From 4b5f39637933ba35e1f9286fa197fbca7341431f Mon Sep 17 00:00:00 2001
From: Takumi Shotoku <sinsoku.listy@gmail.com>
Date: Sat, 5 Sep 2026 17:47:59 +0900
Subject: [PATCH] Report super outside a method instead of crashing

Only a method definition sets lenv.forward_args, which a bare `super`
shares with `...` forwarding, so `define_method(:foo) { |x| super }` ran
a bare `raise` and surfaced as a RuntimeError with no message. Report a
diagnostic instead and treat the call as taking no arguments. Ruby's own
wording differs by context, an implicit argument passing error from
define_method and "super called outside of method" at the top level, and
TypeProf only knows that forward_args is missing, so the message quotes
neither.
---
 lib/typeprof/core/ast/call.rb                | 12 +++++++++---
 scenario/diagnostics/super-outside-method.rb |  9 +++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 scenario/diagnostics/super-outside-method.rb

diff --git a/lib/typeprof/core/ast/call.rb b/lib/typeprof/core/ast/call.rb
index 2d794240e..e2768f0bd 100644
--- a/lib/typeprof/core/ast/call.rb
+++ b/lib/typeprof/core/ast/call.rb
@@ -124,7 +124,13 @@ def install0(genv)
         end
 
         if @forwarding_arguments
-          forward_a_args = (@lenv.forward_args || raise).to_actual_arguments(
+          forward_args = @lenv.forward_args
+          # `...` needs a method definition, so only a bare `super` can reach here
+          @changes.add_diagnostic(:code_range, "implicit argument passing of super is not supported here") unless forward_args
+        end
+
+        if forward_args
+          forward_a_args = forward_args.to_actual_arguments(
             genv,
             @changes,
             self,
@@ -211,11 +217,11 @@ def install0(genv)
           blk_ty = @block_pass.install(genv)
         elsif @anonymous_block_forwarding
           blk_ty = @lenv.get_var(:"*anonymous_block")
-        elsif @forwarding_arguments
+        elsif forward_args
           blk_ty = forward_a_args.block
         end
 
-        if @forwarding_arguments
+        if forward_args
           a_args = a_args.with_block(blk_ty, omittable: !@block_body && !@block_pass && !@anonymous_block_forwarding)
         else
           a_args = a_args.with_block(blk_ty)
diff --git a/scenario/diagnostics/super-outside-method.rb b/scenario/diagnostics/super-outside-method.rb
new file mode 100644
index 000000000..a7d7e2b17
--- /dev/null
+++ b/scenario/diagnostics/super-outside-method.rb
@@ -0,0 +1,9 @@
+## update
+define_method(:foo) do |x|
+  super
+end
+
+## diagnostics
+(1,0)-(1,13): undefined method: Object#define_method
+(2,2)-(2,7): implicit argument passing of super is not supported here
+(2,2)-(2,7): undefined method: Object#define_method