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[patch] Restore isinf, isinfl, isnanf and isnanl for C++11

It was pointed out to me that my patch for BZ #19439 (committed as
d9b965fa56350d6eea9f7f438a0714c7ffbb183f on Jan 11) does more than I
intended it to. Only the double versions of isinf and isnan conflict
with C++11 functions, but my patch also prevents the long double and
float versions from being declared.

C++11 code using isinf and isnan continues to compile after that
change, because the C++11 standard library provides its own versions
conforming to the C++11 requirements. However, the C++11 library
doesn't provide isinff, isinfl etc. and so code using those
(non-standard) functions will no longer compile if they are not
declared by glibc.

This patch tweaks my change so that only the isinf(double) and
isnan(double) declarations are suppressed, and the float and long
double versions are still declared, even for C++11.

We would like this to get into 2.23 as well, so that only the
problematic functions that conflict with C++11 get removed in glibc
2.23, and the other functions remain.

Sorry for the unintended consequences of my previous patch.
commit 48746aa5a013aab5ca89ee8c29761baec8850c0f
Author: Jakub Jelinek <>
Date:   Mon Feb 1 16:17:55 2016 +0000

    Restore isinf, isinfl, isnanf and isnanl for C++11

diff --git a/math/bits/mathcalls.h b/math/bits/mathcalls.h
index a48345d..9a7b3f0 100644
--- a/math/bits/mathcalls.h
+++ b/math/bits/mathcalls.h
@@ -196,7 +196,9 @@ __MATHDECL_1 (int,__finite,, (_Mdouble_ __value)) __attribute__ ((__const__));
 #ifdef __USE_MISC
-# if !defined __cplusplus || __cplusplus < 201103L /* Conflicts with C++11.  */
+# if (!defined __cplusplus \
+      || __cplusplus < 201103L /* isinf conflicts with C++11.  */ \
+      || __MATH_DECLARING_DOUBLE == 0) /* isinff or isinfl don't.  */
 /* Return 0 if VALUE is finite or NaN, +1 if it
    is +Infinity, -1 if it is -Infinity.  */
 __MATHDECL_1 (int,isinf,, (_Mdouble_ __value)) __attribute__ ((__const__));
@@ -232,7 +234,9 @@ __END_NAMESPACE_C99
 __MATHDECL_1 (int,__isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
 #if defined __USE_MISC || (defined __USE_XOPEN && !defined __USE_XOPEN2K)
-# if !defined __cplusplus || __cplusplus < 201103L /* Conflicts with C++11.  */
+# if (!defined __cplusplus \
+      || __cplusplus < 201103L /* isnan conflicts with C++11.  */ \
+      || __MATH_DECLARING_DOUBLE == 0) /* isnanf or isnanl don't.  */
 /* Return nonzero if VALUE is not a number.  */
 __MATHDECL_1 (int,isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
 # endif

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