[Bug #18955] format single character for `%c`

1 files changed, 5 insertions, 6 deletions

diff --git a/sprintf.c b/sprintf.c
index 5f7227e619..22edf398fe 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -441,12 +441,10 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 
                 tmp = rb_check_string_type(val);
                 if (!NIL_P(tmp)) {
-                    rb_encoding *valenc = rb_enc_get(tmp);
-                    if (rb_enc_strlen(RSTRING_PTR(tmp), RSTRING_END(tmp), valenc) != 1) {
-                        rb_raise(rb_eArgError, "%%c requires a character");
-                    }
-                    c = rb_enc_codepoint_len(RSTRING_PTR(tmp), RSTRING_END(tmp), &n, valenc);
-                    RB_GC_GUARD(tmp);
+                    flags |= FPREC;
+                    prec = 1;
+                    str = tmp;
+                    goto format_s1;
                 }
                 else {
                     c = NUM2INT(val);
@@ -488,6 +486,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
                 else {
                     str = rb_obj_as_string(arg);
                 }
+              format_s1:
                 len = RSTRING_LEN(str);
                 rb_str_set_len(result, blen);
                 if (coderange != ENC_CODERANGE_BROKEN && scanned < blen) {