75312ae3ab
This is the portion of gdb_test which performs the match against
the RE (regular expression) passed to it:
return [gdb_test_multiple $command $message {
-re "\[\r\n\]*($pattern)\[\r\n\]+$gdb_prompt $" {
if ![string match "" $message] then {
pass "$message"
}
}
In a test that I've been working on recently, I wanted to use
a backreference - that's the \1 in the the RE below:
gdb_test "info threads" \
{.*[\r\n]+\* +([0-9]+) +Thread[^\r\n]* do_something \(n=\1\) at.*}
Put into English, I wanted to make sure that the value of n passed to
do_something() is the same as the thread number shown in the "info
threads" Id column. (I've structured the test case so that this
*should* be the case.)
It didn't work though. It turned out that ($pattern) in the RE
noted above is capturing the attempted backreference. So, in this
case, the backreference does not refer to ([0-9]+) as intended, but
instead refers to ($pattern). This is wrong because it's not what I
intended, but is also wrong because, if allowed, it could only match a
string of infinite length.
This problem can be fixed by using parens for a "noncapturing
subpattern". The way that this is done, syntactically, is to use
(?:$pattern) instead of ($pattern).
My research shows that this feature has been present since tcl8.1 which
was released in 1999.
The current tcl version is 8.6 - at least that's what I have on my
machine. It appears to me that mingw uses some subversion of tcl8.4
which will also have this feature (since 8.4 > 8.1).
So it seems to me that any platform upon which we might wish to test
GDB will have a version of tcl which has this feature. That being the
case, my hope is that there won't be any objections to its use.
When I looked at the implementation of gdb_test, I wondered whether
the parens were needed at all. I've concluded that they are. In the
event that $pattern is an RE which uses alternation at the top level,
e.g. a|b, we need to make $pattern a subpattern (via parens) to limit
the extend of the alternation. I.e, we don't want the alternation to
extend to the other portions of the RE which gdb_test uses to match
potential blank lines at the beginning of the pattern or the gdb
prompt at the end.
gdb/testsuite/ChangeLog:
* gdb.exp (gdb_test): Using noncapturing parens for the $pattern
subpattern.
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| binutils | ||
| config | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| zlib | ||
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| .gitattributes | ||
| .gitignore | ||
| ChangeLog | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| COPYING.LIB | ||
| COPYING.LIBGLOSS | ||
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| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
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| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| README | ||
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| setup.com | ||
| src-release.sh | ||
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| ylwrap | ||
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.