Merge pull request #397 from Shopify/at-rbs-nilable-procs

Protect nilable procs with parenthesis when translating to RBS

lib/rbi/rbs_printer.rb

@@ -891,7 +891,14 @@ def visit_attached_class(type)
 
     sig { params(type: Type::Nilable).void }
     def visit_nilable(type)
-      visit(type.type)
+      inner = type.type
+      if inner.is_a?(Type::Proc)
+        @string << "("
+      end
+      visit(inner)
+      if inner.is_a?(Type::Proc)
+        @string << ")"
+      end
       @string << "?"
     end
 
@@ -964,6 +971,12 @@ def visit_proc(type)
         end
         @string << ") "
       end
+      proc_bind = type.proc_bind
+      if proc_bind
+        @string << "[self: "
+        visit(proc_bind)
+        @string << "] "
+      end
       @string << "-> "
       visit(type.proc_returns)
     end

test/rbi/rbs_printer_test.rb

@@ -616,6 +616,32 @@ def e: -> Class[untyped]
       RBI
     end
 
+    def test_print_procs
+      rbi = parse_rbi(<<~RBI)
+        sig { params(x: T.nilable(T.proc.void)) }
+        def proc1(x); end
+
+        sig { params(x: T.proc.bind(T.untyped).void) }
+        def proc2(x); end
+
+        sig { params(block: T.nilable(T.proc.void)) }
+        def block1(&block); end
+
+        sig { params(block: T.proc.bind(T.untyped).void) }
+        def block2(&block); end
+      RBI
+
+      assert_equal(<<~RBI, rbi.rbs_string)
+        def proc1: ((^-> void)? x) -> void
+
+        def proc2: (^[self: untyped] -> void x) -> void
+
+        def block1: ?{ -> void } -> void
+
+        def block2: { [self: untyped] -> void } -> void
+      RBI
+    end
+
     def test_print_t_structs
       rbi = parse_rbi(<<~RBI)
         class Foo < T::Struct; end