Re-add #[inline] to Eq::assert_fields_are_eq

Fixes a compile-time regressions, non-inline methods are generally
codegen'd while inline methods are deferred (and this should never be
called, so deferring is the right choice).

compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs

@@ -32,6 +32,9 @@ pub(crate) fn expand_deriving_eq(
             nonself_args: vec![],
             ret_ty: Unit,
             attributes: thin_vec![
+                // This method will never be called, so doing codegen etc. for it is unnecessary.
+                // We prevent this by adding `#[inline]`, which improves compile-time.
+                cx.attr_word(sym::inline, span),
                 cx.attr_nested_word(sym::doc, sym::hidden, span),
                 cx.attr_nested_word(sym::coverage, sym::off, span),
             ],

tests/ui/deriving/deriving-all-codegen.stdout

@@ -62,6 +62,7 @@ impl ::core::cmp::PartialEq for Empty {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Empty {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {}
@@ -138,6 +139,7 @@ impl ::core::cmp::PartialEq for Point {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Point {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -225,6 +227,7 @@ impl ::core::cmp::PartialEq for PackedPoint {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for PackedPoint {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -307,6 +310,7 @@ impl ::core::cmp::PartialEq for TupleSingleField {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for TupleSingleField {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -381,6 +385,7 @@ impl ::core::cmp::PartialEq for SingleField {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for SingleField {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -485,6 +490,7 @@ impl ::core::cmp::PartialEq for Big {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Big {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -748,6 +754,7 @@ impl ::core::cmp::PartialEq for Unsized {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Unsized {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -842,6 +849,7 @@ impl<T: ::core::cmp::PartialEq + Trait, U: ::core::cmp::PartialEq>
 #[automatically_derived]
 impl<T: ::core::cmp::Eq + Trait, U: ::core::cmp::Eq> ::core::cmp::Eq for
     Generic<T, U> where T::A: ::core::cmp::Eq {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -963,6 +971,7 @@ impl<T: ::core::cmp::PartialEq + ::core::marker::Copy + Trait,
 impl<T: ::core::cmp::Eq + ::core::marker::Copy + Trait, U: ::core::cmp::Eq +
     ::core::marker::Copy> ::core::cmp::Eq for PackedGeneric<T, U> where
     T::A: ::core::cmp::Eq + ::core::marker::Copy {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -1047,6 +1056,7 @@ impl ::core::cmp::PartialEq for Enum0 {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Enum0 {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {}
@@ -1116,6 +1126,7 @@ impl ::core::cmp::PartialEq for Enum1 {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Enum1 {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -1181,6 +1192,7 @@ impl ::core::cmp::PartialEq for Fieldless1 {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Fieldless1 {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {}
@@ -1257,6 +1269,7 @@ impl ::core::cmp::PartialEq for Fieldless {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Fieldless {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {}
@@ -1366,6 +1379,7 @@ impl ::core::cmp::PartialEq for Mixed {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Mixed {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -1563,6 +1577,7 @@ impl ::core::cmp::PartialEq for Fielded {
 }
 #[automatically_derived]
 impl ::core::cmp::Eq for Fielded {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {
@@ -1684,6 +1699,7 @@ impl<T: ::core::cmp::PartialEq, U: ::core::cmp::PartialEq>
 #[automatically_derived]
 impl<T: ::core::cmp::Eq, U: ::core::cmp::Eq> ::core::cmp::Eq for
     EnumGeneric<T, U> {
+    #[inline]
     #[doc(hidden)]
     #[coverage(off)]
     fn assert_fields_are_eq(&self) {

tests/ui/stats/macro-stats.stderr

@@ -8,7 +8,7 @@ macro-stats #[derive(Hash)]                       2         17        8.5
 macro-stats q!                                    1         26       26.0        519      519.0
 macro-stats #[derive(Ord)]                        1         15       15.0        503      503.0
 macro-stats #[derive(Default)]                    2         16        8.0        403      201.5
-macro-stats #[derive(Eq)]                         1         10       10.0        298      298.0
+macro-stats #[derive(Eq)]                         1         11       11.0        312      312.0
 macro-stats #[derive(Debug)]                      1          8        8.0        277      277.0
 macro-stats #[derive(PartialEq)]                  1          9        9.0        267      267.0
 macro-stats #[derive(Copy)]                       1          2        2.0         61       61.0