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Use clog10 not __clog10 in tgmath.h log10 macro [committed]

As a GNU extension, for _GNU_SOURCE glibc's complex.h provides a
clog10 function and tgmath.h supports complex arguments to the log10
macro.  However, tgmath.h uses __clog10 not clog10 in defining the

There is no namespace reason (ignoring the block-scope namespace
issues that would apply equally to *every* function called by tgmath.h
macros) for using __clog10 here, since this is only for _GNU_SOURCE so
clog10 is always visible when this macro definition is used.
Furthermore, __clog10f128 is not exported, so supporting _Float128 in
tgmath.h implies using clog10 not __clog10 there.  (__clog10 and
clog10 aren't used in libstdc++ either, although that library would
have a good case for using the __clog10 reserved-namespace export: the
standard C++ library includes log10 of a complex number.)  This patch
duly changes the header to use clog10, and enables tests of the macro
for complex arguments.

Tested for x86_64.  Committed.

2017-06-28  Joseph Myers  <>

	* math/tgmath.h [__USE_GNU] (log10): Use clog10 not __clog10.
	* math/ (Tests.add_all_tests): Test log10 for
	complex arguments.

diff --git a/math/ b/math/
index db6553e..31a3bd2 100755
--- a/math/
+++ b/math/
@@ -497,7 +497,9 @@ class Tests(object):
         self.add_tests('lgamma', 'r', ['r'])
         self.add_tests('llrint', 'long long int', ['r'])
         self.add_tests('llround', 'long long int', ['r'])
-        self.add_tests('log10', 'r', ['r'])
+        # log10 is real-only in ISO C, but supports complex arguments
+        # as a GNU extension.
+        self.add_tests('log10', 'g', ['g'])
         self.add_tests('log1p', 'r', ['r'])
         self.add_tests('log2', 'r', ['r'])
         self.add_tests('logb', 'r', ['r'])
diff --git a/math/tgmath.h b/math/tgmath.h
index a0da104..7afe41e 100644
--- a/math/tgmath.h
+++ b/math/tgmath.h
@@ -319,7 +319,7 @@
 /* Base-ten logarithm of X.  */
 #ifdef __USE_GNU
-# define log10(Val) __TGMATH_UNARY_REAL_IMAG (Val, log10, __clog10)
+# define log10(Val) __TGMATH_UNARY_REAL_IMAG (Val, log10, clog10)
 # define log10(Val) __TGMATH_UNARY_REAL_ONLY (Val, log10)

Joseph S. Myers

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