--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2011-09-30  Bruno Haible  <bruno@clisp.org>
+
+	float, math: Fix 'int' to 'long double' conversion on Linux/SPARC64.
+	* m4/float_h.m4 (gl_FLOAT_H): Test conversion from 'int' to
+	'long double'. Set REPLACE_ITOLD.
+	* lib/float.in.h (_Qp_itoq, _gl_float_fix_itold): New declarations.
+	* lib/math.in.h (_Qp_itoq, _gl_math_fix_itold): New declarations.
+	* lib/itold.c: New file.
+	* modules/float (Files): Add lib/itold.c.
+	(configure.ac): When REPLACE_ITOLD is 1, arrange to compile itold.c.
+	(Makefile.am): Substitute REPLACE_ITOLD.
+	* modules/math (Depends-on): Add float.
+	(Makefile.am): Substitute REPLACE_ITOLD.
+	* doc/posix-headers/float.texi: Mention problem on Linux/SPARC64.
+	* doc/posix-headers/math.texi: Likewise.
+	* doc/posix-functions/logl.texi: Likewise.
+
 2011-09-30  Bruno Haible  <bruno@clisp.org>
 
 	nonblocking tests: Fix test failure on Linux/SPARC (32-bit and 64-bit).

--- a/doc/posix-functions/logl.texi
+++ b/doc/posix-functions/logl.texi
@@ -17,6 +17,9 @@
 @item
 This function is not declared on some platforms:
 MacOS X 10.3.
+@item
+This function returns wrong results on some platforms:
+glibc 2.7 on Linux/SPARC64.
 @end itemize
 
 Portability problems not fixed by Gnulib:

--- a/doc/posix-headers/float.texi
+++ b/doc/posix-headers/float.texi
@@ -8,6 +8,10 @@
 Portability problems fixed by Gnulib:
 @itemize
 @item
+The conversion from @code{int} to @code{long double} in incorrect on some
+platforms:
+glibc 2.7 on Linux/SPARC64.
+@item
 The values of @code{LDBL_*} macros are incorrect on some platforms:
 On OpenBSD 4.0, MirBSD 10, and BeOS, they are the same as the values of the
 @code{DBL_*} macros, although @samp{long double} is a larger type than

--- a/doc/posix-headers/math.texi
+++ b/doc/posix-headers/math.texi
@@ -8,6 +8,11 @@
 Portability problems fixed by Gnulib:
 @itemize
 @item
+The conversion from @code{int} to @code{long double} in incorrect on some
+platforms:
+glibc 2.7 on Linux/SPARC64.
+
+@item
 The macro @code{NAN} is not defined on some platforms:
 OpenBSD 4.0, AIX 5.1, IRIX 6.5, OSF/1 5.1.
 

--- a/lib/float.in.h
+++ b/lib/float.in.h
@@ -173,5 +173,16 @@
 # endif
 #endif
 
+#if @REPLACE_ITOLD@
+/* Pull in a function that fixes the 'int' to 'long double' conversion
+   of glibc 2.7.  */
+extern
+# ifdef __cplusplus
+"C"
+# endif
+void _Qp_itoq (long double *, int);
+static void (*_gl_float_fix_itold) (long double *, int) = _Qp_itoq;
+#endif
+
 #endif /* _@GUARD_PREFIX@_FLOAT_H */
 #endif /* _@GUARD_PREFIX@_FLOAT_H */

--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -67,6 +67,14 @@
    : rpl_ ## func ## l (value))
 
 
+#if @REPLACE_ITOLD@
+/* Pull in a function that fixes the 'int' to 'long double' conversion
+   of glibc 2.7.  */
+_GL_EXTERN_C void _Qp_itoq (long double *, int);
+static void (*_gl_math_fix_itold) (long double *, int) = _Qp_itoq;
+#endif
+
+
 /* POSIX allows platforms that don't support NAN.  But all major
    machines in the past 15 years have supported something close to
    IEEE NaN, so we define this unconditionally.  We also must define

--- a/m4/float_h.m4
+++ b/m4/float_h.m4
@@ -1,4 +1,4 @@
-# float_h.m4 serial 8
+# float_h.m4 serial 9
 dnl Copyright (C) 2007, 2009-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -48,9 +48,51 @@
       fi
       ;;
   esac
+
+  dnl Test against glibc-2.7 Linux/SPARC64 bug.
+  REPLACE_ITOLD=0
+  AC_CACHE_CHECK([whether conversion from 'int' to 'long double' works],
+    [gl_cv_func_itold_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+int i = -1;
+volatile long double ld;
+int main ()
+{
+  ld += i * 1.0L;
+  if (ld > 0)
+    return 1;
+  return 0;
+}]])],
+        [gl_cv_func_itold_works=yes],
+        [gl_cv_func_itold_works=no],
+        [case "$host" in
+           sparc*-*-linux*)
+             AC_EGREP_CPP([yes],
+               [#if defined __LP64__ || defined __arch64__
+                yes
+                #endif],
+               [gl_cv_func_itold_works="guessing no"],
+               [gl_cv_func_itold_works="guessing yes"])
+             ;;
+           *) gl_cv_func_itold_works="guessing yes" ;;
+         esac
+        ])
+    ])
+  case "$gl_cv_func_itold_works" in
+    *no)
+      REPLACE_ITOLD=1
+      dnl We add the workaround to <float.h> but also to <math.h>,
+      dnl to increase the chances that the fix function gets pulled in.
+      FLOAT_H=float.h
+      ;;
+  esac
+
   if test -n "$FLOAT_H"; then
     gl_NEXT_HEADERS([float.h])
   fi
   AC_SUBST([FLOAT_H])
   AM_CONDITIONAL([GL_GENERATE_FLOAT_H], [test -n "$FLOAT_H"])
+  AC_SUBST([REPLACE_ITOLD])
 ])

--- a/modules/float
+++ b/modules/float
@@ -4,6 +4,7 @@
 Files:
 lib/float.in.h
 lib/float.c
+lib/itold.c
 m4/float_h.m4
 
 Depends-on:
@@ -14,6 +15,9 @@
 if test $REPLACE_FLOAT_LDBL = 1; then
   AC_LIBOBJ([float])
 fi
+if test $REPLACE_ITOLD = 1; then
+  AC_LIBOBJ([itold])
+fi
 
 Makefile.am:
 BUILT_SOURCES += $(FLOAT_H)
@@ -29,6 +33,7 @@
 	      -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
 	      -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
 	      -e 's|@''NEXT_FLOAT_H''@|$(NEXT_FLOAT_H)|g' \
+	      -e 's|@''REPLACE_ITOLD''@|$(REPLACE_ITOLD)|g' \
 	      < $(srcdir)/float.in.h; \
 	} > $@-t && \
 	mv $@-t $@

--- a/modules/math
+++ b/modules/math
@@ -10,6 +10,7 @@
 snippet/arg-nonnull
 snippet/c++defs
 snippet/warn-on-use
+float
 
 configure.ac:
 gl_MATH_H
@@ -107,6 +108,7 @@
 	      -e 's|@''REPLACE_ISFINITE''@|$(REPLACE_ISFINITE)|g' \
 	      -e 's|@''REPLACE_ISINF''@|$(REPLACE_ISINF)|g' \
 	      -e 's|@''REPLACE_ISNAN''@|$(REPLACE_ISNAN)|g' \
+	      -e 's|@''REPLACE_ITOLD''@|$(REPLACE_ITOLD)|g' \
 	      -e 's|@''REPLACE_LDEXPL''@|$(REPLACE_LDEXPL)|g' \
 	      -e 's|@''REPLACE_NAN''@|$(REPLACE_NAN)|g' \
 	      -e 's|@''REPLACE_ROUND''@|$(REPLACE_ROUND)|g' \