@@ -307,9 +307,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
307307 if let Some ( missing_trait) = missing_trait {
308308 if op. node == hir:: BinOpKind :: Add &&
309309 self . check_str_addition ( expr, lhs_expr, rhs_expr, lhs_ty,
310- rhs_ty, & mut err) {
310+ rhs_ty, & mut err, true ) {
311311 // This has nothing here because it means we did string
312- // concatenation (e.g. "Hello " + "World!"). This means
312+ // concatenation (e.g. "Hello " += "World!"). This means
313313 // we don't want the note in the else clause to be emitted
314314 } else if let ty:: TyParam ( _) = lhs_ty. sty {
315315 // FIXME: point to span of param
@@ -381,7 +381,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
381381 if let Some ( missing_trait) = missing_trait {
382382 if op. node == hir:: BinOpKind :: Add &&
383383 self . check_str_addition ( expr, lhs_expr, rhs_expr, lhs_ty,
384- rhs_ty, & mut err) {
384+ rhs_ty, & mut err, false ) {
385385 // This has nothing here because it means we did string
386386 // concatenation (e.g. "Hello " + "World!"). This means
387387 // we don't want the note in the else clause to be emitted
@@ -410,13 +410,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
410410 ( lhs_ty, rhs_ty, return_ty)
411411 }
412412
413- fn check_str_addition ( & self ,
414- expr : & ' gcx hir:: Expr ,
415- lhs_expr : & ' gcx hir:: Expr ,
416- rhs_expr : & ' gcx hir:: Expr ,
417- lhs_ty : Ty < ' tcx > ,
418- rhs_ty : Ty < ' tcx > ,
419- err : & mut errors:: DiagnosticBuilder ) -> bool {
413+ fn check_str_addition (
414+ & self ,
415+ expr : & ' gcx hir:: Expr ,
416+ lhs_expr : & ' gcx hir:: Expr ,
417+ rhs_expr : & ' gcx hir:: Expr ,
418+ lhs_ty : Ty < ' tcx > ,
419+ rhs_ty : Ty < ' tcx > ,
420+ err : & mut errors:: DiagnosticBuilder ,
421+ is_assign : bool ,
422+ ) -> bool {
420423 let codemap = self . tcx . sess . codemap ( ) ;
421424 let msg = "`to_owned()` can be used to create an owned `String` \
422425\
@@ -428,34 +431,36 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
428431 match ( & lhs_ty. sty , & rhs_ty. sty ) {
429432 ( & TyRef ( _, l_ty, _) , & TyRef ( _, r_ty, _) )
430433 if l_ty. sty == TyStr && r_ty. sty == TyStr => {
431- err. span_label ( expr. span ,
432- "`+` can't be used to concatenate two `&str` strings" ) ;
433- match codemap. span_to_snippet ( lhs_expr. span ) {
434- Ok ( lstring) => err. span_suggestion ( lhs_expr. span ,
435- msg,
436- format ! ( "{}.to_owned()" , lstring) ) ,
437- _ => err. help ( msg) ,
438- } ;
434+ if !is_assign {
435+ err. span_label ( expr. span ,
436+ "`+` can't be used to concatenate two `&str` strings" ) ;
437+ match codemap. span_to_snippet ( lhs_expr. span ) {
438+ Ok ( lstring) => err. span_suggestion ( lhs_expr. span ,
439+ msg,
440+ format ! ( "{}.to_owned()" , lstring) ) ,
441+ _ => err. help ( msg) ,
442+ } ;
443+ }
439444 true
440445 }
441446 ( & TyRef ( _, l_ty, _) , & TyAdt ( ..) )
442447 if l_ty. sty == TyStr && & format ! ( "{:?}" , rhs_ty) == "std::string::String" => {
443448 err. span_label ( expr. span ,
444449 "`+` can't be used to concatenate a `&str` with a `String`" ) ;
445- match codemap. span_to_snippet ( lhs_expr. span ) {
446- Ok ( lstring) => err. span_suggestion ( lhs_expr. span ,
447- msg,
448- format ! ( "{}.to_owned()" , lstring) ) ,
449- _ => err. help ( msg) ,
450- } ;
451- match codemap. span_to_snippet ( rhs_expr. span ) {
452- Ok ( rstring) => {
453- err. span_suggestion ( rhs_expr. span ,
454- "you also need to borrow the `String` on the right to \
455- ,
456- format ! ( "&{}" , rstring) ) ;
450+ match (
451+ codemap. span_to_snippet ( lhs_expr. span ) ,
452+ codemap. span_to_snippet ( rhs_expr. span ) ,
453+ is_assign,
454+ ) {
455+ ( Ok ( l) , Ok ( r) , false ) => {
456+ err. multipart_suggestion ( msg, vec ! [
457+ ( lhs_expr. span, format!( "{}.to_owned()" , l) ) ,
458+ ( rhs_expr. span, format!( "&{}" , r) ) ,
459+ ] ) ;
460+ }
461+ _ => {
462+ err. help ( msg) ;
457463 }
458- _ => { }
459464 } ;
460465 true
461466 }
0 commit comments