Support other types of pluralization in pluralize macro

compiler/rustc_lint_defs/src/lib.rs

@@ -20,6 +20,12 @@ macro_rules! pluralize {
     ($x:expr) => {
         if $x != 1 { "s" } else { "" }
     };
+    ("is", $x:expr) => {
+        if $x == 1 { "is" } else { "are" }
+    };
+    ("this", $x:expr) => {
+        if $x == 1 { "this" } else { "these" }
+    };
 }
 
 /// Indicates the confidence in the correctness of a suggestion.

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -400,7 +400,7 @@ impl fmt::Display for UndefinedBehaviorInfo<'_> {
                 Pointer::new(*alloc, access.access_offset),
                 access.uninit_size.bytes(),
                 pluralize!(access.uninit_size.bytes()),
-                if access.uninit_size.bytes() != 1 { "are" } else { "is" },
+                pluralize!("is", access.uninit_size.bytes()),
                 Pointer::new(*alloc, access.uninit_offset),
             ),
             InvalidUninitBytes(None) => write!(

compiler/rustc_middle/src/ty/error.rs

@@ -847,7 +847,7 @@ fn foo(&self) -> Self::T { String::new() }
                 "{some} method{s} {are} available that return{r} `{ty}`",
                 some = if methods.len() == 1 { "a" } else { "some" },
                 s = pluralize!(methods.len()),
-                are = if methods.len() == 1 { "is" } else { "are" },
+                are = pluralize!("is", methods.len()),
                 r = if methods.len() == 1 { "s" } else { "" },
                 ty = expected
             );

compiler/rustc_passes/src/check_attr.rs

@@ -1410,7 +1410,7 @@ impl CheckAttrVisitor<'_> {
                             span,
                             format!(
                                 "there {} only {} argument{}",
-                                if arg_count != 1 { "are" } else { "is" },
+                                pluralize!("is", arg_count),
                                 arg_count,
                                 pluralize!(arg_count)
                             ),

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -504,9 +504,9 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                     for sp in spans {
                         let msg = if sp == last_bound_span {
                             format!(
-                                "...because of {} bound{}",
-                                if bounds.len() <= 2 { "this" } else { "these" },
-                                if bounds.len() <= 2 { "" } else { "s" },
+                                "...because of {these} bound{s}",
+                                these = pluralize!("this", bounds.len() - 1),
+                                s = pluralize!(bounds.len() - 1),
                             )
                         } else {
                             String::new()

compiler/rustc_typeck/src/check/pat.rs

@@ -1761,7 +1761,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             sp,
             &format!(
                 "include the missing field{} in the pattern{}",
-                if len == 1 { "" } else { "s" },
+                pluralize!(len),
                 if have_inaccessible_fields { " and ignore the inaccessible fields" } else { "" }
             ),
             format!(
@@ -1780,10 +1780,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err.span_suggestion(
             sp,
             &format!(
-                "if you don't care about {} missing field{}, you can explicitly ignore {}",
-                if len == 1 { "this" } else { "these" },
-                if len == 1 { "" } else { "s" },
-                if len == 1 { "it" } else { "them" },
+                "if you don't care about {these} missing field{s}, you can explicitly ignore {them}",
+                these = pluralize!("this", len),
+                s = pluralize!(len),
+                them = if len == 1 { "it" } else { "them" },
             ),
             format!("{}..{}", prefix, postfix),
             Applicability::MachineApplicable,

compiler/rustc_typeck/src/coherence/inherent_impls.rs

@@ -7,7 +7,7 @@
 //! `tcx.inherent_impls(def_id)`). That value, however,
 //! is computed by selecting an idea from this table.
 
-use rustc_errors::struct_span_err;
+use rustc_errors::{pluralize, struct_span_err};
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
@@ -410,7 +410,6 @@ impl<'tcx> InherentCollect<'tcx> {
                 let to_implement = if assoc_items.is_empty() {
                     String::new()
                 } else {
-                    let plural = assoc_items.len() > 1;
                     let assoc_items_kind = {
                         let item_types = assoc_items.iter().map(|x| x.kind);
                         if item_types.clone().all(|x| x == hir::AssocItemKind::Const) {
@@ -427,9 +426,9 @@ impl<'tcx> InherentCollect<'tcx> {
 
                     format!(
                         " to implement {} {}{}",
-                        if plural { "these" } else { "this" },
+                        pluralize!("this", assoc_items.len()),
                         assoc_items_kind,
-                        if plural { "s" } else { "" }
+                        pluralize!(assoc_items.len()),
                     )
                 };
 

compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs

@@ -657,10 +657,9 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
 
             let num_redundant_lt_args = lt_arg_spans.len() - self.num_expected_lifetime_args();
             let msg_lifetimes = format!(
-                "remove {} {} argument{}",
-                if num_redundant_lt_args == 1 { "this" } else { "these" },
-                "lifetime",
-                pluralize!(num_redundant_lt_args),
+                "remove {these} lifetime argument{s}",
+                these = pluralize!("this", num_redundant_lt_args),
+                s = pluralize!(num_redundant_lt_args),
             );
 
             err.span_suggestion(
@@ -700,10 +699,9 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
             let num_redundant_gen_args =
                 gen_arg_spans.len() - self.num_expected_type_or_const_args();
             let msg_types_or_consts = format!(
-                "remove {} {} argument{}",
-                if num_redundant_gen_args == 1 { "this" } else { "these" },
-                "generic",
-                pluralize!(num_redundant_type_or_const_args),
+                "remove {these} generic argument{s}",
+                these = pluralize!("this", num_redundant_gen_args),
+                s = pluralize!(num_redundant_gen_args),
             );
 
             err.span_suggestion(