Rollup merge of #71801 - matthewjasper:operator-subtyping, r=varkor

Correctly check comparison operator in MIR typeck

The subtyping for comparisons between pointers was reversed in MIR typeck.
There also wasn't a check that comparisons between numeric types had matching types.

2 files changed, 5 insertions, 17 deletions

diff --git a/src/test/ui/nll/type-check-pointer-comparisons.rs b/src/test/ui/nll/type-check-pointer-comparisons.rs
index 298a6ef7ab3..3c900356fab 100644
--- a/src/test/ui/nll/type-check-pointer-comparisons.rs
+++ b/src/test/ui/nll/type-check-pointer-comparisons.rs
@@ -21,13 +21,13 @@ fn compare_fn_ptr<'a, 'b, 'c>(f: fn(&'c mut &'a i32), g: fn(&'c mut &'b i32)) {
 }
 
 fn compare_hr_fn_ptr<'a>(f: fn(&'a i32), g: fn(&i32)) {
-    f == g;
-    //~^ ERROR higher-ranked subtype error
+    // Ideally this should compile with the operands swapped as well, but HIR
+    // type checking prevents it (and stops compilation) for now.
+    f == g; // OK
 }
 
 fn compare_const_fn_ptr<'a>(f: *const fn(&'a i32), g: *const fn(&i32)) {
-    f == g;
-    //~^ ERROR higher-ranked subtype error
+    f == g; // OK
 }
 
 fn main() {}
diff --git a/src/test/ui/nll/type-check-pointer-comparisons.stderr b/src/test/ui/nll/type-check-pointer-comparisons.stderr
index 0fc7480260f..f350b861eb6 100644
--- a/src/test/ui/nll/type-check-pointer-comparisons.stderr
+++ b/src/test/ui/nll/type-check-pointer-comparisons.stderr
@@ -76,17 +76,5 @@ LL |     f == g;
 
 help: `'a` and `'b` must be the same: replace one with the other
 
-error: higher-ranked subtype error
-  --> $DIR/type-check-pointer-comparisons.rs:24:5
-   |
-LL |     f == g;
-   |     ^^^^^^
-
-error: higher-ranked subtype error
-  --> $DIR/type-check-pointer-comparisons.rs:29:5
-   |
-LL |     f == g;
-   |     ^^^^^^
-
-error: aborting due to 8 previous errors
+error: aborting due to 6 previous errors