Add missing RB_GC_GUARDs related to DATA_PTR

I discovered the problem in `compile.c` from a failing
TestIseqLoad#test_stressful_roundtrip test with ASAN enabled. The other
two changes in array.c and string.c I found by auditing similar usages
of DATA_PTR in the codebase.

[Bug #20402]

3 files changed, 3 insertions, 0 deletions

diff --git a/array.c b/array.c
index 00f5ab9181..bcf98fc012 100644
--- a/array.c
+++ b/array.c
@@ -6643,6 +6643,7 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
         });
         DATA_PTR(vmemo) = 0;
         st_free_table(memo);
+        RB_GC_GUARD(vmemo);
     }
     else {
         result = rb_ary_dup(ary);
diff --git a/compile.c b/compile.c
index ab041e6e89..a66d5e1b93 100644
--- a/compile.c
+++ b/compile.c
@@ -11318,6 +11318,7 @@ iseq_build_from_ary_body(rb_iseq_t *iseq, LINK_ANCHOR *const anchor,
         }
     }
     DATA_PTR(labels_wrapper) = 0;
+    RB_GC_GUARD(labels_wrapper);
     validate_labels(iseq, labels_table);
     if (!ret) return ret;
     return iseq_setup(iseq, anchor);
diff --git a/string.c b/string.c
index 5c29718dff..ecd6b97f88 100644
--- a/string.c
+++ b/string.c
@@ -1148,6 +1148,7 @@ str_cat_conv_enc_opts(VALUE newstr, long ofs, const char *ptr, long len,
         rb_str_resize(newstr, olen);
     }
     DATA_PTR(econv_wrapper) = 0;
+    RB_GC_GUARD(econv_wrapper);
     rb_econv_close(ec);
     switch (ret) {
       case econv_finished: