Rollup merge of #100970 - Xiretza:derive-multipart-suggestion, r=davidtwco

Allow deriving multipart suggestions

This turned into a bit more of a rewrite than I was initially hoping for... Still, I think the `SessionSubdiagnostic` derive is a little cleaner overall now, and closer to the `SessionDiagnostic` derive to make future code sharing easier.

r? ``@davidtwco``

2 files changed, 292 insertions, 100 deletions

diff --git a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
index ddfc0d3365d..89eaec78c6f 100644
--- a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
+++ b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
@@ -167,8 +167,8 @@ enum P {
 #[derive(SessionSubdiagnostic)]
 enum Q {
     #[bar]
-//~^ ERROR `#[bar]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -179,8 +179,8 @@ enum Q {
 #[derive(SessionSubdiagnostic)]
 enum R {
     #[bar = "..."]
-//~^ ERROR `#[bar = ...]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar = ...]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -191,8 +191,8 @@ enum R {
 #[derive(SessionSubdiagnostic)]
 enum S {
     #[bar = 4]
-//~^ ERROR `#[bar = ...]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar = ...]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -203,8 +203,8 @@ enum S {
 #[derive(SessionSubdiagnostic)]
 enum T {
     #[bar("...")]
-//~^ ERROR `#[bar("...")]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar(...)]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -215,7 +215,7 @@ enum T {
 #[derive(SessionSubdiagnostic)]
 enum U {
     #[label(code = "...")]
-//~^ ERROR diagnostic slug must be first argument of a `#[label(...)]` attribute
+    //~^ ERROR diagnostic slug must be first argument of a `#[label(...)]` attribute
     A {
         #[primary_span]
         span: Span,
@@ -232,7 +232,7 @@ enum V {
         var: String,
     },
     B {
-//~^ ERROR subdiagnostic kind not specified
+    //~^ ERROR subdiagnostic kind not specified
         #[primary_span]
         span: Span,
         var: String,
@@ -310,10 +310,8 @@ union AC {
 #[derive(SessionSubdiagnostic)]
 #[label(parser::add_paren)]
 //~^ NOTE previously specified here
-//~^^ NOTE previously specified here
 #[label(parser::add_paren)]
 //~^ ERROR specified multiple times
-//~^^ ERROR specified multiple times
 struct AD {
     #[primary_span]
     span: Span,
@@ -331,16 +329,16 @@ struct AE {
 #[label(parser::add_paren)]
 struct AF {
     #[primary_span]
-//~^ NOTE previously specified here
+    //~^ NOTE previously specified here
     span_a: Span,
     #[primary_span]
-//~^ ERROR specified multiple times
+    //~^ ERROR specified multiple times
     span_b: Span,
 }
 
 #[derive(SessionSubdiagnostic)]
 struct AG {
-//~^ ERROR subdiagnostic kind not specified
+    //~^ ERROR subdiagnostic kind not specified
     #[primary_span]
     span: Span,
 }
@@ -392,27 +390,25 @@ struct AK {
     #[primary_span]
     span: Span,
     #[applicability]
-//~^ NOTE previously specified here
+    //~^ NOTE previously specified here
     applicability_a: Applicability,
     #[applicability]
-//~^ ERROR specified multiple times
+    //~^ ERROR specified multiple times
     applicability_b: Applicability,
 }
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AL {
     #[primary_span]
     span: Span,
     #[applicability]
-//~^ ERROR the `#[applicability]` attribute can only be applied to fields of type `Applicability`
+    //~^ ERROR the `#[applicability]` attribute can only be applied to fields of type `Applicability`
     applicability: Span,
 }
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AM {
     #[primary_span]
     span: Span,
@@ -448,8 +444,7 @@ struct AQ;
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
-//~^^ ERROR suggestion without `#[primary_span]` field
+//~^ ERROR suggestion without `#[primary_span]` field
 struct AR {
     var: String,
 }
@@ -519,3 +514,120 @@ struct AZ {
     #[primary_span]
     span: Span,
 }
+
+#[derive(SessionSubdiagnostic)]
+#[suggestion(parser::add_paren, code = "...")]
+//~^ ERROR suggestion without `#[primary_span]` field
+struct BA {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part]` is not a valid attribute
+    span: Span,
+    #[suggestion_part(code = "...")]
+    //~^ ERROR `#[suggestion_part(...)]` is not a valid attribute
+    span2: Span,
+    #[applicability]
+    applicability: Applicability,
+    var: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
+//~^ ERROR multipart suggestion without any `#[suggestion_part(...)]` fields
+//~| ERROR `code` is not a valid nested attribute of a `multipart_suggestion` attribute
+struct BBa {
+    var: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BBb {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BBc {
+    #[suggestion_part()]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+//~^ ERROR multipart suggestion without any `#[suggestion_part(...)]` fields
+struct BC {
+    #[primary_span]
+    //~^ ERROR `#[primary_span]` is not a valid attribute
+    span: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+struct BD {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+    #[suggestion_part()]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span2: Span,
+    #[suggestion_part(foo = "bar")]
+    //~^ ERROR `#[suggestion_part(foo = ...)]` is not a valid attribute
+    span4: Span,
+    #[suggestion_part(code = "...")]
+    //~^ ERROR the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+    s1: String,
+    #[suggestion_part()]
+    //~^ ERROR the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+    s2: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BE {
+    #[suggestion_part(code = "...", code = ",,,")]
+    //~^ ERROR specified multiple times
+    //~| NOTE previously specified here
+    span: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BF {
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+struct BG {
+    #[applicability]
+    appl: Applicability,
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+//~^ NOTE previously specified here
+struct BH {
+    #[applicability]
+    //~^ ERROR specified multiple times
+    appl: Applicability,
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BI {
+    #[suggestion_part(code = "")]
+    spans: Vec<Span>,
+}
diff --git a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
index a289c4fffd9..75a34f44bbe 100644
--- a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
+++ b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
@@ -65,16 +65,16 @@ LL | #[label()]
    | ^^^^^^^^^^
 
 error: `code` is not a valid nested attribute of a `label` attribute
-  --> $DIR/subdiagnostic-derive.rs:137:1
+  --> $DIR/subdiagnostic-derive.rs:137:28
    |
 LL | #[label(parser::add_paren, code = "...")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                            ^^^^^^^^^^^^
 
 error: `applicability` is not a valid nested attribute of a `label` attribute
-  --> $DIR/subdiagnostic-derive.rs:146:1
+  --> $DIR/subdiagnostic-derive.rs:146:28
    |
 LL | #[label(parser::add_paren, applicability = "machine-applicable")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: unsupported type attribute for subdiagnostic enum
   --> $DIR/subdiagnostic-derive.rs:155:1
@@ -100,13 +100,11 @@ error: `#[bar = ...]` is not a valid attribute
 LL |     #[bar = 4]
    |     ^^^^^^^^^^
 
-error: `#[bar("...")]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:205:11
+error: `#[bar(...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:205:5
    |
 LL |     #[bar("...")]
-   |           ^^^^^
-   |
-   = help: first argument of the attribute should be the diagnostic slug
+   |     ^^^^^^^^^^^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
   --> $DIR/subdiagnostic-derive.rs:217:5
@@ -163,6 +161,8 @@ error: `#[bar(...)]` is not a valid attribute
    |
 LL |     #[bar("...")]
    |     ^^^^^^^^^^^^^
+   |
+   = help: only `primary_span`, `applicability` and `skip_arg` are valid field attributes
 
 error: unexpected unsupported untagged union
   --> $DIR/subdiagnostic-derive.rs:304:1
@@ -175,19 +175,7 @@ LL | | }
    | |_^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:314:1
-   |
-LL | #[label(parser::add_paren)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:311:1
-   |
-LL | #[label(parser::add_paren)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:314:1
+  --> $DIR/subdiagnostic-derive.rs:313:1
    |
 LL | #[label(parser::add_paren)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -199,7 +187,7 @@ LL | #[label(parser::add_paren)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[label(parser::add_paren)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:323:28
+  --> $DIR/subdiagnostic-derive.rs:321:28
    |
 LL | #[label(parser::add_paren, parser::add_paren)]
    |                            ^^^^^^^^^^^^^^^^^
@@ -207,133 +195,225 @@ LL | #[label(parser::add_paren, parser::add_paren)]
    = help: a diagnostic slug must be the first argument to the attribute
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:336:5
+  --> $DIR/subdiagnostic-derive.rs:334:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:333:5
+  --> $DIR/subdiagnostic-derive.rs:331:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: subdiagnostic kind not specified
-  --> $DIR/subdiagnostic-derive.rs:342:8
+  --> $DIR/subdiagnostic-derive.rs:340:8
    |
 LL | struct AG {
    |        ^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:379:47
+  --> $DIR/subdiagnostic-derive.rs:377:47
    |
 LL | #[suggestion(parser::add_paren, code = "...", code = "...")]
    |                                               ^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:379:33
+  --> $DIR/subdiagnostic-derive.rs:377:33
    |
 LL | #[suggestion(parser::add_paren, code = "...", code = "...")]
    |                                 ^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:397:5
+  --> $DIR/subdiagnostic-derive.rs:395:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:394:5
+  --> $DIR/subdiagnostic-derive.rs:392:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: the `#[applicability]` attribute can only be applied to fields of type `Applicability`
-  --> $DIR/subdiagnostic-derive.rs:408:5
+  --> $DIR/subdiagnostic-derive.rs:405:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:403:1
+error: suggestion without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:418:1
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
-LL | |
-LL | | struct AL {
-LL | |     #[primary_span]
-...  |
-LL | |     applicability: Span,
-LL | | }
-   | |_^
+LL | #[suggestion(parser::add_paren)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: invalid applicability
+  --> $DIR/subdiagnostic-derive.rs:428:46
+   |
+LL | #[suggestion(parser::add_paren, code ="...", applicability = "foo")]
+   |                                              ^^^^^^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:414:1
+error: suggestion without `#[primary_span]` field
+  --> $DIR/subdiagnostic-derive.rs:446:1
    |
 LL | / #[suggestion(parser::add_paren, code = "...")]
 LL | |
-LL | | struct AM {
-LL | |     #[primary_span]
-LL | |     span: Span,
+LL | | struct AR {
+LL | |     var: String,
 LL | | }
    | |_^
 
-error: suggestion without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:422:1
+error: unsupported type attribute for subdiagnostic enum
+  --> $DIR/subdiagnostic-derive.rs:460:1
+   |
+LL | #[label]
+   | ^^^^^^^^
+
+error: `var` doesn't refer to a field on this type
+  --> $DIR/subdiagnostic-derive.rs:480:39
+   |
+LL | #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
+   |                                       ^^^^^^^
+
+error: `var` doesn't refer to a field on this type
+  --> $DIR/subdiagnostic-derive.rs:499:43
+   |
+LL |     #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
+   |                                           ^^^^^^^
+
+error: `#[suggestion_part]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:522:5
+   |
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = help: `#[suggestion_part(...)]` is only valid in multipart suggestions, use `#[primary_span]` instead
+
+error: `#[suggestion_part(...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:525:5
+   |
+LL |     #[suggestion_part(code = "...")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-LL | / #[suggestion(parser::add_paren)]
+   = help: `#[suggestion_part(...)]` is only valid in multipart suggestions
+
+error: suggestion without `#[primary_span]` field
+  --> $DIR/subdiagnostic-derive.rs:519:1
+   |
+LL | / #[suggestion(parser::add_paren, code = "...")]
 LL | |
-LL | | struct AN {
-LL | |     #[primary_span]
+LL | | struct BA {
+LL | |     #[suggestion_part]
 ...  |
-LL | |     applicability: Applicability,
+LL | |     var: String,
 LL | | }
    | |_^
 
-error: invalid applicability
-  --> $DIR/subdiagnostic-derive.rs:432:46
+error: `code` is not a valid nested attribute of a `multipart_suggestion` attribute
+  --> $DIR/subdiagnostic-derive.rs:534:43
    |
-LL | #[suggestion(parser::add_paren, code ="...", applicability = "foo")]
-   |                                              ^^^^^^^^^^^^^^^^^^^^^
+LL | #[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
+   |                                           ^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:450:1
+error: multipart suggestion without any `#[suggestion_part(...)]` fields
+  --> $DIR/subdiagnostic-derive.rs:534:1
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
+LL | / #[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
 LL | |
 LL | |
-LL | | struct AR {
+LL | | struct BBa {
 LL | |     var: String,
 LL | | }
    | |_^
 
-error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:450:1
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:544:5
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:552:5
+   |
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: `#[primary_span]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:561:5
+   |
+LL |     #[primary_span]
+   |     ^^^^^^^^^^^^^^^
+   |
+   = help: multipart suggestions use one or more `#[suggestion_part]`s rather than one `#[primary_span]`
+
+error: multipart suggestion without any `#[suggestion_part(...)]` fields
+  --> $DIR/subdiagnostic-derive.rs:558:1
+   |
+LL | / #[multipart_suggestion(parser::add_paren)]
 LL | |
+LL | | struct BC {
+LL | |     #[primary_span]
 LL | |
-LL | | struct AR {
-LL | |     var: String,
+LL | |     span: Span,
 LL | | }
    | |_^
 
-error: unsupported type attribute for subdiagnostic enum
-  --> $DIR/subdiagnostic-derive.rs:465:1
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:569:5
    |
-LL | #[label]
-   | ^^^^^^^^
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
 
-error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:485:39
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:572:5
    |
-LL | #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
-   |                                       ^^^^^^^
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
 
-error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:504:43
+error: `#[suggestion_part(foo = ...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:575:23
    |
-LL |     #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
-   |                                           ^^^^^^^
+LL |     #[suggestion_part(foo = "bar")]
+   |                       ^^^^^^^^^^^
+   |
+   = help: `code` is the only valid nested attribute
+
+error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+  --> $DIR/subdiagnostic-derive.rs:578:5
+   |
+LL |     #[suggestion_part(code = "...")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+  --> $DIR/subdiagnostic-derive.rs:581:5
+   |
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: specified multiple times
+  --> $DIR/subdiagnostic-derive.rs:589:37
+   |
+LL |     #[suggestion_part(code = "...", code = ",,,")]
+   |                                     ^^^^^^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/subdiagnostic-derive.rs:589:23
+   |
+LL |     #[suggestion_part(code = "...", code = ",,,")]
+   |                       ^^^^^^^^^^^^
+
+error: specified multiple times
+  --> $DIR/subdiagnostic-derive.rs:619:5
+   |
+LL |     #[applicability]
+   |     ^^^^^^^^^^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/subdiagnostic-derive.rs:616:43
+   |
+LL | #[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: cannot find attribute `foo` in this scope
   --> $DIR/subdiagnostic-derive.rs:63:3
@@ -395,6 +475,6 @@ error[E0425]: cannot find value `slug` in module `rustc_errors::fluent`
 LL | #[label(slug)]
    |         ^^^^ not found in `rustc_errors::fluent`
 
-error: aborting due to 52 previous errors
+error: aborting due to 64 previous errors
 
 For more information about this error, try `rustc --explain E0425`.