AC_SUBST_FILE bug

[tisser_n]

Hi !

While using the AC_SUBST_FILE macro, on autoconf 2.57, I found the
following problem.

Given this simple set of input files :

address@hidden:~/work/autoconf/ac_subst_file_bug ls                         
23:47
configure.ac  foo.txt  output.txt.in
address@hidden:~/work/autoconf/ac_subst_file_bug cat configure.ac           
23:49
AC_INIT
FOO='foo.txt'
AC_SUBST_FILE([FOO])
AC_CONFIG_FILES([output.txt])
AC_OUTPUT
address@hidden:~/work/autoconf/ac_subst_file_bug cat output.txt.in          
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first line of output
@FOO@
last line of output
address@hidden:~/work/autoconf/ac_subst_file_bug cat foo.txt                
23:49
first line of foo
last  line of foo
address@hidden:~/work/autoconf/ac_subst_file_bug                            
23:49

When running autoconf and the produced configure script, I obtain :

address@hidden:~/work/autoconf/ac_subst_file_bug autoconf                   
23:51
address@hidden:~/work/autoconf/ac_subst_file_bug ./configure                
23:51
configure: creating ./config.status
config.status: creating output.txt
address@hidden:~/work/autoconf/ac_subst_file_bug cat output.txt             
23:51
first line of output

first line of foo
last  line of foo
last line of output
address@hidden:~/work/autoconf/ac_subst_file_bug                            
23:51

The file ``output.txt'' contains an empty line before the actual
substitution of ``foo.txt''.

I do not know if this a deliberate behavior ... but this is quit
annoying :(

In the case that it should considered as a bug, I have joined a
tarball of the files used above and a microscopic patch that seem to
correct the problem.

Thanks.
--
Nicolas Tisserand

ac_subst_file_bug.tar.bz2
Description: application/tbz

ac_subst_file_bug.patch
Description: Text Data