Document the many uses of SVf_FAKE.

p4raw-id: //depot/perl@27258

diff --git a/sv.h b/sv.h
index 09a27d5..515645b 100644 (file)
--- a/sv.h
+++ b/sv.h
@@ -220,7 +220,18 @@ perform the upgrade if necessary.  See C<svtype>.
 #define SVf_POK                0x00040000      /* has valid public pointer value */
 #define SVf_ROK                0x00080000      /* has a valid reference pointer */
 
-#define SVf_FAKE       0x00100000      /* glob or lexical is just a copy */
+#define SVf_FAKE       0x00100000      /* 0: glob or lexical is just a copy
+                                          1: SV head arena wasn't malloc()ed
+                                          2: in conjunction with SVf_READONLY
+                                             marks a shared hash key scalar
+                                             (SvLEN == 0) or a copy on write
+                                             string (SvLEN != 0) [SvIsCOW(sv)]
+                                          3: For PVCV, whether CvUNIQUE(cv)
+                                             refers to an eval or once only
+                                             [CvEVAL(cv), CvSPECIAL(cv)]
+                                          4: Whether the regexp pointer is in
+                                             fact an offset [SvREPADTMP(sv)]
+                                       */
 #define SVf_OOK                0x00200000      /* has valid offset value
                                           For a PVHV this means that a
                                           hv_aux struct is present after the