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According to Reuben Thomas on 3/17/2009 6:23 AM:
> Looking through the manual, I see three types of use of test with =/!=:
>
> 1. if test $fstype = no
>
> In this particular case, $fstype is guaranteed to be defined, but isn't
> it better always to write
>
> if test "$fstype" = no
>
> as then one doesn't have to check?
I'm not a fan of excess typing. So I'd rather make it a point in the
manual that when a variable is entirely under your control, you can take
advantage of that fact.
>
> 2. if test "$package_foo_enabled" = "yes"
>
> I like this!
I'm not a fan of the redundant quotes around the yes. I know that others
are, but there were more places in the manual that avoided the redundant
quotes than used them. But you are correct that this is not protected
against $package_foo_enabled with odd contents, so I'm adjusting it to add
the x prefix.
>
> 3. if test "x$with_readline" != xno
>
> Why not write:
>
> if test "$with_readline" != no
>
> ?
Because if $with_readline starts with -, then this can confuse some
versions of test. The manual discusses this, under test:
http://www.gnu.org/software/autoconf/manual/autoconf.html#Limitations-of-Builtins
>
> It would be nice if this could be made consistent.
>
Here's what I will be pushing soon.
- --
Don't work too hard, make some time for fun as well!
Eric Blake e...@byu.net
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>From efb3e8a738994924dfed0e1d73c91e0678622b3b Mon Sep 17 00:00:00 2001
From: Eric Blake <e...@byu.net>
Date: Tue, 17 Mar 2009 07:39:40 -0600
Subject: [PATCH] Use test consistently in examples.
* doc/autoconf.texi (Subdirectories, Caching Results)
(Common Shell Constructs, Prerequisite Macros, Coding Style)
(Changed Results, Particular Programs, Defining Symbols):
Protect against arbitrary user strings.
(Multiple Cases): Mention why $fstype does not need protection.
Reported by Reuben Thomas.
Signed-off-by: Eric Blake <e...@byu.net>
---
ChangeLog | 8 ++++++++
doc/autoconf.texi | 34 ++++++++++++++++++----------------
2 files changed, 26 insertions(+), 16 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 9a5fd5d..05e3a4d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
2009-03-17 Eric Blake <e...@byu.net>
+ Use test consistently in examples.
+ * doc/autoconf.texi (Subdirectories, Caching Results)
+ (Common Shell Constructs, Prerequisite Macros, Coding Style)
+ (Changed Results, Particular Programs, Defining Symbols):
+ Protect against arbitrary user strings.
+ (Multiple Cases): Mention why $fstype does not need protection.
+ Reported by Reuben Thomas.
+
Improve confusing section names.
* doc/autoconf.texi (Specifying Names): Rename node...
(Specifying Target Triplets): ...to this.
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index e821cbd..a0a19b8 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -3510,7 +3510,7 @@ Subdirectories
be a literal, i.e., please do not use:
@example
-if test "$package_foo_enabled" = yes; then
+if test "x$package_foo_enabled" = xyes; then
$my_subdirs="$my_subdirs foo"
fi
AC_CONFIG_SUBDIRS([$my_subdirs])
@@ -3522,7 +3522,7 @@ Subdirectories
write:
@example
-if test "$package_foo_enabled" = yes; then
+if test "x$package_foo_enabled" = xyes; then
AC_CONFIG_SUBDIRS([foo])
fi
@end example
@@ -3930,7 +3930,7 @@ Particular Programs
@example
AC_PROG_LEX
-if test "$LEX" != flex; then
+if test "x$LEX" != xflex; then
LEX="$SHELL $missing_dir/missing flex"
AC_SUBST([LEX_OUTPUT_ROOT], [lex.yy])
AC_SUBST([LEXLIB], [''])
@@ -8606,7 +8606,9 @@ Multiple Cases
way to perform the operation has been found yet.
Here is an example that uses the shell variable @code{fstype} to keep
-track of whether the remaining cases need to be checked.
+track of whether the remaining cases need to be checked. Note that
+since the value of @code{fstype} is under our control, we don't have to
+use the longer @samp{test "x$fstype" = xno}.
@example
@group
@@ -8674,7 +8676,7 @@ Defining Symbols
@example
AC_CHECK_FUNC([vprintf], [AC_DEFINE([HAVE_VPRINTF], [1],
[Define if vprintf exists.])])
-if test "$ac_cv_func_vprintf" != yes; then
+if test "x$ac_cv_func_vprintf" != xyes; then
AC_CHECK_FUNC([_doprnt], [AC_DEFINE([HAVE_DOPRNT], [1],
[Define if _doprnt exists.])])
fi
@@ -9016,7 +9018,7 @@ Caching Results
[AC_CACHE_CHECK([whether true(1) works], [my_cv_shell_true_works],
[my_cv_shell_true_works=no
(true) 2>/dev/null && my_cv_shell_true_works=yes
- if test "$my_cv_shell_true_works" = yes; then
+ if test "x$my_cv_shell_true_works" = xyes; then
AC_DEFINE([TRUE_WORKS], [1],
[Define if `true(1)' works properly.])
fi])
@@ -9035,7 +9037,7 @@ Caching Results
[AC_CACHE_CHECK([whether true(1) works], [my_cv_shell_true_works],
[my_cv_shell_true_works=no
(true) 2>/dev/null && my_cv_shell_true_works=yes])
- if test "$my_cv_shell_true_works" = yes; then
+ if test "x$my_cv_shell_true_works" = xyes; then
AC_DEFINE([TRUE_WORKS], [1],
[Define if `true(1)' works properly.])
fi
@@ -12408,8 +12410,8 @@ Common Shell Constructs
is empty. For example,
@example
-AS_IF([test "$foo" = yes], [HANDLE_FOO([yes])],
- [test "$foo" != no], [HANDLE_FOO([maybe])],
+AS_IF([test "x$foo" = xyes], [HANDLE_FOO([yes])],
+ [test "x$foo" != xno], [HANDLE_FOO([maybe])],
[echo foo not specified])
@end example
@@ -12462,7 +12464,7 @@ Common Shell Constructs
# This outputs "Have it!".
header="sys/some file.h"
AS_TR_SH([HAVE_$header])=yes
-if test "$HAVE_sys_some_file_h" = yes; then echo "Have it!"; fi
+if test "x$HAVE_sys_some_file_h" = xyes; then echo "Have it!"; fi
@end example
@end defmac
@@ -13142,7 +13144,7 @@ Prerequisite Macros
[test "$body_temperature_in_celsius" -gt "38" &&
dance_floor=occupied])
AC_DEFUN([NEWTON_JOHN],
-[test "$hair_style" = "curly" &&
+[test "x$hair_style" = xcurly &&
dance_floor=occupied])
@end group
@@ -13161,7 +13163,7 @@ Prerequisite Macros
@example
AC_INIT([Dance Manager], [1.0], [bug-dance@@example.org])
RESERVE_DANCE_FLOOR
-if test "$dance_floor" = occupied; then
+if test "x$dance_floor" = xoccupied; then
AC_MSG_ERROR([cannot pick up here, let's move])
fi
@end example
@@ -13174,7 +13176,7 @@ Prerequisite Macros
@group
test "$body_temperature_in_Celsius" -gt "38" &&
dance_floor=occupied
-test "$hair_style" = "curly" &&
+test "x$hair_style" = xcurly &&
dance_floor=occupied
fi
if date | grep '^Sat.*pm' >/dev/null 2>&1; then
@@ -13606,7 +13608,7 @@ Coding Style
[AC_CACHE_CHECK(for EMX OS/2 environment, ac_cv_emxos2,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(, return __EMX__;)],
ac_cv_emxos2=yes, ac_cv_emxos2=no)])
-test "$ac_cv_emxos2" = yes && EMXOS2=yes])
+test "x$ac_cv_emxos2" = xyes && EMXOS2=yes])
@end example
@noindent
@@ -13621,7 +13623,7 @@ Coding Style
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [return __EMX__;])],
[ac_cv_emxos2=yes],
[ac_cv_emxos2=no])])
-test "$ac_cv_emxos2" = yes && EMXOS2=yes[]dnl
+test "x$ac_cv_emxos2" = xyes && EMXOS2=yes[]dnl
])# _AC_EMXOS2
@end example
@@ -21447,7 +21449,7 @@ Changed Results
@example
AC_CHECK_FUNCS([syslog])
-if test $ac_cv_func_syslog = no; then
+if test "x$ac_cv_func_syslog" = xno; then
# syslog is not in the default libraries. See if it's in some other.
for lib in bsd socket inet; do
AC_CHECK_LIB([$lib], [syslog], [AC_DEFINE([HAVE_SYSLOG])
--
1.6.1.2
