add note about ithreads and Thread.pm (too many people are

confused by the fact that Thread.pm is built and installed
under non-5005threads but doesn't work)

p4raw-id: //depot/maint-5.6/perl@9646

2 files changed, 16 insertions, 1 deletions

diff --git a/ext/Thread/Thread.pm b/ext/Thread/Thread.pm
index c752e3d6dd..23f9fe5138 100644
--- a/ext/Thread/Thread.pm
+++ b/ext/Thread/Thread.pm
@@ -12,6 +12,15 @@ $VERSION = "1.0";
 
 Thread - manipulate threads in Perl (EXPERIMENTAL, subject to change)
 
+=head1 CAVEAT
+
+The Thread extension requires Perl to be built in a particular way to
+enable the older 5.005 threading model.  Just to confuse matters, there
+is an alternate threading model known as "ithreads" that does NOT
+support this extension.  If you are using a binary distribution such
+as ActivePerl that is built with ithreads support, this extension CANNOT
+be used.
+
 =head1 SYNOPSIS
 
     use Thread;
diff --git a/ext/Thread/Thread.xs b/ext/Thread/Thread.xs
index a113eb74e1..15e2aa27c3 100644
--- a/ext/Thread/Thread.xs
+++ b/ext/Thread/Thread.xs
@@ -321,7 +321,13 @@ newthread (pTHX_ SV *startsv, AV *initargs, char *classname)
 
     return sv;
 #else
-    croak("No threads in this perl");
+#  ifdef USE_ITHREADS
+    croak("This perl was built for \"ithreads\", which currently does not support Thread.pm.\n"
+	  "Run \"perldoc Thread\" for more information");
+#  else
+    croak("This perl was not built with support for 5.005-style threads.\n"
+	  "Run \"perldoc Thread\" for more information");
+#  endif
     return &PL_sv_undef;
 #endif
 }