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58 changes: 55 additions & 3 deletions src/librustc_typeck/check/op.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
use super::{FnCtxt, Needs};
use super::method::MethodCallee;
use rustc::ty::{self, Ty, TypeFoldable};
use rustc::ty::TyKind::{Ref, Adt, Str, Uint, Never, Tuple, Char, Array};
use rustc::ty::TyKind::{Ref, Adt, FnDef, Str, Uint, Never, Tuple, Char, Array};
use rustc::ty::adjustment::{Adjustment, Adjust, AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
use rustc::infer::type_variable::TypeVariableOrigin;
use errors::{self,Applicability};
Expand Down Expand Up @@ -333,8 +333,18 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
lhs_ty);

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());
self.add_type_neq_err_label(&mut err,
lhs_expr.span,
lhs_ty,
rhs_ty,
op,
is_assign);
self.add_type_neq_err_label(&mut err,
rhs_expr.span,
rhs_ty,
lhs_ty,
op,
is_assign);
}

let mut suggested_deref = false;
Expand Down Expand Up @@ -415,6 +425,48 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
(lhs_ty, rhs_ty, return_ty)
}

fn add_type_neq_err_label(
&self,
err: &mut errors::DiagnosticBuilder<'_>,
span: Span,
ty: Ty<'tcx>,
other_ty: Ty<'tcx>,
op: hir::BinOp,
is_assign: IsAssign,
) {
err.span_label(span, ty.to_string());
if let FnDef(def_id, _) = ty.sty {
let source_map = self.tcx.sess.source_map();
let hir_id = &self.tcx.hir().as_local_hir_id(def_id).unwrap();
let fn_sig = {
match self.tcx.typeck_tables_of(def_id).liberated_fn_sigs().get(*hir_id) {
Some(f) => f.clone(),
None => {
bug!("No fn-sig entry for def_id={:?}", def_id);
}
}
};

if self.lookup_op_method(fn_sig.output(),
&[other_ty],
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We could have another code branch for the case where both ty and other_ty are fns, so that you can suggest calling both of them, if their return types are the same.

Op::Binary(op, is_assign))
.is_ok() {
let variable_snippet = if fn_sig.inputs().len() > 0 {
format!("{}( /* arguments */ )", source_map.span_to_snippet(span).unwrap())
} else {
format!("{}()", source_map.span_to_snippet(span).unwrap())
};

err.span_suggestion(
span,
"did you forget",
variable_snippet,
Applicability::MachineApplicable,
);
}
}
}

fn check_str_addition(
&self,
expr: &'gcx hir::Expr,
Expand Down
19 changes: 19 additions & 0 deletions src/test/ui/issues/issue-59488.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
// ignore-tidy-linelength

fn foo() -> i32 {
42
}

fn bar(a: i64) -> i64 {
43
}

fn main() {
foo > 12;
//~^ ERROR 12:9: 12:10: binary operation `>` cannot be applied to type `fn() -> i32 {foo}` [E0369]
//~| ERROR 12:11: 12:13: mismatched types [E0308]

bar > 13;
//~^ ERROR 16:9: 16:10: binary operation `>` cannot be applied to type `fn(i64) -> i64 {bar}` [E0369]
//~| ERROR 16:11: 16:13: mismatched types [E0308]
}
44 changes: 44 additions & 0 deletions src/test/ui/issues/issue-59488.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
error[E0369]: binary operation `>` cannot be applied to type `fn() -> i32 {foo}`
--> $DIR/issue-59488.rs:12:9
|
LL | foo > 12;
| --- ^ -- {integer}
| |
| fn() -> i32 {foo}
| help: did you forget: `foo()`
|
= note: an implementation of `std::cmp::PartialOrd` might be missing for `fn() -> i32 {foo}`

error[E0308]: mismatched types
--> $DIR/issue-59488.rs:12:11
|
LL | foo > 12;
| ^^ expected fn item, found integer
|
= note: expected type `fn() -> i32 {foo}`
found type `i32`

error[E0369]: binary operation `>` cannot be applied to type `fn(i64) -> i64 {bar}`
--> $DIR/issue-59488.rs:16:9
|
LL | bar > 13;
| --- ^ -- {integer}
| |
| fn(i64) -> i64 {bar}
| help: did you forget: `bar( /* arguments */ )`
|
= note: an implementation of `std::cmp::PartialOrd` might be missing for `fn(i64) -> i64 {bar}`

error[E0308]: mismatched types
--> $DIR/issue-59488.rs:16:11
|
LL | bar > 13;
| ^^ expected fn item, found integer
|
= note: expected type `fn(i64) -> i64 {bar}`
found type `i64`

error: aborting due to 4 previous errors

Some errors occurred: E0308, E0369.
For more information about an error, try `rustc --explain E0308`.