SessionSubdiagnostic: make #[applicability] optional

compiler/rustc_macros/src/diagnostics/subdiagnostic.rs

@@ -469,14 +469,10 @@ impl<'a> SessionSubdiagnosticDeriveBuilder<'a> {
         };
 
         let span_field = self.span_field.as_ref().map(|(span, _)| span);
-        let applicability = match self.applicability.clone() {
+        let applicability = self.applicability.take().map_or_else(
-            Some((applicability, _)) => Some(applicability),
+            || quote! { rustc_errors::Applicability::Unspecified },
-            None if is_suggestion => {
+            |(applicability, _)| applicability,
-                span_err(self.span, "suggestion without `applicability`").emit();
+        );
-                Some(quote! { rustc_errors::Applicability::Unspecified })
-            }
-            None => None,
-        };
 
         let diag = &self.diag;
         let name = format_ident!("{}{}", if span_field.is_some() { "span_" } else { "" }, kind);

src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs

@@ -401,7 +401,6 @@ struct AK {
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AL {
     #[primary_span]
     span: Span,
@@ -412,7 +411,6 @@ struct AL {
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AM {
     #[primary_span]
     span: Span,
@@ -448,8 +446,7 @@ 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,
 }

src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr

@@ -249,36 +249,13 @@ 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:407:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:403:1
-   |
-LL | / #[suggestion(parser::add_paren, code = "...")]
-LL | |
-LL | | struct AL {
-LL | |     #[primary_span]
-...  |
-LL | |     applicability: Span,
-LL | | }
-   | |_^
-
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:414:1
-   |
-LL | / #[suggestion(parser::add_paren, code = "...")]
-LL | |
-LL | | struct AM {
-LL | |     #[primary_span]
-LL | |     span: Span,
-LL | | }
-   | |_^
-
 error: suggestion without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:422:1
+  --> $DIR/subdiagnostic-derive.rs:420:1
    |
 LL | / #[suggestion(parser::add_paren)]
 LL | |
@@ -290,47 +267,35 @@ LL | | }
    | |_^
 
 error: invalid applicability
-  --> $DIR/subdiagnostic-derive.rs:432:46
+  --> $DIR/subdiagnostic-derive.rs:430:46
    |
 LL | #[suggestion(parser::add_paren, code ="...", applicability = "foo")]
    |                                              ^^^^^^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:450:1
-   |
-LL | / #[suggestion(parser::add_paren, code = "...")]
-LL | |
-LL | |
-LL | | struct AR {
-LL | |     var: String,
-LL | | }
-   | |_^
-
 error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:450:1
+  --> $DIR/subdiagnostic-derive.rs:448:1
    |
 LL | / #[suggestion(parser::add_paren, code = "...")]
 LL | |
-LL | |
 LL | | struct AR {
 LL | |     var: String,
 LL | | }
    | |_^
 
 error: unsupported type attribute for subdiagnostic enum
-  --> $DIR/subdiagnostic-derive.rs:465:1
+  --> $DIR/subdiagnostic-derive.rs:462:1
    |
 LL | #[label]
    | ^^^^^^^^
 
 error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:485:39
+  --> $DIR/subdiagnostic-derive.rs:482:39
    |
 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:504:43
+  --> $DIR/subdiagnostic-derive.rs:501:43
    |
 LL |     #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
    |                                           ^^^^^^^
@@ -395,6 +360,6 @@ 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 49 previous errors
 
 For more information about this error, try `rustc --explain E0425`.