better parser errors

error_test/parser/pattern_errors.sui

@@ -0,0 +1,41 @@
+# Pattern matching errors
+
+# Invalid pattern in match
+fn test() -> int
+    match 42
+        x => x
+    end
+
+# Missing colon in struct pattern
+fn test() -> int
+    struct Point
+        x: int
+        y: int
+    end
+    let p = Point { x: 5, y: 10 }
+    match p
+        Point { x 5, y: 10 } => 1
+    end
+
+# Invalid enum pattern
+fn test() -> int
+    enum Result
+        Ok(int)
+        Err(string)
+    end
+    let r = Result::Ok(42)
+    match r
+        Result::Ok value => value
+    end
+
+# Missing pattern in match arm
+fn test() -> int
+    match 42
+        => 0
+    end
+
+# Missing fat arrow in match arm
+fn test() -> int
+    match 42
+        x 0
+    end