Merge #14715: Drop defunct prevector compat handling

69ca48717c Implement prevector::fill once (Ben Woosley)
7bad78c2c8 Drop defunct IS_TRIVIALLY_CONSTRUCTIBLE handling from prevector.h (Ben Woosley)

Pull request description:

  This is clean-up post #14651:
  * Use one implementation of `prevector::fill`, as it's possible now that the implementations are identical.
  * Only apply the `IS_TRIVIALLY_CONSTRUCTIBLE` handling to the bench file where it is used, and drop the now-unnecessary associated compat includes.

Tree-SHA512: 5930b3a17fccd39af10add40202ad97a297aebecc049af72ca920d0d55b3e4c3c30ce864c8a683355895f0196396d4ea56ba9f9637bdc7d16964cdf66c195485

src/bench/prevector.cpp

@@ -2,13 +2,21 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <compat.h>
 #include <prevector.h>
 #include <serialize.h>
 #include <streams.h>
+#include <type_traits>
 
 #include <bench/bench.h>
 
+// GCC 4.8 is missing some C++11 type_traits,
+// https://www.gnu.org/software/gcc/gcc-5/changes.html
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5
+#define IS_TRIVIALLY_CONSTRUCTIBLE std::has_trivial_default_constructor
+#else
+#define IS_TRIVIALLY_CONSTRUCTIBLE std::is_trivially_default_constructible
+#endif
+
 struct nontrivial_t {
     int x;
     nontrivial_t() :x(-1) {}

src/compat.h

@@ -10,16 +10,6 @@
 #include <config/bitcoin-config.h>
 #endif
 
-#include <type_traits>
-
-// GCC 4.8 is missing some C++11 type_traits,
-// https://www.gnu.org/software/gcc/gcc-5/changes.html
-#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5
-#define IS_TRIVIALLY_CONSTRUCTIBLE std::has_trivial_default_constructor
-#else
-#define IS_TRIVIALLY_CONSTRUCTIBLE std::is_trivially_default_constructible
-#endif
-
 #ifdef WIN32
 #ifdef _WIN32_WINNT
 #undef _WIN32_WINNT

src/prevector.h

@@ -15,8 +15,6 @@
 #include <iterator>
 #include <type_traits>
 
-#include <compat.h>
-
 #pragma pack(push, 1)
 /** Implements a drop-in replacement for std::vector<T> which stores up to N
  *  elements directly (without heap allocation). The types Size and Diff are
@@ -198,11 +196,7 @@ private:
     T* item_ptr(difference_type pos) { return is_direct() ? direct_ptr(pos) : indirect_ptr(pos); }
     const T* item_ptr(difference_type pos) const { return is_direct() ? direct_ptr(pos) : indirect_ptr(pos); }
 
-    void fill(T* dst, ptrdiff_t count) {
-        std::fill_n(dst, count, T{});
-    }
-
-    void fill(T* dst, ptrdiff_t count, const T& value) {
+    void fill(T* dst, ptrdiff_t count, const T& value = T{}) {
         std::fill_n(dst, count, value);
     }