Fix build on gcc < 5 (std::is_trivially_copyable missing)

Ref: https://sourceware.org/ml/gdb-patches/2017-04/msg00660.html

Simply skip the poisoning on older compilers.

gdb/ChangeLog:
2017-04-25  Pedro Alves  <palves@redhat.com>

	* common/poison.h [!HAVE_IS_TRIVIALLY_COPYABLE] (IsRelocatable)
	(BothAreRelocatable, memcopy, memmove): Don't define.
	* common/traits.h (__has_feature, HAVE_IS_TRIVIALLY_COPYABLE): New
	macros.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 26e6370..d1c1942 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2017-04-25  Pedro Alves  <palves@redhat.com>
 
+       * common/poison.h [!HAVE_IS_TRIVIALLY_COPYABLE] (IsRelocatable)
+       (BothAreRelocatable, memcopy, memmove): Don't define.
+       * common/traits.h (__has_feature, HAVE_IS_TRIVIALLY_COPYABLE): New
+       macros.
+
+2017-04-25  Pedro Alves  <palves@redhat.com>
+
        * common/common-defs.h: Include "common/poison.h".
        * common/function-view.h: (Not, Or, Requires): Move to traits.h
        and adjust.

diff --git a/gdb/common/poison.h b/gdb/common/poison.h
index a875568..37dd35e 100644 (file)
--- a/gdb/common/poison.h
+++ b/gdb/common/poison.h
@@ -55,6 +55,8 @@ template <typename T,
          typename = gdb::Requires<gdb::Not<IsMemsettable<T>>>>
 void *memset (T *s, int c, size_t n) = delete;
 
+#if HAVE_IS_TRIVIALLY_COPYABLE
+
 /* Similarly, poison memcpy and memmove of non trivially-copyable
    types, which is undefined.  */
 
@@ -80,4 +82,6 @@ template <typename D, typename S,
          typename = gdb::Requires<gdb::Not<BothAreRelocatable<D, S>>>>
 void *memmove (D *dest, const S *src, size_t n) = delete;
 
+#endif /* HAVE_IS_TRIVIALLY_COPYABLE */
+
 #endif /* COMMON_POISON_H */

diff --git a/gdb/common/traits.h b/gdb/common/traits.h
index 4f7161b..8c41b03 100644 (file)
--- a/gdb/common/traits.h
+++ b/gdb/common/traits.h
@@ -20,6 +20,19 @@
 
 #include <type_traits>
 
+/* GCC does not understand __has_feature.  */
+#if !defined(__has_feature)
+# define __has_feature(x) 0
+#endif
+
+/* HAVE_IS_TRIVIALLY_COPYABLE is defined as 1 iff
+   std::is_trivially_copyable is available.  GCC only implemented it
+   in GCC 5.  */
+#if (__has_feature(is_trivially_copyable) \
+     || (defined __GNUC__ && __GNUC__ >= 5))
+# define HAVE_IS_TRIVIALLY_COPYABLE 1
+#endif
+
 namespace gdb {
 
 /* Pre C++14-safe (CWG 1558) version of C++17's std::void_t.  See