From 5ec1fc52c1640c75899972ad99734ff22a90694a Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Thu, 24 Aug 2023 19:10:33 +0900
Subject: [PATCH] Escape non-ascii characters in prelude C comments

Non-ASCII code are often warned by localized compilers.
---
 template/prelude.c.tmpl          | 6 +++++-
 tool/ruby_vm/helpers/c_escape.rb | 5 ++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/template/prelude.c.tmpl b/template/prelude.c.tmpl
index aa8b0c1fef..74f6c08da7 100644
--- a/template/prelude.c.tmpl
+++ b/template/prelude.c.tmpl
@@ -43,7 +43,10 @@ class Prelude
     lineno = 0
     result = [@preludes.size, @vpath.strip(filename), lines, sub]
     @vpath.foreach(filename) do |line|
-      line.force_encoding("ASCII-8BIT") if line.respond_to?(:force_encoding)
+      if line.respond_to?(:force_encoding)
+        enc = line.encoding
+        line.force_encoding("ASCII-8BIT")
+      end
       line.rstrip!
       lineno += 1
       @preludes[filename] ||= result
@@ -71,6 +74,7 @@ class Prelude
           orig
         end
       end
+      comment.force_encoding(enc) if enc and comment
       lines << [line, comment]
     end
     result << (start_line || 1)
diff --git a/tool/ruby_vm/helpers/c_escape.rb b/tool/ruby_vm/helpers/c_escape.rb
index 34fafd1e34..2a99e408da 100644
--- a/tool/ruby_vm/helpers/c_escape.rb
+++ b/tool/ruby_vm/helpers/c_escape.rb
@@ -17,7 +17,10 @@ module RubyVM::CEscape
 
   # generate comment, with escaps.
   def commentify str
-    return "/* #{str.b.gsub('*/', '*\\/').gsub('/*', '/\\*')} */"
+    unless str = str.dump[/\A"\K.*(?="\z)/]
+      raise Encoding::CompatibilityError, "must be ASCII-compatible (#{str.encoding})"
+    end
+    return "/* #{str.gsub('*/', '*\\/').gsub('/*', '/\\*')} */"
   end
 
   # Mimic gensym of CL.