Add coments to places where STATIC_ASSERT is used.

Update issue 96
Status: FixedInGit

generator/nanopb_generator.py

@@ -822,16 +822,6 @@ def generate_source(headername, enums, messages, extensions, options):
     if worst > 255 or checks:
         yield '\n/* Check that field information fits in pb_field_t */\n'
         
-        if worst < 65536:
-            yield '#if !defined(PB_FIELD_16BIT) && !defined(PB_FIELD_32BIT)\n'
-            if worst > 255:
-                yield '#error Field descriptor for %s is too large. Define PB_FIELD_16BIT to fix this.\n' % worst_field
-            else:
-                assertion = ' && '.join(str(c) + ' < 256' for c in checks)
-                msgs = '_'.join(str(n) for n in checks_msgnames)
-                yield 'STATIC_ASSERT((%s), YOU_MUST_DEFINE_PB_FIELD_16BIT_FOR_MESSAGES_%s)\n'%(assertion,msgs)
-            yield '#endif\n\n'
-        
         if worst > 65535 or checks:
             yield '#if !defined(PB_FIELD_32BIT)\n'
             if worst > 65535:
@@ -839,8 +829,32 @@ def generate_source(headername, enums, messages, extensions, options):
             else:
                 assertion = ' && '.join(str(c) + ' < 65536' for c in checks)
                 msgs = '_'.join(str(n) for n in checks_msgnames)
+                yield '/* If you get an error here, it means that you need to define PB_FIELD_32BIT\n'
+                yield ' * compile-time option. You can do that in pb.h or on compiler command line.\n'
+                yield ' * \n'
+                yield ' * The reason you need to do this is that some of your messages contain tag\n'
+                yield ' * numbers or field sizes that are larger than what can fit in 8 or 16 bit\n'
+                yield ' * field descriptors.\n'
+                yield ' */\n'
                 yield 'STATIC_ASSERT((%s), YOU_MUST_DEFINE_PB_FIELD_32BIT_FOR_MESSAGES_%s)\n'%(assertion,msgs)
-            yield '#endif\n'
+            yield '#endif\n\n'
+        
+        if worst < 65536:
+            yield '#if !defined(PB_FIELD_16BIT) && !defined(PB_FIELD_32BIT)\n'
+            if worst > 255:
+                yield '#error Field descriptor for %s is too large. Define PB_FIELD_16BIT to fix this.\n' % worst_field
+            else:
+                assertion = ' && '.join(str(c) + ' < 256' for c in checks)
+                msgs = '_'.join(str(n) for n in checks_msgnames)
+                yield '/* If you get an error here, it means that you need to define PB_FIELD_16BIT\n'
+                yield ' * compile-time option. You can do that in pb.h or on compiler command line.\n'
+                yield ' * \n'
+                yield ' * The reason you need to do this is that some of your messages contain tag\n'
+                yield ' * numbers or field sizes that are larger than what can fit in the default\n'
+                yield ' * 8 bit descriptors.\n'
+                yield ' */\n'
+                yield 'STATIC_ASSERT((%s), YOU_MUST_DEFINE_PB_FIELD_16BIT_FOR_MESSAGES_%s)\n'%(assertion,msgs)
+            yield '#endif\n\n'
     
     # Add check for sizeof(double)
     has_double = False

pb.h

@@ -96,8 +96,14 @@
 #endif
 
 /* Compile-time assertion, used for checking compatible compilation options.
- * If this fails on your compiler for some reason, use #define STATIC_ASSERT
+ * If this does not work properly on your compiler, use #define STATIC_ASSERT
- * to disable it. */
+ * to disable it.
+ *
+ * But before doing that, check carefully the error message / place where it
+ * comes from to see if the error has a real cause. Unfortunately the error
+ * message is not always very clear to read, but you can see the reason better
+ * in the place where the STATIC_ASSERT macro was called.
+ */
 #ifndef STATIC_ASSERT
 #define STATIC_ASSERT(COND,MSG) typedef char STATIC_ASSERT_MSG(MSG, __LINE__, __COUNTER__)[(COND)?1:-1];
 #define STATIC_ASSERT_MSG(MSG, LINE, COUNTER) STATIC_ASSERT_MSG_(MSG, LINE, COUNTER)
@@ -210,7 +216,11 @@ struct _pb_field_t {
 PB_PACKED_STRUCT_END
 
 /* Make sure that the standard integer types are of the expected sizes.
- * All kinds of things may break otherwise.. atleast all fixed* types. */
+ * All kinds of things may break otherwise.. atleast all fixed* types.
+ *
+ * If you get errors here, it probably means that your stdint.h is not
+ * correct for your platform.
+ */
 STATIC_ASSERT(sizeof(int8_t) == 1, INT8_T_WRONG_SIZE)
 STATIC_ASSERT(sizeof(uint8_t) == 1, UINT8_T_WRONG_SIZE)
 STATIC_ASSERT(sizeof(int16_t) == 2, INT16_T_WRONG_SIZE)