diff --git a/compiler/rustc_typeck/src/check/op.rs b/compiler/rustc_typeck/src/check/op.rs index 8ebfcdd539b67..81662b752b7b0 100644 --- a/compiler/rustc_typeck/src/check/op.rs +++ b/compiler/rustc_typeck/src/check/op.rs @@ -549,16 +549,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { is_assign: IsAssign, op: hir::BinOp, ) -> bool { - let source_map = self.tcx.sess.source_map(); - let remove_borrow_msg = "String concatenation appends the string on the right to the \ - string on the left and may require reallocation. This \ - requires ownership of the string on the left"; - - let msg = "`to_owned()` can be used to create an owned `String` \ - from a string reference. String concatenation \ - appends the string on the right to the string \ - on the left and may require reallocation. This \ - requires ownership of the string on the left"; + let str_concat_note = "string concatenation requires an owned `String` on the left"; + let rm_borrow_msg = "remove the borrow to obtain an owned `String`"; + let to_owned_msg = "create an owned `String` from a string reference"; let string_type = self.tcx.get_diagnostic_item(sym::String); let is_std_string = |ty: Ty<'tcx>| match ty.ty_adt_def() { @@ -574,31 +567,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ) => { if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str` - err.span_label( - op.span, - "`+` cannot be used to concatenate two `&str` strings", - ); - match source_map.span_to_snippet(lhs_expr.span) { - Ok(lstring) => { - err.span_suggestion( - lhs_expr.span, - if lstring.starts_with('&') { - remove_borrow_msg - } else { - msg - }, - if let Some(stripped) = lstring.strip_prefix('&') { - // let a = String::new(); - // let _ = &a + "bar"; - stripped.to_string() - } else { - format!("{}.to_owned()", lstring) - }, - Applicability::MachineApplicable, - ) - } - _ => err.help(msg), - }; + err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings"); + err.note(str_concat_note); + if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { + err.span_suggestion_verbose( + lhs_expr.span.until(lhs_inner_expr.span), + rm_borrow_msg, + "".to_owned(), + Applicability::MachineApplicable + ); + } else { + err.span_suggestion_verbose( + lhs_expr.span.shrink_to_hi(), + to_owned_msg, + ".to_owned()".to_owned(), + Applicability::MachineApplicable + ); + } } true } @@ -609,32 +594,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { op.span, "`+` cannot be used to concatenate a `&str` with a `String`", ); - match ( - source_map.span_to_snippet(lhs_expr.span), - source_map.span_to_snippet(rhs_expr.span), - is_assign, - ) { - (Ok(l), Ok(r), IsAssign::No) => { - let to_string = if let Some(stripped) = l.strip_prefix('&') { - // let a = String::new(); let b = String::new(); - // let _ = &a + b; - stripped.to_string() + match is_assign { + IsAssign::No => { + let sugg_msg; + let lhs_sugg = if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { + sugg_msg = "remove the borrow on the left and add one on the right"; + (lhs_expr.span.until(lhs_inner_expr.span), "".to_owned()) } else { - format!("{}.to_owned()", l) + sugg_msg = "create an owned `String` on the left and add a borrow on the right"; + (lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned()) }; - err.multipart_suggestion( - msg, - vec![ - (lhs_expr.span, to_string), - (rhs_expr.span, format!("&{}", r)), - ], + let suggestions = vec![ + lhs_sugg, + (rhs_expr.span.shrink_to_lo(), "&".to_owned()), + ]; + err.multipart_suggestion_verbose( + sugg_msg, + suggestions, Applicability::MachineApplicable, ); } - _ => { - err.help(msg); + IsAssign::Yes => { + err.note(str_concat_note); } - }; + } true } _ => false, diff --git a/src/test/ui/issues/issue-47377.stderr b/src/test/ui/issues/issue-47377.stderr index a7b8b1ca86167..4f0fd948e7604 100644 --- a/src/test/ui/issues/issue-47377.stderr +++ b/src/test/ui/issues/issue-47377.stderr @@ -7,10 +7,11 @@ LL | let _a = b + ", World!"; | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _a = b.to_owned() + ", World!"; - | ~~~~~~~~~~~~ + | +++++++++++ error: aborting due to previous error diff --git a/src/test/ui/issues/issue-47380.stderr b/src/test/ui/issues/issue-47380.stderr index f6222c77e2e25..b04ac5536c41f 100644 --- a/src/test/ui/issues/issue-47380.stderr +++ b/src/test/ui/issues/issue-47380.stderr @@ -7,10 +7,11 @@ LL | println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!"; | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!"; - | ~~~~~~~~~~~~ + | +++++++++++ error: aborting due to previous error diff --git a/src/test/ui/span/issue-39018.stderr b/src/test/ui/span/issue-39018.stderr index 92e86bf5d6c91..e2e7ce1ed18e7 100644 --- a/src/test/ui/span/issue-39018.stderr +++ b/src/test/ui/span/issue-39018.stderr @@ -7,10 +7,11 @@ LL | let x = "Hello " + "World!"; | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let x = "Hello ".to_owned() + "World!"; - | ~~~~~~~~~~~~~~~~~~~ + | +++++++++++ error[E0369]: cannot add `World` to `World` --> $DIR/issue-39018.rs:8:26 @@ -46,10 +47,10 @@ LL | let x = "Hello " + "World!".to_owned(); | | `+` cannot be used to concatenate a `&str` with a `String` | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left +help: create an owned `String` on the left and add a borrow on the right | LL | let x = "Hello ".to_owned() + &"World!".to_owned(); - | ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~ + | +++++++++++ + error[E0369]: cannot add `&String` to `&String` --> $DIR/issue-39018.rs:26:16 @@ -60,10 +61,12 @@ LL | let _ = &a + &b; | | `+` cannot be used to concatenate two `&str` strings | &String | -help: String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: remove the borrow to obtain an owned `String` | -LL | let _ = a + &b; - | ~ +LL - let _ = &a + &b; +LL + let _ = a + &b; + | error[E0369]: cannot add `String` to `&String` --> $DIR/issue-39018.rs:27:16 @@ -74,10 +77,11 @@ LL | let _ = &a + b; | | `+` cannot be used to concatenate a `&str` with a `String` | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left +help: remove the borrow on the left and add one on the right | -LL | let _ = a + &b; - | ~ ~~ +LL - let _ = &a + b; +LL + let _ = a + &b; + | error[E0308]: mismatched types --> $DIR/issue-39018.rs:29:17 @@ -97,10 +101,10 @@ LL | let _ = e + b; | | `+` cannot be used to concatenate a `&str` with a `String` | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left +help: create an owned `String` on the left and add a borrow on the right | LL | let _ = e.to_owned() + &b; - | ~~~~~~~~~~~~ ~~ + | +++++++++++ + error[E0369]: cannot add `&String` to `&String` --> $DIR/issue-39018.rs:31:15 @@ -111,10 +115,11 @@ LL | let _ = e + &b; | | `+` cannot be used to concatenate two `&str` strings | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = e.to_owned() + &b; - | ~~~~~~~~~~~~ + | +++++++++++ error[E0369]: cannot add `&str` to `&String` --> $DIR/issue-39018.rs:32:15 @@ -125,10 +130,11 @@ LL | let _ = e + d; | | `+` cannot be used to concatenate two `&str` strings | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = e.to_owned() + d; - | ~~~~~~~~~~~~ + | +++++++++++ error[E0369]: cannot add `&&str` to `&String` --> $DIR/issue-39018.rs:33:15 @@ -139,10 +145,11 @@ LL | let _ = e + &d; | | `+` cannot be used to concatenate two `&str` strings | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = e.to_owned() + &d; - | ~~~~~~~~~~~~ + | +++++++++++ error[E0369]: cannot add `&&str` to `&&str` --> $DIR/issue-39018.rs:34:16 @@ -169,10 +176,11 @@ LL | let _ = c + &d; | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = c.to_owned() + &d; - | ~~~~~~~~~~~~ + | +++++++++++ error[E0369]: cannot add `&str` to `&str` --> $DIR/issue-39018.rs:37:15 @@ -183,10 +191,11 @@ LL | let _ = c + d; | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = c.to_owned() + d; - | ~~~~~~~~~~~~ + | +++++++++++ error: aborting due to 14 previous errors diff --git a/src/test/ui/str/str-concat-on-double-ref.stderr b/src/test/ui/str/str-concat-on-double-ref.stderr index dee28897f4ddd..bd354679f7888 100644 --- a/src/test/ui/str/str-concat-on-double-ref.stderr +++ b/src/test/ui/str/str-concat-on-double-ref.stderr @@ -7,10 +7,11 @@ LL | let c = a + b; | | `+` cannot be used to concatenate two `&str` strings | &String | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let c = a.to_owned() + b; - | ~~~~~~~~~~~~ + | +++++++++++ error: aborting due to previous error diff --git a/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr b/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr index 480f442fedd28..bf277362dbab2 100644 --- a/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr +++ b/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr @@ -7,10 +7,11 @@ LL | ...ཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔ | | `+` cannot be used to concatenate two `&str` strings | &str | -help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left + = note: string concatenation requires an owned `String` on the left +help: create an owned `String` from a string reference | LL | let _ = "ༀ༁༂༃༄༅༆༇༈༉༊་༌།༎༏༐༑༒༓༔༕༖༗༘༙༚༛༜༝༞༟༠༡༢༣༤༥༦༧༨༩༪༫༬༭༮༯༰༱༲༳༴༵༶༷༸༹༺༻༼༽༾༿ཀཁགགྷངཅཆཇ཈ཉཊཋཌཌྷཎཏཐདདྷནཔཕབབྷམཙཚཛཛྷཝཞཟའཡརལཤཥསཧཨཀྵཪཫཬ཭཮཯཰ཱཱཱིིུུྲྀཷླྀཹེཻོཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗ྘ྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྽྾྿࿀࿁࿂࿃࿄࿅࿆࿇࿈࿉࿊࿋࿌࿍࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun.to_owned() + " really fun!"; - | ~~~~~~~~~~~~~~~~~~~~~~~~~ + | +++++++++++ error: aborting due to previous error