Auto merge of #63057 - Centril:rollup-z3a3c6v, r=Centril

Rollup of 8 pull requests

Successful merges:

 - #61207 (Allow lifetime elision in `Pin<&(mut) Self>`)
 - #62074 (squash of all commits for nth_back on ChunksMut)
 - #62771 (Break dependencies between `syntax_ext` and other crates)
 - #62883 (Refactoring use common code between option, result and accum)
 - #62949 (Re-enable assertions in PPC dist builder)
 - #62996 (tidy: Add a check for inline unit tests)
 - #63038 (Make more informative error on outer attribute after inner)
 - #63050 (ci: download awscli from our mirror)

Failed merges:

r? @ghost

13 files changed, 1029 insertions, 801 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 0ab14bee160..bb7834a133f 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -1,6 +1,6 @@
 use crate::ast::{self, Attribute, Name, PatKind};
 use crate::attr::{HasAttrs, Stability, Deprecation};
-use crate::source_map::{SourceMap, Spanned, FileName, respan};
+use crate::source_map::{SourceMap, Spanned, respan};
 use crate::edition::Edition;
 use crate::ext::expand::{self, AstFragment, Invocation};
 use crate::ext::hygiene::{ExpnId, SyntaxContext, Transparency};
@@ -14,7 +14,7 @@ use crate::tokenstream::{self, TokenStream, TokenTree};
 
 use errors::{DiagnosticBuilder, DiagnosticId};
 use smallvec::{smallvec, SmallVec};
-use syntax_pos::{Span, MultiSpan, DUMMY_SP};
+use syntax_pos::{FileName, Span, MultiSpan, DUMMY_SP};
 use syntax_pos::hygiene::{ExpnInfo, ExpnKind};
 
 use rustc_data_structures::fx::FxHashMap;
diff --git a/src/libsyntax/ext/derive.rs b/src/libsyntax/ext/derive.rs
deleted file mode 100644
index ff9ad46deec..00000000000
--- a/src/libsyntax/ext/derive.rs
+++ /dev/null
@@ -1,72 +0,0 @@
-use crate::attr::HasAttrs;
-use crate::ast;
-use crate::source_map::{ExpnInfo, ExpnKind};
-use crate::ext::base::{ExtCtxt, MacroKind};
-use crate::ext::build::AstBuilder;
-use crate::parse::parser::PathStyle;
-use crate::symbol::{Symbol, sym};
-use crate::errors::Applicability;
-
-use syntax_pos::Span;
-use rustc_data_structures::fx::FxHashSet;
-
-pub fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>) -> Vec<ast::Path> {
-    let mut result = Vec::new();
-    attrs.retain(|attr| {
-        if attr.path != sym::derive {
-            return true;
-        }
-        if !attr.is_meta_item_list() {
-            cx.struct_span_err(attr.span, "malformed `derive` attribute input")
-                .span_suggestion(
-                    attr.span,
-                    "missing traits to be derived",
-                    "#[derive(Trait1, Trait2, ...)]".to_owned(),
-                    Applicability::HasPlaceholders,
-                ).emit();
-            return false;
-        }
-
-        match attr.parse_list(cx.parse_sess,
-                              |parser| parser.parse_path_allowing_meta(PathStyle::Mod)) {
-            Ok(traits) => {
-                result.extend(traits);
-                true
-            }
-            Err(mut e) => {
-                e.emit();
-                false
-            }
-        }
-    });
-    result
-}
-
-pub fn add_derived_markers<T>(cx: &mut ExtCtxt<'_>, span: Span, traits: &[ast::Path], item: &mut T)
-    where T: HasAttrs,
-{
-    let (mut names, mut pretty_name) = (FxHashSet::default(), String::new());
-    for (i, path) in traits.iter().enumerate() {
-        if i > 0 {
-            pretty_name.push_str(", ");
-        }
-        pretty_name.push_str(&path.to_string());
-        names.insert(unwrap_or!(path.segments.get(0), continue).ident.name);
-    }
-
-    let span = span.fresh_expansion(cx.current_expansion.id, ExpnInfo::allow_unstable(
-        ExpnKind::Macro(MacroKind::Derive, Symbol::intern(&pretty_name)), span,
-        cx.parse_sess.edition, cx.allow_derive_markers.clone(),
-    ));
-
-    item.visit_attrs(|attrs| {
-        if names.contains(&sym::Eq) && names.contains(&sym::PartialEq) {
-            let meta = cx.meta_word(span, sym::structural_match);
-            attrs.push(cx.attribute(span, meta));
-        }
-        if names.contains(&sym::Copy) {
-            let meta = cx.meta_word(span, sym::rustc_copy_clone_marker);
-            attrs.push(cx.attribute(span, meta));
-        }
-    });
-}
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 640daaccc3a..cd602d08c5b 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -4,7 +4,7 @@ use crate::attr::{self, HasAttrs};
 use crate::source_map::{dummy_spanned, respan};
 use crate::config::StripUnconfigured;
 use crate::ext::base::*;
-use crate::ext::derive::{add_derived_markers, collect_derives};
+use crate::ext::proc_macro::{add_derived_markers, collect_derives};
 use crate::ext::hygiene::{ExpnId, SyntaxContext, ExpnInfo, ExpnKind};
 use crate::ext::placeholders::{placeholder, PlaceholderExpander};
 use crate::feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
diff --git a/src/libsyntax/ext/proc_macro.rs b/src/libsyntax/ext/proc_macro.rs
new file mode 100644
index 00000000000..425b9813f59
--- /dev/null
+++ b/src/libsyntax/ext/proc_macro.rs
@@ -0,0 +1,249 @@
+use crate::ast::{self, ItemKind, Attribute, Mac};
+use crate::attr::{mark_used, mark_known, HasAttrs};
+use crate::errors::{Applicability, FatalError};
+use crate::ext::base::{self, *};
+use crate::ext::build::AstBuilder;
+use crate::ext::proc_macro_server;
+use crate::parse::{self, token};
+use crate::parse::parser::PathStyle;
+use crate::symbol::{sym, Symbol};
+use crate::tokenstream::{self, TokenStream};
+use crate::visit::Visitor;
+
+use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::sync::Lrc;
+use syntax_pos::hygiene::{ExpnInfo, ExpnKind};
+use syntax_pos::{Span, DUMMY_SP};
+
+const EXEC_STRATEGY: proc_macro::bridge::server::SameThread =
+    proc_macro::bridge::server::SameThread;
+
+pub struct BangProcMacro {
+    pub client: proc_macro::bridge::client::Client<
+        fn(proc_macro::TokenStream) -> proc_macro::TokenStream,
+    >,
+}
+
+impl base::ProcMacro for BangProcMacro {
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt<'_>,
+                   span: Span,
+                   input: TokenStream)
+                   -> TokenStream {
+        let server = proc_macro_server::Rustc::new(ecx);
+        match self.client.run(&EXEC_STRATEGY, server, input) {
+            Ok(stream) => stream,
+            Err(e) => {
+                let msg = "proc macro panicked";
+                let mut err = ecx.struct_span_fatal(span, msg);
+                if let Some(s) = e.as_str() {
+                    err.help(&format!("message: {}", s));
+                }
+
+                err.emit();
+                FatalError.raise();
+            }
+        }
+    }
+}
+
+pub struct AttrProcMacro {
+    pub client: proc_macro::bridge::client::Client<
+        fn(proc_macro::TokenStream, proc_macro::TokenStream) -> proc_macro::TokenStream,
+    >,
+}
+
+impl base::AttrProcMacro for AttrProcMacro {
+    fn expand<'cx>(&self,
+                   ecx: &'cx mut ExtCtxt<'_>,
+                   span: Span,
+                   annotation: TokenStream,
+                   annotated: TokenStream)
+                   -> TokenStream {
+        let server = proc_macro_server::Rustc::new(ecx);
+        match self.client.run(&EXEC_STRATEGY, server, annotation, annotated) {
+            Ok(stream) => stream,
+            Err(e) => {
+                let msg = "custom attribute panicked";
+                let mut err = ecx.struct_span_fatal(span, msg);
+                if let Some(s) = e.as_str() {
+                    err.help(&format!("message: {}", s));
+                }
+
+                err.emit();
+                FatalError.raise();
+            }
+        }
+    }
+}
+
+pub struct ProcMacroDerive {
+    pub client: proc_macro::bridge::client::Client<
+        fn(proc_macro::TokenStream) -> proc_macro::TokenStream,
+    >,
+    pub attrs: Vec<ast::Name>,
+}
+
+impl MultiItemModifier for ProcMacroDerive {
+    fn expand(&self,
+              ecx: &mut ExtCtxt<'_>,
+              span: Span,
+              _meta_item: &ast::MetaItem,
+              item: Annotatable)
+              -> Vec<Annotatable> {
+        let item = match item {
+            Annotatable::Item(item) => item,
+            Annotatable::ImplItem(_) |
+            Annotatable::TraitItem(_) |
+            Annotatable::ForeignItem(_) |
+            Annotatable::Stmt(_) |
+            Annotatable::Expr(_) => {
+                ecx.span_err(span, "proc-macro derives may only be \
+                                    applied to a struct, enum, or union");
+                return Vec::new()
+            }
+        };
+        match item.node {
+            ItemKind::Struct(..) |
+            ItemKind::Enum(..) |
+            ItemKind::Union(..) => {},
+            _ => {
+                ecx.span_err(span, "proc-macro derives may only be \
+                                    applied to a struct, enum, or union");
+                return Vec::new()
+            }
+        }
+
+        // Mark attributes as known, and used.
+        MarkAttrs(&self.attrs).visit_item(&item);
+
+        let token = token::Interpolated(Lrc::new(token::NtItem(item)));
+        let input = tokenstream::TokenTree::token(token, DUMMY_SP).into();
+
+        let server = proc_macro_server::Rustc::new(ecx);
+        let stream = match self.client.run(&EXEC_STRATEGY, server, input) {
+            Ok(stream) => stream,
+            Err(e) => {
+                let msg = "proc-macro derive panicked";
+                let mut err = ecx.struct_span_fatal(span, msg);
+                if let Some(s) = e.as_str() {
+                    err.help(&format!("message: {}", s));
+                }
+
+                err.emit();
+                FatalError.raise();
+            }
+        };
+
+        let error_count_before = ecx.parse_sess.span_diagnostic.err_count();
+        let msg = "proc-macro derive produced unparseable tokens";
+
+        let mut parser = parse::stream_to_parser(ecx.parse_sess, stream, Some("proc-macro derive"));
+        let mut items = vec![];
+
+        loop {
+            match parser.parse_item() {
+                Ok(None) => break,
+                Ok(Some(item)) => {
+                    items.push(Annotatable::Item(item))
+                }
+                Err(mut err) => {
+                    // FIXME: handle this better
+                    err.cancel();
+                    ecx.struct_span_fatal(span, msg).emit();
+                    FatalError.raise();
+                }
+            }
+        }
+
+
+        // fail if there have been errors emitted
+        if ecx.parse_sess.span_diagnostic.err_count() > error_count_before {
+            ecx.struct_span_fatal(span, msg).emit();
+            FatalError.raise();
+        }
+
+        items
+    }
+}
+
+struct MarkAttrs<'a>(&'a [ast::Name]);
+
+impl<'a> Visitor<'a> for MarkAttrs<'a> {
+    fn visit_attribute(&mut self, attr: &Attribute) {
+        if let Some(ident) = attr.ident() {
+            if self.0.contains(&ident.name) {
+                mark_used(attr);
+                mark_known(attr);
+            }
+        }
+    }
+
+    fn visit_mac(&mut self, _mac: &Mac) {}
+}
+
+pub fn is_proc_macro_attr(attr: &Attribute) -> bool {
+    [sym::proc_macro, sym::proc_macro_attribute, sym::proc_macro_derive]
+        .iter().any(|kind| attr.check_name(*kind))
+}
+
+crate fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>) -> Vec<ast::Path> {
+    let mut result = Vec::new();
+    attrs.retain(|attr| {
+        if attr.path != sym::derive {
+            return true;
+        }
+        if !attr.is_meta_item_list() {
+            cx.struct_span_err(attr.span, "malformed `derive` attribute input")
+                .span_suggestion(
+                    attr.span,
+                    "missing traits to be derived",
+                    "#[derive(Trait1, Trait2, ...)]".to_owned(),
+                    Applicability::HasPlaceholders,
+                ).emit();
+            return false;
+        }
+
+        match attr.parse_list(cx.parse_sess,
+                              |parser| parser.parse_path_allowing_meta(PathStyle::Mod)) {
+            Ok(traits) => {
+                result.extend(traits);
+                true
+            }
+            Err(mut e) => {
+                e.emit();
+                false
+            }
+        }
+    });
+    result
+}
+
+crate fn add_derived_markers<T: HasAttrs>(
+    cx: &mut ExtCtxt<'_>, span: Span, traits: &[ast::Path], item: &mut T
+) {
+    let (mut names, mut pretty_name) = (FxHashSet::default(), String::new());
+    for (i, path) in traits.iter().enumerate() {
+        if i > 0 {
+            pretty_name.push_str(", ");
+        }
+        pretty_name.push_str(&path.to_string());
+        names.insert(unwrap_or!(path.segments.get(0), continue).ident.name);
+    }
+
+    let span = span.fresh_expansion(cx.current_expansion.id, ExpnInfo::allow_unstable(
+        ExpnKind::Macro(MacroKind::Derive, Symbol::intern(&pretty_name)), span,
+        cx.parse_sess.edition, cx.allow_derive_markers.clone(),
+    ));
+
+    item.visit_attrs(|attrs| {
+        if names.contains(&sym::Eq) && names.contains(&sym::PartialEq) {
+            let meta = cx.meta_word(span, sym::structural_match);
+            attrs.push(cx.attribute(span, meta));
+        }
+        if names.contains(&sym::Copy) {
+            let meta = cx.meta_word(span, sym::rustc_copy_clone_marker);
+            attrs.push(cx.attribute(span, meta));
+        }
+    });
+}
diff --git a/src/libsyntax/ext/proc_macro_server.rs b/src/libsyntax/ext/proc_macro_server.rs
new file mode 100644
index 00000000000..8d0023c9ab1
--- /dev/null
+++ b/src/libsyntax/ext/proc_macro_server.rs
@@ -0,0 +1,715 @@
+use crate::ast;
+use crate::ext::base::ExtCtxt;
+use crate::parse::{self, token, ParseSess};
+use crate::parse::lexer::comments;
+use crate::tokenstream::{self, DelimSpan, IsJoint::*, TokenStream, TreeAndJoint};
+
+use errors::{Diagnostic, DiagnosticBuilder};
+use rustc_data_structures::sync::Lrc;
+use syntax_pos::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
+use syntax_pos::hygiene::{SyntaxContext, Transparency};
+use syntax_pos::symbol::{kw, sym, Symbol};
+
+use proc_macro::{Delimiter, Level, LineColumn, Spacing};
+use proc_macro::bridge::{server, TokenTree};
+use std::{ascii, panic};
+use std::ops::Bound;
+
+trait FromInternal<T> {
+    fn from_internal(x: T) -> Self;
+}
+
+trait ToInternal<T> {
+    fn to_internal(self) -> T;
+}
+
+impl FromInternal<token::DelimToken> for Delimiter {
+    fn from_internal(delim: token::DelimToken) -> Delimiter {
+        match delim {
+            token::Paren => Delimiter::Parenthesis,
+            token::Brace => Delimiter::Brace,
+            token::Bracket => Delimiter::Bracket,
+            token::NoDelim => Delimiter::None,
+        }
+    }
+}
+
+impl ToInternal<token::DelimToken> for Delimiter {
+    fn to_internal(self) -> token::DelimToken {
+        match self {
+            Delimiter::Parenthesis => token::Paren,
+            Delimiter::Brace => token::Brace,
+            Delimiter::Bracket => token::Bracket,
+            Delimiter::None => token::NoDelim,
+        }
+    }
+}
+
+impl FromInternal<(TreeAndJoint, &'_ ParseSess, &'_ mut Vec<Self>)>
+    for TokenTree<Group, Punct, Ident, Literal>
+{
+    fn from_internal(((tree, is_joint), sess, stack): (TreeAndJoint, &ParseSess, &mut Vec<Self>))
+                    -> Self {
+        use crate::parse::token::*;
+
+        let joint = is_joint == Joint;
+        let Token { kind, span } = match tree {
+            tokenstream::TokenTree::Delimited(span, delim, tts) => {
+                let delimiter = Delimiter::from_internal(delim);
+                return TokenTree::Group(Group {
+                    delimiter,
+                    stream: tts.into(),
+                    span,
+                });
+            }
+            tokenstream::TokenTree::Token(token) => token,
+        };
+
+        macro_rules! tt {
+            ($ty:ident { $($field:ident $(: $value:expr)*),+ $(,)? }) => (
+                TokenTree::$ty(self::$ty {
+                    $($field $(: $value)*,)+
+                    span,
+                })
+            );
+            ($ty:ident::$method:ident($($value:expr),*)) => (
+                TokenTree::$ty(self::$ty::$method($($value,)* span))
+            );
+        }
+        macro_rules! op {
+            ($a:expr) => {
+                tt!(Punct::new($a, joint))
+            };
+            ($a:expr, $b:expr) => {{
+                stack.push(tt!(Punct::new($b, joint)));
+                tt!(Punct::new($a, true))
+            }};
+            ($a:expr, $b:expr, $c:expr) => {{
+                stack.push(tt!(Punct::new($c, joint)));
+                stack.push(tt!(Punct::new($b, true)));
+                tt!(Punct::new($a, true))
+            }};
+        }
+
+        match kind {
+            Eq => op!('='),
+            Lt => op!('<'),
+            Le => op!('<', '='),
+            EqEq => op!('=', '='),
+            Ne => op!('!', '='),
+            Ge => op!('>', '='),
+            Gt => op!('>'),
+            AndAnd => op!('&', '&'),
+            OrOr => op!('|', '|'),
+            Not => op!('!'),
+            Tilde => op!('~'),
+            BinOp(Plus) => op!('+'),
+            BinOp(Minus) => op!('-'),
+            BinOp(Star) => op!('*'),
+            BinOp(Slash) => op!('/'),
+            BinOp(Percent) => op!('%'),
+            BinOp(Caret) => op!('^'),
+            BinOp(And) => op!('&'),
+            BinOp(Or) => op!('|'),
+            BinOp(Shl) => op!('<', '<'),
+            BinOp(Shr) => op!('>', '>'),
+            BinOpEq(Plus) => op!('+', '='),
+            BinOpEq(Minus) => op!('-', '='),
+            BinOpEq(Star) => op!('*', '='),
+            BinOpEq(Slash) => op!('/', '='),
+            BinOpEq(Percent) => op!('%', '='),
+            BinOpEq(Caret) => op!('^', '='),
+            BinOpEq(And) => op!('&', '='),
+            BinOpEq(Or) => op!('|', '='),
+            BinOpEq(Shl) => op!('<', '<', '='),
+            BinOpEq(Shr) => op!('>', '>', '='),
+            At => op!('@'),
+            Dot => op!('.'),
+            DotDot => op!('.', '.'),
+            DotDotDot => op!('.', '.', '.'),
+            DotDotEq => op!('.', '.', '='),
+            Comma => op!(','),
+            Semi => op!(';'),
+            Colon => op!(':'),
+            ModSep => op!(':', ':'),
+            RArrow => op!('-', '>'),
+            LArrow => op!('<', '-'),
+            FatArrow => op!('=', '>'),
+            Pound => op!('#'),
+            Dollar => op!('$'),
+            Question => op!('?'),
+            SingleQuote => op!('\''),
+
+            Ident(name, false) if name == kw::DollarCrate => tt!(Ident::dollar_crate()),
+            Ident(name, is_raw) => tt!(Ident::new(name, is_raw)),
+            Lifetime(name) => {
+                let ident = ast::Ident::new(name, span).without_first_quote();
+                stack.push(tt!(Ident::new(ident.name, false)));
+                tt!(Punct::new('\'', true))
+            }
+            Literal(lit) => tt!(Literal { lit }),
+            DocComment(c) => {
+                let style = comments::doc_comment_style(&c.as_str());
+                let stripped = comments::strip_doc_comment_decoration(&c.as_str());
+                let mut escaped = String::new();
+                for ch in stripped.chars() {
+                    escaped.extend(ch.escape_debug());
+                }
+                let stream = vec![
+                    Ident(sym::doc, false),
+                    Eq,
+                    TokenKind::lit(token::Str, Symbol::intern(&escaped), None),
+                ]
+                .into_iter()
+                .map(|kind| tokenstream::TokenTree::token(kind, span))
+                .collect();
+                stack.push(TokenTree::Group(Group {
+                    delimiter: Delimiter::Bracket,
+                    stream,
+                    span: DelimSpan::from_single(span),
+                }));
+                if style == ast::AttrStyle::Inner {
+                    stack.push(tt!(Punct::new('!', false)));
+                }
+                tt!(Punct::new('#', false))
+            }
+
+            Interpolated(nt) => {
+                let stream = nt.to_tokenstream(sess, span);
+                TokenTree::Group(Group {
+                    delimiter: Delimiter::None,
+                    stream,
+                    span: DelimSpan::from_single(span),
+                })
+            }
+
+            OpenDelim(..) | CloseDelim(..) => unreachable!(),
+            Whitespace | Comment | Shebang(..) | Eof => unreachable!(),
+        }
+    }
+}
+
+impl ToInternal<TokenStream> for TokenTree<Group, Punct, Ident, Literal> {
+    fn to_internal(self) -> TokenStream {
+        use crate::parse::token::*;
+
+        let (ch, joint, span) = match self {
+            TokenTree::Punct(Punct { ch, joint, span }) => (ch, joint, span),
+            TokenTree::Group(Group {
+                delimiter,
+                stream,
+                span,
+            }) => {
+                return tokenstream::TokenTree::Delimited(
+                    span,
+                    delimiter.to_internal(),
+                    stream.into(),
+                )
+                .into();
+            }
+            TokenTree::Ident(self::Ident { sym, is_raw, span }) => {
+                return tokenstream::TokenTree::token(Ident(sym, is_raw), span).into();
+            }
+            TokenTree::Literal(self::Literal {
+                lit: token::Lit { kind: token::Integer, symbol, suffix },
+                span,
+            }) if symbol.as_str().starts_with("-") => {
+                let minus = BinOp(BinOpToken::Minus);
+                let symbol = Symbol::intern(&symbol.as_str()[1..]);
+                let integer = TokenKind::lit(token::Integer, symbol, suffix);
+                let a = tokenstream::TokenTree::token(minus, span);
+                let b = tokenstream::TokenTree::token(integer, span);
+                return vec![a, b].into_iter().collect();
+            }
+            TokenTree::Literal(self::Literal {
+                lit: token::Lit { kind: token::Float, symbol, suffix },
+                span,
+            }) if symbol.as_str().starts_with("-") => {
+                let minus = BinOp(BinOpToken::Minus);
+                let symbol = Symbol::intern(&symbol.as_str()[1..]);
+                let float = TokenKind::lit(token::Float, symbol, suffix);
+                let a = tokenstream::TokenTree::token(minus, span);
+                let b = tokenstream::TokenTree::token(float, span);
+                return vec![a, b].into_iter().collect();
+            }
+            TokenTree::Literal(self::Literal { lit, span }) => {
+                return tokenstream::TokenTree::token(Literal(lit), span).into()
+            }
+        };
+
+        let kind = match ch {
+            '=' => Eq,
+            '<' => Lt,
+            '>' => Gt,
+            '!' => Not,
+            '~' => Tilde,
+            '+' => BinOp(Plus),
+            '-' => BinOp(Minus),
+            '*' => BinOp(Star),
+            '/' => BinOp(Slash),
+            '%' => BinOp(Percent),
+            '^' => BinOp(Caret),
+            '&' => BinOp(And),
+            '|' => BinOp(Or),
+            '@' => At,
+            '.' => Dot,
+            ',' => Comma,
+            ';' => Semi,
+            ':' => Colon,
+            '#' => Pound,
+            '$' => Dollar,
+            '?' => Question,
+            '\'' => SingleQuote,
+            _ => unreachable!(),
+        };
+
+        let tree = tokenstream::TokenTree::token(kind, span);
+        TokenStream::new(vec![(tree, if joint { Joint } else { NonJoint })])
+    }
+}
+
+impl ToInternal<errors::Level> for Level {
+    fn to_internal(self) -> errors::Level {
+        match self {
+            Level::Error => errors::Level::Error,
+            Level::Warning => errors::Level::Warning,
+            Level::Note => errors::Level::Note,
+            Level::Help => errors::Level::Help,
+            _ => unreachable!("unknown proc_macro::Level variant: {:?}", self),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct TokenStreamIter {
+    cursor: tokenstream::Cursor,
+    stack: Vec<TokenTree<Group, Punct, Ident, Literal>>,
+}
+
+#[derive(Clone)]
+pub struct Group {
+    delimiter: Delimiter,
+    stream: TokenStream,
+    span: DelimSpan,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Punct {
+    ch: char,
+    // NB. not using `Spacing` here because it doesn't implement `Hash`.
+    joint: bool,
+    span: Span,
+}
+
+impl Punct {
+    fn new(ch: char, joint: bool, span: Span) -> Punct {
+        const LEGAL_CHARS: &[char] = &['=', '<', '>', '!', '~', '+', '-', '*', '/', '%', '^',
+                                       '&', '|', '@', '.', ',', ';', ':', '#', '$', '?', '\''];
+        if !LEGAL_CHARS.contains(&ch) {
+            panic!("unsupported character `{:?}`", ch)
+        }
+        Punct { ch, joint, span }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Ident {
+    sym: Symbol,
+    is_raw: bool,
+    span: Span,
+}
+
+impl Ident {
+    fn is_valid(string: &str) -> bool {
+        let mut chars = string.chars();
+        if let Some(start) = chars.next() {
+            (start == '_' || start.is_xid_start())
+                && chars.all(|cont| cont == '_' || cont.is_xid_continue())
+        } else {
+            false
+        }
+    }
+    fn new(sym: Symbol, is_raw: bool, span: Span) -> Ident {
+        let string = sym.as_str();
+        if !Self::is_valid(&string) {
+            panic!("`{:?}` is not a valid identifier", string)
+        }
+        // Get rid of gensyms to conservatively check rawness on the string contents only.
+        if is_raw && !sym.as_interned_str().as_symbol().can_be_raw() {
+            panic!("`{}` cannot be a raw identifier", string);
+        }
+        Ident { sym, is_raw, span }
+    }
+    fn dollar_crate(span: Span) -> Ident {
+        // `$crate` is accepted as an ident only if it comes from the compiler.
+        Ident { sym: kw::DollarCrate, is_raw: false, span }
+    }
+}
+
+// FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
+#[derive(Clone, Debug)]
+pub struct Literal {
+    lit: token::Lit,
+    span: Span,
+}
+
+pub(crate) struct Rustc<'a> {
+    sess: &'a ParseSess,
+    def_site: Span,
+    call_site: Span,
+}
+
+impl<'a> Rustc<'a> {
+    pub fn new(cx: &'a ExtCtxt<'_>) -> Self {
+        // No way to determine def location for a proc macro right now, so use call location.
+        let location = cx.current_expansion.id.expn_info().unwrap().call_site;
+        let to_span = |transparency| {
+            location.with_ctxt(
+                SyntaxContext::empty()
+                    .apply_mark_with_transparency(cx.current_expansion.id, transparency),
+            )
+        };
+        Rustc {
+            sess: cx.parse_sess,
+            def_site: to_span(Transparency::Opaque),
+            call_site: to_span(Transparency::Transparent),
+        }
+    }
+
+    fn lit(&mut self, kind: token::LitKind, symbol: Symbol, suffix: Option<Symbol>) -> Literal {
+        Literal {
+            lit: token::Lit::new(kind, symbol, suffix),
+            span: server::Span::call_site(self),
+        }
+    }
+}
+
+impl server::Types for Rustc<'_> {
+    type TokenStream = TokenStream;
+    type TokenStreamBuilder = tokenstream::TokenStreamBuilder;
+    type TokenStreamIter = TokenStreamIter;
+    type Group = Group;
+    type Punct = Punct;
+    type Ident = Ident;
+    type Literal = Literal;
+    type SourceFile = Lrc<SourceFile>;
+    type MultiSpan = Vec<Span>;
+    type Diagnostic = Diagnostic;
+    type Span = Span;
+}
+
+impl server::TokenStream for Rustc<'_> {
+    fn new(&mut self) -> Self::TokenStream {
+        TokenStream::empty()
+    }
+    fn is_empty(&mut self, stream: &Self::TokenStream) -> bool {
+        stream.is_empty()
+    }
+    fn from_str(&mut self, src: &str) -> Self::TokenStream {
+        parse::parse_stream_from_source_str(
+            FileName::proc_macro_source_code(src),
+            src.to_string(),
+            self.sess,
+            Some(self.call_site),
+        )
+    }
+    fn to_string(&mut self, stream: &Self::TokenStream) -> String {
+        stream.to_string()
+    }
+    fn from_token_tree(
+        &mut self,
+        tree: TokenTree<Self::Group, Self::Punct, Self::Ident, Self::Literal>,
+    ) -> Self::TokenStream {
+        tree.to_internal()
+    }
+    fn into_iter(&mut self, stream: Self::TokenStream) -> Self::TokenStreamIter {
+        TokenStreamIter {
+            cursor: stream.trees(),
+            stack: vec![],
+        }
+    }
+}
+
+impl server::TokenStreamBuilder for Rustc<'_> {
+    fn new(&mut self) -> Self::TokenStreamBuilder {
+        tokenstream::TokenStreamBuilder::new()
+    }
+    fn push(&mut self, builder: &mut Self::TokenStreamBuilder, stream: Self::TokenStream) {
+        builder.push(stream);
+    }
+    fn build(&mut self, builder: Self::TokenStreamBuilder) -> Self::TokenStream {
+        builder.build()
+    }
+}
+
+impl server::TokenStreamIter for Rustc<'_> {
+    fn next(
+        &mut self,
+        iter: &mut Self::TokenStreamIter,
+    ) -> Option<TokenTree<Self::Group, Self::Punct, Self::Ident, Self::Literal>> {
+        loop {
+            let tree = iter.stack.pop().or_else(|| {
+                let next = iter.cursor.next_with_joint()?;
+                Some(TokenTree::from_internal((next, self.sess, &mut iter.stack)))
+            })?;
+            // HACK: The condition "dummy span + group with empty delimiter" represents an AST
+            // fragment approximately converted into a token stream. This may happen, for
+            // example, with inputs to proc macro attributes, including derives. Such "groups"
+            // need to flattened during iteration over stream's token trees.
+            // Eventually this needs to be removed in favor of keeping original token trees
+            // and not doing the roundtrip through AST.
+            if let TokenTree::Group(ref group) = tree {
+                if group.delimiter == Delimiter::None && group.span.entire().is_dummy() {
+                    iter.cursor.append(group.stream.clone());
+                    continue;
+                }
+            }
+            return Some(tree);
+        }
+    }
+}
+
+impl server::Group for Rustc<'_> {
+    fn new(&mut self, delimiter: Delimiter, stream: Self::TokenStream) -> Self::Group {
+        Group {
+            delimiter,
+            stream,
+            span: DelimSpan::from_single(server::Span::call_site(self)),
+        }
+    }
+    fn delimiter(&mut self, group: &Self::Group) -> Delimiter {
+        group.delimiter
+    }
+    fn stream(&mut self, group: &Self::Group) -> Self::TokenStream {
+        group.stream.clone()
+    }
+    fn span(&mut self, group: &Self::Group) -> Self::Span {
+        group.span.entire()
+    }
+    fn span_open(&mut self, group: &Self::Group) -> Self::Span {
+        group.span.open
+    }
+    fn span_close(&mut self, group: &Self::Group) -> Self::Span {
+        group.span.close
+    }
+    fn set_span(&mut self, group: &mut Self::Group, span: Self::Span) {
+        group.span = DelimSpan::from_single(span);
+    }
+}
+
+impl server::Punct for Rustc<'_> {
+    fn new(&mut self, ch: char, spacing: Spacing) -> Self::Punct {
+        Punct::new(ch, spacing == Spacing::Joint, server::Span::call_site(self))
+    }
+    fn as_char(&mut self, punct: Self::Punct) -> char {
+        punct.ch
+    }
+    fn spacing(&mut self, punct: Self::Punct) -> Spacing {
+        if punct.joint {
+            Spacing::Joint
+        } else {
+            Spacing::Alone
+        }
+    }
+    fn span(&mut self, punct: Self::Punct) -> Self::Span {
+        punct.span
+    }
+    fn with_span(&mut self, punct: Self::Punct, span: Self::Span) -> Self::Punct {
+        Punct { span, ..punct }
+    }
+}
+
+impl server::Ident for Rustc<'_> {
+    fn new(&mut self, string: &str, span: Self::Span, is_raw: bool) -> Self::Ident {
+        Ident::new(Symbol::intern(string), is_raw, span)
+    }
+    fn span(&mut self, ident: Self::Ident) -> Self::Span {
+        ident.span
+    }
+    fn with_span(&mut self, ident: Self::Ident, span: Self::Span) -> Self::Ident {
+        Ident { span, ..ident }
+    }
+}
+
+impl server::Literal for Rustc<'_> {
+    // FIXME(eddyb) `Literal` should not expose internal `Debug` impls.
+    fn debug(&mut self, literal: &Self::Literal) -> String {
+        format!("{:?}", literal)
+    }
+    fn integer(&mut self, n: &str) -> Self::Literal {
+        self.lit(token::Integer, Symbol::intern(n), None)
+    }
+    fn typed_integer(&mut self, n: &str, kind: &str) -> Self::Literal {
+        self.lit(token::Integer, Symbol::intern(n), Some(Symbol::intern(kind)))
+    }
+    fn float(&mut self, n: &str) -> Self::Literal {
+        self.lit(token::Float, Symbol::intern(n), None)
+    }
+    fn f32(&mut self, n: &str) -> Self::Literal {
+        self.lit(token::Float, Symbol::intern(n), Some(sym::f32))
+    }
+    fn f64(&mut self, n: &str) -> Self::Literal {
+        self.lit(token::Float, Symbol::intern(n), Some(sym::f64))
+    }
+    fn string(&mut self, string: &str) -> Self::Literal {
+        let mut escaped = String::new();
+        for ch in string.chars() {
+            escaped.extend(ch.escape_debug());
+        }
+        self.lit(token::Str, Symbol::intern(&escaped), None)
+    }
+    fn character(&mut self, ch: char) -> Self::Literal {
+        let mut escaped = String::new();
+        escaped.extend(ch.escape_unicode());
+        self.lit(token::Char, Symbol::intern(&escaped), None)
+    }
+    fn byte_string(&mut self, bytes: &[u8]) -> Self::Literal {
+        let string = bytes
+            .iter()
+            .cloned()
+            .flat_map(ascii::escape_default)
+            .map(Into::<char>::into)
+            .collect::<String>();
+        self.lit(token::ByteStr, Symbol::intern(&string), None)
+    }
+    fn span(&mut self, literal: &Self::Literal) -> Self::Span {
+        literal.span
+    }
+    fn set_span(&mut self, literal: &mut Self::Literal, span: Self::Span) {
+        literal.span = span;
+    }
+    fn subspan(
+        &mut self,
+        literal: &Self::Literal,
+        start: Bound<usize>,
+        end: Bound<usize>,
+    ) -> Option<Self::Span> {
+        let span = literal.span;
+        let length = span.hi().to_usize() - span.lo().to_usize();
+
+        let start = match start {
+            Bound::Included(lo) => lo,
+            Bound::Excluded(lo) => lo + 1,
+            Bound::Unbounded => 0,
+        };
+
+        let end = match end {
+            Bound::Included(hi) => hi + 1,
+            Bound::Excluded(hi) => hi,
+            Bound::Unbounded => length,
+        };
+
+        // Bounds check the values, preventing addition overflow and OOB spans.
+        if start > u32::max_value() as usize
+            || end > u32::max_value() as usize
+            || (u32::max_value() - start as u32) < span.lo().to_u32()
+            || (u32::max_value() - end as u32) < span.lo().to_u32()
+            || start >= end
+            || end > length
+        {
+            return None;
+        }
+
+        let new_lo = span.lo() + BytePos::from_usize(start);
+        let new_hi = span.lo() + BytePos::from_usize(end);
+        Some(span.with_lo(new_lo).with_hi(new_hi))
+    }
+}
+
+impl server::SourceFile for Rustc<'_> {
+    fn eq(&mut self, file1: &Self::SourceFile, file2: &Self::SourceFile) -> bool {
+        Lrc::ptr_eq(file1, file2)
+    }
+    fn path(&mut self, file: &Self::SourceFile) -> String {
+        match file.name {
+            FileName::Real(ref path) => path
+                .to_str()
+                .expect("non-UTF8 file path in `proc_macro::SourceFile::path`")
+                .to_string(),
+            _ => file.name.to_string(),
+        }
+    }
+    fn is_real(&mut self, file: &Self::SourceFile) -> bool {
+        file.is_real_file()
+    }
+}
+
+impl server::MultiSpan for Rustc<'_> {
+    fn new(&mut self) -> Self::MultiSpan {
+        vec![]
+    }
+    fn push(&mut self, spans: &mut Self::MultiSpan, span: Self::Span) {
+        spans.push(span)
+    }
+}
+
+impl server::Diagnostic for Rustc<'_> {
+    fn new(&mut self, level: Level, msg: &str, spans: Self::MultiSpan) -> Self::Diagnostic {
+        let mut diag = Diagnostic::new(level.to_internal(), msg);
+        diag.set_span(MultiSpan::from_spans(spans));
+        diag
+    }
+    fn sub(
+        &mut self,
+        diag: &mut Self::Diagnostic,
+        level: Level,
+        msg: &str,
+        spans: Self::MultiSpan,
+    ) {
+        diag.sub(level.to_internal(), msg, MultiSpan::from_spans(spans), None);
+    }
+    fn emit(&mut self, diag: Self::Diagnostic) {
+        DiagnosticBuilder::new_diagnostic(&self.sess.span_diagnostic, diag).emit()
+    }
+}
+
+impl server::Span for Rustc<'_> {
+    fn debug(&mut self, span: Self::Span) -> String {
+        format!("{:?} bytes({}..{})", span.ctxt(), span.lo().0, span.hi().0)
+    }
+    fn def_site(&mut self) -> Self::Span {
+        self.def_site
+    }
+    fn call_site(&mut self) -> Self::Span {
+        self.call_site
+    }
+    fn source_file(&mut self, span: Self::Span) -> Self::SourceFile {
+        self.sess.source_map().lookup_char_pos(span.lo()).file
+    }
+    fn parent(&mut self, span: Self::Span) -> Option<Self::Span> {
+        span.ctxt().outer_expn_info().map(|i| i.call_site)
+    }
+    fn source(&mut self, span: Self::Span) -> Self::Span {
+        span.source_callsite()
+    }
+    fn start(&mut self, span: Self::Span) -> LineColumn {
+        let loc = self.sess.source_map().lookup_char_pos(span.lo());
+        LineColumn {
+            line: loc.line,
+            column: loc.col.to_usize(),
+        }
+    }
+    fn end(&mut self, span: Self::Span) -> LineColumn {
+        let loc = self.sess.source_map().lookup_char_pos(span.hi());
+        LineColumn {
+            line: loc.line,
+            column: loc.col.to_usize(),
+        }
+    }
+    fn join(&mut self, first: Self::Span, second: Self::Span) -> Option<Self::Span> {
+        let self_loc = self.sess.source_map().lookup_char_pos(first.lo());
+        let other_loc = self.sess.source_map().lookup_char_pos(second.lo());
+
+        if self_loc.file.name != other_loc.file.name {
+            return None;
+        }
+
+        Some(first.to(second))
+    }
+    fn resolved_at(&mut self, span: Self::Span, at: Self::Span) -> Self::Span {
+        span.with_ctxt(at.ctxt())
+    }
+    fn source_text(&mut self,  span: Self::Span) -> Option<String> {
+        self.sess.source_map().span_to_snippet(span).ok()
+    }
+}
diff --git a/src/libsyntax/ext/source_util.rs b/src/libsyntax/ext/source_util.rs
deleted file mode 100644
index ae080c05eec..00000000000
--- a/src/libsyntax/ext/source_util.rs
+++ /dev/null
@@ -1,165 +0,0 @@
-use crate::ast;
-use crate::ext::base::{self, *};
-use crate::ext::build::AstBuilder;
-use crate::parse::{self, token, DirectoryOwnership};
-use crate::print::pprust;
-use crate::ptr::P;
-use crate::symbol::Symbol;
-use crate::tokenstream;
-
-use smallvec::SmallVec;
-use syntax_pos::{self, Pos, Span};
-
-use std::fs;
-use std::io::ErrorKind;
-use rustc_data_structures::sync::Lrc;
-
-// These macros all relate to the file system; they either return
-// the column/row/filename of the expression, or they include
-// a given file into the current one.
-
-/// line!(): expands to the current line number
-pub fn expand_line(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                   -> Box<dyn base::MacResult+'static> {
-    base::check_zero_tts(cx, sp, tts, "line!");
-
-    let topmost = cx.expansion_cause().unwrap_or(sp);
-    let loc = cx.source_map().lookup_char_pos(topmost.lo());
-
-    base::MacEager::expr(cx.expr_u32(topmost, loc.line as u32))
-}
-
-/* column!(): expands to the current column number */
-pub fn expand_column(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                  -> Box<dyn base::MacResult+'static> {
-    base::check_zero_tts(cx, sp, tts, "column!");
-
-    let topmost = cx.expansion_cause().unwrap_or(sp);
-    let loc = cx.source_map().lookup_char_pos(topmost.lo());
-
-    base::MacEager::expr(cx.expr_u32(topmost, loc.col.to_usize() as u32 + 1))
-}
-
-/// file!(): expands to the current filename */
-/// The source_file (`loc.file`) contains a bunch more information we could spit
-/// out if we wanted.
-pub fn expand_file(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                   -> Box<dyn base::MacResult+'static> {
-    base::check_zero_tts(cx, sp, tts, "file!");
-
-    let topmost = cx.expansion_cause().unwrap_or(sp);
-    let loc = cx.source_map().lookup_char_pos(topmost.lo());
-    base::MacEager::expr(cx.expr_str(topmost, Symbol::intern(&loc.file.name.to_string())))
-}
-
-pub fn expand_stringify(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                        -> Box<dyn base::MacResult+'static> {
-    let s = pprust::tts_to_string(tts);
-    base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&s)))
-}
-
-pub fn expand_mod(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                  -> Box<dyn base::MacResult+'static> {
-    base::check_zero_tts(cx, sp, tts, "module_path!");
-    let mod_path = &cx.current_expansion.module.mod_path;
-    let string = mod_path.iter().map(|x| x.to_string()).collect::<Vec<String>>().join("::");
-
-    base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&string)))
-}
-
-/// include! : parse the given file as an expr
-/// This is generally a bad idea because it's going to behave
-/// unhygienically.
-pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                           -> Box<dyn base::MacResult+'cx> {
-    let file = match get_single_str_from_tts(cx, sp, tts, "include!") {
-        Some(f) => f,
-        None => return DummyResult::any(sp),
-    };
-    // The file will be added to the code map by the parser
-    let file = cx.resolve_path(file, sp);
-    let directory_ownership = DirectoryOwnership::Owned { relative: None };
-    let p = parse::new_sub_parser_from_file(cx.parse_sess(), &file, directory_ownership, None, sp);
-
-    struct ExpandResult<'a> {
-        p: parse::parser::Parser<'a>,
-    }
-    impl<'a> base::MacResult for ExpandResult<'a> {
-        fn make_expr(mut self: Box<ExpandResult<'a>>) -> Option<P<ast::Expr>> {
-            Some(panictry!(self.p.parse_expr()))
-        }
-
-        fn make_items(mut self: Box<ExpandResult<'a>>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
-            let mut ret = SmallVec::new();
-            while self.p.token != token::Eof {
-                match panictry!(self.p.parse_item()) {
-                    Some(item) => ret.push(item),
-                    None => self.p.diagnostic().span_fatal(self.p.token.span,
-                                                           &format!("expected item, found `{}`",
-                                                                    self.p.this_token_to_string()))
-                                               .raise()
-                }
-            }
-            Some(ret)
-        }
-    }
-
-    Box::new(ExpandResult { p })
-}
-
-// include_str! : read the given file, insert it as a literal string expr
-pub fn expand_include_str(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                          -> Box<dyn base::MacResult+'static> {
-    let file = match get_single_str_from_tts(cx, sp, tts, "include_str!") {
-        Some(f) => f,
-        None => return DummyResult::expr(sp)
-    };
-    let file = cx.resolve_path(file, sp);
-    match fs::read_to_string(&file) {
-        Ok(src) => {
-            let interned_src = Symbol::intern(&src);
-
-            // Add this input file to the code map to make it available as
-            // dependency information
-            cx.source_map().new_source_file(file.into(), src);
-
-            base::MacEager::expr(cx.expr_str(sp, interned_src))
-        },
-        Err(ref e) if e.kind() == ErrorKind::InvalidData => {
-            cx.span_err(sp, &format!("{} wasn't a utf-8 file", file.display()));
-            DummyResult::expr(sp)
-        }
-        Err(e) => {
-            cx.span_err(sp, &format!("couldn't read {}: {}", file.display(), e));
-            DummyResult::expr(sp)
-        }
-    }
-}
-
-pub fn expand_include_bytes(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                            -> Box<dyn base::MacResult+'static> {
-    let file = match get_single_str_from_tts(cx, sp, tts, "include_bytes!") {
-        Some(f) => f,
-        None => return DummyResult::expr(sp)
-    };
-    let file = cx.resolve_path(file, sp);
-    match fs::read(&file) {
-        Ok(bytes) => {
-            // Add the contents to the source map if it contains UTF-8.
-            let (contents, bytes) = match String::from_utf8(bytes) {
-                Ok(s) => {
-                    let bytes = s.as_bytes().to_owned();
-                    (s, bytes)
-                },
-                Err(e) => (String::new(), e.into_bytes()),
-            };
-            cx.source_map().new_source_file(file.into(), contents);
-
-            base::MacEager::expr(cx.expr_lit(sp, ast::LitKind::ByteStr(Lrc::new(bytes))))
-        },
-        Err(e) => {
-            cx.span_err(sp, &format!("couldn't read {}: {}", file.display(), e));
-            DummyResult::expr(sp)
-        }
-    }
-}
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 75b4e89ec01..bb6a8dfb141 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -18,12 +18,17 @@
 #![feature(label_break_value)]
 #![feature(mem_take)]
 #![feature(nll)]
+#![feature(proc_macro_diagnostic)]
+#![feature(proc_macro_internals)]
+#![feature(proc_macro_span)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(try_trait)]
 #![feature(unicode_internals)]
 
 #![recursion_limit="256"]
 
+extern crate proc_macro;
+
 pub use errors;
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::bit_set::GrowableBitSet;
@@ -37,6 +42,7 @@ const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
 // way towards a non-panic!-prone parser. It should be used for fatal parsing
 // errors; eventually we plan to convert all code using panictry to just use
 // normal try.
+#[macro_export]
 macro_rules! panictry {
     ($e:expr) => ({
         use std::result::Result::{Ok, Err};
@@ -147,10 +153,8 @@ pub mod mut_visit;
 pub mod parse;
 pub mod ptr;
 pub mod show_span;
-pub mod std_inject;
 pub use syntax_pos::edition;
 pub use syntax_pos::symbol;
-pub mod test;
 pub mod tokenstream;
 pub mod visit;
 
@@ -161,14 +165,15 @@ pub mod print {
 }
 
 pub mod ext {
+    mod placeholders;
+    mod proc_macro_server;
+
     pub use syntax_pos::hygiene;
     pub mod allocator;
     pub mod base;
     pub mod build;
-    pub mod derive;
     pub mod expand;
-    pub mod placeholders;
-    pub mod source_util;
+    pub mod proc_macro;
 
     pub mod tt {
         pub mod transcribe;
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index 1758d0b0bb9..af484c886ab 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -4,6 +4,7 @@ use crate::parse::{SeqSep, PResult};
 use crate::parse::token::{self, Nonterminal, DelimToken};
 use crate::parse::parser::{Parser, TokenType, PathStyle};
 use crate::tokenstream::{TokenStream, TokenTree};
+use crate::source_map::Span;
 
 use log::debug;
 use smallvec::smallvec;
@@ -11,7 +12,7 @@ use smallvec::smallvec;
 #[derive(Debug)]
 enum InnerAttributeParsePolicy<'a> {
     Permitted,
-    NotPermitted { reason: &'a str },
+    NotPermitted { reason: &'a str, saw_doc_comment: bool, prev_attr_sp: Option<Span> },
 }
 
 const DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG: &str = "an inner attribute is not \
@@ -42,7 +43,11 @@ impl<'a> Parser<'a> {
                         DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG
                     };
                     let inner_parse_policy =
-                        InnerAttributeParsePolicy::NotPermitted { reason: inner_error_reason };
+                        InnerAttributeParsePolicy::NotPermitted {
+                            reason: inner_error_reason,
+                            saw_doc_comment: just_parsed_doc_comment,
+                            prev_attr_sp: attrs.last().and_then(|a| Some(a.span))
+                        };
                     let attr = self.parse_attribute_with_inner_parse_policy(inner_parse_policy)?;
                     attrs.push(attr);
                     just_parsed_doc_comment = false;
@@ -76,8 +81,11 @@ impl<'a> Parser<'a> {
         let inner_parse_policy = if permit_inner {
             InnerAttributeParsePolicy::Permitted
         } else {
-            InnerAttributeParsePolicy::NotPermitted
-                { reason: DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG }
+            InnerAttributeParsePolicy::NotPermitted {
+                reason: DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG,
+                saw_doc_comment: false,
+                prev_attr_sp: None
+            }
         };
         self.parse_attribute_with_inner_parse_policy(inner_parse_policy)
     }
@@ -98,19 +106,9 @@ impl<'a> Parser<'a> {
                 if let InnerAttributeParsePolicy::Permitted = inner_parse_policy {
                     self.expected_tokens.push(TokenType::Token(token::Not));
                 }
+
                 let style = if self.token == token::Not {
                     self.bump();
-                    if let InnerAttributeParsePolicy::NotPermitted { reason } = inner_parse_policy
-                    {
-                        let span = self.token.span;
-                        self.diagnostic()
-                            .struct_span_err(span, reason)
-                            .note("inner attributes, like `#![no_std]`, annotate the item \
-                                   enclosing them, and are usually found at the beginning of \
-                                   source files. Outer attributes, like `#[test]`, annotate the \
-                                   item following them.")
-                            .emit()
-                    }
                     ast::AttrStyle::Inner
                 } else {
                     ast::AttrStyle::Outer
@@ -121,7 +119,38 @@ impl<'a> Parser<'a> {
                 self.expect(&token::CloseDelim(token::Bracket))?;
                 let hi = self.prev_span;
 
-                (lo.to(hi), path, tokens, style)
+                let attr_sp = lo.to(hi);
+
+                // Emit error if inner attribute is encountered and not permitted
+                if style == ast::AttrStyle::Inner {
+                    if let InnerAttributeParsePolicy::NotPermitted { reason,
+                        saw_doc_comment, prev_attr_sp } = inner_parse_policy {
+                        let prev_attr_note = if saw_doc_comment {
+                            "previous doc comment"
+                        } else {
+                            "previous outer attribute"
+                        };
+
+                        let mut diagnostic = self
+                            .diagnostic()
+                            .struct_span_err(attr_sp, reason);
+
+                        if let Some(prev_attr_sp) = prev_attr_sp {
+                            diagnostic
+                                .span_label(attr_sp, "not permitted following an outer attibute")
+                                .span_label(prev_attr_sp, prev_attr_note);
+                        }
+
+                        diagnostic
+                            .note("inner attributes, like `#![no_std]`, annotate the item \
+                                   enclosing them, and are usually found at the beginning of \
+                                   source files. Outer attributes, like `#[test]`, annotate the \
+                                   item following them.")
+                            .emit()
+                    }
+                }
+
+                (attr_sp, path, tokens, style)
             }
             _ => {
                 let token_str = self.this_token_to_string();
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 52f65e1b474..3cd5464f357 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -794,7 +794,7 @@ mod tests {
     use std::path::PathBuf;
     use syntax_pos::{BytePos, Span, NO_EXPANSION, edition::Edition};
     use rustc_data_structures::fx::{FxHashSet, FxHashMap};
-    use rustc_data_structures::sync::Lock;
+    use rustc_data_structures::sync::{Lock, Once};
 
     fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
         let emitter = errors::emitter::EmitterWriter::new(Box::new(io::sink()),
@@ -817,6 +817,7 @@ mod tests {
             param_attr_spans: Lock::new(Vec::new()),
             let_chains_spans: Lock::new(Vec::new()),
             async_closure_spans: Lock::new(Vec::new()),
+            injected_crate_name: Once::new(),
         }
     }
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 225065c1cf1..1aac8bbb7aa 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -10,9 +10,10 @@ use crate::parse::token::TokenKind;
 use crate::tokenstream::{TokenStream, TokenTree};
 use crate::diagnostics::plugin::ErrorMap;
 use crate::print::pprust;
+use crate::symbol::Symbol;
 
 use errors::{Applicability, FatalError, Level, Handler, ColorConfig, Diagnostic, DiagnosticBuilder};
-use rustc_data_structures::sync::{Lrc, Lock};
+use rustc_data_structures::sync::{Lrc, Lock, Once};
 use syntax_pos::{Span, SourceFile, FileName, MultiSpan};
 use syntax_pos::edition::Edition;
 
@@ -58,6 +59,7 @@ pub struct ParseSess {
     pub let_chains_spans: Lock<Vec<Span>>,
     // Places where `async || ..` exprs were used and should be feature gated.
     pub async_closure_spans: Lock<Vec<Span>>,
+    pub injected_crate_name: Once<Symbol>,
 }
 
 impl ParseSess {
@@ -86,6 +88,7 @@ impl ParseSess {
             param_attr_spans: Lock::new(Vec::new()),
             let_chains_spans: Lock::new(Vec::new()),
             async_closure_spans: Lock::new(Vec::new()),
+            injected_crate_name: Once::new(),
         }
     }
 
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 16e0bace925..c4623576395 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -10,7 +10,6 @@ use crate::parse::{self, ParseSess};
 use crate::print::pp::{self, Breaks};
 use crate::print::pp::Breaks::{Consistent, Inconsistent};
 use crate::ptr::P;
-use crate::std_inject;
 use crate::symbol::{kw, sym};
 use crate::tokenstream::{self, TokenStream, TokenTree};
 
@@ -114,7 +113,7 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
         is_expanded,
     };
 
-    if is_expanded && std_inject::injected_crate_name().is_some() {
+    if is_expanded && sess.injected_crate_name.try_get().is_some() {
         // We need to print `#![no_std]` (and its feature gate) so that
         // compiling pretty-printed source won't inject libstd again.
         // However we don't want these attributes in the AST because
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
deleted file mode 100644
index 3fba81c0b69..00000000000
--- a/src/libsyntax/std_inject.rs
+++ /dev/null
@@ -1,112 +0,0 @@
-use crate::ast;
-use crate::attr;
-use crate::edition::Edition;
-use crate::ext::hygiene::{ExpnId, MacroKind};
-use crate::symbol::{Ident, Symbol, kw, sym};
-use crate::source_map::{ExpnInfo, ExpnKind, dummy_spanned, respan};
-use crate::ptr::P;
-use crate::tokenstream::TokenStream;
-
-use std::cell::Cell;
-use std::iter;
-use syntax_pos::DUMMY_SP;
-
-pub fn injected_crate_name() -> Option<&'static str> {
-    INJECTED_CRATE_NAME.with(|name| name.get())
-}
-
-thread_local! {
-    // A `Symbol` might make more sense here, but it doesn't work, probably for
-    // reasons relating to the use of thread-local storage for the Symbol
-    // interner.
-    static INJECTED_CRATE_NAME: Cell<Option<&'static str>> = Cell::new(None);
-}
-
-pub fn maybe_inject_crates_ref(
-    mut krate: ast::Crate,
-    alt_std_name: Option<&str>,
-    edition: Edition,
-) -> ast::Crate {
-    let rust_2018 = edition >= Edition::Edition2018;
-
-    // the first name in this list is the crate name of the crate with the prelude
-    let names: &[&str] = if attr::contains_name(&krate.attrs, sym::no_core) {
-        return krate;
-    } else if attr::contains_name(&krate.attrs, sym::no_std) {
-        if attr::contains_name(&krate.attrs, sym::compiler_builtins) {
-            &["core"]
-        } else {
-            &["core", "compiler_builtins"]
-        }
-    } else {
-        &["std"]
-    };
-
-    // .rev() to preserve ordering above in combination with insert(0, ...)
-    let alt_std_name = alt_std_name.map(Symbol::intern);
-    for orig_name_str in names.iter().rev() {
-        // HACK(eddyb) gensym the injected crates on the Rust 2018 edition,
-        // so they don't accidentally interfere with the new import paths.
-        let orig_name_sym = Symbol::intern(orig_name_str);
-        let orig_name_ident = Ident::with_empty_ctxt(orig_name_sym);
-        let (rename, orig_name) = if rust_2018 {
-            (orig_name_ident.gensym(), Some(orig_name_sym))
-        } else {
-            (orig_name_ident, None)
-        };
-        krate.module.items.insert(0, P(ast::Item {
-            attrs: vec![attr::mk_attr_outer(
-                DUMMY_SP,
-                attr::mk_attr_id(),
-                attr::mk_word_item(ast::Ident::with_empty_ctxt(sym::macro_use))
-            )],
-            vis: dummy_spanned(ast::VisibilityKind::Inherited),
-            node: ast::ItemKind::ExternCrate(alt_std_name.or(orig_name)),
-            ident: rename,
-            id: ast::DUMMY_NODE_ID,
-            span: DUMMY_SP,
-            tokens: None,
-        }));
-    }
-
-    // the crates have been injected, the assumption is that the first one is the one with
-    // the prelude.
-    let name = names[0];
-
-    INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
-
-    let span = DUMMY_SP.fresh_expansion(ExpnId::root(), ExpnInfo::allow_unstable(
-        ExpnKind::Macro(MacroKind::Attr, sym::std_inject), DUMMY_SP, edition,
-        [sym::prelude_import][..].into(),
-    ));
-
-    krate.module.items.insert(0, P(ast::Item {
-        attrs: vec![ast::Attribute {
-            style: ast::AttrStyle::Outer,
-            path: ast::Path::from_ident(ast::Ident::new(sym::prelude_import, span)),
-            tokens: TokenStream::empty(),
-            id: attr::mk_attr_id(),
-            is_sugared_doc: false,
-            span,
-        }],
-        vis: respan(span.shrink_to_lo(), ast::VisibilityKind::Inherited),
-        node: ast::ItemKind::Use(P(ast::UseTree {
-            prefix: ast::Path {
-                segments: iter::once(ast::Ident::with_empty_ctxt(kw::PathRoot))
-                    .chain(
-                        [name, "prelude", "v1"].iter().cloned()
-                            .map(ast::Ident::from_str)
-                    ).map(ast::PathSegment::from_ident).collect(),
-                span,
-            },
-            kind: ast::UseTreeKind::Glob,
-            span,
-        })),
-        id: ast::DUMMY_NODE_ID,
-        ident: ast::Ident::invalid(),
-        span,
-        tokens: None,
-    }));
-
-    krate
-}
diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs
deleted file mode 100644
index 2ada7104843..00000000000
--- a/src/libsyntax/test.rs
+++ /dev/null
@@ -1,424 +0,0 @@
-// Code that generates a test runner to run all the tests in a crate
-
-#![allow(dead_code)]
-#![allow(unused_imports)]
-
-use HasTestSignature::*;
-
-use std::iter;
-use std::slice;
-use std::mem;
-use std::vec;
-
-use log::debug;
-use smallvec::{smallvec, SmallVec};
-use syntax_pos::{DUMMY_SP, NO_EXPANSION, Span, SourceFile, BytePos};
-
-use crate::attr::{self, HasAttrs};
-use crate::source_map::{self, SourceMap, ExpnInfo, ExpnKind, dummy_spanned, respan};
-use crate::config;
-use crate::entry::{self, EntryPointType};
-use crate::ext::base::{ExtCtxt, Resolver};
-use crate::ext::build::AstBuilder;
-use crate::ext::expand::ExpansionConfig;
-use crate::ext::hygiene::{self, ExpnId, SyntaxContext, MacroKind};
-use crate::mut_visit::{*, ExpectOne};
-use crate::feature_gate::Features;
-use crate::util::map_in_place::MapInPlace;
-use crate::parse::{token, ParseSess};
-use crate::ast::{self, Ident};
-use crate::ptr::P;
-use crate::symbol::{self, Symbol, kw, sym};
-use crate::ThinVec;
-
-struct Test {
-    span: Span,
-    path: Vec<Ident>,
-}
-
-struct TestCtxt<'a> {
-    span_diagnostic: &'a errors::Handler,
-    path: Vec<Ident>,
-    ext_cx: ExtCtxt<'a>,
-    test_cases: Vec<Test>,
-    reexport_test_harness_main: Option<Symbol>,
-    is_libtest: bool,
-    features: &'a Features,
-    test_runner: Option<ast::Path>,
-
-    // top-level re-export submodule, filled out after folding is finished
-    toplevel_reexport: Option<Ident>,
-}
-
-// Traverse the crate, collecting all the test functions, eliding any
-// existing main functions, and synthesizing a main test harness
-pub fn modify_for_testing(sess: &ParseSess,
-                          resolver: &mut dyn Resolver,
-                          should_test: bool,
-                          krate: &mut ast::Crate,
-                          span_diagnostic: &errors::Handler,
-                          features: &Features) {
-    // Check for #[reexport_test_harness_main = "some_name"] which
-    // creates a `use __test::main as some_name;`. This needs to be
-    // unconditional, so that the attribute is still marked as used in
-    // non-test builds.
-    let reexport_test_harness_main =
-        attr::first_attr_value_str_by_name(&krate.attrs, sym::reexport_test_harness_main);
-
-    // Do this here so that the test_runner crate attribute gets marked as used
-    // even in non-test builds
-    let test_runner = get_test_runner(span_diagnostic, &krate);
-
-    if should_test {
-        generate_test_harness(sess, resolver, reexport_test_harness_main,
-                              krate, span_diagnostic, features, test_runner)
-    }
-}
-
-struct TestHarnessGenerator<'a> {
-    cx: TestCtxt<'a>,
-    tests: Vec<Ident>,
-
-    // submodule name, gensym'd identifier for re-exports
-    tested_submods: Vec<(Ident, Ident)>,
-}
-
-impl<'a> MutVisitor for TestHarnessGenerator<'a> {
-    fn visit_crate(&mut self, c: &mut ast::Crate) {
-        noop_visit_crate(c, self);
-
-        // Create a main function to run our tests
-        let test_main = {
-            let unresolved = mk_main(&mut self.cx);
-            self.cx.ext_cx.monotonic_expander().flat_map_item(unresolved).pop().unwrap()
-        };
-
-        c.module.items.push(test_main);
-    }
-
-    fn flat_map_item(&mut self, i: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
-        let ident = i.ident;
-        if ident.name != kw::Invalid {
-            self.cx.path.push(ident);
-        }
-        debug!("current path: {}", path_name_i(&self.cx.path));
-
-        let mut item = i.into_inner();
-        if is_test_case(&item) {
-            debug!("this is a test item");
-
-            let test = Test {
-                span: item.span,
-                path: self.cx.path.clone(),
-            };
-            self.cx.test_cases.push(test);
-            self.tests.push(item.ident);
-        }
-
-        // We don't want to recurse into anything other than mods, since
-        // mods or tests inside of functions will break things
-        if let ast::ItemKind::Mod(mut module) = item.node {
-            let tests = mem::take(&mut self.tests);
-            let tested_submods = mem::take(&mut self.tested_submods);
-            noop_visit_mod(&mut module, self);
-            let tests = mem::replace(&mut self.tests, tests);
-            let tested_submods = mem::replace(&mut self.tested_submods, tested_submods);
-
-            if !tests.is_empty() || !tested_submods.is_empty() {
-                let (it, sym) = mk_reexport_mod(&mut self.cx, item.id, tests, tested_submods);
-                module.items.push(it);
-
-                if !self.cx.path.is_empty() {
-                    self.tested_submods.push((self.cx.path[self.cx.path.len()-1], sym));
-                } else {
-                    debug!("pushing nothing, sym: {:?}", sym);
-                    self.cx.toplevel_reexport = Some(sym);
-                }
-            }
-            item.node = ast::ItemKind::Mod(module);
-        }
-        if ident.name != kw::Invalid {
-            self.cx.path.pop();
-        }
-        smallvec![P(item)]
-    }
-
-    fn visit_mac(&mut self, _mac: &mut ast::Mac) {
-        // Do nothing.
-    }
-}
-
-/// A folder used to remove any entry points (like fn main) because the harness
-/// generator will provide its own
-struct EntryPointCleaner {
-    // Current depth in the ast
-    depth: usize,
-}
-
-impl MutVisitor for EntryPointCleaner {
-    fn flat_map_item(&mut self, i: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
-        self.depth += 1;
-        let item = noop_flat_map_item(i, self).expect_one("noop did something");
-        self.depth -= 1;
-
-        // Remove any #[main] or #[start] from the AST so it doesn't
-        // clash with the one we're going to add, but mark it as
-        // #[allow(dead_code)] to avoid printing warnings.
-        let item = match entry::entry_point_type(&item, self.depth) {
-            EntryPointType::MainNamed |
-            EntryPointType::MainAttr |
-            EntryPointType::Start =>
-                item.map(|ast::Item {id, ident, attrs, node, vis, span, tokens}| {
-                    let allow_ident = Ident::with_empty_ctxt(sym::allow);
-                    let dc_nested = attr::mk_nested_word_item(Ident::from_str("dead_code"));
-                    let allow_dead_code_item = attr::mk_list_item(DUMMY_SP, allow_ident,
-                                                                  vec![dc_nested]);
-                    let allow_dead_code = attr::mk_attr_outer(DUMMY_SP,
-                                                              attr::mk_attr_id(),
-                                                              allow_dead_code_item);
-
-                    ast::Item {
-                        id,
-                        ident,
-                        attrs: attrs.into_iter()
-                            .filter(|attr| {
-                                !attr.check_name(sym::main) && !attr.check_name(sym::start)
-                            })
-                            .chain(iter::once(allow_dead_code))
-                            .collect(),
-                        node,
-                        vis,
-                        span,
-                        tokens,
-                    }
-                }),
-            EntryPointType::None |
-            EntryPointType::OtherMain => item,
-        };
-
-        smallvec![item]
-    }
-
-    fn visit_mac(&mut self, _mac: &mut ast::Mac) {
-        // Do nothing.
-    }
-}
-
-/// Creates an item (specifically a module) that "pub use"s the tests passed in.
-/// Each tested submodule will contain a similar reexport module that we will export
-/// under the name of the original module. That is, `submod::__test_reexports` is
-/// reexported like so `pub use submod::__test_reexports as submod`.
-fn mk_reexport_mod(cx: &mut TestCtxt<'_>,
-                   parent: ast::NodeId,
-                   tests: Vec<Ident>,
-                   tested_submods: Vec<(Ident, Ident)>)
-                   -> (P<ast::Item>, Ident) {
-    let super_ = Ident::with_empty_ctxt(kw::Super);
-
-    let items = tests.into_iter().map(|r| {
-        cx.ext_cx.item_use_simple(DUMMY_SP, dummy_spanned(ast::VisibilityKind::Public),
-                                  cx.ext_cx.path(DUMMY_SP, vec![super_, r]))
-    }).chain(tested_submods.into_iter().map(|(r, sym)| {
-        let path = cx.ext_cx.path(DUMMY_SP, vec![super_, r, sym]);
-        cx.ext_cx.item_use_simple_(DUMMY_SP, dummy_spanned(ast::VisibilityKind::Public),
-                                   Some(r), path)
-    })).collect();
-
-    let reexport_mod = ast::Mod {
-        inline: true,
-        inner: DUMMY_SP,
-        items,
-    };
-
-    let name = Ident::from_str("__test_reexports").gensym();
-    let parent = if parent == ast::DUMMY_NODE_ID { ast::CRATE_NODE_ID } else { parent };
-    cx.ext_cx.current_expansion.id = cx.ext_cx.resolver.get_module_scope(parent);
-    let it = cx.ext_cx.monotonic_expander().flat_map_item(P(ast::Item {
-        ident: name,
-        attrs: Vec::new(),
-        id: ast::DUMMY_NODE_ID,
-        node: ast::ItemKind::Mod(reexport_mod),
-        vis: dummy_spanned(ast::VisibilityKind::Public),
-        span: DUMMY_SP,
-        tokens: None,
-    })).pop().unwrap();
-
-    (it, name)
-}
-
-/// Crawl over the crate, inserting test reexports and the test main function
-fn generate_test_harness(sess: &ParseSess,
-                         resolver: &mut dyn Resolver,
-                         reexport_test_harness_main: Option<Symbol>,
-                         krate: &mut ast::Crate,
-                         sd: &errors::Handler,
-                         features: &Features,
-                         test_runner: Option<ast::Path>) {
-    // Remove the entry points
-    let mut cleaner = EntryPointCleaner { depth: 0 };
-    cleaner.visit_crate(krate);
-
-    let mut econfig = ExpansionConfig::default("test".to_string());
-    econfig.features = Some(features);
-
-    let cx = TestCtxt {
-        span_diagnostic: sd,
-        ext_cx: ExtCtxt::new(sess, econfig, resolver),
-        path: Vec::new(),
-        test_cases: Vec::new(),
-        reexport_test_harness_main,
-        // N.B., doesn't consider the value of `--crate-name` passed on the command line.
-        is_libtest: attr::find_crate_name(&krate.attrs)
-            .map(|s| s == sym::test).unwrap_or(false),
-        toplevel_reexport: None,
-        features,
-        test_runner
-    };
-
-    TestHarnessGenerator {
-        cx,
-        tests: Vec::new(),
-        tested_submods: Vec::new(),
-    }.visit_crate(krate);
-}
-
-enum HasTestSignature {
-    Yes,
-    No(BadTestSignature),
-}
-
-#[derive(PartialEq)]
-enum BadTestSignature {
-    NotEvenAFunction,
-    WrongTypeSignature,
-    NoArgumentsAllowed,
-    ShouldPanicOnlyWithNoArgs,
-}
-
-/// Creates a function item for use as the main function of a test build.
-/// This function will call the `test_runner` as specified by the crate attribute
-fn mk_main(cx: &mut TestCtxt<'_>) -> P<ast::Item> {
-    // Writing this out by hand:
-    //        pub fn main() {
-    //            #![main]
-    //            test::test_main_static(&[..tests]);
-    //        }
-    let sp = DUMMY_SP.fresh_expansion(ExpnId::root(), ExpnInfo::allow_unstable(
-        ExpnKind::Macro(MacroKind::Attr, sym::test_case), DUMMY_SP, cx.ext_cx.parse_sess.edition,
-        [sym::main, sym::test, sym::rustc_attrs][..].into(),
-    ));
-    let ecx = &cx.ext_cx;
-    let test_id = Ident::with_empty_ctxt(sym::test);
-
-    // test::test_main_static(...)
-    let mut test_runner = cx.test_runner.clone().unwrap_or(
-        ecx.path(sp, vec![
-            test_id, ecx.ident_of("test_main_static")
-        ]));
-
-    test_runner.span = sp;
-
-    let test_main_path_expr = ecx.expr_path(test_runner);
-    let call_test_main = ecx.expr_call(sp, test_main_path_expr,
-                                       vec![mk_tests_slice(cx)]);
-    let call_test_main = ecx.stmt_expr(call_test_main);
-
-    // #![main]
-    let main_meta = ecx.meta_word(sp, sym::main);
-    let main_attr = ecx.attribute(sp, main_meta);
-
-    // extern crate test as test_gensym
-    let test_extern_stmt = ecx.stmt_item(sp, ecx.item(sp,
-        test_id,
-        vec![],
-        ast::ItemKind::ExternCrate(None)
-    ));
-
-    // pub fn main() { ... }
-    let main_ret_ty = ecx.ty(sp, ast::TyKind::Tup(vec![]));
-
-    // If no test runner is provided we need to import the test crate
-    let main_body = if cx.test_runner.is_none() {
-        ecx.block(sp, vec![test_extern_stmt, call_test_main])
-    } else {
-        ecx.block(sp, vec![call_test_main])
-    };
-
-    let main = ast::ItemKind::Fn(ecx.fn_decl(vec![], ast::FunctionRetTy::Ty(main_ret_ty)),
-                           ast::FnHeader::default(),
-                           ast::Generics::default(),
-                           main_body);
-
-    // Honor the reexport_test_harness_main attribute
-    let main_id = match cx.reexport_test_harness_main {
-        Some(sym) => Ident::new(sym, sp),
-        None => Ident::from_str_and_span("main", sp).gensym(),
-    };
-
-    P(ast::Item {
-        ident: main_id,
-        attrs: vec![main_attr],
-        id: ast::DUMMY_NODE_ID,
-        node: main,
-        vis: dummy_spanned(ast::VisibilityKind::Public),
-        span: sp,
-        tokens: None,
-    })
-
-}
-
-fn path_name_i(idents: &[Ident]) -> String {
-    let mut path_name = "".to_string();
-    let mut idents_iter = idents.iter().peekable();
-    while let Some(ident) = idents_iter.next() {
-        path_name.push_str(&ident.as_str());
-        if idents_iter.peek().is_some() {
-            path_name.push_str("::")
-        }
-    }
-    path_name
-}
-
-/// Creates a slice containing every test like so:
-/// &[path::to::test1, path::to::test2]
-fn mk_tests_slice(cx: &TestCtxt<'_>) -> P<ast::Expr> {
-    debug!("building test vector from {} tests", cx.test_cases.len());
-    let ref ecx = cx.ext_cx;
-
-    ecx.expr_vec_slice(DUMMY_SP,
-        cx.test_cases.iter().map(|test| {
-            ecx.expr_addr_of(test.span,
-                ecx.expr_path(ecx.path(test.span, visible_path(cx, &test.path))))
-        }).collect())
-}
-
-/// Creates a path from the top-level __test module to the test via __test_reexports
-fn visible_path(cx: &TestCtxt<'_>, path: &[Ident]) -> Vec<Ident>{
-    let mut visible_path = vec![];
-    match cx.toplevel_reexport {
-        Some(id) => visible_path.push(id),
-        None => {
-            cx.span_diagnostic.bug("expected to find top-level re-export name, but found None");
-        }
-    }
-    visible_path.extend_from_slice(path);
-    visible_path
-}
-
-fn is_test_case(i: &ast::Item) -> bool {
-    attr::contains_name(&i.attrs, sym::rustc_test_marker)
-}
-
-fn get_test_runner(sd: &errors::Handler, krate: &ast::Crate) -> Option<ast::Path> {
-    let test_attr = attr::find_by_name(&krate.attrs, sym::test_runner)?;
-    test_attr.meta_item_list().map(|meta_list| {
-        if meta_list.len() != 1 {
-            sd.span_fatal(test_attr.span,
-                "`#![test_runner(..)]` accepts exactly 1 argument").raise()
-        }
-        match meta_list[0].meta_item() {
-            Some(meta_item) if meta_item.is_word() => meta_item.path.clone(),
-            _ => sd.span_fatal(test_attr.span, "`test_runner` argument must be a path").raise()
-        }
-    })
-}