diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 991bebc647d0f..7ffba41e2569a 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -614,7 +614,7 @@ impl<'a> CrateLoader<'a> {
             match decl {
                 ProcMacro::CustomDerive { trait_name, attributes, client } => {
                     let attrs = attributes.iter().cloned().map(Symbol::intern).collect::<Vec<_>>();
-                    (trait_name, SyntaxExtension::ProcMacroDerive(
+                    (trait_name, SyntaxExtension::Derive(
                         Box::new(ProcMacroDerive {
                             client,
                             attrs: attrs.clone(),
@@ -624,13 +624,13 @@ impl<'a> CrateLoader<'a> {
                     ))
                 }
                 ProcMacro::Attr { name, client } => {
-                    (name, SyntaxExtension::AttrProcMacro(
+                    (name, SyntaxExtension::Attr(
                         Box::new(AttrProcMacro { client }),
                         root.edition,
                     ))
                 }
                 ProcMacro::Bang { name, client } => {
-                    (name, SyntaxExtension::ProcMacro {
+                    (name, SyntaxExtension::Bang {
                         expander: Box::new(BangProcMacro { client }),
                         allow_internal_unstable: None,
                         edition: root.edition,
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index db452bb4ac7bc..35faa1df82b84 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -430,7 +430,7 @@ impl cstore::CStore {
             use syntax_ext::proc_macro_impl::BangProcMacro;
 
             let client = proc_macro::bridge::client::Client::expand1(proc_macro::quote);
-            let ext = SyntaxExtension::ProcMacro {
+            let ext = SyntaxExtension::Bang {
                 expander: Box::new(BangProcMacro { client }),
                 allow_internal_unstable: Some(vec![sym::proc_macro_def_site].into()),
                 edition: data.root.edition,
diff --git a/src/librustc_plugin/registry.rs b/src/librustc_plugin/registry.rs
index f4b4bcb043c42..dd5e42684c427 100644
--- a/src/librustc_plugin/registry.rs
+++ b/src/librustc_plugin/registry.rs
@@ -4,7 +4,7 @@ use rustc::lint::{EarlyLintPassObject, LateLintPassObject, LintId, Lint};
 use rustc::session::Session;
 use rustc::util::nodemap::FxHashMap;
 
-use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension, NormalTT};
+use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension};
 use syntax::ext::base::MacroExpanderFn;
 use syntax::ext::hygiene::Transparency;
 use syntax::symbol::{Symbol, sym};
@@ -89,7 +89,7 @@ impl<'a> Registry<'a> {
         if name == sym::macro_rules {
             panic!("user-defined macros may not be named `macro_rules`");
         }
-        if let NormalTT { def_info: ref mut def_info @ None, .. } = extension {
+        if let SyntaxExtension::LegacyBang { def_info: ref mut def_info @ None, .. } = extension {
             *def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
         }
         self.syntax_exts.push((name, extension));
@@ -98,10 +98,10 @@ impl<'a> Registry<'a> {
     /// Register a macro of the usual kind.
     ///
     /// This is a convenience wrapper for `register_syntax_extension`.
-    /// It builds for you a `NormalTT` that calls `expander`,
+    /// It builds for you a `SyntaxExtension::LegacyBang` that calls `expander`,
     /// and also takes care of interning the macro's name.
     pub fn register_macro(&mut self, name: &str, expander: MacroExpanderFn) {
-        self.register_syntax_extension(Symbol::intern(name), NormalTT {
+        self.register_syntax_extension(Symbol::intern(name), SyntaxExtension::LegacyBang {
             expander: Box::new(expander),
             def_info: None,
             transparency: Transparency::SemiTransparent,
diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs
index b5af7bb74a644..2369bddf4f75f 100644
--- a/src/librustc_resolve/macros.rs
+++ b/src/librustc_resolve/macros.rs
@@ -242,7 +242,7 @@ impl<'a> base::Resolver for Resolver<'a> {
     fn check_unused_macros(&self) {
         for did in self.unused_macros.iter() {
             let id_span = match *self.macro_map[did] {
-                SyntaxExtension::NormalTT { def_info, .. } => def_info,
+                SyntaxExtension::LegacyBang { def_info, .. } => def_info,
                 _ => None,
             };
             if let Some((id, span)) = id_span {
@@ -586,7 +586,7 @@ impl<'a> Resolver<'a> {
                         match self.resolve_macro_to_res(derive, MacroKind::Derive,
                                                         &parent_scope, true, force) {
                             Ok((_, ext)) => {
-                                if let SyntaxExtension::ProcMacroDerive(_, helpers, _) = &*ext {
+                                if let SyntaxExtension::Derive(_, helpers, _) = &*ext {
                                     if helpers.contains(&ident.name) {
                                         let binding =
                                             (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 15108a7dbb91c..5a5540e7e3855 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -471,7 +471,7 @@ fn build_macro(cx: &DocContext<'_>, did: DefId, name: ast::Name) -> clean::ItemE
         }
         LoadedMacro::ProcMacro(ext) => {
             let helpers = match &*ext {
-                &SyntaxExtension::ProcMacroDerive(_, ref syms, ..) => { syms.clean(cx) }
+                &SyntaxExtension::Derive(_, ref syms, ..) => { syms.clean(cx) }
                 _ => Vec::new(),
             };
 
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index 1e824e6fdfba0..7fbfc3e1fc0f4 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -433,7 +433,7 @@ fn macro_resolve(cx: &DocContext<'_>, path_str: &str) -> Option<Res> {
             if let Res::Def(DefKind::Macro(MacroKind::ProcMacroStub), _) = res {
                 // skip proc-macro stubs, they'll cause `get_macro` to crash
             } else {
-                if let SyntaxExtension::NormalTT { .. } = *resolver.get_macro(res) {
+                if let SyntaxExtension::LegacyBang { .. } = *resolver.get_macro(res) {
                     return Some(res.map_id(|_| panic!("unexpected id")));
                 }
             }
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 4e5971a075f10..045e45071d1c6 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -1,5 +1,3 @@
-pub use SyntaxExtension::*;
-
 use crate::ast::{self, Attribute, Name, PatKind};
 use crate::attr::HasAttrs;
 use crate::source_map::{SourceMap, Spanned, respan};
@@ -550,7 +548,7 @@ impl MacroKind {
 /// An enum representing the different kinds of syntax extensions.
 pub enum SyntaxExtension {
     /// A token-based function-like macro.
-    ProcMacro {
+    Bang {
         /// An expander with signature TokenStream -> TokenStream.
         expander: Box<dyn ProcMacro + sync::Sync + sync::Send>,
         /// Whitelist of unstable features that are treated as stable inside this macro.
@@ -560,7 +558,7 @@ pub enum SyntaxExtension {
     },
 
     /// An AST-based function-like macro.
-    NormalTT {
+    LegacyBang {
         /// An expander with signature TokenStream -> AST.
         expander: Box<dyn TTMacroExpander + sync::Sync + sync::Send>,
         /// Some info about the macro's definition point.
@@ -580,7 +578,7 @@ pub enum SyntaxExtension {
     },
 
     /// A token-based attribute macro.
-    AttrProcMacro(
+    Attr(
         /// An expander with signature (TokenStream, TokenStream) -> TokenStream.
         /// The first TokenSteam is the attribute itself, the second is the annotated item.
         /// The produced TokenSteam replaces the input TokenSteam.
@@ -590,7 +588,7 @@ pub enum SyntaxExtension {
     ),
 
     /// An AST-based attribute macro.
-    MultiModifier(
+    LegacyAttr(
         /// An expander with signature (AST, AST) -> AST.
         /// The first AST fragment is the attribute itself, the second is the annotated item.
         /// The produced AST fragment replaces the input AST fragment.
@@ -605,7 +603,7 @@ pub enum SyntaxExtension {
     },
 
     /// A token-based derive macro.
-    ProcMacroDerive(
+    Derive(
         /// An expander with signature TokenStream -> TokenStream (not yet).
         /// The produced TokenSteam is appended to the input TokenSteam.
         Box<dyn MultiItemModifier + sync::Sync + sync::Send>,
@@ -616,7 +614,7 @@ pub enum SyntaxExtension {
     ),
 
     /// An AST-based derive macro.
-    BuiltinDerive(
+    LegacyDerive(
         /// An expander with signature AST -> AST.
         /// The produced AST fragment is appended to the input AST fragment.
         Box<dyn MultiItemModifier + sync::Sync + sync::Send>,
@@ -627,41 +625,38 @@ impl SyntaxExtension {
     /// Returns which kind of macro calls this syntax extension.
     pub fn kind(&self) -> MacroKind {
         match *self {
-            SyntaxExtension::NormalTT { .. } |
-            SyntaxExtension::ProcMacro { .. } =>
-                MacroKind::Bang,
-            SyntaxExtension::NonMacroAttr { .. } |
-            SyntaxExtension::MultiModifier(..) |
-            SyntaxExtension::AttrProcMacro(..) =>
-                MacroKind::Attr,
-            SyntaxExtension::ProcMacroDerive(..) |
-            SyntaxExtension::BuiltinDerive(..) =>
-                MacroKind::Derive,
+            SyntaxExtension::Bang { .. } |
+            SyntaxExtension::LegacyBang { .. } => MacroKind::Bang,
+            SyntaxExtension::Attr(..) |
+            SyntaxExtension::LegacyAttr(..) |
+            SyntaxExtension::NonMacroAttr { .. } => MacroKind::Attr,
+            SyntaxExtension::Derive(..) |
+            SyntaxExtension::LegacyDerive(..) => MacroKind::Derive,
         }
     }
 
     pub fn default_transparency(&self) -> Transparency {
         match *self {
-            SyntaxExtension::NormalTT { transparency, .. } => transparency,
-            SyntaxExtension::ProcMacro { .. } |
-            SyntaxExtension::AttrProcMacro(..) |
-            SyntaxExtension::ProcMacroDerive(..) |
+            SyntaxExtension::LegacyBang { transparency, .. } => transparency,
+            SyntaxExtension::Bang { .. } |
+            SyntaxExtension::Attr(..) |
+            SyntaxExtension::Derive(..) |
             SyntaxExtension::NonMacroAttr { .. } => Transparency::Opaque,
-            SyntaxExtension::MultiModifier(..) |
-            SyntaxExtension::BuiltinDerive(..) => Transparency::SemiTransparent,
+            SyntaxExtension::LegacyAttr(..) |
+            SyntaxExtension::LegacyDerive(..) => Transparency::SemiTransparent,
         }
     }
 
     pub fn edition(&self, default_edition: Edition) -> Edition {
         match *self {
-            SyntaxExtension::NormalTT { edition, .. } |
-            SyntaxExtension::ProcMacro { edition, .. } |
-            SyntaxExtension::AttrProcMacro(.., edition) |
-            SyntaxExtension::ProcMacroDerive(.., edition) => edition,
+            SyntaxExtension::Bang { edition, .. } |
+            SyntaxExtension::LegacyBang { edition, .. } |
+            SyntaxExtension::Attr(.., edition) |
+            SyntaxExtension::Derive(.., edition) => edition,
             // Unstable legacy stuff
             SyntaxExtension::NonMacroAttr { .. } |
-            SyntaxExtension::MultiModifier(..) |
-            SyntaxExtension::BuiltinDerive(..) => default_edition,
+            SyntaxExtension::LegacyAttr(..) |
+            SyntaxExtension::LegacyDerive(..) => default_edition,
         }
     }
 }
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 8b49b9b028441..cdb2348f8afe4 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -389,7 +389,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         let item = match self.cx.resolver.resolve_macro_path(
                                 path, MacroKind::Derive, Mark::root(), Vec::new(), false) {
                             Ok(ext) => match *ext {
-                                BuiltinDerive(..) => item_with_markers.clone(),
+                                SyntaxExtension::LegacyDerive(..) => item_with_markers.clone(),
                                 _ => item.clone(),
                             },
                             _ => item.clone(),
@@ -548,7 +548,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             _ => unreachable!(),
         };
 
-        if let NonMacroAttr { mark_used: false } = *ext {} else {
+        if let SyntaxExtension::NonMacroAttr { mark_used: false } = *ext {} else {
             // Macro attrs are always used when expanded,
             // non-macro attrs are considered used when the field says so.
             attr::mark_used(&attr);
@@ -564,18 +564,18 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         });
 
         match *ext {
-            NonMacroAttr { .. } => {
+            SyntaxExtension::NonMacroAttr { .. } => {
                 attr::mark_known(&attr);
                 item.visit_attrs(|attrs| attrs.push(attr));
                 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
             }
-            MultiModifier(ref mac) => {
+            SyntaxExtension::LegacyAttr(ref mac) => {
                 let meta = attr.parse_meta(self.cx.parse_sess)
                                .map_err(|mut e| { e.emit(); }).ok()?;
                 let item = mac.expand(self.cx, attr.span, &meta, item);
                 Some(invoc.fragment_kind.expect_from_annotatables(item))
             }
-            AttrProcMacro(ref mac, ..) => {
+            SyntaxExtension::Attr(ref mac, ..) => {
                 self.gate_proc_macro_attr_item(attr.span, &item);
                 let item_tok = TokenTree::Token(DUMMY_SP, Token::Interpolated(Lrc::new(match item {
                     Annotatable::Item(item) => token::NtItem(item),
@@ -592,7 +592,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 self.gate_proc_macro_expansion(attr.span, &res);
                 res
             }
-            ProcMacroDerive(..) | BuiltinDerive(..) => {
+            SyntaxExtension::Derive(..) | SyntaxExtension::LegacyDerive(..) => {
                 self.cx.span_err(attr.span, &format!("`{}` is a derive macro", attr.path));
                 self.cx.trace_macros_diag();
                 invoc.fragment_kind.dummy(attr.span)
@@ -747,7 +747,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
 
         let opt_expanded = match *ext {
-            NormalTT {
+            SyntaxExtension::LegacyBang {
                 ref expander,
                 def_info,
                 ref allow_internal_unstable,
@@ -774,20 +774,22 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 }
             }
 
-            MultiModifier(..) | AttrProcMacro(..) | SyntaxExtension::NonMacroAttr { .. } => {
+            SyntaxExtension::Attr(..) |
+            SyntaxExtension::LegacyAttr(..) |
+            SyntaxExtension::NonMacroAttr { .. } => {
                 self.cx.span_err(path.span,
                                  &format!("`{}` can only be used in attributes", path));
                 self.cx.trace_macros_diag();
                 kind.dummy(span)
             }
 
-            ProcMacroDerive(..) | BuiltinDerive(..) => {
+            SyntaxExtension::Derive(..) | SyntaxExtension::LegacyDerive(..) => {
                 self.cx.span_err(path.span, &format!("`{}` is a derive macro", path));
                 self.cx.trace_macros_diag();
                 kind.dummy(span)
             }
 
-            SyntaxExtension::ProcMacro { ref expander, ref allow_internal_unstable, edition } => {
+            SyntaxExtension::Bang { ref expander, ref allow_internal_unstable, edition } => {
                 if ident.name != kw::Invalid {
                     let msg =
                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
@@ -885,9 +887,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
 
         match ext {
-            ProcMacroDerive(expander, ..) | BuiltinDerive(expander) => {
+            SyntaxExtension::Derive(expander, ..) | SyntaxExtension::LegacyDerive(expander) => {
                 let meta = match ext {
-                    ProcMacroDerive(..) => ast::MetaItem { // FIXME(jseyfried) avoid this
+                    SyntaxExtension::Derive(..) => ast::MetaItem { // FIXME(jseyfried) avoid this
                         path: Path::from_ident(Ident::invalid()),
                         span: DUMMY_SP,
                         node: ast::MetaItemKind::Word,
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 8c4072db27b17..f262ab3e5fc93 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -1,7 +1,6 @@
 use crate::{ast, attr};
 use crate::edition::Edition;
-use crate::ext::base::{DummyResult, ExtCtxt, MacResult, SyntaxExtension};
-use crate::ext::base::{NormalTT, TTMacroExpander};
+use crate::ext::base::{DummyResult, ExtCtxt, MacResult, SyntaxExtension, TTMacroExpander};
 use crate::ext::expand::{AstFragment, AstFragmentKind};
 use crate::ext::hygiene::Transparency;
 use crate::ext::tt::macro_parser::{Success, Error, Failure};
@@ -426,7 +425,7 @@ pub fn compile(
         }
     });
 
-    NormalTT {
+    SyntaxExtension::LegacyBang {
         expander,
         def_info: Some((def.id, def.span)),
         transparency,
diff --git a/src/libsyntax_ext/deriving/mod.rs b/src/libsyntax_ext/deriving/mod.rs
index d6d16d0dbd155..7a8e624cb9894 100644
--- a/src/libsyntax_ext/deriving/mod.rs
+++ b/src/libsyntax_ext/deriving/mod.rs
@@ -55,7 +55,7 @@ macro_rules! derive_traits {
             $(
                 resolver.add_builtin(
                     ast::Ident::with_empty_ctxt(Symbol::intern($name)),
-                    Lrc::new(SyntaxExtension::BuiltinDerive(Box::new($func)))
+                    Lrc::new(SyntaxExtension::LegacyDerive(Box::new($func)))
                 );
             )*
         }
diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 7d6abd14a4a00..7c4085aa09653 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -41,7 +41,8 @@ pub mod proc_macro_impl;
 
 use rustc_data_structures::sync::Lrc;
 use syntax::ast;
-use syntax::ext::base::{MacroExpanderFn, NormalTT, NamedSyntaxExtension, MultiModifier};
+
+use syntax::ext::base::{MacroExpanderFn, NamedSyntaxExtension, SyntaxExtension};
 use syntax::ext::hygiene::Transparency;
 use syntax::edition::Edition;
 use syntax::symbol::{sym, Symbol};
@@ -57,7 +58,7 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
     macro_rules! register {
         ($( $name:ident: $f:expr, )*) => { $(
             register(Symbol::intern(stringify!($name)),
-                     NormalTT {
+                     SyntaxExtension::LegacyBang {
                         expander: Box::new($f as MacroExpanderFn),
                         def_info: None,
                         transparency: Transparency::SemiTransparent,
@@ -95,13 +96,13 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
         assert: assert::expand_assert,
     }
 
-    register(sym::test_case, MultiModifier(Box::new(test_case::expand)));
-    register(sym::test, MultiModifier(Box::new(test::expand_test)));
-    register(sym::bench, MultiModifier(Box::new(test::expand_bench)));
+    register(sym::test_case, SyntaxExtension::LegacyAttr(Box::new(test_case::expand)));
+    register(sym::test, SyntaxExtension::LegacyAttr(Box::new(test::expand_test)));
+    register(sym::bench, SyntaxExtension::LegacyAttr(Box::new(test::expand_bench)));
 
     // format_args uses `unstable` things internally.
     register(Symbol::intern("format_args"),
-             NormalTT {
+             SyntaxExtension::LegacyBang {
                 expander: Box::new(format::expand_format_args),
                 def_info: None,
                 transparency: Transparency::SemiTransparent,
@@ -112,7 +113,7 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
                 edition,
             });
     register(sym::format_args_nl,
-             NormalTT {
+             SyntaxExtension::LegacyBang {
                  expander: Box::new(format::expand_format_args_nl),
                  def_info: None,
                  transparency: Transparency::SemiTransparent,
diff --git a/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs b/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
index cf12b80848436..330459fc08f55 100644
--- a/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
+++ b/src/test/run-pass-fulldeps/auxiliary/plugin-args.rs
@@ -10,12 +10,10 @@ extern crate rustc_plugin;
 
 use std::borrow::ToOwned;
 use syntax::ast;
-use syntax::ext::hygiene;
 use syntax::ext::build::AstBuilder;
-use syntax::ext::base::{TTMacroExpander, ExtCtxt, MacResult, MacEager, NormalTT};
+use syntax::ext::base::{SyntaxExtension, TTMacroExpander, ExtCtxt, MacResult, MacEager};
 use syntax::ext::hygiene::Transparency;
 use syntax::print::pprust;
-use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
 use syntax::tokenstream::TokenStream;
@@ -30,7 +28,7 @@ impl TTMacroExpander for Expander {
                    ecx: &'cx mut ExtCtxt,
                    sp: Span,
                    _: TokenStream,
-                   _: Option<Span>) -> Box<MacResult+'cx> {
+                   _: Option<Span>) -> Box<dyn MacResult+'cx> {
         let args = self.args.iter().map(|i| pprust::meta_list_item_to_string(i))
             .collect::<Vec<_>>().join(", ");
         MacEager::expr(ecx.expr_str(sp, Symbol::intern(&args)))
@@ -41,7 +39,7 @@ impl TTMacroExpander for Expander {
 pub fn plugin_registrar(reg: &mut Registry) {
     let args = reg.args().to_owned();
     reg.register_syntax_extension(Symbol::intern("plugin_args"),
-        NormalTT {
+        SyntaxExtension::LegacyBang {
             expander: Box::new(Expander { args: args, }),
             def_info: None,
             transparency: Transparency::SemiTransparent,