Get rid of the ternary operator in the pb_field_t initialization.

Some compilers where unable to detect that the ternary operator
can be evaluated at the compile time. This commit does the evaluation
on the Python side, which should fix the problem.

The new .pb.c files are generated using PB_FIELD2() macro. The old
PB_FIELD() macro remains, so that previously generated files keep
working.

2 files changed, 39 insertions, 20 deletions

diff --git a/generator/nanopb_generator.py b/generator/nanopb_generator.py
index d70938a1..e463b6ca 100755
--- a/generator/nanopb_generator.py
+++ b/generator/nanopb_generator.py
@@ -246,13 +246,14 @@ class Field:
         '''Return the pb_field_t initializer to use in the constant array.
         prev_field_name is the name of the previous field or None.
         '''
-        result  = '    PB_FIELD(%3d, ' % self.tag
+        result  = '    PB_FIELD2(%3d, ' % self.tag
         result += '%-8s, ' % self.pbtype
         result += '%s, ' % self.rules
         result += '%s, ' % self.allocation
         result += '%s, ' % self.struct_name
         result += '%s, ' % self.name
         result += '%s, ' % (prev_field_name or self.name)
+        result += '%s, ' % ("first" if not prev_field_name else "other")
         
         if self.pbtype == 'MESSAGE':
             result += '&%s_fields)' % self.submsgname
diff --git a/pb.h b/pb.h
index e3e68ce5..fe91ccd8 100644
--- a/pb.h
+++ b/pb.h
@@ -320,58 +320,66 @@ struct _pb_extension_t {
 };
 
 /* These macros are used to declare pb_field_t's in the constant array. */
+/* Size of a structure member, in bytes. */
 #define pb_membersize(st, m) (sizeof ((st*)0)->m)
+/* Number of entries in an array. */
 #define pb_arraysize(st, m) (pb_membersize(st, m) / pb_membersize(st, m[0]))
+/* Delta from start of one member to the start of another member. */
 #define pb_delta(st, m1, m2) ((int)offsetof(st, m1) - (int)offsetof(st, m2))
-#define pb_delta_end(st, m1, m2) (int)(offsetof(st, m1) == offsetof(st, m2) \
-                                  ? offsetof(st, m1) \
-                                  : offsetof(st, m1) - offsetof(st, m2) - pb_membersize(st, m2))
+/* Delta from start of structure to member. */
+#define pb_fielddelta_first(st, m1, m2) (offsetof(st, m1))
+/* Delta from end of one field to start of another field. */
+#define pb_fielddelta_other(st, m1, m2) (offsetof(st, m1) - offsetof(st, m2) - pb_membersize(st, m2))
+/* Choose between pb_fielddelta_first and pb_fielddelta_other (backwards compatibility) */
+#define pb_fielddelta_choose(st, m1, m2) (int)(offsetof(st, m1) == offsetof(st, m2) \
+                                  ? pb_fielddelta_first(st, m1, m2) \
+                                  : pb_fielddelta_other(st, m1, m2))
 #define PB_LAST_FIELD {0,(pb_type_t) 0,0,0,0,0,0}
 
 /* Required fields are the simplest. They just have delta (padding) from
  * previous field end, and the size of the field. Pointer is used for
  * submessages and default values.
  */
-#define PB_REQUIRED_STATIC(tag, st, m, pm, ltype, ptr) \
+#define PB_REQUIRED_STATIC(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_STATIC | PB_HTYPE_REQUIRED | ltype, \
-    pb_delta_end(st, m, pm), 0, pb_membersize(st, m), 0, ptr}
+    fd, 0, pb_membersize(st, m), 0, ptr}
 
 /* Optional fields add the delta to the has_ variable. */
-#define PB_OPTIONAL_STATIC(tag, st, m, pm, ltype, ptr) \
+#define PB_OPTIONAL_STATIC(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_STATIC | PB_HTYPE_OPTIONAL | ltype, \
-    pb_delta_end(st, m, pm), \
+    fd, \
     pb_delta(st, has_ ## m, m), \
     pb_membersize(st, m), 0, ptr}
 
 /* Repeated fields have a _count field and also the maximum number of entries. */
-#define PB_REPEATED_STATIC(tag, st, m, pm, ltype, ptr) \
+#define PB_REPEATED_STATIC(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_STATIC | PB_HTYPE_REPEATED | ltype, \
-    pb_delta_end(st, m, pm), \
+    fd, \
     pb_delta(st, m ## _count, m), \
     pb_membersize(st, m[0]), \
     pb_arraysize(st, m), ptr}
 
 /* Callbacks are much like required fields except with special datatype. */
-#define PB_REQUIRED_CALLBACK(tag, st, m, pm, ltype, ptr) \
+#define PB_REQUIRED_CALLBACK(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_CALLBACK | PB_HTYPE_REQUIRED | ltype, \
-    pb_delta_end(st, m, pm), 0, pb_membersize(st, m), 0, ptr}
+    fd, 0, pb_membersize(st, m), 0, ptr}
 
-#define PB_OPTIONAL_CALLBACK(tag, st, m, pm, ltype, ptr) \
+#define PB_OPTIONAL_CALLBACK(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_CALLBACK | PB_HTYPE_OPTIONAL | ltype, \
-    pb_delta_end(st, m, pm), 0, pb_membersize(st, m), 0, ptr}
+    fd, 0, pb_membersize(st, m), 0, ptr}
     
-#define PB_REPEATED_CALLBACK(tag, st, m, pm, ltype, ptr) \
+#define PB_REPEATED_CALLBACK(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_CALLBACK | PB_HTYPE_REPEATED | ltype, \
-    pb_delta_end(st, m, pm), 0, pb_membersize(st, m), 0, ptr}
+    fd, 0, pb_membersize(st, m), 0, ptr}
 
 /* Optional extensions don't have the has_ field, as that would be redundant. */
-#define PB_OPTEXT_STATIC(tag, st, m, pm, ltype, ptr) \
+#define PB_OPTEXT_STATIC(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_STATIC | PB_HTYPE_OPTIONAL | ltype, \
     0, \
     0, \
     pb_membersize(st, m), 0, ptr}
 
-#define PB_OPTEXT_CALLBACK(tag, st, m, pm, ltype, ptr) \
+#define PB_OPTEXT_CALLBACK(tag, st, m, fd, ltype, ptr) \
     {tag, PB_ATYPE_CALLBACK | PB_HTYPE_OPTIONAL | ltype, \
     0, 0, pb_membersize(st, m), 0, ptr}
 
@@ -410,8 +418,18 @@ struct _pb_extension_t {
  */
 
 #define PB_FIELD(tag, type, rules, allocation, message, field, prevfield, ptr) \
-    PB_ ## rules ## _ ## allocation(tag, message, field, prevfield, \
-                                    PB_LTYPE_MAP_ ## type, ptr)
+    PB_ ## rules ## _ ## allocation(tag, message, field, \
+        pb_fielddelta_choose(message, field, prevfield), \
+        PB_LTYPE_MAP_ ## type, ptr)
+
+/* This is a new version of the macro used by nanopb generator from
+ * version 0.2.3 onwards. It avoids the use of a ternary expression in
+ * the initialization, which confused some compilers.
+ */
+#define PB_FIELD2(tag, type, rules, allocation, message, field, prevfield, pos, ptr) \
+    PB_ ## rules ## _ ## allocation(tag, message, field, \
+        pb_fielddelta_ ## pos(message, field, prevfield), \
+        PB_LTYPE_MAP_ ## type, ptr)
 
 
 /* These macros are used for giving out error messages.