Add check for when left and right overlap and change span for explanation to point at operator

hgallagher1993 · hgallagher1993 · commit 4644c3a6aa0f · 2019-03-28T13:54:29.000-04:00
diff --git a/src/librustc_typeck/check/op.rs b/src/librustc_typeck/check/op.rs
@@ -306,7 +306,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                             if let Some(missing_trait) = missing_trait {
                                 if op.node == hir::BinOpKind::Add &&
                                     self.check_str_addition(expr, lhs_expr, rhs_expr, lhs_ty,
-                                                            rhs_ty, &mut err, true) {
+                                                            rhs_ty, &mut err, true, op) {
                                     // This has nothing here because it means we did string
                                     // concatenation (e.g., "Hello " += "World!"). This means
                                     // we don't want the note in the else clause to be emitted
@@ -332,8 +332,10 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                 op.node.as_str(),
                                 lhs_ty);
 
-                            err.span_label(lhs_expr.span, lhs_ty.to_string());
-                            err.span_label(rhs_expr.span, rhs_ty.to_string());
+                            if !lhs_expr.span.eq(&rhs_expr.span) {
+                                err.span_label(lhs_expr.span, lhs_ty.to_string());
+                                err.span_label(rhs_expr.span, rhs_ty.to_string());
+                            }
 
                             let mut suggested_deref = false;
                             if let Ref(_, mut rty, _) = lhs_ty.sty {
@@ -384,7 +386,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                             if let Some(missing_trait) = missing_trait {
                                 if op.node == hir::BinOpKind::Add &&
                                     self.check_str_addition(expr, lhs_expr, rhs_expr, lhs_ty,
-                                                            rhs_ty, &mut err, false) {
+                                                            rhs_ty, &mut err, false, op) {
                                     // This has nothing here because it means we did string
                                     // concatenation (e.g., "Hello " + "World!"). This means
                                     // we don't want the note in the else clause to be emitted
@@ -422,6 +424,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         rhs_ty: Ty<'tcx>,
         err: &mut errors::DiagnosticBuilder<'_>,
         is_assign: bool,
+        op: hir::BinOp,
     ) -> bool {
         let source_map = self.tcx.sess.source_map();
         let msg = "`to_owned()` can be used to create an owned `String` \
@@ -435,7 +438,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (&Ref(_, l_ty, _), &Ref(_, r_ty, _))
             if l_ty.sty == Str && r_ty.sty == Str => {
                 if !is_assign {
-                    err.span_label(expr.span,
+                    err.span_label(op.span,
                                    "`+` can't be used to concatenate two `&str` strings");
                     match source_map.span_to_snippet(lhs_expr.span) {
                         Ok(lstring) => err.span_suggestion(
diff --git a/src/test/ui/derives/derives-span-PartialEq-enum-struct-variant.stderr b/src/test/ui/derives/derives-span-PartialEq-enum-struct-variant.stderr
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
    |
 LL |      x: Error
    |      ^^^^^^^^
-   |      |
-   |      Error
-   |      Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
    |
 LL |      x: Error
    |      ^^^^^^^^
-   |      |
-   |      Error
-   |      Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
diff --git a/src/test/ui/derives/derives-span-PartialEq-enum.stderr b/src/test/ui/derives/derives-span-PartialEq-enum.stderr
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
    |
 LL |      Error
    |      ^^^^^
-   |      |
-   |      Error
-   |      Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
    |
 LL |      Error
    |      ^^^^^
-   |      |
-   |      Error
-   |      Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
diff --git a/src/test/ui/derives/derives-span-PartialEq-struct.stderr b/src/test/ui/derives/derives-span-PartialEq-struct.stderr
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
    |
 LL |     x: Error
    |     ^^^^^^^^
-   |     |
-   |     Error
-   |     Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
    |
 LL |     x: Error
    |     ^^^^^^^^
-   |     |
-   |     Error
-   |     Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
diff --git a/src/test/ui/derives/derives-span-PartialEq-tuple-struct.stderr b/src/test/ui/derives/derives-span-PartialEq-tuple-struct.stderr
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
    |
 LL |     Error
    |     ^^^^^
-   |     |
-   |     Error
-   |     Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
    |
 LL |     Error
    |     ^^^^^
-   |     |
-   |     Error
-   |     Error
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
 
diff --git a/src/test/ui/derives/deriving-no-inner-impl-error-message.stderr b/src/test/ui/derives/deriving-no-inner-impl-error-message.stderr
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `NoCloneOrEq`
    |
 LL |     x: NoCloneOrEq
    |     ^^^^^^^^^^^^^^
-   |     |
-   |     NoCloneOrEq
-   |     NoCloneOrEq
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
 
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `NoCloneOrEq`
    |
 LL |     x: NoCloneOrEq
    |     ^^^^^^^^^^^^^^
-   |     |
-   |     NoCloneOrEq
-   |     NoCloneOrEq
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
 
diff --git a/src/test/ui/issues/issue-47377.stderr b/src/test/ui/issues/issue-47377.stderr
@@ -2,11 +2,10 @@ error[E0369]: binary operation `+` cannot be applied to type `&str`
   --> $DIR/issue-47377.rs:4:14
    |
 LL |      let _a = b + ", World!";
-   |               --^-----------
-   |               |   |
-   |               |   &str
+   |               - ^ ---------- &str
+   |               | |
+   |               | `+` can't be used to concatenate two `&str` strings
    |               &str
-   |               `+` can't be used to concatenate two `&str` strings
 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
    |
 LL |      let _a = b.to_owned() + ", World!";
diff --git a/src/test/ui/issues/issue-47380.stderr b/src/test/ui/issues/issue-47380.stderr
@@ -2,11 +2,10 @@ error[E0369]: binary operation `+` cannot be applied to type `&str`
   --> $DIR/issue-47380.rs:3:35
    |
 LL |     println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!";
-   |                                      --^-----------
-   |                                      |   |
-   |                                      |   &str
+   |                                      - ^ ---------- &str
+   |                                      | |
+   |                                      | `+` can't be used to concatenate two `&str` strings
    |                                      &str
-   |                                      `+` can't be used to concatenate two `&str` strings
 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
    |
 LL |     println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!";
diff --git a/src/test/ui/span/issue-39018.stderr b/src/test/ui/span/issue-39018.stderr
@@ -2,11 +2,10 @@ error[E0369]: binary operation `+` cannot be applied to type `&str`
   --> $DIR/issue-39018.rs:2:22
    |
 LL |     let x = "Hello " + "World!";
-   |             ---------^---------
-   |             |          |
-   |             |          &str
+   |             -------- ^ -------- &str
+   |             |        |
+   |             |        `+` can't be used to concatenate two `&str` strings
    |             &str
-   |             `+` can't be used to concatenate two `&str` strings
 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
    |
 LL |     let x = "Hello ".to_owned() + "World!";

Original file line number	Diff line number	Diff line change
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
`3`	`3`	`\|`
`4`	`4`	`LL \| x: Error`
`5`	`5`	`\| ^^^^^^^^`
`6`		`- \| \|`
`7`		`- \| Error`
`8`		`- \| Error`
`9`	`6`	`\|`
`10`	`7`	= note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
`11`	`8`
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
`14`	`11`	`\|`
`15`	`12`	`LL \| x: Error`
`16`	`13`	`\| ^^^^^^^^`
`17`		`- \| \|`
`18`		`- \| Error`
`19`		`- \| Error`
`20`	`14`	`\|`
`21`	`15`	= note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
`22`	`16`
Original file line number	Diff line number	Diff line change
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `Error`
`3`	`3`	`\|`
`4`	`4`	`LL \| Error`
`5`	`5`	`\| ^^^^^`
`6`		`- \| \|`
`7`		`- \| Error`
`8`		`- \| Error`
`9`	`6`	`\|`
`10`	`7`	= note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
`11`	`8`
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `Error`
`14`	`11`	`\|`
`15`	`12`	`LL \| Error`
`16`	`13`	`\| ^^^^^`
`17`		`- \| \|`
`18`		`- \| Error`
`19`		`- \| Error`
`20`	`14`	`\|`
`21`	`15`	= note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
`22`	`16`
Original file line number	Diff line number	Diff line change
@@ -3,9 +3,6 @@ error[E0369]: binary operation `==` cannot be applied to type `NoCloneOrEq`
`3`	`3`	`\|`
`4`	`4`	`LL \| x: NoCloneOrEq`
`5`	`5`	`\| ^^^^^^^^^^^^^^`
`6`		`- \| \|`
`7`		`- \| NoCloneOrEq`
`8`		`- \| NoCloneOrEq`
`9`	`6`	`\|`
`10`	`7`	= note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
`11`	`8`
@@ -14,9 +11,6 @@ error[E0369]: binary operation `!=` cannot be applied to type `NoCloneOrEq`
`14`	`11`	`\|`
`15`	`12`	`LL \| x: NoCloneOrEq`
`16`	`13`	`\| ^^^^^^^^^^^^^^`
`17`		`- \| \|`
`18`		`- \| NoCloneOrEq`
`19`		`- \| NoCloneOrEq`
`20`	`14`	`\|`
`21`	`15`	= note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
`22`	`16`