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1 724 jeremybenn
 
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FIXINCLUDES OPERATION
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=====================
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See also:  http://autogen.SourceForge.net/fixinc.html
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The set of fixes required was distilled down to just the data required
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to specify what needed to happen for each fix.  Those data were edited
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into a file named fixincludes/inclhack.def.  A program called AutoGen
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(http://autogen.SourceForge.net) uses these definitions to instantiate
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several different templates that then produces code for a fixinclude
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program (fixincl.x) and a shell script to test its functioning.  On
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certain platforms (viz. those that do not have functional bidirectional
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pipes), the fixincl program is split into two.  This should only concern
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you on DOS and BeOS.
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Regards,
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        Bruce 
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GCC MAINTAINER INFORMATION
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==========================
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If you are having some problem with a system header that is either
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broken by the manufacturer, or is broken by the fixinclude process,
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then you will need to alter or add information to the include fix
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definitions file, ``inclhack.def''.  Please also send relevant
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information to gcc-bugs@gcc.gnu.org, gcc-patches@gcc.gnu.org and,
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please, to me:  bkorb@gnu.org.
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To make your fix, you will need to do several things:
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1.  Obtain access to the AutoGen program on some platform.  It does
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    not have to be your build platform, but it is more convenient.
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2.  Edit "inclhack.def" to reflect the changes you need to make.
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    See below for information on how to make those changes.
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3.  Run the "genfixes" shell script to produce a new copy of
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    the "fixincl.x" file.
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4.  Rebuild the compiler and check the header causing the issue.
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    Make sure it is now properly handled.  Add tests to the
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    "test_text" entry(ies) that validate your fix.  This will
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    help ensure that future fixes won't negate your work.
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5.  Go into the fixincludes build directory and type, "make check".
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    You are guaranteed to have issues printed out as a result.
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    Look at the diffs produced.  Make sure you have not clobbered
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    the proper functioning of a different fix.  Make sure your
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    fix is properly tested and it does what it is supposed to do.
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6.  Now that you have the right things happening, synchronize the
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    $(srcdir)/tests/base directory with the $(builddir)/tests/res
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    directory.  The output of "make check" will be some diffs that
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    should give you some hints about what to do.
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7.  Rerun "make check" and verify that there are no issues left.
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MAKING CHANGES TO INCLHACK.DEF
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==============================
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0.  If you are not the fixincludes maintainer, please send that
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    person email about any changes you may want to make.  Thanks!
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1.  Every fix must have a "hackname" that is compatible with C syntax
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    for variable names and is unique without regard to alphabetic case.
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    Please keep them alphabetical by this name.  :-)
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2.  If the problem is known to exist only in certain files, then
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    identify the files with "files = " entries.  If you use fnmatch(3C)
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    wild card characters in a "files" entry, be certain that the first
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    "files" entry has no such character.  Otherwise, the "make check"
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    machinery will attempt to create files with those characters in the
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    name.  That is inconvenient.
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3.  It is relatively expensive to fire off a process to fix a source
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    file, therefore write apply tests to avoid unnecessary fix
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    processes.  The preferred apply tests are "select", "bypass", "mach"
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    and "c-test" because they are performed internally:
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    * select - Run a regex on the contents of the file being considered.
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               All such regex-es must match.  Matching is done with
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               extended regular expressions.
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    * bypass - Run a regex on the contents of the file being considered.
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               No such regex may match.
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    * c_test - call a function in fixtests.c.  See that file.
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    * files  - the "fnmatch" pattern of the file(s) to examine for
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               the issue.  There may be several copies of this attribute.
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               If the header lives in a /usr/include subdirectory, be
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               sure to include that subdirectory in the name. e.g. net/if.h
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    * mach   - Match the output of config.guess against a series of fnmatch
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               patterns.  It must match at least one of the patterns, unless
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               "not-machine" has also been specified.  In that case, the
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               config.guess output must not match any of the patterns.
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    The next test is relatively slow because it must be handled in a
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    separate shell process.  Some platforms do not support server shells,
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    so the whole process is even slower and more cumbersome there.
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    * test   - These should be arguments to the program, "/bin/test".
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               You may perform multiple commands, if you enclose them
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               in backquotes and echo out valid test arguments.  For
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               example, you might echo out '0 -eq 1' if you want a false
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               result, or '0 -eq 0' for a true result.
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    These tests are required to:
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    1.  Be positive for all header files that require the fix.
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    It is desirable to:
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    2.  Be negative as often as possible whenever the fix is not
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        required, avoiding the process overhead.
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    It is nice if:
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    3.  The expression is as simple as possible to both
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        process and understand by people.  :-)
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        Please take advantage of the fact AutoGen will glue
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        together string fragments.  It helps.  Also take note
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        that double quote strings and single quote strings have
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        different formation rules.  Double quote strings are a
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        tiny superset of ANSI-C string syntax.  Single quote
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        strings follow shell single quote string formation
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        rules, except that the backslash is processed before
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        '\\', '\'' and '#' characters (using C character syntax).
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    Each test must pass or the fix is not applied.  For example,
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    all "select" expressions must be found and not one "bypass"
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    selection may be found.
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    Examples of test specifications:
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      hackname = broken_assert_stdio;
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      files    = assert.h;
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      select   = stderr;
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      bypass   = "include.*stdio.h";
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    The ``broken_assert_stdio'' fix will be applied only to a file
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    named "assert.h" if it contains the string "stderr" _and_ it
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    does _not_ contain the expression "include.*stdio.h".
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      hackname = no_double_slash;
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      c_test   = "double_slash";
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    The ``no_double_slash'' fix will be applied if the
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    ``double_slash_test()'' function says to.  See ``fixtests.c''
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    for documentation on how to include new functions into that
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    module.
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4.  There are currently four methods of fixing a file:
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    1.  a series of sed expressions.  Each will be an individual
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        "-e" argument to a single invocation of sed.
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    2.  a shell script.  These scripts are _required_ to read all
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        of stdin in order to avoid pipe stalls.  They may choose to
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        discard the input.
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    3.  Replacement text.  If the replacement is empty, then no
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        fix is applied.  Otherwise, the replacement text is
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        written to the output file and no further fixes are
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        applied.  If you really want a no-op file, replace the
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        file with a comment.
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        Replacement text "fixes" must be first in this file!!
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    4.  A C language subroutine method for both tests and fixes.
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        See ``fixtests.c'' for instructions on writing C-language
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        applicability tests and ``fixfixes.c'' for C-language fixing.
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        These files also contain tables that describe the currently
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        implemented fixes and tests.
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    If at all possible, you should try to use one of the C language
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    fixes as it is far more efficient.  There are currently five
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    such fixes, three of which are very special purpose:
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    i) char_macro_def - This function repairs the definition of an
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        ioctl macro that presumes CPP macro substitution within
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        pairs of single quote characters.
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    ii) char_macro_use - This function repairs the usage of ioctl
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        macros that no longer can wrap an argument with single quotes.
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    iii) machine_name - This function will look at "#if", "#ifdef",
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        "#ifndef" and "#elif" directive lines and replace the first
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        occurrence of a non-reserved name that is traditionally
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        pre-defined by the native compiler.
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    The next two are for general use:
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    iv) wrap - wraps the entire file with "#ifndef", "#define" and
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        "#endif" self-exclusionary text.  It also, optionally, inserts
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        a prolog after the "#define" and an epilog just before the
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        "#endif".  You can use this for a fix as follows:
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            c_fix     = wrap;
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            c_fix_arg = "/* prolog text */";
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            c_fix_arg = "/* epilog text */";
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        If you want an epilog without a prolog, set the first "c_fix_arg"
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        to the empty string.  Both or the second "c_fix_arg"s may be
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        omitted and the file will still be wrapped.
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        THERE IS A SPECIAL EXCEPTION TO THIS, HOWEVER:
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        If the regular expression '#if.*__need' is found, then it is
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        assumed that the file needs to be read and interpreted more
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        than once.  However, the prolog and epilog text (if any) will
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        be inserted.
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    v) format - Replaces text selected with a regular expression with
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        a specialized formating string.  The formatting works as follows:
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        The format text is copied to the output until a '%' character
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        is found.  If the character after the '%' is another '%', then
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        one '%' is output and processing continues.  If the following
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        character is not a digit, then the '%' and that character are
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        copied and processing continues.  Finally, if the '%' *is*
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        followed by a digit, that digit is used as an index into the
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        regmatch_t array to replace the two characters with the matched
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        text.  i.e.: "%0" is replaced by the full matching text, "%1"
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        is the first matching sub-expression, etc.
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        This is used as follows:
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            c_fix     = format;
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            c_fix_arg = "#ifndef %1\n%0\n#endif";
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            c_fix_arg = "#define[ \t]+([A-Z][A-Z0-9a-z_]*).*";
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        This would wrap a one line #define inside of a "#ifndef"/"#endif"
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        pair.  The second "c_fix_arg" may be omitted *IF* there is at least
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        one select clause and the first one identifies the text you wish to
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        reformat.  It will then be used as the second "c_fix_arg".  You may
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        delete the selected text by supplying an empty string for the
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        replacement format (the first "c_fix_arg").
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        Note: In general, a format c_fix may be used in place of one
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        sed expression.  However, it will need to be rewritten by
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        hand.  For example:
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        sed = 's@^#if __GNUC__ == 2 && __GNUC_MINOR__ >= 7$'
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               '@& || __GNUC__ >= 3@';
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        may be rewritten using a format c_fix as:
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        c_fix     = format;
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        c_fix_arg = '%0 || __GNUC__ >= 3';
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        c_fix_arg = '^#if __GNUC__ == 2 && __GNUC_MINOR__ >= 7$';
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        Multiple sed substitution expressions probably ought to remain sed
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        expressions in order to maintain clarity.  Also note that if the
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        second sed expression is the same as the first select expression,
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        then you may omit the second c_fix_arg.  The select expression will
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        be picked up and used in its absence.
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EXAMPLES OF FIXES:
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==================
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      hackname = AAA_ki_iface;
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      replace; /* empty replacement -> no fixing the file */
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    When this ``fix'' is invoked, it will prevent any fixes
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    from being applied.
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    ------------------
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      hackname = AAB_svr4_no_varargs;
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      replace  = "/* This file was generated by fixincludes.  */\n"
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                 "#ifndef _SYS_VARARGS_H\n"
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                 "#define _SYS_VARARGS_H\n\n"
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                 "#ifdef __STDC__\n"
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                 "#include \n"
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                 "#else\n"
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                 "#include \n"
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                 "#endif\n\n"
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                 "#endif  /* _SYS_VARARGS_H */\n";
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    When this ``fix'' is invoked, the replacement text will be
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    emitted into the replacement include file.  No further fixes
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    will be applied.
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    ------------------
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        hackname  = hpux11_fabsf;
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        files     = math.h;
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        select    = "^[ \t]*#[ \t]*define[ \t]+fabsf\\(.*";
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        bypass    = "__cplusplus";
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        c_fix     = format;
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        c_fix_arg = "#ifndef __cplusplus\n%0\n#endif";
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        test_text =
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        "#  define fabsf(x) ((float)fabs((double)(float)(x)))\n";
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    This fix will ensure that the #define for fabs is wrapped
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    with C++ protection, providing the header is not already
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    C++ aware.
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    ------------------
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5.  Testing fixes.
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    The brute force method is, of course, to configure and build
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    GCC.  But you can also:
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        cd ${top_builddir}/gcc
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        rm -rf fixinc.sh include/ stmp-fixinc
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        make stmp-fixinc
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    I would really recommend, however:
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        cd ${top_builddir}/fixincludes
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        make check
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    To do this, you *must* have autogen installed on your system.
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    The "check" step will proceed to construct a shell script that
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    will exercise all the fixes, using the sample test_text
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    provided with each fix.  Once done, the changes made will
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    be compared against the changes saved in the source directory.
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    If you are changing the tests or fixes, the change will likely
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    be highlighted.

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