Disallow #[primary_span] on LintDiagnostics

Author: Xiretza

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -340,11 +340,20 @@ impl DiagnosticDeriveBuilder {
                 Ok(quote! {})
             }
             "primary_span" => {
-                report_error_if_not_applied_to_span(attr, &info)?;
+                match self.kind {
+                    DiagnosticDeriveKind::SessionDiagnostic => {
+                        report_error_if_not_applied_to_span(attr, &info)?;
 
-                Ok(quote! {
-                    #diag.set_span(#binding);
-                })
+                        Ok(quote! {
+                            #diag.set_span(#binding);
+                        })
+                    }
+                    DiagnosticDeriveKind::LintDiagnostic => {
+                        throw_invalid_attr!(attr, &meta, |diag| {
+                            diag.help("the `primary_span` field attribute is not valid for lint diagnostics")
+                        })
+                    }
+                }
             }
             "label" => {
                 report_error_if_not_applied_to_span(attr, &info)?;

compiler/rustc_passes/src/errors.rs

@@ -613,7 +613,6 @@ pub struct NonExportedMacroInvalidAttrs {
 #[derive(LintDiagnostic)]
 #[lint(passes::unused_duplicate)]
 pub struct UnusedDuplicate {
-    #[primary_span]
     #[suggestion(code = "", applicability = "machine-applicable")]
     pub this: Span,
     #[note]

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

@@ -551,6 +551,14 @@ struct LintsGood {
 struct ErrorsBad {
 }
 
+#[derive(LintDiagnostic)]
+#[lint(typeck::ambiguous_lifetime_bound)]
+struct PrimarySpanOnLint {
+    #[primary_span]
+    //~^ ERROR `#[primary_span]` is not a valid attribute
+    span: Span,
+}
+
 #[derive(SessionDiagnostic)]
 #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithMultiSpan {

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

@@ -355,6 +355,14 @@ LL | #[error(typeck::ambiguous_lifetime_bound)]
    |
    = help: use the `#[lint(...)]` attribute to create a lint
 
+error: `#[primary_span]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:557:5
+   |
+LL |     #[primary_span]
+   |     ^^^^^^^^^^^^^^^
+   |
+   = help: the `primary_span` field attribute is not valid for lint diagnostics
+
 error: cannot find attribute `nonsense` in this scope
   --> $DIR/diagnostic-derive.rs:53:3
    |
@@ -387,7 +395,7 @@ LL |         arg: impl IntoDiagnosticArg,
    |                   ^^^^^^^^^^^^^^^^^ required by this bound in `DiagnosticBuilder::<'a, G>::set_arg`
    = note: this error originates in the derive macro `SessionDiagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 46 previous errors
+error: aborting due to 47 previous errors
 
 Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.