Use "do...while (0)", not "if (1)..else" in macro definitions.

3 files changed, 16 insertions, 6 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 9fcc90c2391..396ce321f72 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,15 @@
 2008-02-07  Jim Meyering  <meyering@redhat.com>
 
+        Use "do...while (0)", not "if (1)..else" in macro definitions.
+        The latter provokes a warning from gcc about the empty else, when
+        followed by ";".  Also, without that trailing semicolon, it would
+        silently swallow up any following statement.
+        * syntax.h (SETUP_SYNTAX_TABLE):
+        (SETUP_SYNTAX_TABLE_FOR_OBJECT): Likewise.
+        * buffer.h (DECODE_POSITION): Likewise.
+
+2008-02-07  Jim Meyering  <meyering@redhat.com>
+
         * lread.c [lint]: Don't include <sys/inode.h>.
 
 2008-02-07  Stefan Monnier  <monnier@iro.umontreal.ca>
diff --git a/src/buffer.h b/src/buffer.h
index 87d646f35fe..8345c8fa06f 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -266,7 +266,7 @@ extern void enlarge_buffer_text P_ ((struct buffer *, int));
    and store the charpos in CHARPOS and the bytepos in BYTEPOS.  */
 
 #define DECODE_POSITION(charpos, bytepos, pos)                  \
-if (1)                                                          \
+do                                                              \
   {                                                             \
     Lisp_Object __pos = (pos);                                  \
     if (NUMBERP (__pos))                                        \
@@ -282,7 +282,7 @@ if (1)								\
     else                                                        \
       wrong_type_argument (Qinteger_or_marker_p, __pos);        \
   }                                                             \
-else
+while (0)
 
 /* Return the address of byte position N in current buffer.  */
 
diff --git a/src/syntax.h b/src/syntax.h
index 5a5a8a96da3..1138dca9887 100644
--- a/src/syntax.h
+++ b/src/syntax.h
@@ -256,7 +256,7 @@ extern char syntax_code_spec[16];
  */
 
 #define SETUP_SYNTAX_TABLE(FROM, COUNT)                                 \
-if (1)                                                                  \
+do                                                                      \
   {                                                                     \
     gl_state.b_property = BEGV;                                         \
     gl_state.e_property = ZV + 1;                                       \
@@ -269,7 +269,7 @@ if (1)									\
         update_syntax_table ((COUNT) > 0 ? (FROM) : (FROM) - 1, (COUNT),\
                              1, Qnil);                                  \
   }                                                                     \
-else
+while (0)
 
 /* Same as above, but in OBJECT.  If OBJECT is nil, use current buffer.
    If it is t, ignore properties altogether.
@@ -279,7 +279,7 @@ else
    So if it is a buffer, we set the offset field to BEGV.  */
 
 #define SETUP_SYNTAX_TABLE_FOR_OBJECT(OBJECT, FROM, COUNT)              \
-if (1)                                                                  \
+do                                                                      \
   {                                                                     \
     gl_state.object = (OBJECT);                                         \
     if (BUFFERP (gl_state.object))                                      \
@@ -314,7 +314,7 @@ if (1)									\
                             + (COUNT > 0 ? 0 :  -1)),                   \
                            COUNT, 1, gl_state.object);                  \
   }                                                                     \
-else
+while (0)
 
 struct gl_state_s
 {