[Bug #18892] Reset `ARGF.lineno` after reading shebang

io.c

@@ -9866,6 +9866,12 @@ argf_lineno_setter(VALUE val, ID id, VALUE *var)
     ARGF.last_lineno = ARGF.lineno = n;
 }
 
+void
+rb_reset_argf_lineno(long n)
+{
+    ARGF.last_lineno = ARGF.lineno = n;
+}
+
 static VALUE argf_gets(int, VALUE *, VALUE);
 
 /*

ruby.c

@@ -2151,6 +2151,8 @@ warn_cr_in_shebang(const char *str, long len)
 #define warn_cr_in_shebang(str, len) (void)0
 #endif
 
+void rb_reset_argf_lineno(long n);
+
 struct load_file_arg {
     VALUE parser;
     VALUE fname;
@@ -2247,6 +2249,7 @@ load_file_internal(VALUE argp_v)
         if (NIL_P(c)) {
 	    argp->f = f = Qnil;
 	}
+        rb_reset_argf_lineno(0);
         ruby_opt_init(opt);
     }
     if (opt->src.enc.index >= 0) {

test/ruby/test_argf.rb

@@ -143,6 +143,17 @@ class TestArgf < Test::Unit::TestCase
     };
   end
 
+  def test_lineno_after_shebang
+    expected = %w"1 1 1 2 2 2 3 3 1 4 4 2"
+    assert_in_out_err(["--enable=gems", "-", @t1.path, @t2.path], "#{<<~"{#"}\n#{<<~'};'}", expected)
+    #!/usr/bin/env ruby
+    {#
+      ARGF.each do |line|
+        puts [$., ARGF.lineno, ARGF.file.lineno]
+      end
+    };
+  end
+
   def test_new_lineno_each
     f = ARGF.class.new(@t1.path, @t2.path, @t3.path)
     result = []