Make sure that labels are defined after the primary span in diagnostics

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -269,6 +269,7 @@ impl DiagnosticDeriveVariantBuilder {
  let field_binding = &binding_info.binding;
 
  let inner_ty = FieldInnerTy::from_type(&field.ty);
+ let mut seen_label = false;
 
  field
  .attrs
@@ -280,6 +281,14 @@ impl DiagnosticDeriveVariantBuilder {
  }
 
  let name = attr.path().segments.last().unwrap().ident.to_string();
+
+ if name == "primary_span" && seen_label {
+ span_err(attr.span().unwrap(), format!("`#[primary_span]` must be placed before labels, since it overwrites the span of the diagnostic")).emit();
+ }
+ if name == "label" {
+ seen_label = true;
+ }
+
  let needs_clone =
  name == "primary_span" && matches!(inner_ty, FieldInnerTy::Vec(_));
  let (binding, needs_destructure) = if needs_clone {

compiler/rustc_resolve/src/errors.rs

@@ -1089,8 +1089,8 @@ pub(crate) struct ToolWasAlreadyRegistered {
 #[derive(Diagnostic)]
 #[diag(resolve_tool_only_accepts_identifiers)]
 pub(crate) struct ToolOnlyAcceptsIdentifiers {
- #[label]
  #[primary_span]
+ #[label]
  pub(crate) span: Span,
  pub(crate) tool: Symbol,
 }

tests/ui/tool-attributes/invalid-tool.rs

@@ -0,0 +1,6 @@
+#![feature(register_tool)]
+
+#![register_tool(1)]
+//~^ ERROR `register_tool` only accepts identifiers
+
+fn main() {}

tests/ui/tool-attributes/invalid-tool.stderr

@@ -0,0 +1,8 @@
+error: `register_tool` only accepts identifiers
+ --> $DIR/invalid-tool.rs:3:18
+ |
+LL | #![register_tool(1)]
+ | ^ not an identifier
+
+error: aborting due to 1 previous error
+