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diff --git a/contrib/perl5/hints/README.hints b/contrib/perl5/hints/README.hints new file mode 100644 index 0000000..e36bd6d --- /dev/null +++ b/contrib/perl5/hints/README.hints @@ -0,0 +1,213 @@ +=head1 NAME + +README.hints + +=head1 DESCRIPTION + +These files are used by Configure to set things which Configure either +can't or doesn't guess properly. Most of these hint files have been +tested with at least some version of perl5, but some are still left +over from perl4. + +Please send any problems or suggested changes to perlbug@perl.com. + +Hint file naming convention: Each hint file name should have only +one '.'. (This is for portability to non-unix file systems.) Names +should also fit in <= 14 characters, for portability to older SVR3 +systems. File names are of the form $osname_$osvers.sh, with all '.' +changed to '_', and all characters (such as '/') that don't belong in +Unix filenames omitted. + +For example, consider Sun OS 4.1.3. Configure determines $osname=sunos +(all names are converted to lower case) and $osvers=4.1.3. Configure +will search for an appropriate hint file in the following order: + + sunos_4_1_3.sh + sunos_4_1.sh + sunos_4.sh + sunos.sh + +If you need to create a hint file, please try to use as general a name +as possible and include minor version differences inside case or test +statements. For example, for IRIX 6.X, we have the following hints +files: + + irix_6_0.sh + irix_6_1.sh + irix_6.sh + +That is, 6.0 and 6.1 have their own special hints, but 6.2, 6.3, and +up are all handled by the same irix_6.sh. That way, we don't have to +make a new hint file every time the IRIX O/S is upgraded. + +If you need to test for specific minor version differences in your +hints file, be sure to include a default choice. (See aix.sh for one +example.) That way, if you write a hint file for foonix 3.2, it might +still work without any changes when foonix 3.3 is released. + +Please also comment carefully on why the different hints are needed. +That way, a future version of Configure may be able to automatically +detect what is needed. + +A glossary of config.sh variables is in the file Porting/Glossary. + +=head1 Hint file tricks + +=head2 Printing critical messages + +[This is still experimental] + +If you have a *REALLY* important message that the user ought to see at +the end of the Configure run, you can store it in the file +'config.msg'. At the end of the Configure run, Configure will display +the contents of this file. Currently, the only place this is used is +in Configure itself to warn about the need to set LD_LIBRARY_PATH if +you are building a shared libperl.so. + +To use this feature, just do something like the following + + $cat <<EOM | $tee -a ../config.msg >&4 + + This is a really important message. Be sure to read it + before you type 'make'. + EOM + +This message will appear on the screen as the hint file is being +processed and again at the end of Configure. + +Please use this sparingly. + +=head2 Propagating variables to config.sh + +Sometimes, you want an extra variable to appear in config.sh. For +example, if your system can't compile toke.c with the optimizer on, +you can put + + toke_cflags='optimize=""' + +at the beginning of a line in your hints file. Configure will then +extract that variable and place it in your config.sh file. Later, +while compiling toke.c, the cflags shell script will eval $toke_cflags +and hence compile toke.c without optimization. + +Note that for this to work, the variable you want to propagate must +appear in the first column of the hint file. It is extracted by +Configure with a simple sed script, so beware that surrounding case +statements aren't any help. + +By contrast, if you don't want Configure to propagate your temporary +variable, simply indent it by a leading tab in your hint file. + +For example, prior to 5.002, a bug in scope.c led to perl crashing +when compiled with -O in AIX 4.1.1. The following "obvious" +workaround in hints/aix.sh wouldn't work as expected: + + case "$osvers" in + 4.1.1) + scope_cflags='optimize=""' + ;; + esac + +because Configure doesn't parse the surrounding 'case' statement, it +just blindly propagates any variable that starts in the first column. +For this particular case, that's probably harmless anyway. + +Three possible fixes are: + +=over + +=item 1 + +Create an aix_4_1_1.sh hint file that contains the scope_cflags +line and then sources the regular aix hints file for the rest of +the information. + +=item 2 + +Do the following trick: + + scope_cflags='case "$osvers" in 4.1*) optimize=" ";; esac' + +Now when $scope_cflags is eval'd by the cflags shell script, the +case statement is executed. Of course writing scripts to be eval'd is +tricky, especially if there is complex quoting. Or, + +=item 3 + +Write directly to Configure's temporary file UU/config.sh. +You can do this with + + case "$osvers" in + 4.1.1) + echo "scope_cflags='optimize=\"\"'" >> UU/config.sh + scope_cflags='optimize=""' + ;; + esac + +Note you have to both write the definition to the temporary +UU/config.sh file and set the variable to the appropriate value. + +This is sneaky, but it works. Still, if you need anything this +complex, perhaps you should create the separate hint file for +aix 4.1.1. + +=back + +=head2 Call-backs + +=over 4 + +=item Warning + +All of the following is experimental and subject to change. But it +probably won't change much. :-) + +=item Compiler-related flags + +The settings of some things, such as optimization flags, may depend on +the particular compiler used. For example, for ISC we have the +following: + + case "$cc" in + *gcc*) ccflags="$ccflags -posix" + ldflags="$ldflags -posix" + ;; + *) ccflags="$ccflags -Xp -D_POSIX_SOURCE" + ldflags="$ldflags -Xp" + ;; + esac + +However, the hints file is processed before the user is asked which +compiler should be used. Thus in order for these hints to be useful, +the user must specify sh Configure -Dcc=gcc on the command line, as +advised by the INSTALL file. + +For versions of perl later than 5.004_61, this problem can +be circumvented by the use of "call-back units". That is, the hints +file can tuck this information away into a file UU/cc.cbu. Then, +after Configure prompts the user for the C compiler, it will load in +and run the UU/cc.cbu "call-back" unit. See hints/solaris_2.sh for an +example. + +=item Threading-related flags + +Similarly, after Configure prompts the user about whether or not to +compile Perl with threads, it will look for a "call-back" unit +usethreads.cbu. See hints/linux.sh for an example. + +=item Future status + +I hope this "call-back" scheme is simple enough to use but powerful +enough to deal with most situations. Still, there are certainly cases +where it's not enough. For example, for aix we actually change +compilers if we are using threads. + +I'd appreciate feedback on whether this is sufficiently general to be +helpful, or whether we ought to simply continue to require folks to +say things like "sh Configure -Dcc=gcc -Dusethreads" on the command line. + +=back + +Have the appropriate amount of fun :-) + + Andy Dougherty doughera@lafcol.lafayette.edu |
