add notes in INSTALL about Configure -Accflags=-DFOO

p4raw-id: //depot/perl@4239

1 files changed, 50 insertions, 27 deletions

diff --git a/INSTALL b/INSTALL
index c90f6b34e8..8014a41ac6 100644
--- a/INSTALL
+++ b/INSTALL
@@ -41,11 +41,18 @@ pod/perldelta.pod file.  For more detailed information about specific
 changes, see the Changes file.
 
 IMPORTANT NOTE:  5.005_53 and later releases do not export unadorned
-global symbols anymore.  This means most CPAN modules probably won't
-build under this release without adding '-DPERL_POLLUTE' to ccflags
-in config.sh.  This is not the default because we want the modules
-to get fixed *before* the 5.6 release.  pod/perldelta.pod contains
-additional notes about this.
+global symbols anymore.  This means you may need to build older
+extensions that have not been updated for the new naming convention
+with:
+
+	perl Makefile.PL POLLUTE=1
+	
+Alternatively, you can enable CPP symbol pollution wholesale by
+building perl itself with:
+
+	sh Configure -Accflags=-DPERL_POLLUTE
+
+pod/perldelta.pod contains more details about this.
 
 =head1 DESCRIPTION
 
@@ -71,18 +78,26 @@ system.  (Unixware users should use the svr4.sh hint file.)  If
 there is a README file for your platform, then you should read
 that too.  Additional information is in the Porting/ directory.
 
-=head1 WARNING:  This version is not binary compatible with Perl 5.005.
+=head1 WARNING:  This version may not be binary compatible with Perl 5.005.
+
+Using the default Configure options for building perl should get you
+a perl that will be binary compatible with the 5.005 release.
 
-If you have dynamically loaded extensions that you built under perl
-5.005, you will need to rebuild and reinstall those extensions to use
-them with 5.6.  Pure perl modules should continue to work just fine
-without reinstallation.  See the discussions below on L<"Coexistence
-with earlier versions of perl5"> and L<"Upgrading from 5.005 to
-5.6"> for more details.
+However, if you run Configure with any custom options, such as
+-Dusethreads, -Dusemultiplicity, -Dusemymalloc, -Ubincompat5005 etc.,
+the resulting perl will not be binary compatible.  Under these
+circumstances, if you have dynamically loaded extensions that were
+built under perl 5.005, you will need to rebuild and reinstall all
+those extensions to use them with 5.6.
+
+Pure perl modules without XS or C code should continue to work fine
+without reinstallation.  See the discussions below on
+L<"Coexistence with earlier versions of perl5"> and
+L<"Upgrading from 5.005 to 5.6"> for more details.
 
 The standard extensions supplied with Perl will be handled automatically.
 
-In a related issue, old modules may possibly be affected by the
+On a related issue, old modules may possibly be affected by the
 changes in the Perl language in the current release.  Please see
 pod/perldelta.pod (and pod/perl500Xdelta.pod) for a description of
 what's changed.  See also your installed copy of the perllocal.pod
@@ -180,6 +195,21 @@ defaults from then on.
 After it runs, Configure will perform variable substitution on all the
 *.SH files and offer to run make depend.
 
+=head2 Altering config.sh variables for C compiler switches etc.
+
+For most users, all of the Configure defaults are fine.  Configure
+also has several convenient options which are all described below.
+However, if Configure doesn't have an option to do what you want,
+you can change Configure variables after the platform hints have been
+run, by using Configure's -A switch.  For example, here's how to add
+a couple of extra flags to C compiler invocations:
+
+	sh Configure -Accflags="-DPERL_Y2KWARN -DPERL_POLLUTE_MALLOC"
+
+For more help on Configure switches, run:
+
+	sh Configure -h
+
 =head2 Common Configure options
 
 Configure supports a number of useful options.  Run B<Configure -h> to
@@ -819,16 +849,6 @@ it's convenient to have both.
 If you are using a shared libperl, see the warnings about multiple
 versions of perl under L<Building a shared libperl.so Perl library>.
 
-=head2 Other Compiler Flags
-
-For most users, all of the Configure defaults are fine.  However, you
-can change a number of factors in the way perl is built by adding
-appropriate -D directives to your ccflags variable in config.sh.
-
-You should also run Configure interactively to verify that a hint file
-doesn't inadvertently override your ccflags setting.  (Hints files
-shouldn't do that, but some might.)
-
 =head2 Extensions
 
 By default, Configure will offer to build every extension which appears
@@ -1359,10 +1379,13 @@ with B<make depend; make>.
 
 =item CRIPPLED_CC
 
-If you still can't compile successfully, try adding a -DCRIPPLED_CC
-flag.  (Just because you get no errors doesn't mean it compiled right!)
-This simplifies some complicated expressions for compilers that get
-indigestion easily.
+If you still can't compile successfully, try:
+
+	sh Configure -Accflags=-DCRIPPLED_CC
+
+This flag simplifies some complicated expressions for compilers that get
+indigestion easily.  (Just because you get no errors doesn't mean it
+compiled right!)
 
 =item Missing functions