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authorbors <bors@rust-lang.org>2019-07-28 01:03:16 +0000
committerbors <bors@rust-lang.org>2019-07-28 01:03:16 +0000
commit9a239ef4ded03d155c72b68b5a2dd7aff013e141 (patch)
treeddecacf7cf04b32211999b7d65dae0bbf2012102 /src/libsyntax_ext
parentc798dffac9dc8c82374db48f5b474690cc6e9686 (diff)
parent34c0f4698bda7e06d66ee9040a2923250b0c12d0 (diff)
downloadrust-9a239ef4ded03d155c72b68b5a2dd7aff013e141.tar.gz
rust-9a239ef4ded03d155c72b68b5a2dd7aff013e141.zip
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
Diffstat (limited to 'src/libsyntax_ext')
-rw-r--r--src/libsyntax_ext/Cargo.toml8
-rw-r--r--src/libsyntax_ext/deriving/custom.rs119
-rw-r--r--src/libsyntax_ext/deriving/generic/mod.rs44
-rw-r--r--src/libsyntax_ext/deriving/generic/ty.rs8
-rw-r--r--src/libsyntax_ext/deriving/mod.rs1
-rw-r--r--src/libsyntax_ext/lib.rs23
-rw-r--r--src/libsyntax_ext/proc_macro_harness.rs (renamed from src/libsyntax_ext/proc_macro_decls.rs)14
-rw-r--r--src/libsyntax_ext/proc_macro_impl.rs68
-rw-r--r--src/libsyntax_ext/proc_macro_server.rs717
-rw-r--r--src/libsyntax_ext/source_util.rs165
-rw-r--r--src/libsyntax_ext/standard_library_imports.rs95
-rw-r--r--src/libsyntax_ext/test.rs33
-rw-r--r--src/libsyntax_ext/test_case.rs44
-rw-r--r--src/libsyntax_ext/test_harness.rs394
14 files changed, 703 insertions, 1030 deletions
diff --git a/src/libsyntax_ext/Cargo.toml b/src/libsyntax_ext/Cargo.toml
index eafbe6371a3..73310df305b 100644
--- a/src/libsyntax_ext/Cargo.toml
+++ b/src/libsyntax_ext/Cargo.toml
@@ -10,11 +10,11 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-fmt_macros = { path = "../libfmt_macros" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
-syntax = { path = "../libsyntax" }
-syntax_pos = { path = "../libsyntax_pos" }
+fmt_macros = { path = "../libfmt_macros" }
+log = "0.4"
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
-log = "0.4"
+syntax = { path = "../libsyntax" }
+syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/libsyntax_ext/deriving/custom.rs b/src/libsyntax_ext/deriving/custom.rs
deleted file mode 100644
index 98465d75e46..00000000000
--- a/src/libsyntax_ext/deriving/custom.rs
+++ /dev/null
@@ -1,119 +0,0 @@
-use crate::proc_macro_impl::EXEC_STRATEGY;
-use crate::proc_macro_server;
-
-use errors::FatalError;
-use rustc_data_structures::sync::Lrc;
-use syntax::ast::{self, ItemKind, Attribute, Mac};
-use syntax::attr::{mark_used, mark_known};
-use syntax::source_map::Span;
-use syntax::ext::base::*;
-use syntax::parse;
-use syntax::parse::token;
-use syntax::tokenstream;
-use syntax::visit::Visitor;
-use syntax_pos::DUMMY_SP;
-
-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 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
-    }
-}
diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index 12482f7248e..7f27769f236 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -1770,50 +1770,6 @@ pub fn cs_fold1<F, B>(use_foldl: bool,
     }
 }
 
-/// Call the method that is being derived on all the fields, and then
-/// process the collected results. i.e.
-///
-/// ```ignore (only-for-syntax-highlight)
-/// f(cx, span, vec![self_1.method(__arg_1_1, __arg_2_1),
-///                  self_2.method(__arg_1_2, __arg_2_2)])
-/// ```
-#[inline]
-pub fn cs_same_method<F>(f: F,
-                         mut enum_nonmatch_f: EnumNonMatchCollapsedFunc<'_>,
-                         cx: &mut ExtCtxt<'_>,
-                         trait_span: Span,
-                         substructure: &Substructure<'_>)
-                         -> P<Expr>
-    where F: FnOnce(&mut ExtCtxt<'_>, Span, Vec<P<Expr>>) -> P<Expr>
-{
-    match *substructure.fields {
-        EnumMatching(.., ref all_fields) |
-        Struct(_, ref all_fields) => {
-            // call self_n.method(other_1_n, other_2_n, ...)
-            let called = all_fields.iter()
-                .map(|field| {
-                    cx.expr_method_call(field.span,
-                                        field.self_.clone(),
-                                        substructure.method_ident,
-                                        field.other
-                                            .iter()
-                                            .map(|e| cx.expr_addr_of(field.span, e.clone()))
-                                            .collect())
-                })
-                .collect();
-
-            f(cx, trait_span, called)
-        }
-        EnumNonMatchingCollapsed(ref all_self_args, _, tuple) => {
-            enum_nonmatch_f(cx,
-                            trait_span,
-                            (&all_self_args[..], tuple),
-                            substructure.nonself_args)
-        }
-        StaticEnum(..) | StaticStruct(..) => cx.span_bug(trait_span, "static function in `derive`"),
-    }
-}
-
 /// Returns `true` if the type has no value fields
 /// (for an enum, no variant has any fields)
 pub fn is_type_without_fields(item: &Annotatable) -> bool {
diff --git a/src/libsyntax_ext/deriving/generic/ty.rs b/src/libsyntax_ext/deriving/generic/ty.rs
index fef1b4eebcf..394beb14171 100644
--- a/src/libsyntax_ext/deriving/generic/ty.rs
+++ b/src/libsyntax_ext/deriving/generic/ty.rs
@@ -18,6 +18,7 @@ pub enum PtrTy<'a> {
     /// &'lifetime mut
     Borrowed(Option<&'a str>, ast::Mutability),
     /// *mut
+    #[allow(dead_code)]
     Raw(ast::Mutability),
 }
 
@@ -107,13 +108,6 @@ pub enum Ty<'a> {
     Tuple(Vec<Ty<'a>>),
 }
 
-/// A const expression. Supports literals and blocks.
-#[derive(Clone, Eq, PartialEq)]
-pub enum Const {
-    Literal,
-    Block,
-}
-
 pub fn borrowed_ptrty<'r>() -> PtrTy<'r> {
     Borrowed(None, ast::Mutability::Immutable)
 }
diff --git a/src/libsyntax_ext/deriving/mod.rs b/src/libsyntax_ext/deriving/mod.rs
index 1a865099288..cad79917af2 100644
--- a/src/libsyntax_ext/deriving/mod.rs
+++ b/src/libsyntax_ext/deriving/mod.rs
@@ -26,7 +26,6 @@ pub mod decodable;
 pub mod hash;
 pub mod debug;
 pub mod default;
-pub mod custom;
 
 #[path="cmp/partial_eq.rs"]
 pub mod partial_eq;
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 7940abed245..fae884860ed 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -1,4 +1,5 @@
-//! Syntax extensions in the Rust compiler.
+//! This crate contains implementations of built-in macros and other code generating facilities
+//! injecting code into the crate before it is lowered to HIR.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
@@ -7,21 +8,15 @@
 
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
+#![feature(mem_take)]
 #![feature(nll)]
-#![feature(proc_macro_diagnostic)]
-#![feature(proc_macro_internals)]
-#![feature(proc_macro_span)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(unicode_internals)]
-
-extern crate proc_macro;
 
 use crate::deriving::*;
 
 use syntax::ast::Ident;
 use syntax::edition::Edition;
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind, MacroExpanderFn};
-use syntax::ext::source_util;
 use syntax::symbol::sym;
 
 mod error_codes;
@@ -32,21 +27,21 @@ mod cfg;
 mod compile_error;
 mod concat;
 mod concat_idents;
+mod deriving;
 mod env;
 mod format;
 mod format_foreign;
 mod global_allocator;
 mod global_asm;
 mod log_syntax;
-mod proc_macro_server;
+mod source_util;
 mod test;
-mod test_case;
 mod trace_macros;
 
-pub mod deriving;
 pub mod plugin_macro_defs;
-pub mod proc_macro_decls;
-pub mod proc_macro_impl;
+pub mod proc_macro_harness;
+pub mod standard_library_imports;
+pub mod test_harness;
 
 pub fn register_builtin_macros(resolver: &mut dyn syntax::ext::base::Resolver, edition: Edition) {
     let mut register = |name, kind| resolver.register_builtin_macro(
@@ -93,7 +88,7 @@ pub fn register_builtin_macros(resolver: &mut dyn syntax::ext::base::Resolver, e
         bench: test::expand_bench,
         global_allocator: global_allocator::expand,
         test: test::expand_test,
-        test_case: test_case::expand,
+        test_case: test::expand_test_case,
     }
 
     register_derive! {
diff --git a/src/libsyntax_ext/proc_macro_decls.rs b/src/libsyntax_ext/proc_macro_harness.rs
index 303d5f00deb..fc6cd5dc94c 100644
--- a/src/libsyntax_ext/proc_macro_decls.rs
+++ b/src/libsyntax_ext/proc_macro_harness.rs
@@ -7,21 +7,15 @@ use syntax::ext::base::{ExtCtxt, MacroKind};
 use syntax::ext::build::AstBuilder;
 use syntax::ext::expand::ExpansionConfig;
 use syntax::ext::hygiene::ExpnId;
+use syntax::ext::proc_macro::is_proc_macro_attr;
 use syntax::mut_visit::MutVisitor;
 use syntax::parse::ParseSess;
 use syntax::ptr::P;
-use syntax::symbol::Symbol;
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
 
 use syntax_pos::{Span, DUMMY_SP};
 
-const PROC_MACRO_KINDS: [Symbol; 3] = [
-    sym::proc_macro_derive,
-    sym::proc_macro_attribute,
-    sym::proc_macro
-];
-
 struct ProcMacroDerive {
     trait_name: ast::Name,
     function_name: Ident,
@@ -44,7 +38,7 @@ struct CollectProcMacros<'a> {
     is_test_crate: bool,
 }
 
-pub fn modify(sess: &ParseSess,
+pub fn inject(sess: &ParseSess,
               resolver: &mut dyn (::syntax::ext::base::Resolver),
               mut krate: ast::Crate,
               is_proc_macro_crate: bool,
@@ -88,10 +82,6 @@ pub fn modify(sess: &ParseSess,
     krate
 }
 
-pub fn is_proc_macro_attr(attr: &ast::Attribute) -> bool {
-    PROC_MACRO_KINDS.iter().any(|kind| attr.check_name(*kind))
-}
-
 impl<'a> CollectProcMacros<'a> {
     fn check_not_pub_in_root(&self, vis: &ast::Visibility, sp: Span) {
         if self.is_proc_macro_crate && self.in_root && vis.node.is_pub() {
diff --git a/src/libsyntax_ext/proc_macro_impl.rs b/src/libsyntax_ext/proc_macro_impl.rs
deleted file mode 100644
index f0fc6392cd7..00000000000
--- a/src/libsyntax_ext/proc_macro_impl.rs
+++ /dev/null
@@ -1,68 +0,0 @@
-use crate::proc_macro_server;
-
-use errors::FatalError;
-use syntax::source_map::Span;
-use syntax::ext::base::{self, *};
-use syntax::tokenstream::TokenStream;
-
-pub const EXEC_STRATEGY: proc_macro::bridge::server::SameThread =
-    proc_macro::bridge::server::SameThread;
-
-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 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();
-            }
-        }
-    }
-}
diff --git a/src/libsyntax_ext/proc_macro_server.rs b/src/libsyntax_ext/proc_macro_server.rs
deleted file mode 100644
index e94d79a140d..00000000000
--- a/src/libsyntax_ext/proc_macro_server.rs
+++ /dev/null
@@ -1,717 +0,0 @@
-use errors::{Diagnostic, DiagnosticBuilder};
-
-use std::panic;
-
-use proc_macro::bridge::{server, TokenTree};
-use proc_macro::{Delimiter, Level, LineColumn, Spacing};
-
-use rustc_data_structures::sync::Lrc;
-use std::ascii;
-use std::ops::Bound;
-use syntax::ast;
-use syntax::ext::base::ExtCtxt;
-use syntax::parse::lexer::comments;
-use syntax::parse::{self, token, ParseSess};
-use syntax::tokenstream::{self, DelimSpan, IsJoint::*, TokenStream, TreeAndJoint};
-use syntax_pos::hygiene::{SyntaxContext, Transparency};
-use syntax_pos::symbol::{kw, sym, Symbol};
-use syntax_pos::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
-
-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 syntax::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 syntax::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
new file mode 100644
index 00000000000..8ecfd4ddda7
--- /dev/null
+++ b/src/libsyntax_ext/source_util.rs
@@ -0,0 +1,165 @@
+use syntax::{ast, panictry};
+use syntax::ext::base::{self, *};
+use syntax::ext::build::AstBuilder;
+use syntax::parse::{self, token, DirectoryOwnership};
+use syntax::print::pprust;
+use syntax::ptr::P;
+use syntax::symbol::Symbol;
+use syntax::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.sess.span_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_ext/standard_library_imports.rs b/src/libsyntax_ext/standard_library_imports.rs
new file mode 100644
index 00000000000..81bb32d79a2
--- /dev/null
+++ b/src/libsyntax_ext/standard_library_imports.rs
@@ -0,0 +1,95 @@
+use syntax::{ast, attr};
+use syntax::edition::Edition;
+use syntax::ext::hygiene::{ExpnId, MacroKind};
+use syntax::ptr::P;
+use syntax::source_map::{ExpnInfo, ExpnKind, dummy_spanned, respan};
+use syntax::symbol::{Ident, Symbol, kw, sym};
+use syntax::tokenstream::TokenStream;
+use syntax_pos::DUMMY_SP;
+
+use std::iter;
+
+pub fn inject(
+    mut krate: ast::Crate, alt_std_name: Option<&str>, edition: Edition
+) -> (ast::Crate, Option<Symbol>) {
+    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, None);
+    } 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];
+
+    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, Some(Symbol::intern(name)))
+}
diff --git a/src/libsyntax_ext/test.rs b/src/libsyntax_ext/test.rs
index d381c42f9ce..a2d93d01cec 100644
--- a/src/libsyntax_ext/test.rs
+++ b/src/libsyntax_ext/test.rs
@@ -7,11 +7,44 @@ use syntax::ext::base::*;
 use syntax::ext::build::AstBuilder;
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::print::pprust;
+use syntax::source_map::respan;
 use syntax::symbol::{Symbol, sym};
 use syntax_pos::Span;
 
 use std::iter;
 
+// #[test_case] is used by custom test authors to mark tests
+// When building for test, it needs to make the item public and gensym the name
+// Otherwise, we'll omit the item. This behavior means that any item annotated
+// with #[test_case] is never addressable.
+//
+// We mark item with an inert attribute "rustc_test_marker" which the test generation
+// logic will pick up on.
+pub fn expand_test_case(
+    ecx: &mut ExtCtxt<'_>,
+    attr_sp: Span,
+    meta_item: &ast::MetaItem,
+    anno_item: Annotatable
+) -> Vec<Annotatable> {
+    check_builtin_macro_attribute(ecx, meta_item, sym::test_case);
+
+    if !ecx.ecfg.should_test { return vec![]; }
+
+    let sp = attr_sp.with_ctxt(SyntaxContext::empty().apply_mark(ecx.current_expansion.id));
+    let mut item = anno_item.expect_item();
+    item = item.map(|mut item| {
+        item.vis = respan(item.vis.span, ast::VisibilityKind::Public);
+        item.ident = item.ident.gensym();
+        item.attrs.push(
+            ecx.attribute(sp,
+                ecx.meta_word(sp, sym::rustc_test_marker))
+        );
+        item
+    });
+
+    return vec![Annotatable::Item(item)]
+}
+
 pub fn expand_test(
     cx: &mut ExtCtxt<'_>,
     attr_sp: Span,
diff --git a/src/libsyntax_ext/test_case.rs b/src/libsyntax_ext/test_case.rs
deleted file mode 100644
index ea4a8d541ab..00000000000
--- a/src/libsyntax_ext/test_case.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-// http://rust-lang.org/COPYRIGHT.
-//
-
-// #[test_case] is used by custom test authors to mark tests
-// When building for test, it needs to make the item public and gensym the name
-// Otherwise, we'll omit the item. This behavior means that any item annotated
-// with #[test_case] is never addressable.
-//
-// We mark item with an inert attribute "rustc_test_marker" which the test generation
-// logic will pick up on.
-
-use syntax::ast;
-use syntax::attr::check_builtin_macro_attribute;
-use syntax::ext::base::*;
-use syntax::ext::build::AstBuilder;
-use syntax::ext::hygiene::SyntaxContext;
-use syntax::source_map::respan;
-use syntax::symbol::sym;
-use syntax_pos::Span;
-
-pub fn expand(
-    ecx: &mut ExtCtxt<'_>,
-    attr_sp: Span,
-    meta_item: &ast::MetaItem,
-    anno_item: Annotatable
-) -> Vec<Annotatable> {
-    check_builtin_macro_attribute(ecx, meta_item, sym::test_case);
-
-    if !ecx.ecfg.should_test { return vec![]; }
-
-    let sp = attr_sp.with_ctxt(SyntaxContext::empty().apply_mark(ecx.current_expansion.id));
-    let mut item = anno_item.expect_item();
-    item = item.map(|mut item| {
-        item.vis = respan(item.vis.span, ast::VisibilityKind::Public);
-        item.ident = item.ident.gensym();
-        item.attrs.push(
-            ecx.attribute(sp,
-                ecx.meta_word(sp, sym::rustc_test_marker))
-        );
-        item
-    });
-
-    return vec![Annotatable::Item(item)]
-}
diff --git a/src/libsyntax_ext/test_harness.rs b/src/libsyntax_ext/test_harness.rs
new file mode 100644
index 00000000000..848c797856e
--- /dev/null
+++ b/src/libsyntax_ext/test_harness.rs
@@ -0,0 +1,394 @@
+// Code that generates a test runner to run all the tests in a crate
+
+use log::debug;
+use smallvec::{smallvec, SmallVec};
+use syntax::ast::{self, Ident};
+use syntax::attr;
+use syntax::entry::{self, EntryPointType};
+use syntax::ext::base::{ExtCtxt, Resolver};
+use syntax::ext::build::AstBuilder;
+use syntax::ext::expand::ExpansionConfig;
+use syntax::ext::hygiene::{ExpnId, MacroKind};
+use syntax::feature_gate::Features;
+use syntax::mut_visit::{*, ExpectOne};
+use syntax::parse::ParseSess;
+use syntax::ptr::P;
+use syntax::source_map::{ExpnInfo, ExpnKind, dummy_spanned};
+use syntax::symbol::{kw, sym, Symbol};
+use syntax_pos::{Span, DUMMY_SP};
+
+use std::{iter, mem};
+
+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>,
+    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 inject(
+    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,
+        toplevel_reexport: None,
+        test_runner
+    };
+
+    TestHarnessGenerator {
+        cx,
+        tests: Vec::new(),
+        tested_submods: Vec::new(),
+    }.visit_crate(krate);
+}
+
+/// 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()
+        }
+    })
+}