rustc_span: Revert addition of proc_macro field to ExpnKind::Macro

The flag has a vague meaning and is used for a single diagnostic change that is low benefit and appears only under `-Z macro_backtrace`.

Author: petrochenkov

clippy_lints/src/misc.rs

@@ -662,14 +662,7 @@ fn in_attributes_expansion(expr: &Expr<'_>) -> bool {
     use rustc_span::hygiene::MacroKind;
     if expr.span.from_expansion() {
         let data = expr.span.ctxt().outer_expn_data();
-        matches!(
-            data.kind,
-            ExpnKind::Macro {
-                kind: MacroKind::Attr,
-                name: _,
-                proc_macro: _
-            }
-        )
+        matches!(data.kind, ExpnKind::Macro(MacroKind::Attr, _))
     } else {
         false
     }

clippy_lints/src/unit_types/unit_cmp.rs

@@ -8,12 +8,7 @@ use super::UNIT_CMP;
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
     if expr.span.from_expansion() {
         if let Some(callee) = expr.span.source_callee() {
-            if let ExpnKind::Macro {
-                kind: MacroKind::Bang,
-                name: symbol,
-                proc_macro: _,
-            } = callee.kind
-            {
+            if let ExpnKind::Macro(MacroKind::Bang, symbol) = callee.kind {
                 if let ExprKind::Binary(ref cmp, left, _) = expr.kind {
                     let op = cmp.node;
                     if op.is_comparison() && cx.typeck_results().expr_ty(left).is_unit() {

clippy_utils/src/lib.rs

@@ -953,12 +953,7 @@ pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
             let data = span.ctxt().outer_expn_data();
             let new_span = data.call_site;
 
-            if let ExpnKind::Macro {
-                kind: MacroKind::Bang,
-                name: mac_name,
-                proc_macro: _,
-            } = data.kind
-            {
+            if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
                 if mac_name.as_str() == name {
                     return Some(new_span);
                 }
@@ -986,12 +981,7 @@ pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
         let data = span.ctxt().outer_expn_data();
         let new_span = data.call_site;
 
-        if let ExpnKind::Macro {
-            kind: MacroKind::Bang,
-            name: mac_name,
-            proc_macro: _,
-        } = data.kind
-        {
+        if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
             if mac_name.as_str() == name {
                 return Some(new_span);
             }