truncate: Fix compilation error on Android

[Bruno Haible]

Compiling a testdir for Android 4.3, I'm seeing this error:

In file included from test-truncate.c:21:0:
test-truncate.c:22:18: error: 'truncate' undeclared here (not in a function)
 SIGNATURE_CHECK (truncate, int, (const char *, off_t));
                  ^

The reason is that AC_SYS_LARGEFILE is in effect, and while later versions
of Android have a redirect from 'truncate' to a function 'truncate64' that
takes a 64-bit off_t, in Android 4.0 .. 4.4 this function does not
yet exist, and 'truncate' is accordingly not declared in <unistd.h>.


2018-05-13  Bruno Haible  <address@hidden>

        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.

diff --git a/doc/posix-functions/truncate.texi 
b/doc/posix-functions/truncate.texi
index b443d31..8cbd940 100644
--- a/doc/posix-functions/truncate.texi
+++ b/doc/posix-functions/truncate.texi
@@ -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
diff --git a/lib/unistd.in.h b/lib/unistd.in.h
index 98a5abe..075cab3 100644
--- a/lib/unistd.in.h
+++ b/lib/unistd.in.h
@@ -1489,7 +1489,7 @@ _GL_FUNCDECL_RPL (truncate, int, (const char *filename, 
off_t length)
                                  _GL_ARG_NONNULL ((1)));
 _GL_CXXALIAS_RPL (truncate, int, (const char *filename, off_t length));
 # else
-#  if address@hidden@
+#  if address@hidden@
 _GL_FUNCDECL_SYS (truncate, int, (const char *filename, off_t length)
                                  _GL_ARG_NONNULL ((1)));
 #  endif
diff --git a/m4/truncate.m4 b/m4/truncate.m4
index d46ff2b..87f0493 100644
--- a/m4/truncate.m4
+++ b/m4/truncate.m4
@@ -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_DEFUN([gl_FUNC_TRUNCATE],
 [
   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 @@ AC_DEFUN([gl_FUNC_TRUNCATE],
       :
     ])
   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
 ])
 
diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4
index 77110a9..159c48a 100644
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@@ -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 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   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 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   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])
diff --git a/modules/truncate b/modules/truncate
index e141b1a..b6fb377 100644
--- a/modules/truncate
+++ b/modules/truncate
@@ -9,12 +9,12 @@ Depends-on:
 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
diff --git a/modules/unistd b/modules/unistd
index 98b6f9e..25bf9fa 100644
--- a/modules/unistd
+++ b/modules/unistd
@@ -115,7 +115,6 @@ unistd.h: unistd.in.h $(top_builddir)/config.status 
$(CXXDEFS_H) $(ARG_NONNULL_H
              -e 's|@''HAVE_SLEEP''@|$(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 @@ unistd.h: unistd.in.h $(top_builddir)/config.status 
$(CXXDEFS_H) $(ARG_NONNULL_H
              -e 's|@''HAVE_DECL_GETPAGESIZE''@|$(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' \