Rollup merge of #62771 - petrochenkov:depext, r=eddyb

Break dependencies between `syntax_ext` and other crates

Move `source_util` macros into `syntax_ext`.
Move other early code generation facilities like standard library injection into `syntax_ext`.

The only crate that depends on `syntax_ext` now is `rustc_interface` which is one of the "final" crates that depend on everything.

Minor: Cleanup dependencies of `rustc_driver`, many of them are no longer used after introduction of `rustc_interface`.

r? @eddyb

32 files changed, 394 insertions, 546 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 6384560b672..46d8b3de806 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2863,31 +2863,20 @@ dependencies = [
 name = "rustc_driver"
 version = "0.0.0"
 dependencies = [
- "arena 0.0.0",
  "env_logger 0.5.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
- "rustc-rayon 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_ast_borrowck 0.0.0",
  "rustc_codegen_utils 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_errors 0.0.0",
- "rustc_incremental 0.0.0",
  "rustc_interface 0.0.0",
- "rustc_lint 0.0.0",
  "rustc_metadata 0.0.0",
  "rustc_mir 0.0.0",
- "rustc_passes 0.0.0",
- "rustc_plugin 0.0.0",
- "rustc_privacy 0.0.0",
- "rustc_resolve 0.0.0",
  "rustc_save_analysis 0.0.0",
  "rustc_target 0.0.0",
- "rustc_traits 0.0.0",
- "rustc_typeck 0.0.0",
  "serialize 0.0.0",
- "smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syntax 0.0.0",
  "syntax_pos 0.0.0",
 ]
@@ -3019,7 +3008,6 @@ dependencies = [
  "smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "stable_deref_trait 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "syntax 0.0.0",
- "syntax_ext 0.0.0",
  "syntax_pos 0.0.0",
 ]
 
@@ -3064,9 +3052,7 @@ dependencies = [
  "rustc 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_errors 0.0.0",
- "rustc_mir 0.0.0",
  "syntax 0.0.0",
- "syntax_ext 0.0.0",
  "syntax_pos 0.0.0",
 ]
 
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 639994ed14d..eb0ea9e08a4 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -63,7 +63,6 @@ use syntax::errors;
 use syntax::ext::hygiene::ExpnId;
 use syntax::print::pprust;
 use syntax::source_map::{respan, ExpnInfo, ExpnKind, DesugaringKind, Spanned};
-use syntax::std_inject;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::{self, Token};
@@ -241,7 +240,7 @@ pub fn lower_crate(
     dep_graph.assert_ignored();
 
     LoweringContext {
-        crate_root: std_inject::injected_crate_name().map(Symbol::intern),
+        crate_root: sess.parse_sess.injected_crate_name.try_get().copied(),
         sess,
         cstore,
         resolver,
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index e8c9828a202..42aa8203cba 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -10,30 +10,19 @@ path = "lib.rs"
 crate-type = ["dylib"]
 
 [dependencies]
-arena = { path = "../libarena" }
 graphviz = { path = "../libgraphviz" }
 log = "0.4"
 env_logger = { version = "0.5", default-features = false }
-rayon = { version = "0.2.0", package = "rustc-rayon" }
 rustc = { path = "../librustc" }
 rustc_target = { path = "../librustc_target" }
 rustc_ast_borrowck = { path = "../librustc_ast_borrowck" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
-rustc_incremental = { path = "../librustc_incremental" }
-rustc_lint = { path = "../librustc_lint" }
 rustc_metadata = { path = "../librustc_metadata" }
 rustc_mir = { path = "../librustc_mir" }
-rustc_passes = { path = "../librustc_passes" }
-rustc_plugin = { path = "../librustc_plugin" }
-rustc_privacy = { path = "../librustc_privacy" }
-rustc_resolve = { path = "../librustc_resolve" }
 rustc_save_analysis = { path = "../librustc_save_analysis" }
-rustc_traits = { path = "../librustc_traits" }
 rustc_codegen_utils = { path = "../librustc_codegen_utils" }
-rustc_typeck = { path = "../librustc_typeck" }
 rustc_interface = { path = "../librustc_interface" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
-smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 2754c55ea06..3c7d854b36b 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -278,7 +278,12 @@ pub fn register_plugins<'a>(
 
     krate = time(sess, "crate injection", || {
         let alt_std_name = sess.opts.alt_std_name.as_ref().map(|s| &**s);
-        syntax::std_inject::maybe_inject_crates_ref(krate, alt_std_name, sess.edition())
+        let (krate, name) =
+            syntax_ext::standard_library_imports::inject(krate, alt_std_name, sess.edition());
+        if let Some(name) = name {
+            sess.parse_sess.injected_crate_name.set(name);
+        }
+        krate
     });
 
     let registrars = time(sess, "plugin loading", || {
@@ -456,7 +461,7 @@ fn configure_and_expand_inner<'a>(
     sess.profiler(|p| p.end_activity("macro expansion"));
 
     time(sess, "maybe building test harness", || {
-        syntax::test::modify_for_testing(
+        syntax_ext::test_harness::inject(
             &sess.parse_sess,
             &mut resolver,
             sess.opts.test,
@@ -485,7 +490,7 @@ fn configure_and_expand_inner<'a>(
             let num_crate_types = crate_types.len();
             let is_proc_macro_crate = crate_types.contains(&config::CrateType::ProcMacro);
             let is_test_crate = sess.opts.test;
-            syntax_ext::proc_macro_decls::modify(
+            syntax_ext::proc_macro_harness::inject(
                 &sess.parse_sess,
                 &mut resolver,
                 krate,
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index a9f054d5e8b..5ff60a9267b 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -21,5 +21,4 @@ rustc_target = { path = "../librustc_target" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 stable_deref_trait = "1.0.0"
 syntax = { path = "../libsyntax" }
-syntax_ext = { path = "../libsyntax_ext" }
 syntax_pos = { path = "../libsyntax_pos" }
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 3404ec5e173..d5f1e715186 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -586,8 +586,7 @@ impl<'a> CrateLoader<'a> {
         use std::{env, mem};
         use crate::dynamic_lib::DynamicLibrary;
         use proc_macro::bridge::client::ProcMacro;
-        use syntax_ext::deriving::custom::ProcMacroDerive;
-        use syntax_ext::proc_macro_impl::{AttrProcMacro, BangProcMacro};
+        use syntax::ext::proc_macro::{BangProcMacro, AttrProcMacro, ProcMacroDerive};
 
         let path = match dylib {
             Some(dylib) => dylib,
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index 914084d7e9e..ee1175e798d 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -31,10 +31,10 @@ use syntax::attr;
 use syntax::source_map;
 use syntax::edition::Edition;
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
+use syntax::ext::proc_macro::BangProcMacro;
 use syntax::parse::source_file_to_stream;
 use syntax::parse::parser::emit_unclosed_delims;
 use syntax::symbol::{Symbol, sym};
-use syntax_ext::proc_macro_impl::BangProcMacro;
 use syntax_pos::{Span, NO_EXPANSION, FileName};
 use rustc_data_structures::bit_set::BitSet;
 
diff --git a/src/librustc_passes/Cargo.toml b/src/librustc_passes/Cargo.toml
index de2476775b0..596ec6c19bc 100644
--- a/src/librustc_passes/Cargo.toml
+++ b/src/librustc_passes/Cargo.toml
@@ -11,9 +11,7 @@ path = "lib.rs"
 [dependencies]
 log = "0.4"
 rustc = { path = "../librustc" }
-rustc_mir = { path = "../librustc_mir"}
 rustc_data_structures = { path = "../librustc_data_structures" }
 syntax = { path = "../libsyntax" }
-syntax_ext = { path = "../libsyntax_ext" }
 syntax_pos = { path = "../libsyntax_pos" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
diff --git a/src/librustc_passes/ast_validation.rs b/src/librustc_passes/ast_validation.rs
index b550029d978..562865ef55f 100644
--- a/src/librustc_passes/ast_validation.rs
+++ b/src/librustc_passes/ast_validation.rs
@@ -14,12 +14,12 @@ use rustc::session::Session;
 use rustc_data_structures::fx::FxHashMap;
 use syntax::ast::*;
 use syntax::attr;
+use syntax::ext::proc_macro::is_proc_macro_attr;
 use syntax::feature_gate::is_builtin_attr;
 use syntax::source_map::Spanned;
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
 use syntax::{span_err, struct_span_err, walk_list};
-use syntax_ext::proc_macro_decls::is_proc_macro_attr;
 use syntax_pos::{Span, MultiSpan};
 use errors::{Applicability, FatalError};
 
diff --git a/src/librustc_resolve/build_reduced_graph.rs b/src/librustc_resolve/build_reduced_graph.rs
index f52f7d9cfb3..41349cf72a1 100644
--- a/src/librustc_resolve/build_reduced_graph.rs
+++ b/src/librustc_resolve/build_reduced_graph.rs
@@ -34,7 +34,6 @@ use syntax::ext::hygiene::ExpnId;
 use syntax::feature_gate::is_builtin_attr;
 use syntax::parse::token::{self, Token};
 use syntax::span_err;
-use syntax::std_inject::injected_crate_name;
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
 
@@ -367,8 +366,10 @@ impl<'a> Resolver<'a> {
                 };
 
                 self.populate_module_if_necessary(module);
-                if injected_crate_name().map_or(false, |name| ident.name.as_str() == name) {
-                    self.injected_crate = Some(module);
+                if let Some(name) = self.session.parse_sess.injected_crate_name.try_get() {
+                    if name.as_str() == ident.name.as_str() {
+                        self.injected_crate = Some(module);
+                    }
                 }
 
                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
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
index e94d79a140d..8d0023c9ab1 100644
--- a/src/libsyntax_ext/proc_macro_server.rs
+++ b/src/libsyntax/ext/proc_macro_server.rs
@@ -1,21 +1,19 @@
-use errors::{Diagnostic, DiagnosticBuilder};
-
-use std::panic;
-
-use proc_macro::bridge::{server, TokenTree};
-use proc_macro::{Delimiter, Level, LineColumn, Spacing};
+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 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::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
 use syntax_pos::hygiene::{SyntaxContext, Transparency};
 use syntax_pos::symbol::{kw, sym, Symbol};
-use syntax_pos::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
+
+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;
@@ -52,7 +50,7 @@ impl FromInternal<(TreeAndJoint, &'_ ParseSess, &'_ mut Vec<Self>)>
 {
     fn from_internal(((tree, is_joint), sess, stack): (TreeAndJoint, &ParseSess, &mut Vec<Self>))
                     -> Self {
-        use syntax::parse::token::*;
+        use crate::parse::token::*;
 
         let joint = is_joint == Joint;
         let Token { kind, span } = match tree {
@@ -193,7 +191,7 @@ impl FromInternal<(TreeAndJoint, &'_ ParseSess, &'_ mut Vec<Self>)>
 
 impl ToInternal<TokenStream> for TokenTree<Group, Punct, Ident, Literal> {
     fn to_internal(self) -> TokenStream {
-        use syntax::parse::token::*;
+        use crate::parse::token::*;
 
         let (ch, joint, span) = match self {
             TokenTree::Punct(Punct { ch, joint, span }) => (ch, joint, span),
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/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_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/source_util.rs b/src/libsyntax_ext/source_util.rs
index ae080c05eec..8ecfd4ddda7 100644
--- a/src/libsyntax/ext/source_util.rs
+++ b/src/libsyntax_ext/source_util.rs
@@ -1,11 +1,11 @@
-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 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};
@@ -94,7 +94,7 @@ pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt<'_>, sp: Span, tts: &[tokenstrea
             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,
+                    None => self.p.sess.span_diagnostic.span_fatal(self.p.token.span,
                                                            &format!("expected item, found `{}`",
                                                                     self.p.this_token_to_string()))
                                                .raise()
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax_ext/standard_library_imports.rs
index 3fba81c0b69..81bb32d79a2 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax_ext/standard_library_imports.rs
@@ -1,37 +1,22 @@
-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::{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;
 
-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);
-}
+use std::iter;
 
-pub fn maybe_inject_crates_ref(
-    mut krate: ast::Crate,
-    alt_std_name: Option<&str>,
-    edition: Edition,
-) -> ast::Crate {
+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;
+        return (krate, None);
     } else if attr::contains_name(&krate.attrs, sym::no_std) {
         if attr::contains_name(&krate.attrs, sym::compiler_builtins) {
             &["core"]
@@ -73,8 +58,6 @@ pub fn maybe_inject_crates_ref(
     // 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(),
@@ -108,5 +91,5 @@ pub fn maybe_inject_crates_ref(
         tokens: None,
     }));
 
-    krate
+    (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/test.rs b/src/libsyntax_ext/test_harness.rs
index 2ada7104843..848c797856e 100644
--- a/src/libsyntax/test.rs
+++ b/src/libsyntax_ext/test_harness.rs
@@ -1,35 +1,23 @@
 // 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;
+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,
@@ -42,22 +30,21 @@ struct TestCtxt<'a> {
     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) {
+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
@@ -267,11 +254,7 @@ fn generate_test_harness(sess: &ParseSess,
         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
     };
 
@@ -282,19 +265,6 @@ fn generate_test_harness(sess: &ParseSess,
     }.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> {