From d249b047c234879ca70e036f5fd686c2a893af94 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 26 Apr 2017 20:13:07 +0000
Subject: [PATCH] error.c: send as a single string

* error.c (rb_warn_m): send the arguments as a single string
  concatenated with a newline, so it can be filtered easily.
  [ruby-core:80875] [Feature #12944]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58490 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 error.c                     | 21 +++++++++++++++++++--
 test/ruby/test_exception.rb |  4 ++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/error.c b/error.c
index 6ec37f6273..709fcf3612 100644
--- a/error.c
+++ b/error.c
@@ -48,6 +48,7 @@ VALUE rb_eEAGAIN;
 VALUE rb_eEWOULDBLOCK;
 VALUE rb_eEINPROGRESS;
 VALUE rb_mWarning;
+VALUE rb_cWarningBuffer;
 
 static ID id_warn;
 
@@ -279,6 +280,13 @@ rb_enc_warning(rb_encoding *enc, const char *fmt, ...)
 }
 #endif
 
+static inline int
+end_with_asciichar(VALUE str, int c)
+{
+    return RB_TYPE_P(str, T_STRING) &&
+	rb_str_end_with_asciichar(str, c);
+}
+
 /*
  * call-seq:
  *    warn(msg, ...)   -> nil
@@ -301,7 +309,14 @@ static VALUE
 rb_warn_m(int argc, VALUE *argv, VALUE exc)
 {
     if (!NIL_P(ruby_verbose) && argc > 0) {
-	rb_io_puts(argc, argv, rb_mWarning);
+	VALUE str = argv[0];
+	if (argc > 1 || !end_with_asciichar(str, '\n')) {
+	    str = rb_str_tmp_new(0);
+	    RBASIC_SET_CLASS(str, rb_cWarningBuffer);
+	    rb_io_puts(argc, argv, str);
+	    RBASIC_SET_CLASS(str, rb_cString);
+	}
+	rb_write_warning_str(str);
     }
     return Qnil;
 }
@@ -2175,9 +2190,11 @@ Init_Exception(void)
 
     rb_mWarning = rb_define_module("Warning");
     rb_define_method(rb_mWarning, "warn", rb_warning_s_warn, 1);
-    rb_define_method(rb_mWarning, "write", rb_warning_s_warn, 1);
     rb_extend_object(rb_mWarning, rb_mWarning);
 
+    rb_cWarningBuffer = rb_define_class_under(rb_mWarning, "buffer", rb_cString);
+    rb_define_method(rb_cWarningBuffer, "write", rb_str_append, 1);
+
     rb_define_global_function("warn", rb_warn_m, -1);
 
     id_new = rb_intern_const("new");
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 8a8edd2ff2..e53569c158 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -973,6 +973,10 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
   def test_warning_warn
     warning = capture_warning_warn {@a}
     assert_match(/instance variable @a not initialized/, warning[0])
+
+    assert_equal(["a\nz\n"], capture_warning_warn {warn "a\n", "z"})
+    assert_equal([],         capture_warning_warn {warn})
+    assert_equal(["\n"],     capture_warning_warn {warn ""})
   end
 
   def test_warning_warn_invalid_argument