[libcxx-commits] [libcxx] WIP: [libc++][asan] Suppress SSO with _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS_FOR_STRING (PR #195740)

[Vitaly Buka via libcxx-commits]

https://github.com/vitalybuka created https://github.com/llvm/llvm-project/pull/195740

None

>From 3723463fb4791f2a071051eac08fd415e494d24e Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Mon, 4 May 2026 13:54:10 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
 =?UTF-8?q?l=20version?=
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Created using spr 1.3.7
---
 libcxx/include/string | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/libcxx/include/string b/libcxx/include/string
index 002ce63ce5af9..c4b2eaef5806d 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -2288,12 +2288,18 @@ private:
     if (__size > max_size())
       __throw_length_error();
 
-    if (__fits_in_sso(__size)) {
+    size_type __min_cap_val = __size;
+#  if _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS_FOR_STRING
+    if (!__libcpp_is_constant_evaluated())
+      __min_cap_val = std::max(__min_cap_val, size_type(32));
+#  endif
+
+    if (__fits_in_sso(__min_cap_val)) {
       __set_short_size(__size);
       __annotate_new(__size);
       return __get_short_pointer();
     } else {
-      __rep_.__l = __allocate_long_buffer(__alloc_, __size);
+      __rep_.__l = __allocate_long_buffer(__alloc_, __size, __min_cap_val);
       __annotate_new(__size);
       return __get_long_pointer();
     }
@@ -2327,7 +2333,11 @@ private:
 #  endif
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_new(size_type __current_size) const _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_new(size_type __current_size) _NOEXCEPT {
+#  if _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS_FOR_STRING
+    if (__libcpp_is_constant_evaluated() && !__is_long())
+      __rep_.__l = __allocate_long_buffer(__alloc_, __current_size, 32);
+#  endif
     __annotate_contiguous_container(data() + capacity() + 1, data() + __current_size + 1);
   }