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String-like settings (var_string, var_filename, var_optional_filename, var_string_noescape) currently take a pointer to a `char *` storage variable (typically global) that holds the setting's value. I'd like to "mordernize" this by changing them to use an std::string for storage. An obvious reason is that string operations on std::string are often easier to write than with C strings. And they avoid having to do any manual memory management. Another interesting reason is that, with `char *`, nullptr and an empty string often both have the same meaning of "no value". String settings are initially nullptr (unless initialized otherwise). But when doing "set foo" (where `foo` is a string setting), the setting now points to an empty string. For example, solib_search_path is nullptr at startup, but points to an empty string after doing "set solib-search-path". This leads to some code that needs to check for both to check for "no value". Or some code that converts back and forth between NULL and "" when getting or setting the value. I find this very error-prone, because it is very easy to forget one or the other. With std::string, we at least know that the variable is not "NULL". There is only one way of representing an empty string setting, that is with an empty string. I was wondering whether the distinction between NULL and "" would be important for some setting, but it doesn't seem so. If that ever happens, it would be more C++-y and self-descriptive to use optional<string> anyway. Actually, there's one spot where this distinction mattered, it's in init_history, for the test gdb.base/gdbinit-history.exp. init_history sets the history filename to the default ".gdb_history" if it sees that the setting was never set - if history_filename is nullptr. If history_filename is an empty string, it means the setting was explicitly cleared, so it leaves it as-is. With the change to std::string, this distinction doesn't exist anymore. This can be fixed by moving the code that chooses a good default value for history_filename to _initialize_top. This is ran before -ex commands are processed, so an -ex command can then clear that value if needed (what gdb.base/gdbinit-history.exp tests). Another small improvement, in my opinion is that we can now easily give string parameters initial values, by simply initializing the global variables, instead of xstrdup-ing it in the _initialize function. In Python and Guile, when registering a string-like parameter, we allocate (with new) an std::string that is owned by the param_smob (in Guile) and the parmpy_object (in Python) objects. This patch started by changing all relevant add_setshow_* commands to take an `std::string *` instead of a `char **` and fixing everything that failed to build. That includes of course all string setting variable and their uses. string_option_def now uses an std::string also, because there's a connection between options and settings (see add_setshow_cmds_for_options). The add_path function in source.c is really complex and twisted, I'd rather not try to change it to work on an std::string right now. Instead, I added an overload that copies the std:string to a `char *` and back. This means more copying, but this is not used in a hot path at all, so I think it is acceptable. Change-Id: I92c50a1bdd8307141cdbacb388248e4e4fc08c93 Co-authored-by: Lancelot SIX <lsix@lancelotsix.com> |
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| binutils | ||
| config | ||
| contrib | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gdbserver | ||
| gdbsupport | ||
| gnulib | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
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| libctf | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| zlib | ||
| .cvsignore | ||
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| ar-lib | ||
| ChangeLog | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
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| configure | ||
| configure.ac | ||
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| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
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| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| multilib.am | ||
| README | ||
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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.