[gcc r11-6146] libstdc++: Only use __builtin_sprintf if supported [PR 96083]

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:96d9670e88333d8896a5d2f2bb0403c1e2ad19ab

commit r11-6146-g96d9670e88333d8896a5d2f2bb0403c1e2ad19ab
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Dec 16 13:50:34 2020 +0000

    libstdc++: Only use __builtin_sprintf if supported [PR 96083]
    
    Clang doesn't support __builtin_sprintf, so use std::sprintf instead.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/96083
            * include/ext/throw_allocator.h: Use __has_builtin to check for
            __builtin_sprintf support, and use std::sprtinf if necessary.

Diff:
---
 libstdc++-v3/include/ext/throw_allocator.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/libstdc++-v3/include/ext/throw_allocator.h b/libstdc++-v3/include/ext/throw_allocator.h
index 0ab174f19a5..2364827a632 100644
--- a/libstdc++-v3/include/ext/throw_allocator.h
+++ b/libstdc++-v3/include/ext/throw_allocator.h
@@ -64,6 +64,10 @@
 #endif
 #include <ext/alloc_traits.h>
 
+#if !__has_builtin(__builtin_sprintf)
+# include <cstdio>
+#endif
+
 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -310,6 +314,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     static void
     log_to_string(std::string& s, const_reference ref)
     {
+#if ! __has_builtin(__builtin_sprintf)
+      __typeof__(&std::sprintf) __builtin_sprintf = &std::sprintf;
+#endif
+
       char buf[40];
       const char tab('\t');
       s += "label: ";
@@ -332,6 +340,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     static void
     log_to_string(std::string& s, const std::pair<const void*, size_t>& ref)
     {
+#if ! __has_builtin(__builtin_sprintf)
+      auto __builtin_sprintf = &std::sprintf;
+#endif
+
       char buf[40];
       const char tab('\t');
       s += "label: ";
@@ -566,6 +578,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static gen_t generator(engine(), distribution);
 #endif
 
+#if ! __has_builtin(__builtin_sprintf)
+      __typeof__(&std::sprintf) __builtin_sprintf = &std::sprintf;
+#endif
+
       double random = generator();
       if (random < distribution.min() || random > distribution.max())
 	{