Using !span.from_expansion() instead of snippets

Author: kper

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

@@ -571,30 +571,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     // Because of this, we modify the error to refer to the original obligation and
                     // return early in the caller.
 
-                    let has_colon = self
-                        .tcx
-                        .sess
-                        .source_map()
-                        .span_to_snippet(span)
-                        .map(|w| w.contains(":"))
-                        .unwrap_or(false);
-
-                    let has_double_colon = self
-                        .tcx
-                        .sess
-                        .source_map()
-                        .span_to_snippet(span)
-                        .map(|w| w.contains("::"))
-                        .unwrap_or(false);
-
-                    let has_bracket = self
-                        .tcx
-                        .sess
-                        .source_map()
-                        .span_to_snippet(span)
-                        .map(|w| w.contains("{"))
-                        .unwrap_or(false);
-
                     let msg = format!(
                         "the trait bound `{}: {}` is not satisfied",
                         found,
@@ -619,7 +595,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     );
 
                     // This if is to prevent a special edge-case
-                    if !has_colon || has_double_colon || has_bracket {
+                    if !span.from_expansion() {
                         // We don't want a borrowing suggestion on the fields in structs,
                         // ```
                         // struct Foo {