avoid many &str to String conversions with MultiSpan::push_span_label

Author: TaKO8Ki

compiler/rustc_expand/src/tests.rs

@@ -136,7 +136,7 @@ fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &
         let mut msp = MultiSpan::from_span(primary_span);
         for span_label in span_labels {
             let span = make_span(&file_text, &span_label.start, &span_label.end);
-            msp.push_span_label(span, span_label.label.to_string());
+            msp.push_span_label(span, span_label.label);
             println!("span: {:?} label: {:?}", span, span_label.label);
             println!("text: {:?}", source_map.span_to_snippet(span));
         }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs

@@ -194,24 +194,18 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         if !v.0.is_empty() {
                             span = v.0.clone().into();
                             for sp in v.0 {
-                                span.push_span_label(
-                                    sp,
-                                    "`'static` requirement introduced here".to_string(),
-                                );
+                                span.push_span_label(sp, "`'static` requirement introduced here");
                             }
                             add_label = false;
                         }
                     }
                     if add_label {
                         span.push_span_label(
                             fn_decl.output.span(),
-                            "requirement introduced by this return type".to_string(),
+                            "requirement introduced by this return type",
                         );
                     }
-                    span.push_span_label(
-                        cause.span,
-                        "because of this returned expression".to_string(),
-                    );
+                    span.push_span_label(cause.span, "because of this returned expression");
                     err.span_note(
                         span,
                         "`'static` lifetime requirement introduced by the return type",
@@ -523,13 +517,11 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             hir_v.visit_ty(&self_ty);
             for span in &traits {
                 let mut multi_span: MultiSpan = vec![*span].into();
-                multi_span.push_span_label(
-                    *span,
-                    "this has an implicit `'static` lifetime requirement".to_string(),
-                );
+                multi_span
+                    .push_span_label(*span, "this has an implicit `'static` lifetime requirement");
                 multi_span.push_span_label(
                     ident.span,
-                    "calling this method introduces the `impl`'s 'static` requirement".to_string(),
+                    "calling this method introduces the `impl`'s 'static` requirement",
                 );
                 err.span_note(multi_span, "the used `impl` has a `'static` requirement");
                 err.span_suggestion_verbose(

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs

@@ -128,10 +128,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         }
         let mut type_param_span: MultiSpan = visitor.types.to_vec().into();
         for &span in &visitor.types {
-            type_param_span.push_span_label(
-                span,
-                "consider borrowing this type parameter in the trait".to_string(),
-            );
+            type_param_span
+                .push_span_label(span, "consider borrowing this type parameter in the trait");
         }
 
         err.note(&format!("expected `{}`\n   found `{}`", expected, found));

compiler/rustc_infer/src/traits/error_reporting/mod.rs

@@ -85,8 +85,7 @@ pub fn report_object_safety_error<'tcx>(
     let has_multi_span = !multi_span.is_empty();
     let mut note_span = MultiSpan::from_spans(multi_span.clone());
     if let (Some(trait_span), true) = (trait_span, has_multi_span) {
-        note_span
-            .push_span_label(trait_span, "this trait cannot be made into an object...".to_string());
+        note_span.push_span_label(trait_span, "this trait cannot be made into an object...");
     }
     for (span, msg) in iter::zip(multi_span, messages) {
         note_span.push_span_label(span, msg);

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -947,7 +947,7 @@ fn adt_defined_here<'p, 'tcx>(
 
         span.push_span_label(def_span, String::new());
         for pat in spans {
-            span.push_span_label(pat, "not covered".to_string());
+            span.push_span_label(pat, "not covered");
         }
         err.span_note(span, &format!("`{}` defined here", ty));
     }

compiler/rustc_parse/src/parser/mod.rs

@@ -887,22 +887,19 @@ impl<'a> Parser<'a> {
         let mut first_note = MultiSpan::from(vec![initial_semicolon]);
         first_note.push_span_label(
             initial_semicolon,
-            "this `;` turns the preceding closure into a statement".to_string(),
+            "this `;` turns the preceding closure into a statement",
         );
         first_note.push_span_label(
             closure_spans.body,
-            "this expression is a statement because of the trailing semicolon".to_string(),
+            "this expression is a statement because of the trailing semicolon",
         );
         expect_err.span_note(first_note, "statement found outside of a block");
 
         let mut second_note = MultiSpan::from(vec![closure_spans.whole_closure]);
-        second_note.push_span_label(
-            closure_spans.whole_closure,
-            "this is the parsed closure...".to_string(),
-        );
+        second_note.push_span_label(closure_spans.whole_closure, "this is the parsed closure...");
         second_note.push_span_label(
             following_token_span,
-            "...but likely you meant the closure to end here".to_string(),
+            "...but likely you meant the closure to end here",
         );
         expect_err.span_note(second_note, "the closure body may be incorrectly delimited");
 

compiler/rustc_passes/src/check_attr.rs

@@ -857,11 +857,8 @@ impl CheckAttrVisitor<'_> {
             if let Some((prev_inline, prev_span)) = *specified_inline {
                 if do_inline != prev_inline {
                     let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
-                    spans.push_span_label(prev_span, String::from("this attribute..."));
-                    spans.push_span_label(
-                        meta.span(),
-                        String::from("...conflicts with this attribute"),
-                    );
+                    spans.push_span_label(prev_span, "this attribute...");
+                    spans.push_span_label(meta.span(), "...conflicts with this attribute");
                     self.tcx
                         .sess
                         .struct_span_err(spans, "conflicting doc inlining attributes")

compiler/rustc_resolve/src/diagnostics.rs

@@ -2561,7 +2561,7 @@ fn show_candidates(
                 let span = source_span[local_def_id];
                 let span = session.source_map().guess_head_span(span);
                 let mut multi_span = MultiSpan::from_span(span);
-                multi_span.push_span_label(span, "not accessible".to_string());
+                multi_span.push_span_label(span, "not accessible");
                 err.span_note(multi_span, &msg);
             } else {
                 err.note(&msg);

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -601,10 +601,8 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                         };
                         multi_span.push_span_label(sp, msg);
                     }
-                    multi_span.push_span_label(
-                        base_error.span,
-                        "expected this type to be a trait...".to_string(),
-                    );
+                    multi_span
+                        .push_span_label(base_error.span, "expected this type to be a trait...");
                     err.span_help(
                         multi_span,
                         "`+` is used to constrain a \"trait object\" type with lifetimes or \
@@ -1227,17 +1225,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                         let mut m: MultiSpan = non_visible_spans.clone().into();
                         non_visible_spans
                             .into_iter()
-                            .for_each(|s| m.push_span_label(s, "private field".to_string()));
+                            .for_each(|s| m.push_span_label(s, "private field"));
                         err.span_note(m, "constructor is not visible here due to private fields");
                     }
 
                     return true;
                 }
 
-                err.span_label(
-                    span,
-                    "constructor is not visible here due to private fields".to_string(),
-                );
+                err.span_label(span, "constructor is not visible here due to private fields");
             }
             (
                 Res::Def(

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2204,8 +2204,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             _ => true,
                         };
                     if !ident.span.overlaps(span) && !same_line {
-                        multispan
-                            .push_span_label(ident.span, "required by a bound in this".to_string());
+                        multispan.push_span_label(ident.span, "required by a bound in this");
                     }
                 }
                 let descr = format!("required by a bound in `{}`", item_name);