GNU C Library master sources branch release/2.26/master updated. glibc-2.26-70-gb1b8d8a

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- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=b1b8d8aa95a055dc7929259679a995189d444809

commit b1b8d8aa95a055dc7929259679a995189d444809
Author: Gabriel F. T. Gomes <gabriel@inconstante.eti.br>
Date:   Fri Oct 20 16:06:19 2017 -0200

    Add missing bug fixes to NEWS

diff --git a/NEWS b/NEWS
index c92ec03..bf4fd66 100644
--- a/NEWS
+++ b/NEWS
@@ -36,6 +36,7 @@ The following bugs are resolved with this release:
   [21972] assert macro requires operator== (int) for its argument type
   [21982] string: stratcliff.c: error: assuming signed overflow does not
     occur with -O3
+  [21987] Fix sparc32 bits/long-double.h
   [22051] libc: zero terminator in the middle of glibc's .eh_frame
   [22078] nss_files performance issue in hosts multi mode
   [22093] x86: Add x86_64 to x86-64 HWCAP
@@ -46,6 +47,7 @@ The following bugs are resolved with this release:
   [22225] math: nearbyint arithmetic moved before feholdexcept
   [22235] Add C++ versions of iscanonical for ldbl-96 and ldbl-128ibm
   [22296] Let signbit use the builtin in C++ mode with gcc < 6.x
+  [22320] glob: Fix one-byte overflow (CVE-2017-15670)
   [22321] sysconf: Fix missing definition of UIO_MAXIOV on Linux
   [22325] glibc: Memory leak in glob with GLOB_TILDE (CVE-2017-15671)
 

http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=f8279a4b3cc66d3ec8bfb8519e9987b8f7727f53

commit f8279a4b3cc66d3ec8bfb8519e9987b8f7727f53
Author: Romain Naour <romain.naour@gmail.com>
Date:   Mon Oct 16 23:21:56 2017 +0200

    Let signbit use the builtin in C++ mode with gcc < 6.x (bug 22296)
    
    When using gcc < 6.x, signbit does not use the type-generic
    __builtin_signbit builtin, instead it uses __MATH_TG.
    However, when library support for float128 is available, __MATH_TG uses
    __builtin_types_compatible_p, which is not available in C++ mode.
    
    On the other hand, libstdc++ undefines (in cmath) many macros from
    math.h, including signbit, so that it can provide its own functions.
    However, during its configure tests, libstdc++ just tests for the
    availability of the macros (it does not undefine them, nor does it
    provide its own functions).
    
    Finally, libstdc++ configure tests include math.h and get the definition
    of signbit that uses __MATH_TG (and __builtin_types_compatible_p).
    Since libstdc++ does not undefine the macros during its configure
    tests, they fail.
    
    This patch lets signbit use the builtin in C++ mode when gcc < 6.x is
    used. This allows the configure test in libstdc++ to work.
    
    Tested for x86_64.
    
    	[BZ #22296]
    	* math/math.h: Let signbit use the builtin in C++ mode with gcc
    	< 6.x
    
    Cc: Gabriel F. T. Gomes <gftg@linux.vnet.ibm.com>
    Cc: Joseph Myers <joseph@codesourcery.com>
    (cherry picked from commit 386e1c26ac473d6863133ab9cbe3bbda16c15816)

diff --git a/ChangeLog b/ChangeLog
index cd59878..6e53277 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-10-17  Romain Naour  <romain.naour@gmail.com>  (tiny change)
+
+	[BZ #22296]
+	* math/math.h: Let signbit use the builtin in C++ mode with gcc
+	< 6.x
+
 2017-10-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ #21265]
diff --git a/NEWS b/NEWS
index 87d4802..c92ec03 100644
--- a/NEWS
+++ b/NEWS
@@ -45,6 +45,7 @@ The following bugs are resolved with this release:
   [22146] Let fpclassify use the builtin when optimizing for size in C++ mode
   [22225] math: nearbyint arithmetic moved before feholdexcept
   [22235] Add C++ versions of iscanonical for ldbl-96 and ldbl-128ibm
+  [22296] Let signbit use the builtin in C++ mode with gcc < 6.x
   [22321] sysconf: Fix missing definition of UIO_MAXIOV on Linux
   [22325] glibc: Memory leak in glob with GLOB_TILDE (CVE-2017-15671)
 
diff --git a/math/math.h b/math/math.h
index 2b216c6..ba26624 100644
--- a/math/math.h
+++ b/math/math.h
@@ -418,6 +418,15 @@ enum
 /* Return nonzero value if sign of X is negative.  */
 # if __GNUC_PREREQ (6,0)
 #  define signbit(x) __builtin_signbit (x)
+# elif defined __cplusplus
+  /* In C++ mode, __MATH_TG cannot be used, because it relies on
+     __builtin_types_compatible_p, which is a C-only builtin.
+     The check for __cplusplus allows the use of the builtin instead of
+     __MATH_TG. This is provided for libstdc++, only to let its configure
+     test work. No further use of this definition of signbit is expected
+     in C++ mode, since libstdc++ provides its own version of signbit
+     in cmath (which undefines signbit). */
+#  define signbit(x) __builtin_signbitl (x)
 # elif __GNUC_PREREQ (4,0)
 #  define signbit(x) __MATH_TG ((x), __builtin_signbit, (x))
 # else

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog   |    6 ++++++
 NEWS        |    3 +++
 math/math.h |    9 +++++++++
 3 files changed, 18 insertions(+), 0 deletions(-)


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