Rollup merge of #59847 - Kampfkarren:try-block-catch, r=estebank

Error when using `catch` after `try`

Part of https://github.com/rust-lang/rust/issues/31436

src/libsyntax/parse/parser.rs

@@ -4091,7 +4091,15 @@ impl<'a> Parser<'a> {
     {
         let (iattrs, body) = self.parse_inner_attrs_and_block()?;
         attrs.extend(iattrs);
-        Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
+        if self.eat_keyword(keywords::Catch) {
+            let mut error = self.struct_span_err(self.prev_span,
+                                                 "keyword `catch` cannot follow a `try` block");
+            error.help("try using `match` on the result of the `try` block instead");
+            error.emit();
+            Err(error)
+        } else {
+            Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
+        }
     }
 
     // `match` token already eaten

src/test/ui/try-block/try-block-catch.rs

@@ -0,0 +1,10 @@
+// compile-flags: --edition 2018
+
+#![feature(try_blocks)]
+
+fn main() {
+    let res: Option<bool> = try {
+        true
+    } catch { };
+    //~^ ERROR keyword `catch` cannot follow a `try` block
+}

src/test/ui/try-block/try-block-catch.stderr

@@ -0,0 +1,10 @@
+error: keyword `catch` cannot follow a `try` block
+  --> $DIR/try-block-catch.rs:8:7
+   |
+LL |     } catch { };
+   |       ^^^^^
+   |
+   = help: try using `match` on the result of the `try` block instead
+
+error: aborting due to previous error
+