From: Jim Meyering <meyering@fb.com>
Date: Mon, 29 Aug 2016 16:45:18 +0000 (-0700)
Subject: intprops.h, xalloc-oversized.h: work with gcc 7
X-Git-Url: https://repo.or.cz/gnulib/ericb.git/commitdiff_plain/175b4e22f99e00996b72f822f5ae54dca8243d19

intprops.h, xalloc-oversized.h: work with gcc 7

In gcc 6, __builtin_add_overflow, __builtin_sub_overflow and
__builtin_mul_overflow each accept a NULL pointer as the third
argument.  However in gcc 7, that is no longer accepted.
Instead, one must use the "_p"-suffixed names, with which, the
third parameter is no longer a pointer.
* lib/intprops.h (_GL_HAS_BUILTIN_OVERFLOW_WITH_NULL): Correct
the definition: not true for gcc 7 and subsequent.
(_GL_HAS_BUILTIN_OVERFLOW_P): Define.
(_GL_ADD_OVERFLOW, _GL_SUBTRACT_OVERFLOW, _GL_MULTIPLY_OVERFLOW):
Provide new definitions for gcc 7 and subsequent.
* lib/xalloc-oversized.h (xalloc_oversized): Provide a definition
that works with gcc-7.
---

diff --git a/ChangeLog b/ChangeLog
index c5e6ee879b..8e7ab74757 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,19 @@
 2016-08-29  Jim Meyering  <meyering@fb.com>
 
+	intprops.h, xalloc-oversized.h: work with gcc 7
+	In gcc 6, __builtin_add_overflow, __builtin_sub_overflow and
+	__builtin_mul_overflow each accept a NULL pointer as the third
+	argument.  However in gcc 7, that is no longer accepted.
+	Instead, one must use the "_p"-suffixed names, with which, the
+	third parameter is no longer a pointer.
+	* lib/intprops.h (_GL_HAS_BUILTIN_OVERFLOW_WITH_NULL): Correct
+	the definition: not true for gcc 7 and subsequent.
+	(_GL_HAS_BUILTIN_OVERFLOW_P): Define.
+	(_GL_ADD_OVERFLOW, _GL_SUBTRACT_OVERFLOW, _GL_MULTIPLY_OVERFLOW):
+	Provide new definitions for gcc 7 and subsequent.
+	* lib/xalloc-oversized.h (xalloc_oversized): Provide a definition
+	that works with gcc-7.
+
 	intprops.h: fix missing-backslash problems
 	* lib/intprops.h (_GL_ADD_OVERFLOW): Add backslash.
 	(_GL_SUBTRACT_OVERFLOW,_GL_MULTIPLY_OVERFLOW): Likewise.
diff --git a/lib/intprops.h b/lib/intprops.h
index 0c45550a9b..d2a65cc5e4 100644
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -229,13 +229,23 @@ verify (TYPE_MAXIMUM (long long int) == LLONG_MAX);
    : (max) >> (b) < (a))
 
 /* True if __builtin_add_overflow (A, B, P) works when P is null.  */
-#define _GL_HAS_BUILTIN_OVERFLOW_WITH_NULL (7 <= __GNUC__)
+#define _GL_HAS_BUILTIN_OVERFLOW_WITH_NULL (6 == __GNUC__)
+
+/* True if __builtin_add_overflow_p (A, B, C) works.  */
+#define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
 
 /* The _GL*_OVERFLOW macros have the same restrictions as the
    *_RANGE_OVERFLOW macros, except that they do not assume that operands
    (e.g., A and B) have the same type as MIN and MAX.  Instead, they assume
    that the result (e.g., A + B) has that type.  */
-#if _GL_HAS_BUILTIN_OVERFLOW_WITH_NULL
+#if _GL_HAS_BUILTIN_OVERFLOW_P
+# define _GL_ADD_OVERFLOW(a, b, min, max)                               \
+   __builtin_add_overflow_p (a, b, (a) + (b))
+# define _GL_SUBTRACT_OVERFLOW(a, b, min, max)                          \
+   __builtin_sub_overflow_p (a, b, (a) - (b))
+# define _GL_MULTIPLY_OVERFLOW(a, b, min, max)                          \
+   __builtin_mul_overflow_p (a, b, (a) * (b))
+#elif _GL_HAS_BUILTIN_OVERFLOW_WITH_NULL
 # define _GL_ADD_OVERFLOW(a, b, min, max)                               \
    __builtin_add_overflow (a, b, (__typeof__ ((a) + (b)) *) 0)
 # define _GL_SUBTRACT_OVERFLOW(a, b, min, max)                          \
diff --git a/lib/xalloc-oversized.h b/lib/xalloc-oversized.h
index 44f16441c7..9954f50336 100644
--- a/lib/xalloc-oversized.h
+++ b/lib/xalloc-oversized.h
@@ -43,9 +43,12 @@
    nonnegative.  This is a macro, not a function, so that it
    works correctly even when SIZE_MAX < N.  */
 
-/* GCC 7 __builtin_mul_overflow should easily compute this.  See:
-   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68120  */
 #if 7 <= __GNUC__
+# define xalloc_oversized(n, s) __builtin_mul_overflow_p (n, s, (size_t) 1)
+
+/* GCC 6 __builtin_mul_overflow should easily compute this.  See:
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68120  */
+#elif 6 == __GNUC__
 # define xalloc_oversized(n, s) __builtin_mul_overflow (n, s, (size_t *) NULL)
 
 /* GCC 5 and Clang __builtin_mul_overflow needs a temporary, and