hygiene: Reuse `MacroKind` in `ExpnKind`

Orthogonality and reuse are good.

12 files changed, 67 insertions, 77 deletions

diff --git a/src/librustc/ich/impls_syntax.rs b/src/librustc/ich/impls_syntax.rs
index f679a65c642..69e8c355019 100644
--- a/src/librustc/ich/impls_syntax.rs
+++ b/src/librustc/ich/impls_syntax.rs
@@ -408,8 +408,7 @@ impl_stable_hash_for!(struct ::syntax_pos::hygiene::ExpnInfo {
 });
 
 impl_stable_hash_for!(enum ::syntax_pos::hygiene::ExpnKind {
-    MacroAttribute(sym),
-    MacroBang(sym),
+    Macro(kind, descr),
     Desugaring(kind)
 });
 
diff --git a/src/librustc/lint/mod.rs b/src/librustc/lint/mod.rs
index 9876d6c1fa5..3c8b0041a98 100644
--- a/src/librustc/lint/mod.rs
+++ b/src/librustc/lint/mod.rs
@@ -38,6 +38,7 @@ use syntax::ast;
 use syntax::source_map::{MultiSpan, ExpnKind, DesugaringKind};
 use syntax::early_buffered_lints::BufferedEarlyLintId;
 use syntax::edition::Edition;
+use syntax::ext::base::MacroKind;
 use syntax::symbol::{Symbol, sym};
 use syntax_pos::Span;
 
@@ -884,10 +885,9 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
     };
 
     match info.kind {
-        ExpnKind::MacroAttribute(..) => true, // definitely a plugin
         ExpnKind::Desugaring(DesugaringKind::ForLoop) => false,
         ExpnKind::Desugaring(_) => true, // well, it's "external"
-        ExpnKind::MacroBang(..) => {
+        ExpnKind::Macro(MacroKind::Bang, _) => {
             if info.def_site.is_dummy() {
                 // dummy span for the def_site means it's an external macro
                 return true;
@@ -898,19 +898,16 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
                 Err(_) => true,
             }
         }
+        ExpnKind::Macro(..) => true, // definitely a plugin
     }
 }
 
 /// Returns whether `span` originates in a derive macro's expansion
 pub fn in_derive_expansion(span: Span) -> bool {
-    let info = match span.ctxt().outer_expn_info() {
-        Some(info) => info,
-        // no ExpnInfo means this span doesn't come from a macro
-        None => return false,
-    };
-
-    match info.kind {
-        ExpnKind::MacroAttribute(symbol) => symbol.as_str().starts_with("derive("),
-        _ => false,
+    if let Some(info) = span.ctxt().outer_expn_info() {
+        if let ExpnKind::Macro(MacroKind::Derive, _) = info.kind {
+            return true;
+        }
     }
+    false
 }
diff --git a/src/librustc_allocator/expand.rs b/src/librustc_allocator/expand.rs
index 18bbb257128..d0eefbb1179 100644
--- a/src/librustc_allocator/expand.rs
+++ b/src/librustc_allocator/expand.rs
@@ -11,7 +11,7 @@ use syntax::{
         respan, ExpnInfo, ExpnKind,
     },
     ext::{
-        base::{ExtCtxt, Resolver},
+        base::{ExtCtxt, MacroKind, Resolver},
         build::AstBuilder,
         expand::ExpansionConfig,
         hygiene::{Mark, SyntaxContext},
@@ -87,7 +87,7 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
         // Create a fresh Mark for the new macro expansion we are about to do
         let mark = Mark::fresh(Mark::root());
         mark.set_expn_info(ExpnInfo::with_unstable(
-            ExpnKind::MacroAttribute(sym::global_allocator), item.span, self.sess.edition,
+            ExpnKind::Macro(MacroKind::Attr, sym::global_allocator), item.span, self.sess.edition,
             &[sym::rustc_attrs],
         ));
 
diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs
index 61300e3ee3c..7f57b0a5052 100644
--- a/src/librustc_resolve/macros.rs
+++ b/src/librustc_resolve/macros.rs
@@ -114,17 +114,21 @@ fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKi
 // We don't want to format a path using pretty-printing,
 // `format!("{}", path)`, because that tries to insert
 // line-breaks and is slow.
-fn fast_print_path(path: &ast::Path) -> String {
-    let mut path_str = String::with_capacity(64);
-    for (i, segment) in path.segments.iter().enumerate() {
-        if i != 0 {
-            path_str.push_str("::");
-        }
-        if segment.ident.name != kw::PathRoot {
-            path_str.push_str(&segment.ident.as_str())
+fn fast_print_path(path: &ast::Path) -> Symbol {
+    if path.segments.len() == 1 {
+        return path.segments[0].ident.name
+    } else {
+        let mut path_str = String::with_capacity(64);
+        for (i, segment) in path.segments.iter().enumerate() {
+            if i != 0 {
+                path_str.push_str("::");
+            }
+            if segment.ident.name != kw::PathRoot {
+                path_str.push_str(&segment.ident.as_str())
+            }
         }
+        Symbol::intern(&path_str)
     }
-    path_str
 }
 
 impl<'a> base::Resolver for Resolver<'a> {
@@ -219,14 +223,10 @@ impl<'a> base::Resolver for Resolver<'a> {
         };
 
         let span = invoc.span();
-        let path = fast_print_path(path);
-        let format = match kind {
-            MacroKind::Derive => format!("derive({})", path),
-            _ => path.clone(),
-        };
-        invoc.expansion_data.mark.set_expn_info(ext.expn_info(span, &format));
+        let descr = fast_print_path(path);
+        invoc.expansion_data.mark.set_expn_info(ext.expn_info(span, descr));
 
-        self.check_stability_and_deprecation(&ext, &path, span);
+        self.check_stability_and_deprecation(&ext, descr, span);
 
         if let Res::Def(_, def_id) = res {
             if after_derive {
@@ -991,7 +991,7 @@ impl<'a> Resolver<'a> {
         }
     }
 
-    fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, path: &str, span: Span) {
+    fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, descr: Symbol, span: Span) {
         if let Some(stability) = &ext.stability {
             if let StabilityLevel::Unstable { reason, issue } = stability.level {
                 let feature = stability.feature;
@@ -1000,14 +1000,14 @@ impl<'a> Resolver<'a> {
                 }
             }
             if let Some(depr) = &stability.rustc_depr {
-                let (message, lint) = stability::rustc_deprecation_message(depr, path);
+                let (message, lint) = stability::rustc_deprecation_message(depr, &descr.as_str());
                 stability::early_report_deprecation(
                     self.session, &message, depr.suggestion, lint, span
                 );
             }
         }
         if let Some(depr) = &ext.deprecation {
-            let (message, lint) = stability::deprecation_message(depr, path);
+            let (message, lint) = stability::deprecation_message(depr, &descr.as_str());
             stability::early_report_deprecation(self.session, &message, None, lint, span);
         }
     }
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index aeaee1887b9..2c8f7a44f5a 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -843,7 +843,8 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
         let callee = span.source_callee()?;
 
         // Ignore attribute macros, their spans are usually mangled
-        if let ExpnKind::MacroAttribute(_) = callee.kind {
+        if let ExpnKind::Macro(MacroKind::Attr, _) |
+               ExpnKind::Macro(MacroKind::Derive, _) = callee.kind {
             return None;
         }
 
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 2f8d6f00ba7..04f124685cb 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -640,18 +640,10 @@ impl SyntaxExtension {
         }
     }
 
-    fn expn_kind(&self, descr: Symbol) -> ExpnKind {
-        match self.kind {
-            SyntaxExtensionKind::Bang(..) |
-            SyntaxExtensionKind::LegacyBang(..) => ExpnKind::MacroBang(descr),
-            _ => ExpnKind::MacroAttribute(descr),
-        }
-    }
-
-    pub fn expn_info(&self, call_site: Span, descr: &str) -> ExpnInfo {
+    pub fn expn_info(&self, call_site: Span, descr: Symbol) -> ExpnInfo {
         ExpnInfo {
             call_site,
-            kind: self.expn_kind(Symbol::intern(descr)),
+            kind: ExpnKind::Macro(self.macro_kind(), descr),
             def_site: self.span,
             default_transparency: self.default_transparency,
             allow_internal_unstable: self.allow_internal_unstable.clone(),
diff --git a/src/libsyntax/ext/derive.rs b/src/libsyntax/ext/derive.rs
index 24050be792b..68e7225c3cf 100644
--- a/src/libsyntax/ext/derive.rs
+++ b/src/libsyntax/ext/derive.rs
@@ -1,7 +1,7 @@
 use crate::attr::HasAttrs;
 use crate::ast;
 use crate::source_map::{ExpnInfo, ExpnKind};
-use crate::ext::base::ExtCtxt;
+use crate::ext::base::{ExtCtxt, MacroKind};
 use crate::ext::build::AstBuilder;
 use crate::parse::parser::PathStyle;
 use crate::symbol::{Symbol, sym};
@@ -46,7 +46,7 @@ pub fn collect_derives(cx: &mut ExtCtxt<'_>, attrs: &mut Vec<ast::Attribute>) ->
 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(), "derive(".to_owned());
+    let (mut names, mut pretty_name) = (FxHashSet::default(), String::new());
     for (i, path) in traits.iter().enumerate() {
         if i > 0 {
             pretty_name.push_str(", ");
@@ -54,11 +54,10 @@ pub fn add_derived_markers<T>(cx: &mut ExtCtxt<'_>, span: Span, traits: &[ast::P
         pretty_name.push_str(&path.to_string());
         names.insert(unwrap_or!(path.segments.get(0), continue).ident.name);
     }
-    pretty_name.push(')');
 
     cx.current_expansion.mark.set_expn_info(ExpnInfo::with_unstable(
-        ExpnKind::MacroAttribute(Symbol::intern(&pretty_name)), span, cx.parse_sess.edition,
-        &[sym::rustc_attrs, sym::structural_match],
+        ExpnKind::Macro(MacroKind::Derive, Symbol::intern(&pretty_name)), span,
+        cx.parse_sess.edition, &[sym::rustc_attrs, sym::structural_match],
     ));
 
     let span = span.with_ctxt(cx.backtrace());
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
index 7ee073117e9..81f9ff9b661 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax/std_inject.rs
@@ -1,7 +1,7 @@
 use crate::ast;
 use crate::attr;
 use crate::edition::Edition;
-use crate::ext::hygiene::{Mark, SyntaxContext};
+use crate::ext::hygiene::{Mark, SyntaxContext, MacroKind};
 use crate::symbol::{Ident, Symbol, kw, sym};
 use crate::source_map::{ExpnInfo, ExpnKind, dummy_spanned, respan};
 use crate::ptr::P;
@@ -17,7 +17,8 @@ use syntax_pos::{DUMMY_SP, Span};
 fn ignored_span(sp: Span, edition: Edition) -> Span {
     let mark = Mark::fresh(Mark::root());
     mark.set_expn_info(ExpnInfo::with_unstable(
-        ExpnKind::MacroAttribute(Symbol::intern("std_inject")), sp, edition, &[sym::prelude_import]
+        ExpnKind::Macro(MacroKind::Attr, Symbol::intern("std_inject")), sp, edition,
+        &[sym::prelude_import],
     ));
     sp.with_ctxt(SyntaxContext::empty().apply_mark(mark))
 }
diff --git a/src/libsyntax/test.rs b/src/libsyntax/test.rs
index 35a1a552a13..7ec7bb6ff45 100644
--- a/src/libsyntax/test.rs
+++ b/src/libsyntax/test.rs
@@ -21,7 +21,7 @@ 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, Mark, SyntaxContext};
+use crate::ext::hygiene::{self, Mark, SyntaxContext, MacroKind};
 use crate::mut_visit::{*, ExpectOne};
 use crate::feature_gate::Features;
 use crate::util::map_in_place::MapInPlace;
@@ -280,7 +280,7 @@ fn generate_test_harness(sess: &ParseSess,
     };
 
     mark.set_expn_info(ExpnInfo::with_unstable(
-        ExpnKind::MacroAttribute(sym::test_case), DUMMY_SP, sess.edition,
+        ExpnKind::Macro(MacroKind::Attr, sym::test_case), DUMMY_SP, sess.edition,
         &[sym::main, sym::test, sym::rustc_attrs],
     ));
 
diff --git a/src/libsyntax_ext/proc_macro_decls.rs b/src/libsyntax_ext/proc_macro_decls.rs
index dee8f4b3eb5..0733a8ec95c 100644
--- a/src/libsyntax_ext/proc_macro_decls.rs
+++ b/src/libsyntax_ext/proc_macro_decls.rs
@@ -5,7 +5,7 @@ use crate::deriving;
 use syntax::ast::{self, Ident};
 use syntax::attr;
 use syntax::source_map::{ExpnInfo, ExpnKind, respan};
-use syntax::ext::base::ExtCtxt;
+use syntax::ext::base::{ExtCtxt, MacroKind};
 use syntax::ext::build::AstBuilder;
 use syntax::ext::expand::ExpansionConfig;
 use syntax::ext::hygiene::Mark;
@@ -348,7 +348,7 @@ fn mk_decls(
 ) -> P<ast::Item> {
     let mark = Mark::fresh(Mark::root());
     mark.set_expn_info(ExpnInfo::with_unstable(
-        ExpnKind::MacroAttribute(sym::proc_macro), DUMMY_SP, cx.parse_sess.edition,
+        ExpnKind::Macro(MacroKind::Attr, sym::proc_macro), DUMMY_SP, cx.parse_sess.edition,
         &[sym::rustc_attrs, Symbol::intern("proc_macro_internals")],
     ));
     let span = DUMMY_SP.apply_mark(mark);
diff --git a/src/libsyntax_pos/hygiene.rs b/src/libsyntax_pos/hygiene.rs
index 67dcdabe701..28d452233cc 100644
--- a/src/libsyntax_pos/hygiene.rs
+++ b/src/libsyntax_pos/hygiene.rs
@@ -135,11 +135,9 @@ impl Mark {
     pub fn looks_like_proc_macro_derive(self) -> bool {
         HygieneData::with(|data| {
             if data.default_transparency(self) == Transparency::Opaque {
-                if let Some(expn_info) = &data.marks[self.0 as usize].expn_info {
-                    if let ExpnKind::MacroAttribute(name) = expn_info.kind {
-                        if name.as_str().starts_with("derive(") {
-                            return true;
-                        }
+                if let Some(expn_info) = data.expn_info(self) {
+                    if let ExpnKind::Macro(MacroKind::Derive, _) = expn_info.kind {
+                        return true;
                     }
                 }
             }
@@ -193,7 +191,7 @@ impl HygieneData {
     }
 
     fn default_transparency(&self, mark: Mark) -> Transparency {
-        self.marks[mark.0 as usize].expn_info.as_ref().map_or(
+        self.expn_info(mark).map_or(
             Transparency::SemiTransparent, |einfo| einfo.default_transparency
         )
     }
@@ -613,7 +611,8 @@ impl fmt::Debug for SyntaxContext {
     }
 }
 
-/// Extra information for tracking spans of macro and syntax sugar expansion
+/// A subset of properties from both macro definition and macro call available through global data.
+/// Avoid using this if you have access to the original definition or call structures.
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 pub struct ExpnInfo {
     // --- The part unique to each expansion.
@@ -627,7 +626,7 @@ pub struct ExpnInfo {
     /// call_site span would have its own ExpnInfo, with the call_site
     /// pointing to the `foo!` invocation.
     pub call_site: Span,
-    /// The format with which the macro was invoked.
+    /// The kind of this expansion - macro or compiler desugaring.
     pub kind: ExpnKind,
 
     // --- The part specific to the macro/desugaring definition.
@@ -675,13 +674,12 @@ impl ExpnInfo {
     }
 }
 
-/// The source of expansion.
+/// Expansion kind.
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 pub enum ExpnKind {
-    /// e.g., #[derive(...)] <item>
-    MacroAttribute(Symbol),
-    /// e.g., `format!()`
-    MacroBang(Symbol),
+    /// Expansion produced by a macro.
+    /// FIXME: Some code injected by the compiler before HIR lowering also gets this kind.
+    Macro(MacroKind, Symbol),
     /// Desugaring done by the compiler during HIR lowering.
     Desugaring(DesugaringKind)
 }
@@ -689,8 +687,8 @@ pub enum ExpnKind {
 impl ExpnKind {
     pub fn descr(&self) -> Symbol {
         match *self {
-            ExpnKind::MacroBang(name) | ExpnKind::MacroAttribute(name) => name,
-            ExpnKind::Desugaring(kind) => kind.descr(),
+            ExpnKind::Macro(_, descr) => descr,
+            ExpnKind::Desugaring(kind) => Symbol::intern(kind.descr()),
         }
     }
 }
@@ -743,8 +741,8 @@ pub enum DesugaringKind {
 }
 
 impl DesugaringKind {
-    pub fn descr(self) -> Symbol {
-        Symbol::intern(match self {
+    pub fn descr(self) -> &'static str {
+        match self {
             DesugaringKind::CondTemporary => "if and while condition",
             DesugaringKind::Async => "async",
             DesugaringKind::Await => "await",
@@ -752,7 +750,7 @@ impl DesugaringKind {
             DesugaringKind::TryBlock => "try block",
             DesugaringKind::ExistentialType => "existential type",
             DesugaringKind::ForLoop => "for loop",
-        })
+        }
     }
 }
 
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index 1369fca3b4a..4fd27ce4f96 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -27,7 +27,7 @@ extern crate serialize as rustc_serialize; // used by deriving
 pub mod edition;
 use edition::Edition;
 pub mod hygiene;
-pub use hygiene::{Mark, SyntaxContext, ExpnInfo, ExpnKind, DesugaringKind};
+pub use hygiene::{Mark, SyntaxContext, ExpnInfo, ExpnKind, MacroKind, DesugaringKind};
 
 mod span_encoding;
 pub use span_encoding::{Span, DUMMY_SP};
@@ -442,9 +442,12 @@ impl Span {
             // Don't print recursive invocations.
             if !info.call_site.source_equal(&prev_span) {
                 let (pre, post) = match info.kind {
-                    ExpnKind::MacroAttribute(..) => ("#[", "]"),
-                    ExpnKind::MacroBang(..) => ("", "!"),
                     ExpnKind::Desugaring(..) => ("desugaring of `", "`"),
+                    ExpnKind::Macro(macro_kind, _) => match macro_kind {
+                        MacroKind::Bang => ("", "!"),
+                        MacroKind::Attr => ("#[", "]"),
+                        MacroKind::Derive => ("#[derive(", ")]"),
+                    }
                 };
                 result.push(MacroBacktrace {
                     call_site: info.call_site,