Rollup merge of #91597 - r00ster91:lessthangreaterthan, r=oli-obk

Recover on invalid operators `<>` and `<=>`

Thanks to #89871 for showing me how to do this.
Next, I think it'd be nice to recover on `<=>` too, like #89871 intended, if this even works.

Author: matthiaskrgr

Diff for: compiler/rustc_parse/src/parser/expr.rs

@@ -213,11 +213,11 @@ impl<'a> Parser<'a> {
                 }
             }
 
+            // Look for JS' `===` and `!==` and recover
             if (op.node == AssocOp::Equal || op.node == AssocOp::NotEqual)
                 && self.token.kind == token::Eq
                 && self.prev_token.span.hi() == self.token.span.lo()
             {
-                // Look for JS' `===` and `!==` and recover 😇
                 let sp = op.span.to(self.token.span);
                 let sugg = match op.node {
                     AssocOp::Equal => "==",
@@ -235,6 +235,38 @@ impl<'a> Parser<'a> {
                 self.bump();
             }
 
+            // Look for PHP's `<>` and recover
+            if op.node == AssocOp::Less
+                && self.token.kind == token::Gt
+                && self.prev_token.span.hi() == self.token.span.lo()
+            {
+                let sp = op.span.to(self.token.span);
+                self.struct_span_err(sp, "invalid comparison operator `<>`")
+                    .span_suggestion_short(
+                        sp,
+                        "`<>` is not a valid comparison operator, use `!=`",
+                        "!=".to_string(),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                self.bump();
+            }
+
+            // Look for C++'s `<=>` and recover
+            if op.node == AssocOp::LessEqual
+                && self.token.kind == token::Gt
+                && self.prev_token.span.hi() == self.token.span.lo()
+            {
+                let sp = op.span.to(self.token.span);
+                self.struct_span_err(sp, "invalid comparison operator `<=>`")
+                    .span_label(
+                        sp,
+                        "`<=>` is not a valid comparison operator, use `std::cmp::Ordering`",
+                    )
+                    .emit();
+                self.bump();
+            }
+
             let op = op.node;
             // Special cases:
             if op == AssocOp::As {

Diff for: src/test/ui/operator-recovery/less-than-greater-than.rs

@@ -0,0 +1,4 @@
+fn main() {
+    println!("{}", 1 <> 2);
+    //~^ERROR invalid comparison operator `<>`
+}

Diff for: src/test/ui/operator-recovery/less-than-greater-than.stderr

@@ -0,0 +1,8 @@
+error: invalid comparison operator `<>`
+  --> $DIR/less-than-greater-than.rs:2:22
+   |
+LL |     println!("{}", 1 <> 2);
+   |                      ^^ help: `<>` is not a valid comparison operator, use `!=`
+
+error: aborting due to previous error
+

Diff for: src/test/ui/operator-recovery/spaceship.rs

@@ -0,0 +1,4 @@
+fn main() {
+    println!("{}", 1 <=> 2);
+    //~^ERROR invalid comparison operator `<=>`
+}

Diff for: src/test/ui/operator-recovery/spaceship.stderr

@@ -0,0 +1,8 @@
+error: invalid comparison operator `<=>`
+  --> $DIR/spaceship.rs:2:22
+   |
+LL |     println!("{}", 1 <=> 2);
+   |                      ^^^ `<=>` is not a valid comparison operator, use `std::cmp::Ordering`
+
+error: aborting due to previous error
+