simplify multispan_sugg interface

- add `multispan_sugg_with_applicability`
- not it gets `&str` instead of `String`, like in `diag.multispan_suggestion`

clippy_lints/src/eq_op.rs

@@ -115,7 +115,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
                                     let rsnip = snippet(cx, r.span, "...").to_string();
                                     multispan_sugg(
                                         diag,
-                                        "use the values directly".to_string(),
+                                        "use the values directly",
                                         vec![(left.span, lsnip), (right.span, rsnip)],
                                     );
                                 },

clippy_lints/src/loops.rs

@@ -1134,7 +1134,7 @@ fn check_for_loop_range<'a, 'tcx>(
                         |diag| {
                             multispan_sugg(
                                 diag,
-                                "consider using an iterator".to_string(),
+                                "consider using an iterator",
                                 vec![
                                     (pat.span, format!("({}, <item>)", ident.name)),
                                     (
@@ -1163,7 +1163,7 @@ fn check_for_loop_range<'a, 'tcx>(
                         |diag| {
                             multispan_sugg(
                                 diag,
-                                "consider using an iterator".to_string(),
+                                "consider using an iterator",
                                 vec![(pat.span, "<item>".to_string()), (arg.span, repl)],
                             );
                         },

clippy_lints/src/matches.rs

@@ -820,7 +820,7 @@ fn check_match_ref_pats(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>
 
         span_lint_and_then(cx, MATCH_REF_PATS, expr.span, title, |diag| {
             if !expr.span.from_expansion() {
-                multispan_sugg(diag, msg.to_owned(), suggs);
+                multispan_sugg(diag, msg, suggs);
             }
         });
     }

clippy_lints/src/needless_pass_by_value.rs

@@ -293,7 +293,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessPassByValue {
                             );
                             spans.sort_by_key(|&(span, _)| span);
                         }
-                        multispan_sugg(diag, "consider taking a reference instead".to_string(), spans);
+                        multispan_sugg(diag, "consider taking a reference instead", spans);
                     };
 
                     span_lint_and_then(

clippy_lints/src/types.rs

@@ -2206,7 +2206,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitHasher {
 
             multispan_sugg(
                 diag,
-                "consider adding a type parameter".to_string(),
+                "consider adding a type parameter",
                 vec![
                     (
                         generics_suggestion_span,

clippy_lints/src/utils/diagnostics.rs

@@ -1,6 +1,6 @@
 //! Clippy wrappers around rustc's diagnostic functions.
 
-use rustc_errors::{Applicability, CodeSuggestion, DiagnosticBuilder, Substitution, SubstitutionPart, SuggestionStyle};
+use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_hir::HirId;
 use rustc_lint::{LateContext, Lint, LintContext};
 use rustc_span::source_map::{MultiSpan, Span};
@@ -198,20 +198,20 @@ pub fn span_lint_and_sugg<'a, T: LintContext>(
 /// appear once per
 /// replacement. In human-readable format though, it only appears once before
 /// the whole suggestion.
-pub fn multispan_sugg<I>(diag: &mut DiagnosticBuilder<'_>, help_msg: String, sugg: I)
+pub fn multispan_sugg<I>(diag: &mut DiagnosticBuilder<'_>, help_msg: &str, sugg: I)
 where
     I: IntoIterator<Item = (Span, String)>,
 {
-    let sugg = CodeSuggestion {
-        substitutions: vec![Substitution {
-            parts: sugg
-                .into_iter()
-                .map(|(span, snippet)| SubstitutionPart { snippet, span })
-                .collect(),
-        }],
-        msg: help_msg,
-        style: SuggestionStyle::ShowCode,
-        applicability: Applicability::Unspecified,
-    };
-    diag.suggestions.push(sugg);
+    multispan_sugg_with_applicability(diag, help_msg, Applicability::Unspecified, sugg)
+}
+
+pub fn multispan_sugg_with_applicability<I>(
+    diag: &mut DiagnosticBuilder<'_>,
+    help_msg: &str,
+    applicability: Applicability,
+    sugg: I,
+) where
+    I: IntoIterator<Item = (Span, String)>,
+{
+    diag.multipart_suggestion(help_msg, sugg.into_iter().collect(), applicability);
 }