-        self.push_str("}");
+
+        for (kind, offset, sub_slice) in CommentCodeSlices::new(comment_snippet) {
+            let sub_slice = transform_missing_snippet(config, sub_slice);
+
+            debug!("close_block: {:?} {:?} {:?}", kind, offset, sub_slice);
+
+            match kind {
+                CodeCharKind::Comment => {
+                    if !unindented && unindent_comment && !align_to_right {
+                        unindented = true;
+                        self.block_indent = self.block_indent.block_unindent(config);
+                    }
+                    let span_in_between = mk_sp(last_hi, span.lo() + BytePos::from_usize(offset));
+                    let snippet_in_between = self.snippet(span_in_between);
+                    let mut comment_on_same_line = !snippet_in_between.contains("\n");
+
+                    let mut comment_shape =
+                        Shape::indented(self.block_indent, config).comment(config);
+                    if self.config.version() == Version::Two && comment_on_same_line {
+                        self.push_str(" ");
+                        // put the first line of the comment on the same line as the
+                        // block's last line
+                        match sub_slice.find("\n") {
+                            None => {
+                                self.push_str(&sub_slice);
+                            }
+                            Some(offset) if offset + 1 == sub_slice.len() => {
+                                self.push_str(&sub_slice[..offset]);
+                            }
+                            Some(offset) => {
+                                let first_line = &sub_slice[..offset];
+                                self.push_str(first_line);
+                                self.push_str(&self.block_indent.to_string_with_newline(config));
+
+                                // put the other lines below it, shaping it as needed
+                                let other_lines = &sub_slice[offset + 1..];
+                                let comment_str =
+                                    rewrite_comment(other_lines, false, comment_shape, config);
+                                match comment_str {
+                                    Some(ref s) => self.push_str(s),
+                                    None => self.push_str(other_lines),
+                                }
+                            }
+                        }
+                    } else {
+                        if comment_on_same_line {
+                            // 1 = a space before `//`
+                            let offset_len = 1 + last_line_width(&self.buffer)
+                                .saturating_sub(self.block_indent.width());
+                            match comment_shape
+                                .visual_indent(offset_len)
+                                .sub_width(offset_len)
+                            {
+                                Some(shp) => comment_shape = shp,
+                                None => comment_on_same_line = false,
+                            }
+                        };
+
+                        if comment_on_same_line {
+                            self.push_str(" ");
+                        } else {
+                            if count_newlines(snippet_in_between) >= 2 || extra_newline {
+                                self.push_str("\n");
+                            }
+                            self.push_str(&self.block_indent.to_string_with_newline(config));
+                        }
+
+                        let comment_str = rewrite_comment(&sub_slice, false, comment_shape, config);
+                        match comment_str {
+                            Some(ref s) => self.push_str(s),
+                            None => self.push_str(&sub_slice),
+                        }
+                    }
+                }
+                CodeCharKind::Normal if skip_normal(&sub_slice) => {
+                    extra_newline = prev_ends_with_newline && sub_slice.contains('\n');
+                    continue;
+                }
+                CodeCharKind::Normal => {
+                    self.push_str(&self.block_indent.to_string_with_newline(config));
+                    self.push_str(sub_slice.trim());
+                }
+            }
+            prev_ends_with_newline = sub_slice.ends_with('\n');
+            extra_newline = false;
+            last_hi = span.lo() + BytePos::from_usize(offset + sub_slice.len());
+        }
+        if unindented {
+            self.block_indent = self.block_indent.block_indent(self.config);
+        }
         self.block_indent = self.block_indent.block_unindent(self.config);
+        self.push_str(&self.block_indent.to_string_with_newline(config));
+        self.push_str("}");
+    }
+
+    fn unindent_comment_on_closing_brace(&self, b: &ast::Block) -> bool {
+        self.is_if_else_block && !b.stmts.is_empty()
     }
 
     // Note that this only gets called for function definitions. Required methods
     // on traits do not get handled here.
-    fn visit_fn(
+    pub(crate) fn visit_fn(
         &mut self,
         fk: visit::FnKind<'_>,
         generics: &ast::Generics,
@@ -256,38 +391,44 @@ fn visit_fn(
         let indent = self.block_indent;
         let block;
         let rewrite = match fk {
-            visit::FnKind::ItemFn(ident, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
+            visit::FnKind::Fn(_, ident, _, _, Some(ref b)) => {
                 block = b;
-                self.rewrite_fn(
+                self.rewrite_fn_before_block(
                     indent,
                     ident,
                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
                     mk_sp(s.lo(), b.span.lo()),
-                    b,
-                    inner_attrs,
                 )
             }
-            visit::FnKind::Closure(_) => unreachable!(),
+            _ => unreachable!(),
         };
 
-        if let Some(fn_str) = rewrite {
+        if let Some((fn_str, fn_brace_style)) = rewrite {
             self.format_missing_with_indent(source!(self, s).lo());
+
+            if let Some(rw) = self.single_line_fn(&fn_str, block, inner_attrs) {
+                self.push_str(&rw);
+                self.last_pos = s.hi();
+                return;
+            }
+
             self.push_str(&fn_str);
-            if let Some(c) = fn_str.chars().last() {
-                if c == '}' {
-                    self.last_pos = source!(self, block.span).hi();
-                    return;
+            match fn_brace_style {
+                FnBraceStyle::SameLine => self.push_str(" "),
+                FnBraceStyle::NextLine => {
+                    self.push_str(&self.block_indent.to_string_with_newline(self.config))
                 }
+                _ => unreachable!(),
             }
+            self.last_pos = source!(self, block.span).lo();
         } else {
             self.format_missing(source!(self, block.span).lo());
         }
 
-        self.last_pos = source!(self, block.span).lo();
         self.visit_block(block, inner_attrs, true)
     }
 
-    pub fn visit_item(&mut self, item: &ast::Item) {
+    pub(crate) fn visit_item(&mut self, item: &ast::Item) {
         skip_out_of_file_lines_range_visitor!(self, item.span);
 
         // This is where we bail out if there is a skip attribute. This is only
@@ -296,25 +437,30 @@ pub fn visit_item(&mut self, item: &ast::Item) {
         // the AST lumps them all together.
         let filtered_attrs;
         let mut attrs = &item.attrs;
-        match item.node {
-            // For use items, skip rewriting attributes. Just check for a skip attribute.
-            ast::ItemKind::Use(..) => {
+        let skip_context_saved = self.skip_context.clone();
+        self.skip_context.update_with_attrs(&attrs);
+
+        let should_visit_node_again = match item.kind {
+            // For use/extern crate items, skip rewriting attributes but check for a skip attribute.
+            ast::ItemKind::Use(..) | ast::ItemKind::ExternCrate(_) => {
                 if contains_skip(attrs) {
                     self.push_skipped_with_span(attrs.as_slice(), item.span(), item.span());
-                    return;
+                    false
+                } else {
+                    true
                 }
             }
             // Module is inline, in this case we treat it like any other item.
             _ if !is_mod_decl(item) => {
                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
                     self.push_skipped_with_span(item.attrs.as_slice(), item.span(), item.span());
-                    return;
+                    false
+                } else {
+                    true
                 }
             }
             // Module is not inline, but should be skipped.
-            ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
-                return;
-            }
+            ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => false,
             // Module is not inline and should not be skipped. We want
             // to process only the attributes in the current file.
             ast::ItemKind::Mod(..) => {
@@ -323,124 +469,157 @@ pub fn visit_item(&mut self, item: &ast::Item) {
                 // the above case.
                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
                 attrs = &filtered_attrs;
+                true
             }
             _ => {
                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
                     self.push_skipped_with_span(item.attrs.as_slice(), item.span(), item.span());
-                    return;
+                    false
+                } else {
+                    true
                 }
             }
-        }
+        };
 
-        match item.node {
-            ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
-            ast::ItemKind::Impl(..) => {
-                let snippet = self.snippet(item.span);
-                let where_span_end = snippet
-                    .find_uncommented("{")
-                    .map(|x| BytePos(x as u32) + source!(self, item.span).lo());
-                let block_indent = self.block_indent;
-                let rw =
-                    self.with_context(|ctx| format_impl(&ctx, item, block_indent, where_span_end));
-                self.push_rewrite(item.span, rw);
-            }
-            ast::ItemKind::Trait(..) => {
-                let block_indent = self.block_indent;
-                let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
-                self.push_rewrite(item.span, rw);
-            }
-            ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
-                let shape = Shape::indented(self.block_indent, self.config);
-                let rw = format_trait_alias(
-                    &self.get_context(),
-                    item.ident,
-                    &item.vis,
-                    generics,
-                    generic_bounds,
-                    shape,
-                );
-                self.push_rewrite(item.span, rw);
-            }
-            ast::ItemKind::ExternCrate(_) => {
-                let rw = rewrite_extern_crate(&self.get_context(), item);
-                self.push_rewrite(item.span, rw);
-            }
-            ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
-                self.visit_struct(&StructParts::from_item(item));
-            }
-            ast::ItemKind::Enum(ref def, ref generics) => {
-                self.format_missing_with_indent(source!(self, item.span).lo());
-                self.visit_enum(item.ident, &item.vis, def, generics, item.span);
-                self.last_pos = source!(self, item.span).hi();
-            }
-            ast::ItemKind::Mod(ref module) => {
-                let is_inline = !is_mod_decl(item);
-                self.format_missing_with_indent(source!(self, item.span).lo());
-                self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
-            }
-            ast::ItemKind::Mac(ref mac) => {
-                self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
-            }
-            ast::ItemKind::ForeignMod(ref foreign_mod) => {
-                self.format_missing_with_indent(source!(self, item.span).lo());
-                self.format_foreign_mod(foreign_mod, item.span);
-            }
-            ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
-                self.visit_static(&StaticParts::from_item(item));
-            }
-            ast::ItemKind::Fn(ref decl, ref fn_header, ref generics, ref body) => {
-                let inner_attrs = inner_attributes(&item.attrs);
-                self.visit_fn(
-                    visit::FnKind::ItemFn(item.ident, fn_header, &item.vis, body),
-                    generics,
-                    decl,
-                    item.span,
-                    ast::Defaultness::Final,
-                    Some(&inner_attrs),
-                )
-            }
-            ast::ItemKind::Ty(ref ty, ref generics) => {
-                let rewrite = rewrite_type_alias(
-                    &self.get_context(),
-                    self.block_indent,
-                    item.ident,
-                    ty,
-                    generics,
-                    &item.vis,
-                );
-                self.push_rewrite(item.span, rewrite);
-            }
-            ast::ItemKind::Existential(ref generic_bounds, ref generics) => {
-                let rewrite = rewrite_existential_type(
-                    &self.get_context(),
-                    self.block_indent,
-                    item.ident,
-                    generic_bounds,
-                    generics,
-                    &item.vis,
-                );
-                self.push_rewrite(item.span, rewrite);
-            }
-            ast::ItemKind::GlobalAsm(..) => {
-                let snippet = Some(self.snippet(item.span).to_owned());
-                self.push_rewrite(item.span, snippet);
-            }
-            ast::ItemKind::MacroDef(ref def) => {
-                let rewrite = rewrite_macro_def(
-                    &self.get_context(),
-                    self.shape(),
-                    self.block_indent,
-                    def,
-                    item.ident,
-                    &item.vis,
-                    item.span,
-                );
-                self.push_rewrite(item.span, rewrite);
-            }
+        if should_visit_node_again {
+            match item.kind {
+                ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
+                ast::ItemKind::Impl { .. } => {
+                    let block_indent = self.block_indent;
+                    let rw = self.with_context(|ctx| format_impl(&ctx, item, block_indent));
+                    self.push_rewrite(item.span, rw);
+                }
+                ast::ItemKind::Trait(..) => {
+                    let block_indent = self.block_indent;
+                    let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
+                    self.push_rewrite(item.span, rw);
+                }
+                ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
+                    let shape = Shape::indented(self.block_indent, self.config);
+                    let rw = format_trait_alias(
+                        &self.get_context(),
+                        item.ident,
+                        &item.vis,
+                        generics,
+                        generic_bounds,
+                        shape,
+                    );
+                    self.push_rewrite(item.span, rw);
+                }
+                ast::ItemKind::ExternCrate(_) => {
+                    let rw = rewrite_extern_crate(&self.get_context(), item, self.shape());
+                    let span = if attrs.is_empty() {
+                        item.span
+                    } else {
+                        mk_sp(attrs[0].span.lo(), item.span.hi())
+                    };
+                    self.push_rewrite(span, rw);
+                }
+                ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
+                    self.visit_struct(&StructParts::from_item(item));
+                }
+                ast::ItemKind::Enum(ref def, ref generics) => {
+                    self.format_missing_with_indent(source!(self, item.span).lo());
+                    self.visit_enum(item.ident, &item.vis, def, generics, item.span);
+                    self.last_pos = source!(self, item.span).hi();
+                }
+                ast::ItemKind::Mod(ref module) => {
+                    let is_inline = !is_mod_decl(item);
+                    self.format_missing_with_indent(source!(self, item.span).lo());
+                    self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
+                }
+                ast::ItemKind::MacCall(ref mac) => {
+                    self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
+                }
+                ast::ItemKind::ForeignMod(ref foreign_mod) => {
+                    self.format_missing_with_indent(source!(self, item.span).lo());
+                    self.format_foreign_mod(foreign_mod, item.span);
+                }
+                ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
+                    self.visit_static(&StaticParts::from_item(item));
+                }
+                ast::ItemKind::Fn(defaultness, ref fn_signature, ref generics, Some(ref body)) => {
+                    let inner_attrs = inner_attributes(&item.attrs);
+                    let fn_ctxt = match fn_signature.header.ext {
+                        ast::Extern::None => visit::FnCtxt::Free,
+                        _ => visit::FnCtxt::Foreign,
+                    };
+                    self.visit_fn(
+                        visit::FnKind::Fn(
+                            fn_ctxt,
+                            item.ident,
+                            &fn_signature,
+                            &item.vis,
+                            Some(body),
+                        ),
+                        generics,
+                        &fn_signature.decl,
+                        item.span,
+                        defaultness,
+                        Some(&inner_attrs),
+                    )
+                }
+                ast::ItemKind::Fn(_, ref fn_signature, ref generics, None) => {
+                    let indent = self.block_indent;
+                    let rewrite = self.rewrite_required_fn(
+                        indent,
+                        item.ident,
+                        &fn_signature,
+                        generics,
+                        item.span,
+                    );
+
+                    self.push_rewrite(item.span, rewrite);
+                }
+                ast::ItemKind::TyAlias(_, ref generics, ref generic_bounds, ref ty) => match ty {
+                    Some(ty) => {
+                        let rewrite = rewrite_type_alias(
+                            item.ident,
+                            Some(&*ty),
+                            generics,
+                            Some(generic_bounds),
+                            &self.get_context(),
+                            self.block_indent,
+                            &item.vis,
+                            item.span,
+                        );
+                        self.push_rewrite(item.span, rewrite);
+                    }
+                    None => {
+                        let rewrite = rewrite_opaque_type(
+                            &self.get_context(),
+                            self.block_indent,
+                            item.ident,
+                            generic_bounds,
+                            generics,
+                            &item.vis,
+                            item.span,
+                        );
+                        self.push_rewrite(item.span, rewrite);
+                    }
+                },
+                ast::ItemKind::GlobalAsm(..) => {
+                    let snippet = Some(self.snippet(item.span).to_owned());
+                    self.push_rewrite(item.span, snippet);
+                }
+                ast::ItemKind::MacroDef(ref def) => {
+                    let rewrite = rewrite_macro_def(
+                        &self.get_context(),
+                        self.shape(),
+                        self.block_indent,
+                        def,
+                        item.ident,
+                        &item.vis,
+                        item.span,
+                    );
+                    self.push_rewrite(item.span, rewrite);
+                }
+            };
         }
+        self.skip_context = skip_context_saved;
     }
 
-    pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
+    pub(crate) fn visit_trait_item(&mut self, ti: &ast::AssocItem) {
         skip_out_of_file_lines_range_visitor!(self, ti.span);
 
         if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
@@ -448,100 +627,141 @@ pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
             return;
         }
 
-        match ti.node {
-            ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
-            ast::TraitItemKind::Method(ref sig, None) => {
+        match ti.kind {
+            ast::AssocItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
+            ast::AssocItemKind::Fn(_, ref sig, ref generics, None) => {
                 let indent = self.block_indent;
-                let rewrite =
-                    self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
+                let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, generics, ti.span);
                 self.push_rewrite(ti.span, rewrite);
             }
-            ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
+            ast::AssocItemKind::Fn(defaultness, ref sig, ref generics, Some(ref body)) => {
                 let inner_attrs = inner_attributes(&ti.attrs);
+                let vis = ast::Visibility {
+                    kind: ast::VisibilityKind::Inherited,
+                    span: DUMMY_SP,
+                    tokens: None,
+                };
+                let fn_ctxt = visit::FnCtxt::Assoc(visit::AssocCtxt::Trait);
                 self.visit_fn(
-                    visit::FnKind::Method(ti.ident, sig, None, body),
-                    &ti.generics,
+                    visit::FnKind::Fn(fn_ctxt, ti.ident, sig, &vis, Some(body)),
+                    generics,
                     &sig.decl,
                     ti.span,
-                    ast::Defaultness::Final,
+                    defaultness,
                     Some(&inner_attrs),
                 );
             }
-            ast::TraitItemKind::Type(ref generic_bounds, ref type_default) => {
-                let rewrite = rewrite_associated_type(
+            ast::AssocItemKind::TyAlias(_, ref generics, ref generic_bounds, ref type_default) => {
+                let rewrite = rewrite_type_alias(
                     ti.ident,
                     type_default.as_ref(),
-                    &ti.generics,
+                    generics,
                     Some(generic_bounds),
                     &self.get_context(),
                     self.block_indent,
+                    &ti.vis,
+                    ti.span,
                 );
                 self.push_rewrite(ti.span, rewrite);
             }
-            ast::TraitItemKind::Macro(ref mac) => {
+            ast::AssocItemKind::MacCall(ref mac) => {
                 self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
             }
         }
     }
 
-    pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
+    pub(crate) fn visit_impl_item(&mut self, ii: &ast::AssocItem) {
         skip_out_of_file_lines_range_visitor!(self, ii.span);
 
         if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
-            self.push_skipped_with_span(ii.attrs.as_slice(), ii.span(), ii.span());
+            self.push_skipped_with_span(ii.attrs.as_slice(), ii.span, ii.span);
             return;
         }
 
-        match ii.node {
-            ast::ImplItemKind::Method(ref sig, ref body) => {
+        match ii.kind {
+            ast::AssocItemKind::Fn(defaultness, ref sig, ref generics, Some(ref body)) => {
                 let inner_attrs = inner_attributes(&ii.attrs);
+                let fn_ctxt = visit::FnCtxt::Assoc(visit::AssocCtxt::Impl);
                 self.visit_fn(
-                    visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
-                    &ii.generics,
+                    visit::FnKind::Fn(fn_ctxt, ii.ident, sig, &ii.vis, Some(body)),
+                    generics,
                     &sig.decl,
                     ii.span,
-                    ii.defaultness,
+                    defaultness,
                     Some(&inner_attrs),
                 );
             }
-            ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
-            ast::ImplItemKind::Type(ref ty) => {
-                let rewrite = rewrite_associated_impl_type(
-                    ii.ident,
-                    ii.defaultness,
-                    Some(ty),
-                    &ii.generics,
-                    &self.get_context(),
-                    self.block_indent,
-                );
+            ast::AssocItemKind::Fn(_, ref sig, ref generics, None) => {
+                let indent = self.block_indent;
+                let rewrite = self.rewrite_required_fn(indent, ii.ident, sig, generics, ii.span);
                 self.push_rewrite(ii.span, rewrite);
             }
-            ast::ImplItemKind::Existential(ref generic_bounds) => {
-                let rewrite = rewrite_existential_impl_type(
-                    &self.get_context(),
-                    ii.ident,
-                    &ii.generics,
-                    generic_bounds,
-                    self.block_indent,
-                );
+            ast::AssocItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
+            ast::AssocItemKind::TyAlias(defaultness, ref generics, _, ref ty) => {
+                let rewrite_associated = || {
+                    rewrite_associated_impl_type(
+                        ii.ident,
+                        &ii.vis,
+                        defaultness,
+                        ty.as_ref(),
+                        &generics,
+                        &self.get_context(),
+                        self.block_indent,
+                        ii.span,
+                    )
+                };
+                let rewrite = match ty {
+                    None => rewrite_associated(),
+                    Some(ty) => match ty.kind {
+                        ast::TyKind::ImplTrait(_, ref bounds) => rewrite_opaque_impl_type(
+                            &self.get_context(),
+                            ii.ident,
+                            generics,
+                            bounds,
+                            self.block_indent,
+                        ),
+                        _ => rewrite_associated(),
+                    },
+                };
                 self.push_rewrite(ii.span, rewrite);
             }
-            ast::ImplItemKind::Macro(ref mac) => {
+            ast::AssocItemKind::MacCall(ref mac) => {
                 self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
             }
         }
     }
 
-    fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
-        skip_out_of_file_lines_range_visitor!(self, mac.span);
+    fn visit_mac(&mut self, mac: &ast::MacCall, ident: Option<symbol::Ident>, pos: MacroPosition) {
+        skip_out_of_file_lines_range_visitor!(self, mac.span());
 
         // 1 = ;
-        let shape = self.shape().sub_width(1).unwrap();
+        let shape = self.shape().saturating_sub_width(1);
         let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
-        self.push_rewrite(mac.span, rewrite);
+        // As of v638 of the rustc-ap-* crates, the associated span no longer includes
+        // the trailing semicolon. This determines the correct span to ensure scenarios
+        // with whitespace between the delimiters and trailing semi (i.e. `foo!(abc)     ;`)
+        // are formatted correctly.
+        let (span, rewrite) = match macro_style(mac, &self.get_context()) {
+            DelimToken::Bracket | DelimToken::Paren if MacroPosition::Item == pos => {
+                let search_span = mk_sp(mac.span().hi(), self.snippet_provider.end_pos());
+                let hi = self.snippet_provider.span_before(search_span, ";");
+                let target_span = mk_sp(mac.span().lo(), hi + BytePos(1));
+                let rewrite = rewrite.map(|rw| {
+                    if !rw.ends_with(";") {
+                        format!("{};", rw)
+                    } else {
+                        rw
+                    }
+                });
+                (target_span, rewrite)
+            }
+            _ => (mac.span(), rewrite),
+        };
+
+        self.push_rewrite(span, rewrite);
     }
 
-    pub fn push_str(&mut self, s: &str) {
+    pub(crate) fn push_str(&mut self, s: &str) {
         self.line_number += count_newlines(s);
         self.buffer.push_str(s);
     }
@@ -552,17 +772,17 @@ fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
             self.push_str(s);
         } else {
             let snippet = self.snippet(span);
-            self.push_str(snippet);
+            self.push_str(snippet.trim());
         }
         self.last_pos = source!(self, span).hi();
     }
 
-    pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
+    pub(crate) fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
         self.format_missing_with_indent(source!(self, span).lo());
         self.push_rewrite_inner(span, rewrite);
     }
 
-    pub fn push_skipped_with_span(
+    pub(crate) fn push_skipped_with_span(
         &mut self,
         attrs: &[ast::Attribute],
         item_span: Span,
@@ -572,40 +792,40 @@ pub fn push_skipped_with_span(
         // do not take into account the lines with attributes as part of the skipped range
         let attrs_end = attrs
             .iter()
-            .map(|attr| self.source_map.lookup_char_pos(attr.span().hi()).line)
+            .map(|attr| self.parse_sess.line_of_byte_pos(attr.span.hi()))
             .max()
             .unwrap_or(1);
-        let first_line = self.source_map.lookup_char_pos(main_span.lo()).line;
+        let first_line = self.parse_sess.line_of_byte_pos(main_span.lo());
         // Statement can start after some newlines and/or spaces
         // or it can be on the same line as the last attribute.
         // So here we need to take a minimum between the two.
         let lo = std::cmp::min(attrs_end + 1, first_line);
         self.push_rewrite_inner(item_span, None);
         let hi = self.line_number + 1;
-        self.skipped_range.push((lo, hi));
+        self.skipped_range.borrow_mut().push((lo, hi));
     }
 
-    pub fn from_context(ctx: &'a RewriteContext<'_>) -> FmtVisitor<'a> {
-        let mut visitor = FmtVisitor::from_source_map(
-            ctx.parse_session,
+    pub(crate) fn from_context(ctx: &'a RewriteContext<'_>) -> FmtVisitor<'a> {
+        let mut visitor = FmtVisitor::from_parse_sess(
+            ctx.parse_sess,
             ctx.config,
             ctx.snippet_provider,
             ctx.report.clone(),
         );
+        visitor.skip_context.update(ctx.skip_context.clone());
         visitor.set_parent_context(ctx);
         visitor
     }
 
-    pub(crate) fn from_source_map(
+    pub(crate) fn from_parse_sess(
         parse_session: &'a ParseSess,
         config: &'a Config,
-        snippet_provider: &'a SnippetProvider<'_>,
+        snippet_provider: &'a SnippetProvider,
         report: FormatReport,
     ) -> FmtVisitor<'a> {
         FmtVisitor {
             parent_context: None,
-            parse_session,
-            source_map: parse_session.source_map(),
+            parse_sess: parse_session,
             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
             last_pos: BytePos(0),
             block_indent: Indent::empty(),
@@ -613,46 +833,52 @@ pub(crate) fn from_source_map(
             is_if_else_block: false,
             snippet_provider,
             line_number: 0,
-            skipped_range: vec![],
+            skipped_range: Rc::new(RefCell::new(vec![])),
+            is_macro_def: false,
             macro_rewrite_failure: false,
             report,
+            skip_context: Default::default(),
         }
     }
 
-    pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
+    pub(crate) fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
         self.snippet_provider.span_to_snippet(span)
     }
 
-    pub fn snippet(&'b self, span: Span) -> &'a str {
+    pub(crate) fn snippet(&'b self, span: Span) -> &'a str {
         self.opt_snippet(span).unwrap()
     }
 
     // Returns true if we should skip the following item.
-    pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
+    pub(crate) fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
         for attr in attrs {
-            if attr.name() == DEPR_SKIP_ANNOTATION {
-                let file_name = self.source_map.span_to_filename(attr.span).into();
+            if attr.has_name(depr_skip_annotation()) {
+                let file_name = self.parse_sess.span_to_filename(attr.span);
                 self.report.append(
                     file_name,
                     vec![FormattingError::from_span(
                         attr.span,
-                        &self.source_map,
+                        self.parse_sess,
                         ErrorKind::DeprecatedAttr,
                     )],
                 );
-            } else if attr.path.segments[0].ident.to_string() == "rustfmt"
-                && (attr.path.segments.len() == 1
-                    || attr.path.segments[1].ident.to_string() != "skip")
-            {
-                let file_name = self.source_map.span_to_filename(attr.span).into();
-                self.report.append(
-                    file_name,
-                    vec![FormattingError::from_span(
-                        attr.span,
-                        &self.source_map,
-                        ErrorKind::BadAttr,
-                    )],
-                );
+            } else {
+                match &attr.kind {
+                    ast::AttrKind::Normal(ref attribute_item, _)
+                        if self.is_unknown_rustfmt_attr(&attribute_item.path.segments) =>
+                    {
+                        let file_name = self.parse_sess.span_to_filename(attr.span);
+                        self.report.append(
+                            file_name,
+                            vec![FormattingError::from_span(
+                                attr.span,
+                                self.parse_sess,
+                                ErrorKind::BadAttr,
+                            )],
+                        );
+                    }
+                    _ => (),
+                }
             }
         }
         if contains_skip(attrs) {
@@ -671,18 +897,18 @@ pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -
         false
     }
 
+    fn is_unknown_rustfmt_attr(&self, segments: &[ast::PathSegment]) -> bool {
+        if segments[0].ident.to_string() != "rustfmt" {
+            return false;
+        }
+        !is_skip_attr(segments)
+    }
+
     fn walk_mod_items(&mut self, m: &ast::Mod) {
         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
     }
 
-    fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
-        fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
-            match stmt.node {
-                ast::StmtKind::Item(ref item) => Some(&**item),
-                _ => None,
-            }
-        }
-
+    fn walk_stmts(&mut self, stmts: &[Stmt<'_>], include_current_empty_semi: bool) {
         if stmts.is_empty() {
             return;
         }
@@ -690,35 +916,43 @@ fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
         // Extract leading `use ...;`.
         let items: Vec<_> = stmts
             .iter()
-            .take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
-            .filter_map(|stmt| to_stmt_item(stmt))
+            .take_while(|stmt| stmt.to_item().map_or(false, is_use_item))
+            .filter_map(|stmt| stmt.to_item())
             .collect();
 
         if items.is_empty() {
-            // The `if` expression at the end of the block should be formatted in a single
-            // line if possible.
-            if self.config.version() == Version::Two
-                && stmts.len() == 1
-                && crate::expr::stmt_is_if(&stmts[0])
-                && !contains_skip(get_attrs_from_stmt(&stmts[0]))
-            {
-                let shape = self.shape();
-                let rewrite = self.with_context(|ctx| {
-                    format_expr(stmt_expr(&stmts[0])?, ExprType::SubExpression, ctx, shape)
-                });
-                self.push_rewrite(stmts[0].span(), rewrite);
+            self.visit_stmt(&stmts[0], include_current_empty_semi);
+
+            // FIXME(calebcartwright 2021-01-03) - This exists strictly to maintain legacy
+            // formatting where rustfmt would preserve redundant semicolons on Items in a
+            // statement position.
+            //
+            // Starting in rustc-ap-* v692 (~2020-12-01) the rustc parser now parses this as
+            // two separate statements (Item and Empty kinds), whereas before it was parsed as
+            // a single statement with the statement's span including the redundant semicolon.
+            //
+            // rustfmt typically tosses unnecessary/redundant semicolons, and eventually we
+            // should toss these as well, but doing so at this time would
+            // break the Stability Guarantee
+            // N.B. This could be updated to utilize the version gates.
+            let include_next_empty = if stmts.len() > 1 {
+                match (&stmts[0].as_ast_node().kind, &stmts[1].as_ast_node().kind) {
+                    (ast::StmtKind::Item(_), ast::StmtKind::Empty) => true,
+                    _ => false,
+                }
             } else {
-                self.visit_stmt(&stmts[0]);
-                self.walk_stmts(&stmts[1..]);
-            }
+                false
+            };
+
+            self.walk_stmts(&stmts[1..], include_next_empty);
         } else {
             self.visit_items_with_reordering(&items);
-            self.walk_stmts(&stmts[items.len()..]);
+            self.walk_stmts(&stmts[items.len()..], false);
         }
     }
 
     fn walk_block_stmts(&mut self, b: &ast::Block) {
-        self.walk_stmts(&b.stmts)
+        self.walk_stmts(&Stmt::from_ast_nodes(b.stmts.iter()), false)
     }
 
     fn format_mod(
@@ -726,12 +960,13 @@ fn format_mod(
         m: &ast::Mod,
         vis: &ast::Visibility,
         s: Span,
-        ident: ast::Ident,
+        ident: symbol::Ident,
         attrs: &[ast::Attribute],
         is_internal: bool,
     ) {
         let vis_str = utils::format_visibility(&self.get_context(), vis);
         self.push_str(&*vis_str);
+        self.push_str(format_unsafety(m.unsafety));
         self.push_str("mod ");
         // Calling `to_owned()` to work around borrow checker.
         let ident_str = rewrite_ident(&self.get_context(), ident).to_owned();
@@ -758,8 +993,8 @@ fn format_mod(
                 self.block_indent = self.block_indent.block_indent(self.config);
                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
                 self.walk_mod_items(m);
-                self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
-                self.close_block(false);
+                let missing_span = self.next_span(m.inner.hi() - BytePos(1));
+                self.close_block(missing_span, false);
             }
             self.last_pos = source!(self, m.inner).hi();
         } else {
@@ -768,18 +1003,22 @@ fn format_mod(
         }
     }
 
-    pub fn format_separate_mod(&mut self, m: &ast::Mod, source_file: &source_map::SourceFile) {
+    pub(crate) fn format_separate_mod(&mut self, m: &Module<'_>, end_pos: BytePos) {
         self.block_indent = Indent::empty();
-        self.walk_mod_items(m);
-        self.format_missing_with_indent(source_file.end_pos);
+        if self.visit_attrs(m.attrs(), ast::AttrStyle::Inner) {
+            self.push_skipped_with_span(m.attrs(), m.as_ref().inner, m.as_ref().inner);
+        } else {
+            self.walk_mod_items(m.as_ref());
+            self.format_missing_with_indent(end_pos);
+        }
     }
 
-    pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
+    pub(crate) fn skip_empty_lines(&mut self, end_pos: BytePos) {
         while let Some(pos) = self
             .snippet_provider
-            .opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
+            .opt_span_after(self.next_span(end_pos), "\n")
         {
-            if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
+            if let Some(snippet) = self.opt_snippet(self.next_span(pos)) {
                 if snippet.trim().is_empty() {
                     self.last_pos = pos;
                 } else {
@@ -789,34 +1028,31 @@ pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
         }
     }
 
-    pub fn with_context<F>(&mut self, f: F) -> Option<String>
+    pub(crate) fn with_context<F>(&mut self, f: F) -> Option<String>
     where
         F: Fn(&RewriteContext<'_>) -> Option<String>,
     {
-        // FIXME borrow checker fighting - can be simplified a lot with NLL.
-        let (result, mrf) = {
-            let context = self.get_context();
-            let result = f(&context);
-            let mrf = &context.macro_rewrite_failure.borrow();
-            (result, *std::ops::Deref::deref(mrf))
-        };
+        let context = self.get_context();
+        let result = f(&context);
 
-        self.macro_rewrite_failure |= mrf;
+        self.macro_rewrite_failure |= context.macro_rewrite_failure.get();
         result
     }
 
-    pub fn get_context(&self) -> RewriteContext<'_> {
+    pub(crate) fn get_context(&self) -> RewriteContext<'_> {
         RewriteContext {
-            parse_session: self.parse_session,
-            source_map: self.source_map,
+            parse_sess: self.parse_sess,
             config: self.config,
-            inside_macro: RefCell::new(false),
-            use_block: RefCell::new(false),
-            is_if_else_block: RefCell::new(false),
-            force_one_line_chain: RefCell::new(false),
+            inside_macro: Rc::new(Cell::new(false)),
+            use_block: Cell::new(false),
+            is_if_else_block: Cell::new(false),
+            force_one_line_chain: Cell::new(false),
             snippet_provider: self.snippet_provider,
-            macro_rewrite_failure: RefCell::new(false),
+            macro_rewrite_failure: Cell::new(false),
+            is_macro_def: self.is_macro_def,
             report: self.report.clone(),
+            skip_context: self.skip_context.clone(),
+            skipped_range: self.skipped_range.clone(),
         }
     }
 }