review comment

Author: estebank

Diff for: compiler/rustc_passes/src/check_attr.rs

@@ -2538,7 +2538,17 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
                         });
                     tcx.sess.emit_err(errors::InvalidAttrAtCrateLevel {
                         span: attr.span,
-                        snippet: tcx.sess.source_map().span_to_snippet(attr.span).ok(),
+                        sugg_span: tcx
+                            .sess
+                            .source_map()
+                            .span_to_snippet(attr.span)
+                            .ok()
+                            .filter(|src| src.starts_with("#!["))
+                            .map(|_| {
+                                attr.span
+                                    .with_lo(attr.span.lo() + BytePos(1))
+                                    .with_hi(attr.span.lo() + BytePos(2))
+                            }),
                         name: *attr_to_check,
                         item,
                     });

Diff for: compiler/rustc_passes/src/errors.rs

@@ -12,7 +12,7 @@ use rustc_errors::{
 use rustc_hir::{self as hir, ExprKind, Target};
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::{MainDefinition, Ty};
-use rustc_span::{BytePos, Span, Symbol, DUMMY_SP};
+use rustc_span::{Span, Symbol, DUMMY_SP};
 
 use crate::check_attr::ProcMacroKind;
 use crate::lang_items::Duplicate;
@@ -849,7 +849,7 @@ pub struct UnknownLangItem {
 
 pub struct InvalidAttrAtCrateLevel {
     pub span: Span,
-    pub snippet: Option<String>,
+    pub sugg_span: Option<Span>,
     pub name: Symbol,
     pub item: Option<ItemFollowingInnerAttr>,
 }
@@ -871,9 +871,9 @@ impl IntoDiagnostic<'_> for InvalidAttrAtCrateLevel {
         diag.set_arg("name", self.name);
         // Only emit an error with a suggestion if we can create a string out
         // of the attribute span
-        if let Some(src) = self.snippet && src.starts_with("#![") {
+        if let Some(span) = self.sugg_span {
             diag.span_suggestion_verbose(
-                self.span.with_lo(self.span.lo() + BytePos(1)).with_hi(self.span.lo() + BytePos(2)),
+                span,
                 fluent::passes_suggestion,
                 String::new(),
                 rustc_errors::Applicability::MachineApplicable,