3 files changed, 40 insertions, 28 deletions
diff --git a/compiler/rustc_macros/src/query.rs b/compiler/rustc_macros/src/query.rs
index 88ea6e07d6e..62bf34ad5ad 100644
--- a/compiler/rustc_macros/src/query.rs
+++ b/compiler/rustc_macros/src/query.rs
@@ -118,11 +118,17 @@ struct QueryModifiers {
     /// Generate a `feed` method to set the query's value from another query.
     feedable: Option<Ident>,
 
-    /// Forward the result on ensure if the query gets recomputed, and
-    /// return `Ok(())` otherwise. Only applicable to queries returning
-    /// `Result<T, ErrorGuaranteed>`. The `T` is not returned from `ensure`
-    /// invocations.
-    ensure_forwards_result_if_red: Option<Ident>,
+    /// When this query is called via `tcx.ensure_ok()`, it returns
+    /// `Result<(), ErrorGuaranteed>` instead of `()`. If the query needs to
+    /// be executed, and that execution returns an error, the error result is
+    /// returned to the caller.
+    ///
+    /// If execution is skipped, a synthetic `Ok(())` is returned, on the
+    /// assumption that a query with all-green inputs must have succeeded.
+    ///
+    /// Can only be applied to queries with a return value of
+    /// `Result<_, ErrorGuaranteed>`.
+    return_result_from_ensure_ok: Option<Ident>,
 }
 
 fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
@@ -138,7 +144,7 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
     let mut depth_limit = None;
     let mut separate_provide_extern = None;
     let mut feedable = None;
-    let mut ensure_forwards_result_if_red = None;
+    let mut return_result_from_ensure_ok = None;
 
     while !input.is_empty() {
         let modifier: Ident = input.parse()?;
@@ -200,8 +206,8 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
             try_insert!(separate_provide_extern = modifier);
         } else if modifier == "feedable" {
             try_insert!(feedable = modifier);
-        } else if modifier == "ensure_forwards_result_if_red" {
-            try_insert!(ensure_forwards_result_if_red = modifier);
+        } else if modifier == "return_result_from_ensure_ok" {
+            try_insert!(return_result_from_ensure_ok = modifier);
         } else {
             return Err(Error::new(modifier.span(), "unknown query modifier"));
         }
@@ -222,7 +228,7 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
         depth_limit,
         separate_provide_extern,
         feedable,
-        ensure_forwards_result_if_red,
+        return_result_from_ensure_ok,
     })
 }
 
@@ -354,7 +360,7 @@ pub(super) fn rustc_queries(input: TokenStream) -> TokenStream {
             eval_always,
             depth_limit,
             separate_provide_extern,
-            ensure_forwards_result_if_red,
+            return_result_from_ensure_ok,
         );
 
         if modifiers.cache.is_some() {
diff --git a/compiler/rustc_macros/src/serialize.rs b/compiler/rustc_macros/src/serialize.rs
index ce692abfb98..2c33a0ac0aa 100644
--- a/compiler/rustc_macros/src/serialize.rs
+++ b/compiler/rustc_macros/src/serialize.rs
@@ -105,11 +105,14 @@ fn decodable_body(
     };
     s.underscore_const(true);
 
-    s.bound_impl(quote!(::rustc_serialize::Decodable<#decoder_ty>), quote! {
-        fn decode(__decoder: &mut #decoder_ty) -> Self {
-            #decode_body
-        }
-    })
+    s.bound_impl(
+        quote!(::rustc_serialize::Decodable<#decoder_ty>),
+        quote! {
+            fn decode(__decoder: &mut #decoder_ty) -> Self {
+                #decode_body
+            }
+        },
+    )
 }
 
 fn decode_field(field: &syn::Field) -> proc_macro2::TokenStream {
@@ -285,13 +288,16 @@ fn encodable_body(
         quote! {}
     };
 
-    s.bound_impl(quote!(::rustc_serialize::Encodable<#encoder_ty>), quote! {
-        fn encode(
-            &self,
-            __encoder: &mut #encoder_ty,
-        ) {
-            #lints
-            #encode_body
-        }
-    })
+    s.bound_impl(
+        quote!(::rustc_serialize::Encodable<#encoder_ty>),
+        quote! {
+            fn encode(
+                &self,
+                __encoder: &mut #encoder_ty,
+            ) {
+                #lints
+                #encode_body
+            }
+        },
+    )
 }
diff --git a/compiler/rustc_macros/src/symbols/tests.rs b/compiler/rustc_macros/src/symbols/tests.rs
index b32ce60e204..9c53453df5b 100644
--- a/compiler/rustc_macros/src/symbols/tests.rs
+++ b/compiler/rustc_macros/src/symbols/tests.rs
@@ -94,8 +94,8 @@ fn check_symbol_order() {
             aardvark,
         }
     };
-    test_symbols_macro(input, &[
-        "Symbol `aardvark` must precede `zebra`",
-        "location of previous symbol `zebra`",
-    ]);
+    test_symbols_macro(
+        input,
+        &["Symbol `aardvark` must precede `zebra`", "location of previous symbol `zebra`"],
+    );
 }