[ruby/prism] Accept a newline after the defined? keyword

[Bug #21197]

https://github.com/ruby/prism/commit/22be955ce9

5 files changed, 73 insertions, 13 deletions

diff --git a/lib/prism/translation/parser/compiler.rb b/lib/prism/translation/parser/compiler.rb
index aa1cb5d20b..c5356555d0 100644
--- a/lib/prism/translation/parser/compiler.rb
+++ b/lib/prism/translation/parser/compiler.rb
@@ -696,13 +696,37 @@ module Prism
         # defined?(a)
         # ^^^^^^^^^^^
         def visit_defined_node(node)
-          builder.keyword_cmd(
-            :defined?,
-            token(node.keyword_loc),
-            token(node.lparen_loc),
-            [visit(node.value)],
-            token(node.rparen_loc)
-          )
+          # Very weird circumstances here where something like:
+          #
+          #     defined?
+          #     (1)
+          #
+          # gets parsed in Ruby as having only the `1` expression but in parser
+          # it gets parsed as having a begin. In this case we need to synthesize
+          # that begin to match parser's behavior.
+          if node.lparen_loc && node.keyword_loc.join(node.lparen_loc).slice.include?("\n")
+            builder.keyword_cmd(
+              :defined?,
+              token(node.keyword_loc),
+              nil,
+              [
+                builder.begin(
+                  token(node.lparen_loc),
+                  visit(node.value),
+                  token(node.rparen_loc)
+                )
+              ],
+              nil
+            )
+          else
+            builder.keyword_cmd(
+              :defined?,
+              token(node.keyword_loc),
+              token(node.lparen_loc),
+              [visit(node.value)],
+              token(node.rparen_loc)
+            )
+          end
         end
 
         # if foo then bar else baz end
diff --git a/lib/prism/translation/ripper.rb b/lib/prism/translation/ripper.rb
index dce96e01ab..95f366ac91 100644
--- a/lib/prism/translation/ripper.rb
+++ b/lib/prism/translation/ripper.rb
@@ -1615,8 +1615,23 @@ module Prism
       # defined?(a)
       # ^^^^^^^^^^^
       def visit_defined_node(node)
+        expression = visit(node.value)
+
+        # Very weird circumstances here where something like:
+        #
+        #     defined?
+        #     (1)
+        #
+        # gets parsed in Ruby as having only the `1` expression but in Ripper it
+        # gets parsed as having a parentheses node. In this case we need to
+        # synthesize that node to match Ripper's behavior.
+        if node.lparen_loc && node.keyword_loc.join(node.lparen_loc).slice.include?("\n")
+          bounds(node.lparen_loc.join(node.rparen_loc))
+          expression = on_paren(on_stmts_add(on_stmts_new, expression))
+        end
+
         bounds(node.location)
-        on_defined(visit(node.value))
+        on_defined(expression)
       end
 
       # if foo then bar else baz end
diff --git a/prism/prism.c b/prism/prism.c
index 8597aa63fa..f52008fe1e 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -19607,18 +19607,27 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
             pm_token_t lparen;
             pm_token_t rparen;
             pm_node_t *expression;
+
             context_push(parser, PM_CONTEXT_DEFINED);
+            bool newline = accept1(parser, PM_TOKEN_NEWLINE);
 
             if (accept1(parser, PM_TOKEN_PARENTHESIS_LEFT)) {
                 lparen = parser->previous;
-                expression = parse_expression(parser, PM_BINDING_POWER_COMPOSITION, true, false, PM_ERR_DEFINED_EXPRESSION, (uint16_t) (depth + 1));
 
-                if (parser->recovering) {
+                if (newline && accept1(parser, PM_TOKEN_PARENTHESIS_RIGHT)) {
+                    expression = (pm_node_t *) pm_parentheses_node_create(parser, &lparen, NULL, &parser->previous, 0);
+                    lparen = not_provided(parser);
                     rparen = not_provided(parser);
                 } else {
-                    accept1(parser, PM_TOKEN_NEWLINE);
-                    expect1(parser, PM_TOKEN_PARENTHESIS_RIGHT, PM_ERR_EXPECT_RPAREN);
-                    rparen = parser->previous;
+                    expression = parse_expression(parser, PM_BINDING_POWER_COMPOSITION, true, false, PM_ERR_DEFINED_EXPRESSION, (uint16_t) (depth + 1));
+
+                    if (parser->recovering) {
+                        rparen = not_provided(parser);
+                    } else {
+                        accept1(parser, PM_TOKEN_NEWLINE);
+                        expect1(parser, PM_TOKEN_PARENTHESIS_RIGHT, PM_ERR_EXPECT_RPAREN);
+                        rparen = parser->previous;
+                    }
                 }
             } else {
                 lparen = not_provided(parser);
diff --git a/test/prism/errors/defined_empty.txt b/test/prism/errors/defined_empty.txt
new file mode 100644
index 0000000000..4d7ea76413
--- /dev/null
+++ b/test/prism/errors/defined_empty.txt
@@ -0,0 +1,3 @@
+defined?()
+        ^ expected an expression after `defined?`
+
diff --git a/test/prism/fixtures/defined.txt b/test/prism/fixtures/defined.txt
index 247fa94e3a..09fc0a29e7 100644
--- a/test/prism/fixtures/defined.txt
+++ b/test/prism/fixtures/defined.txt
@@ -8,3 +8,12 @@ defined? 1
 
 defined?("foo"
 )
+
+defined?
+1
+
+defined?
+(1)
+
+defined?
+()