--- a/ChangeLog	Mon May 14 01:02:02 2018 +0200
+++ b/ChangeLog	Mon May 14 01:48:22 2018 +0200
@@ -1,3 +1,17 @@
+2018-05-13  Bruno Haible  <bruno@clisp.org>
+
+	truncate: Fix compilation error on Android.
+	* m4/truncate.m4 (gl_FUNC_TRUNCATE): Test also whether 'truncate' is
+	declared. Set HAVE_DECL_TRUNCATE, not HAVE_TRUNCATE.
+	* lib/unistd.in.h (truncate): Test HAVE_DECL_TRUNCATE, not
+	HAVE_TRUNCATE.
+	* modules/truncate: Likewise.
+	* m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Initialize HAVE_DECL_TRUNCATE,
+	not HAVE_TRUNCATE.
+	* modules/unistd (Makefile.am): Substitute HAVE_DECL_TRUNCATE, not
+	HAVE_TRUNCATE.
+	* doc/posix-functions/truncate.texi: Mention the issue.
+
 2018-05-13  Bruno Haible  <bruno@clisp.org>
 
 	pthread: Fix compilation error on Android.

--- a/doc/posix-functions/truncate.texi	Mon May 14 01:02:02 2018 +0200
+++ b/doc/posix-functions/truncate.texi	Mon May 14 01:48:22 2018 +0200
@@ -10,7 +10,7 @@
 @itemize
 @item
 This function is missing on some platforms:
-mingw, MSVC 14.
+mingw, MSVC 14, Android 4.4 with @code{AC_SYS_LARGEFILE} in effect.
 @item
 On platforms where @code{off_t} is a 32-bit type, this function is not
 applicable to arbitrary lengths for files larger than 2 GB.  The fix is to

--- a/lib/unistd.in.h	Mon May 14 01:02:02 2018 +0200
+++ b/lib/unistd.in.h	Mon May 14 01:48:22 2018 +0200
@@ -1489,7 +1489,7 @@
                                  _GL_ARG_NONNULL ((1)));
 _GL_CXXALIAS_RPL (truncate, int, (const char *filename, off_t length));
 # else
-#  if !@HAVE_TRUNCATE@
+#  if !@HAVE_DECL_TRUNCATE@
 _GL_FUNCDECL_SYS (truncate, int, (const char *filename, off_t length)
                                  _GL_ARG_NONNULL ((1)));
 #  endif

--- a/m4/truncate.m4	Mon May 14 01:02:02 2018 +0200
+++ b/m4/truncate.m4	Mon May 14 01:48:22 2018 +0200
@@ -1,4 +1,4 @@
-# truncate.m4 serial 1   -*- Autoconf -*-
+# truncate.m4 serial 2   -*- Autoconf -*-
 dnl Copyright (C) 2017-2018 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,7 +8,12 @@
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_CHECK_FUNCS_ONCE([truncate])
-  if test $ac_cv_func_truncate = yes; then
+  dnl AC_CHECK_FUNC is not enough here, because when compiling for Android 4.4
+  dnl or older with _FILE_OFFSET_BITS=64, truncate() is not declared.  There
+  dnl is a function 'truncate' in libc, but it is unsuitable, because it takes
+  dnl only a 32-bit offset argument.
+  AC_CHECK_DECL([truncate], , , [[#include <unistd.h>]])
+  if test $ac_cv_have_decl_truncate = yes; then
     m4_ifdef([gl_LARGEFILE], [
       AC_REQUIRE([AC_CANONICAL_HOST])
       case "$host_os" in
@@ -25,7 +30,11 @@
       :
     ])
   else
-    HAVE_TRUNCATE=0
+    HAVE_DECL_TRUNCATE=0
+    if test $ac_cv_func_truncate = yes; then
+      dnl Avoid a conflict with the 'truncate' in libc.
+      REPLACE_TRUNCATE=1
+    fi
   fi
 ])
 

--- a/m4/unistd_h.m4	Mon May 14 01:02:02 2018 +0200
+++ b/m4/unistd_h.m4	Mon May 14 01:48:22 2018 +0200
@@ -1,4 +1,4 @@
-# unistd_h.m4 serial 72
+# unistd_h.m4 serial 73
 dnl Copyright (C) 2006-2018 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -140,7 +140,6 @@
   HAVE_SLEEP=1;           AC_SUBST([HAVE_SLEEP])
   HAVE_SYMLINK=1;         AC_SUBST([HAVE_SYMLINK])
   HAVE_SYMLINKAT=1;       AC_SUBST([HAVE_SYMLINKAT])
-  HAVE_TRUNCATE=1;        AC_SUBST([HAVE_TRUNCATE])
   HAVE_UNLINKAT=1;        AC_SUBST([HAVE_UNLINKAT])
   HAVE_USLEEP=1;          AC_SUBST([HAVE_USLEEP])
   HAVE_DECL_ENVIRON=1;    AC_SUBST([HAVE_DECL_ENVIRON])
@@ -152,6 +151,7 @@
   HAVE_DECL_GETPAGESIZE=1; AC_SUBST([HAVE_DECL_GETPAGESIZE])
   HAVE_DECL_GETUSERSHELL=1; AC_SUBST([HAVE_DECL_GETUSERSHELL])
   HAVE_DECL_SETHOSTNAME=1; AC_SUBST([HAVE_DECL_SETHOSTNAME])
+  HAVE_DECL_TRUNCATE=1;   AC_SUBST([HAVE_DECL_TRUNCATE])
   HAVE_DECL_TTYNAME_R=1;  AC_SUBST([HAVE_DECL_TTYNAME_R])
   HAVE_OS_H=0;            AC_SUBST([HAVE_OS_H])
   HAVE_SYS_PARAM_H=0;     AC_SUBST([HAVE_SYS_PARAM_H])

--- a/modules/truncate	Mon May 14 01:02:02 2018 +0200
+++ b/modules/truncate	Mon May 14 01:48:22 2018 +0200
@@ -9,12 +9,12 @@
 unistd
 sys_types
 largefile
-open            [test $HAVE_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1]
-ftruncate       [test $HAVE_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1]
+open            [test $HAVE_DECL_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1]
+ftruncate       [test $HAVE_DECL_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1]
 
 configure.ac:
 gl_FUNC_TRUNCATE
-if test $HAVE_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1; then
+if test $HAVE_DECL_TRUNCATE = 0 || test $REPLACE_TRUNCATE = 1; then
   AC_LIBOBJ([truncate])
   gl_PREREQ_TRUNCATE
 fi

--- a/modules/unistd	Mon May 14 01:02:02 2018 +0200
+++ b/modules/unistd	Mon May 14 01:48:22 2018 +0200
@@ -115,7 +115,6 @@
 	      -e 's|@''HAVE_SLEEP''@|$(HAVE_SLEEP)|g' \
 	      -e 's|@''HAVE_SYMLINK''@|$(HAVE_SYMLINK)|g' \
 	      -e 's|@''HAVE_SYMLINKAT''@|$(HAVE_SYMLINKAT)|g' \
-	      -e 's|@''HAVE_TRUNCATE''@|$(HAVE_TRUNCATE)|g' \
 	      -e 's|@''HAVE_UNLINKAT''@|$(HAVE_UNLINKAT)|g' \
 	      -e 's|@''HAVE_USLEEP''@|$(HAVE_USLEEP)|g' \
 	      -e 's|@''HAVE_DECL_ENVIRON''@|$(HAVE_DECL_ENVIRON)|g' \
@@ -127,6 +126,7 @@
 	      -e 's|@''HAVE_DECL_GETPAGESIZE''@|$(HAVE_DECL_GETPAGESIZE)|g' \
 	      -e 's|@''HAVE_DECL_GETUSERSHELL''@|$(HAVE_DECL_GETUSERSHELL)|g' \
 	      -e 's|@''HAVE_DECL_SETHOSTNAME''@|$(HAVE_DECL_SETHOSTNAME)|g' \
+	      -e 's|@''HAVE_DECL_TRUNCATE''@|$(HAVE_DECL_TRUNCATE)|g' \
 	      -e 's|@''HAVE_DECL_TTYNAME_R''@|$(HAVE_DECL_TTYNAME_R)|g' \
 	      -e 's|@''HAVE_OS_H''@|$(HAVE_OS_H)|g' \
 	      -e 's|@''HAVE_SYS_PARAM_H''@|$(HAVE_SYS_PARAM_H)|g' \