2 files changed, 12 insertions, 1 deletions

diff --git a/src/Makefile.in b/src/Makefile.in
index 0326b4a8f22..6d75e3537a6 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -803,6 +803,15 @@ elnlisp := $(addprefix ${lispsource}/,${elnlisp}) $(lisp:.elc=.eln)
         @$(MAKE) $(AM_V_NO_PD) -C ../lisp EMACS="../src/emacs$(EXEEXT)"\
                 THEFILE=$< $<n
 
+## FIXME: this is fragile!  We lie to Make about the files produced by
+## this rule, and we rely on the absence of the native-lisp directory
+## to trigger it.  This means that if anything goes wrong during
+## native compilation, the only way to trigger it again is to remove
+## the directory and re-native-compile everything.  The main
+## underlying problem is that the name of the subdirectory of
+## native-lisp where the *.eln files will be produced, and the exact
+## names of those *.eln files, cannot be known in advance; we must ask
+## Emacs to produce them.
 ../native-lisp: | $(pdmp)
         @if test ! -d $@; then \
           mkdir $@ && $(MAKE) $(AM_V_NO_PD) $(elnlisp); \
diff --git a/src/dispextern.h b/src/dispextern.h
index 6aefe43e195..08dac5d4557 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1326,7 +1326,9 @@ struct glyph_string
   /* The area within row.  */
   enum glyph_row_area area;
 
-  /* Characters to be drawn, and number of characters.  */
+  /* Characters to be drawn, and number of characters.  Note that
+     NCHARS can be zero if this is a composition glyph string, as
+     evidenced by FIRST_GLYPH->type.  */
   unsigned *char2b;
   int nchars;