From 4a938b5b3c475a5a12fa582eca2dd91d76cb0d3e Mon Sep 17 00:00:00 2001
From: Kampfkarren <boynedmaster@gmail.com>
Date: Wed, 10 Apr 2019 10:35:48 -0700
Subject: [PATCH] Special error when using catch after try

---
 src/libsyntax/parse/parser.rs                |  8 +++++++-
 src/test/ui/try-block/try-block-catch.rs     |  9 +++++++++
 src/test/ui/try-block/try-block-catch.stderr | 10 ++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/try-block/try-block-catch.rs
 create mode 100644 src/test/ui/try-block/try-block-catch.stderr

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 5b430d13516..98bad0a80aa 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -3618,7 +3618,13 @@ fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
     {
         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, "`try {} catch` is not a valid syntax");
+            error.help("try using `match` on the result of the `try` block instead");
+            Err(error)
+        } else {
+            Ok(self.mk_expr(span_lo.to(body.span), ExprKind::TryBlock(body), attrs))
+        }
     }
 
     // `match` token already eaten
diff --git a/src/test/ui/try-block/try-block-catch.rs b/src/test/ui/try-block/try-block-catch.rs
new file mode 100644
index 00000000000..8f3d6d87258
--- /dev/null
+++ b/src/test/ui/try-block/try-block-catch.rs
@@ -0,0 +1,9 @@
+// compile-flags: --edition 2018
+
+#![feature(try_blocks)]
+
+fn main() {
+	let res: Option<bool> = try {
+		true
+	} catch { }; //~ ERROR `try {} catch` is not a valid syntax
+}
diff --git a/src/test/ui/try-block/try-block-catch.stderr b/src/test/ui/try-block/try-block-catch.stderr
new file mode 100644
index 00000000000..0689647d3b2
--- /dev/null
+++ b/src/test/ui/try-block/try-block-catch.stderr
@@ -0,0 +1,10 @@
+error: `try {} catch` is not a valid syntax
+  --> $DIR/try-block-catch.rs:8:4
+   |
+LL |     } catch { }; //~ ERROR `try {} catch` is not a valid syntax
+   |       ^^^^^
+   |
+   = help: try using `match` on the result of the `try` block instead
+
+error: aborting due to previous error
+