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Improve suggestions for type errors with string concatenation
Now, multipart suggestions are used instead of `span_to_snippet`, which improves code quality, makes the suggestion work even without access to source code, and, most importantly, improves the rendering of the suggestion.
This commit is contained in:
Noah Lev
parent
124555a69e
commit
2835ace4ca
@ -549,7 +549,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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is_assign: IsAssign,
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op: hir::BinOp,
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) -> bool {
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let source_map = self.tcx.sess.source_map();
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let remove_borrow_msg = "String concatenation appends the string on the right to the \
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string on the left and may require reallocation. This \
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requires ownership of the string on the left";
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@ -574,31 +573,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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) =>
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{
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if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str`
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err.span_label(
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op.span,
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"`+` cannot be used to concatenate two `&str` strings",
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);
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match source_map.span_to_snippet(lhs_expr.span) {
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Ok(lstring) => {
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err.span_suggestion(
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lhs_expr.span,
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if lstring.starts_with('&') {
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remove_borrow_msg
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} else {
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msg
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},
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if let Some(stripped) = lstring.strip_prefix('&') {
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// let a = String::new();
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// let _ = &a + "bar";
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stripped.to_string()
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} else {
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format!("{}.to_owned()", lstring)
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},
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Applicability::MachineApplicable,
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)
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}
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_ => err.help(msg),
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};
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err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings");
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if let hir::ExprKind::AddrOf(_,_,lhs_inner_expr) = lhs_expr.kind {
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err.span_suggestion(
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lhs_expr.span.until(lhs_inner_expr.span),
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remove_borrow_msg,
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"".to_owned(),
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Applicability::MachineApplicable
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);
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} else {
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err.span_suggestion(
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lhs_expr.span.shrink_to_hi(),
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msg,
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".to_owned()".to_owned(),
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Applicability::MachineApplicable
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);
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}
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}
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true
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}
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@ -609,32 +599,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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op.span,
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"`+` cannot be used to concatenate a `&str` with a `String`",
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);
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match (
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source_map.span_to_snippet(lhs_expr.span),
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source_map.span_to_snippet(rhs_expr.span),
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is_assign,
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) {
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(Ok(l), Ok(r), IsAssign::No) => {
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let to_string = if let Some(stripped) = l.strip_prefix('&') {
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// let a = String::new(); let b = String::new();
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// let _ = &a + b;
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stripped.to_string()
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} else {
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format!("{}.to_owned()", l)
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};
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err.multipart_suggestion(
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msg,
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vec![
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(lhs_expr.span, to_string),
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(rhs_expr.span, format!("&{}", r)),
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],
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Applicability::MachineApplicable,
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);
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match is_assign {
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IsAssign::No => {
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let suggestions = vec![
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if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind {
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(lhs_expr.span.until(lhs_inner_expr.span), "".to_owned())
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} else {
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(lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned())
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},
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(rhs_expr.span.shrink_to_lo(), "&".to_owned()),
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];
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err.multipart_suggestion(msg, suggestions, Applicability::MachineApplicable);
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}
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_ => {
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IsAssign::Yes => {
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err.help(msg);
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}
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};
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}
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true
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}
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_ => false,
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@ -10,7 +10,7 @@ LL | let _a = b + ", World!";
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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
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LL | let _a = b.to_owned() + ", World!";
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| ~~~~~~~~~~~~
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| +++++++++++
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error: aborting due to previous error
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@ -10,7 +10,7 @@ LL | println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!";
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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
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LL | println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!";
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| ~~~~~~~~~~~~
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| +++++++++++
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error: aborting due to previous error
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@ -10,7 +10,7 @@ LL | let x = "Hello " + "World!";
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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
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LL | let x = "Hello ".to_owned() + "World!";
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| ~~~~~~~~~~~~~~~~~~~
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| +++++++++++
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error[E0369]: cannot add `World` to `World`
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--> $DIR/issue-39018.rs:8:26
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@ -49,7 +49,7 @@ LL | let x = "Hello " + "World!".to_owned();
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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
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LL | let x = "Hello ".to_owned() + &"World!".to_owned();
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| ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~
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| +++++++++++ +
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error[E0369]: cannot add `&String` to `&String`
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--> $DIR/issue-39018.rs:26:16
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@ -62,8 +62,9 @@ LL | let _ = &a + &b;
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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
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LL | let _ = a + &b;
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| ~
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LL - let _ = &a + &b;
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LL + let _ = a + &b;
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error[E0369]: cannot add `String` to `&String`
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--> $DIR/issue-39018.rs:27:16
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@ -76,8 +77,9 @@ LL | let _ = &a + b;
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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
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LL | let _ = a + &b;
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| ~ ~~
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LL - let _ = &a + b;
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LL + let _ = a + &b;
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error[E0308]: mismatched types
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--> $DIR/issue-39018.rs:29:17
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@ -100,7 +102,7 @@ LL | let _ = e + b;
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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
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LL | let _ = e.to_owned() + &b;
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| ~~~~~~~~~~~~ ~~
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| +++++++++++ +
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error[E0369]: cannot add `&String` to `&String`
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--> $DIR/issue-39018.rs:31:15
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@ -114,7 +116,7 @@ LL | let _ = e + &b;
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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
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LL | let _ = e.to_owned() + &b;
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| ~~~~~~~~~~~~
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| +++++++++++
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error[E0369]: cannot add `&str` to `&String`
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--> $DIR/issue-39018.rs:32:15
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@ -128,7 +130,7 @@ LL | let _ = e + d;
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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
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LL | let _ = e.to_owned() + d;
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| ~~~~~~~~~~~~
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| +++++++++++
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error[E0369]: cannot add `&&str` to `&String`
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--> $DIR/issue-39018.rs:33:15
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@ -142,7 +144,7 @@ LL | let _ = e + &d;
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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
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LL | let _ = e.to_owned() + &d;
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| ~~~~~~~~~~~~
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| +++++++++++
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error[E0369]: cannot add `&&str` to `&&str`
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--> $DIR/issue-39018.rs:34:16
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@ -172,7 +174,7 @@ LL | let _ = c + &d;
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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
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LL | let _ = c.to_owned() + &d;
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| ~~~~~~~~~~~~
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| +++++++++++
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error[E0369]: cannot add `&str` to `&str`
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--> $DIR/issue-39018.rs:37:15
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@ -186,7 +188,7 @@ LL | let _ = c + d;
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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
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LL | let _ = c.to_owned() + d;
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| ~~~~~~~~~~~~
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| +++++++++++
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error: aborting due to 14 previous errors
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@ -10,7 +10,7 @@ LL | let c = a + b;
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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
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LL | let c = a.to_owned() + b;
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| ~~~~~~~~~~~~
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| +++++++++++
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error: aborting due to previous error
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@ -10,7 +10,7 @@ LL | ...ཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔ
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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
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LL | let _ = "ༀ༁༂༃༄༅༆༇༈༉༊་༌།༎༏༐༑༒༓༔༕༖༗༘༙༚༛༜༝༞༟༠༡༢༣༤༥༦༧༨༩༪༫༬༭༮༯༰༱༲༳༴༵༶༷༸༹༺༻༼༽༾༿ཀཁགགྷངཅཆཇཉཊཋཌཌྷཎཏཐདདྷནཔཕབབྷམཙཚཛཛྷཝཞཟའཡརལཤཥསཧཨཀྵཪཫཬཱཱཱིིུུྲྀཷླྀཹེཻོཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྾྿࿀࿁࿂࿃࿄࿅࿆࿇࿈࿉࿊࿋࿌࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun.to_owned() + " really fun!";
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| ~~~~~~~~~~~~~~~~~~~~~~~~~
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| +++++++++++
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error: aborting due to previous error
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