Documentation and commentary improvements

* src/lisp.h:
* src/regex.c:
* src/xgselect.c (xg_select): Improve commentary and formatting.

* doc/lispref/objects.texi (Thread Type, Mutex Type)
(Condition Variable Type): New subsections.
(Type Predicates): Add thread-related predicates.
* doc/lispref/objects.texi (Editing Types):
* doc/lispref/elisp.texi (Top): Update higher-level menus.

3 files changed, 6 insertions, 0 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 72ea50d5f27..3c7c3dde904 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -845,6 +845,7 @@ enum pvec_type
   PVEC_THREAD,
   PVEC_MUTEX,
   PVEC_CONDVAR,
+
   /* These should be last, check internal_equal to see why.  */
   PVEC_COMPILED,
   PVEC_CHAR_TABLE,
@@ -3229,6 +3230,7 @@ union specbinding
     } bt;
   };
 
+/* These 3 are defined as macros in thread.h.  */
 /* extern union specbinding *specpdl; */
 /* extern union specbinding *specpdl_ptr; */
 /* extern ptrdiff_t specpdl_size; */
diff --git a/src/regex.c b/src/regex.c
index e7231d3882b..f1686cf700c 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -1140,6 +1140,7 @@ print_double_string (re_char *where, re_char *string1, ssize_t size1,
 #endif /* not DEBUG */
 
 #ifndef emacs
+
 /* Set by `re_set_syntax' to the current regexp syntax to recognize.  Can
    also be assigned to arbitrarily: each pattern buffer stores its own
    syntax, so it can be changed between regex compilations.  */
diff --git a/src/xgselect.c b/src/xgselect.c
index e418e1a3c4e..2f23764ae41 100644
--- a/src/xgselect.c
+++ b/src/xgselect.c
@@ -76,6 +76,9 @@ xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds,
 
   if (gfds_size < n_gfds)
     {
+      /* Avoid using SAFE_NALLOCA, as that implicitly refers to the
+         current thread.  Using xnmalloc avoids thread-switching
+         problems here.  */
       gfds = xnmalloc (n_gfds, sizeof *gfds);
       must_free = 1;
       gfds_size = n_gfds;