Revert "merge revision(s) e04146129ec6898dd6a9739dad2983c6e9b68056, d5080f6e8b77364483ff6727b1065e45e180f05d: [Backport #20292]"

This reverts commit a54c717c7a74b91a3cdf20742c355e3ea42052d1.

1 files changed, 13 insertions, 5 deletions

diff --git a/string.c b/string.c
index 5af25b875e..6a9eebd687 100644
--- a/string.c
+++ b/string.c
@@ -1934,13 +1934,21 @@ rb_str_init(int argc, VALUE *argv, VALUE str)
                 if (orig == str) n = 0;
             }
             str_modifiable(str);
-            if (STR_EMBED_P(str) || FL_TEST(str, STR_SHARED|STR_NOFREE)) {
-                /* make noembed always */
+            if (STR_EMBED_P(str)) { /* make noembed always */
+                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
+#if USE_RVARGC
+                assert(RSTRING(str)->as.embed.len + 1 <= str_embed_capa(str));
+                memcpy(new_ptr, RSTRING(str)->as.embed.ary, RSTRING(str)->as.embed.len + 1);
+#else
+                memcpy(new_ptr, RSTRING(str)->as.embed.ary, RSTRING_EMBED_LEN_MAX + 1);
+#endif
+                RSTRING(str)->as.heap.ptr = new_ptr;
+            }
+            else if (FL_TEST(str, STR_SHARED|STR_NOFREE)) {
                 const size_t size = (size_t)capa + termlen;
                 const char *const old_ptr = RSTRING_PTR(str);
-                const size_t osize = RSTRING_LEN(str) + TERM_LEN(str);
-                char *new_ptr = ALLOC_N(char, size);
-                if (STR_EMBED_P(str)) RUBY_ASSERT((long)osize <= str_embed_capa(str));
+                const size_t osize = RSTRING(str)->as.heap.len + TERM_LEN(str);
+                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                 memcpy(new_ptr, old_ptr, osize < size ? osize : size);
                 FL_UNSET_RAW(str, STR_SHARED|STR_NOFREE);
                 RSTRING(str)->as.heap.ptr = new_ptr;