https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80888
Bug ID: 80888
Summary: Wide_Text_IO defaults to bracket encoding even if
-gnatW8 specified
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
Assignee: unassigned at gcc dot gnu.org
Reporter: simon at pushface dot org
Target Milestone: ---
Host: x86_64-apple-darwin15
The GNAT reference manual says in 11.6 Wide_Text_IO
<https://gcc.gnu.org/onlinedocs/gnat_rm/Wide_005fText_005fIO.html>,
"The default encoding method for the standard files, and for opened
files for which no WCEM parameter is given in the FORM string matches
the wide character encoding specified for the main program (the
default being brackets encoding if no coding method was specified with
-gnatW)."
This is slightly wrong, in that the UTF-8 coding method is selected
even in the absence of -gnatW8 if the main program's source file has
the appropriate BOM; but the point of this PR is that it is not in
fact true, and even if -gnatW8 is given files are created/opened with
bracket encoding unless the Form parameter is given (Form => "wcem=8").
The attached demonstrator shows this. The file as uploaded begins with
EF BB BF, but compile with -gnatW8 to be sure:
$ gnatmake utf8_encoding -gnatW8
gcc -c -gnatW8 utf8_encoding.adb
gnatbind -x utf8_encoding.ali
gnatlink utf8_encoding.ali
$ ./utf8_encoding
Two files are created, one without the Form parameter:
$ od -tx1 -c -N32 file_without_form
0000000 5b 22 30 33 43 30 22 5d 72 b2 68 0a
[ " 0 3 C 0 " ] r 262 h \n
0000014
and one with:
$ od -tx1 -c -N32 file_with_form
0000000 cf 80 72 c2 b2 68 0a
π ** r ² ** h \n
0000007
