Ported upb to C89, for greater portability.

A large part of this change contains surface-level
porting, like moving variable declarations to the
top of the block.

However there are a few more substantial things too:

- moved internal-only struct definitions to a separate
  file (structdefs.int.h), for greater encapsulation
  and ABI compatibility.

- removed the UPB_UPCAST macro, since it requires access
  to the internal-only struct definitions.  Replaced uses
  with calls to inline, type-safe casting functions.

- removed the UPB_DEFINE_CLASS/UPB_DEFINE_STRUCT macros.
  Class and struct definitions are now more explicit -- you
  get to see the actual class/struct keywords in the source.
  The casting convenience functions have been moved into
  UPB_DECLARE_DERIVED_TYPE() and UPB_DECLARE_DERIVED_TYPE2().

- the new way that we duplicate base methods in derived types
  is also more convenient and requires less duplication.
  It is also less greppable, but hopefully that is not
  too big a problem.

Compiler flags (-std=c89 -pedantic) should help to rigorously
enforce that the code is free of C99-isms.

A few functions are not available in C89 (strtoll).  There
are temporary, hacky solutions in place.

1 files changed, 120 insertions, 92 deletions

diff --git a/upb/descriptor/reader.c b/upb/descriptor/reader.c
index 29a2188..9ed5d12 100644
--- a/upb/descriptor/reader.c
+++ b/upb/descriptor/reader.c
@@ -20,8 +20,8 @@
 #include "upb/sink.h"
 #include "upb/descriptor/descriptor.upb.h"
 
-// upb_deflist is an internal-only dynamic array for storing a growing list of
-// upb_defs.
+/* upb_deflist is an internal-only dynamic array for storing a growing list of
+ * upb_defs. */
 typedef struct {
   upb_def **defs;
   size_t len;
@@ -29,27 +29,27 @@ typedef struct {
   bool owned;
 } upb_deflist;
 
-// We keep a stack of all the messages scopes we are currently in, as well as
-// the top-level file scope.  This is necessary to correctly qualify the
-// definitions that are contained inside.  "name" tracks the name of the
-// message or package (a bare name -- not qualified by any enclosing scopes).
+/* We keep a stack of all the messages scopes we are currently in, as well as
+ * the top-level file scope.  This is necessary to correctly qualify the
+ * definitions that are contained inside.  "name" tracks the name of the
+ * message or package (a bare name -- not qualified by any enclosing scopes). */
 typedef struct {
   char *name;
-  // Index of the first def that is under this scope.  For msgdefs, the
-  // msgdef itself is at start-1.
+  /* Index of the first def that is under this scope.  For msgdefs, the
+   * msgdef itself is at start-1. */
   int start;
 } upb_descreader_frame;
 
-// The maximum number of nested declarations that are allowed, ie.
-// message Foo {
-//   message Bar {
-//     message Baz {
-//     }
-//   }
-// }
-//
-// This is a resource limit that affects how big our runtime stack can grow.
-// TODO: make this a runtime-settable property of the Reader instance.
+/* The maximum number of nested declarations that are allowed, ie.
+ * message Foo {
+ *   message Bar {
+ *     message Baz {
+ *     }
+ *   }
+ * }
+ *
+ * This is a resource limit that affects how big our runtime stack can grow.
+ * TODO: make this a runtime-settable property of the Reader instance. */
 #define UPB_MAX_MESSAGE_NESTING 64
 
 struct upb_descreader {
@@ -76,11 +76,11 @@ static char *upb_strndup(const char *buf, size_t n) {
   return ret;
 }
 
-// Returns a newly allocated string that joins input strings together, for
-// example:
-//   join("Foo.Bar", "Baz") -> "Foo.Bar.Baz"
-//   join("", "Baz") -> "Baz"
-// Caller owns a ref on the returned string.
+/* Returns a newly allocated string that joins input strings together, for
+ * example:
+ *   join("Foo.Bar", "Baz") -> "Foo.Bar.Baz"
+ *   join("", "Baz") -> "Baz"
+ * Caller owns a ref on the returned string. */
 static char *upb_join(const char *base, const char *name) {
   if (!base || strlen(base) == 0) {
     return upb_strdup(name);
@@ -105,8 +105,9 @@ void upb_deflist_init(upb_deflist *l) {
 }
 
 void upb_deflist_uninit(upb_deflist *l) {
+  size_t i;
   if (l->owned)
-    for(size_t i = 0; i < l->len; i++)
+    for(i = 0; i < l->len; i++)
       upb_def_unref(l->defs[i], l);
   free(l->defs);
 }
@@ -124,8 +125,9 @@ bool upb_deflist_push(upb_deflist *l, upb_def *d) {
 }
 
 void upb_deflist_donaterefs(upb_deflist *l, void *owner) {
+  size_t i;
   assert(l->owned);
-  for (size_t i = 0; i < l->len; i++)
+  for (i = 0; i < l->len; i++)
     upb_def_donateref(l->defs[i], l, owner);
   l->owned = false;
 }
@@ -134,9 +136,10 @@ static upb_def *upb_deflist_last(upb_deflist *l) {
   return l->defs[l->len-1];
 }
 
-// Qualify the defname for all defs starting with offset "start" with "str".
+/* Qualify the defname for all defs starting with offset "start" with "str". */
 static void upb_deflist_qualify(upb_deflist *l, char *str, int32_t start) {
-  for (uint32_t i = start; i < l->len; i++) {
+  uint32_t i;
+  for (i = start; i < l->len; i++) {
     upb_def *def = l->defs[i];
     char *name = upb_join(str, upb_def_fullname(def));
     upb_def_setfullname(def, name, NULL);
@@ -148,8 +151,9 @@ static void upb_deflist_qualify(upb_deflist *l, char *str, int32_t start) {
 /* upb_descreader  ************************************************************/
 
 static upb_msgdef *upb_descreader_top(upb_descreader *r) {
+  int index;
   assert(r->stack_len > 1);
-  int index = r->stack[r->stack_len-1].start - 1;
+  index = r->stack[r->stack_len-1].start - 1;
   assert(index >= 0);
   return upb_downcast_msgdef_mutable(r->defs.defs[index]);
 }
@@ -158,8 +162,8 @@ static upb_def *upb_descreader_last(upb_descreader *r) {
   return upb_deflist_last(&r->defs);
 }
 
-// Start/end handlers for FileDescriptorProto and DescriptorProto (the two
-// entities that have names and can contain sub-definitions.
+/* Start/end handlers for FileDescriptorProto and DescriptorProto (the two
+ * entities that have names and can contain sub-definitions. */
 void upb_descreader_startcontainer(upb_descreader *r) {
   upb_descreader_frame *f = &r->stack[r->stack_len++];
   f->start = r->defs.len;
@@ -179,7 +183,7 @@ void upb_descreader_setscopename(upb_descreader *r, char *str) {
   f->name = str;
 }
 
-// Handlers for google.protobuf.FileDescriptorProto.
+/* Handlers for google.protobuf.FileDescriptorProto. */
 static bool file_startmsg(void *r, const void *hd) {
   UPB_UNUSED(hd);
   upb_descreader_startcontainer(r);
@@ -187,27 +191,27 @@ static bool file_startmsg(void *r, const void *hd) {
 }
 
 static bool file_endmsg(void *closure, const void *hd, upb_status *status) {
+  upb_descreader *r = closure;
   UPB_UNUSED(hd);
   UPB_UNUSED(status);
-  upb_descreader *r = closure;
   upb_descreader_endcontainer(r);
   return true;
 }
 
 static size_t file_onpackage(void *closure, const void *hd, const char *buf,
                              size_t n, const upb_bufhandle *handle) {
+  upb_descreader *r = closure;
   UPB_UNUSED(hd);
   UPB_UNUSED(handle);
-  upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
+  /* XXX: see comment at the top of the file. */
   upb_descreader_setscopename(r, upb_strndup(buf, n));
   return n;
 }
 
-// Handlers for google.protobuf.EnumValueDescriptorProto.
+/* Handlers for google.protobuf.EnumValueDescriptorProto. */
 static bool enumval_startmsg(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
   r->saw_number = false;
   r->saw_name = false;
   return true;
@@ -215,10 +219,10 @@ static bool enumval_startmsg(void *closure, const void *hd) {
 
 static size_t enumval_onname(void *closure, const void *hd, const char *buf,
                              size_t n, const upb_bufhandle *handle) {
+  upb_descreader *r = closure;
   UPB_UNUSED(hd);
   UPB_UNUSED(handle);
-  upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
+  /* XXX: see comment at the top of the file. */
   free(r->name);
   r->name = upb_strndup(buf, n);
   r->saw_name = true;
@@ -226,21 +230,23 @@ static size_t enumval_onname(void *closure, const void *hd, const char *buf,
 }
 
 static bool enumval_onnumber(void *closure, const void *hd, int32_t val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
   r->number = val;
   r->saw_number = true;
   return true;
 }
 
 static bool enumval_endmsg(void *closure, const void *hd, upb_status *status) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  upb_enumdef *e;
+  UPB_UNUSED(hd);
+
   if(!r->saw_number || !r->saw_name) {
     upb_status_seterrmsg(status, "Enum value missing name or number.");
     return false;
   }
-  upb_enumdef *e = upb_downcast_enumdef_mutable(upb_descreader_last(r));
+  e = upb_downcast_enumdef_mutable(upb_descreader_last(r));
   upb_enumdef_addval(e, r->name, r->number, status);
   free(r->name);
   r->name = NULL;
@@ -248,18 +254,21 @@ static bool enumval_endmsg(void *closure, const void *hd, upb_status *status) {
 }
 
 
-// Handlers for google.protobuf.EnumDescriptorProto.
+/* Handlers for google.protobuf.EnumDescriptorProto. */
 static bool enum_startmsg(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
-  upb_deflist_push(&r->defs, UPB_UPCAST(upb_enumdef_new(&r->defs)));
+  UPB_UNUSED(hd);
+  upb_deflist_push(&r->defs,
+                   upb_enumdef_upcast_mutable(upb_enumdef_new(&r->defs)));
   return true;
 }
 
 static bool enum_endmsg(void *closure, const void *hd, upb_status *status) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
-  upb_enumdef *e = upb_downcast_enumdef_mutable(upb_descreader_last(r));
+  upb_enumdef *e;
+  UPB_UNUSED(hd);
+
+  e = upb_downcast_enumdef_mutable(upb_descreader_last(r));
   if (upb_def_fullname(upb_descreader_last(r)) == NULL) {
     upb_status_seterrmsg(status, "Enum had no name.");
     return false;
@@ -273,31 +282,31 @@ static bool enum_endmsg(void *closure, const void *hd, upb_status *status) {
 
 static size_t enum_onname(void *closure, const void *hd, const char *buf,
                           size_t n, const upb_bufhandle *handle) {
-  UPB_UNUSED(hd);
-  UPB_UNUSED(handle);
   upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
   char *fullname = upb_strndup(buf, n);
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+  /* XXX: see comment at the top of the file. */
   upb_def_setfullname(upb_descreader_last(r), fullname, NULL);
   free(fullname);
   return n;
 }
 
-// Handlers for google.protobuf.FieldDescriptorProto
+/* Handlers for google.protobuf.FieldDescriptorProto */
 static bool field_startmsg(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
   r->f = upb_fielddef_new(&r->defs);
   free(r->default_string);
   r->default_string = NULL;
 
-  // fielddefs default to packed, but descriptors default to non-packed.
+  /* fielddefs default to packed, but descriptors default to non-packed. */
   upb_fielddef_setpacked(r->f, false);
   return true;
 }
 
-// Converts the default value in string "str" into "d".  Passes a ref on str.
-// Returns true on success.
+/* Converts the default value in string "str" into "d".  Passes a ref on str.
+ * Returns true on success. */
 static bool parse_default(char *str, upb_fielddef *f) {
   bool success = true;
   char *end;
@@ -311,7 +320,8 @@ static bool parse_default(char *str, upb_fielddef *f) {
       break;
     }
     case UPB_TYPE_INT64: {
-      long long val = strtoll(str, &end, 0);
+      /* XXX: Need to write our own strtoll, since it's not available in c89. */
+      long long val = strtol(str, &end, 0);
       if (val > INT64_MAX || val < INT64_MIN || errno == ERANGE || *end)
         success = false;
       else
@@ -327,7 +337,8 @@ static bool parse_default(char *str, upb_fielddef *f) {
       break;
     }
     case UPB_TYPE_UINT64: {
-      unsigned long long val = strtoull(str, &end, 0);
+      /* XXX: Need to write our own strtoull, since it's not available in c89. */
+      unsigned long long val = strtoul(str, &end, 0);
       if (val > UINT64_MAX || errno == ERANGE || *end)
         success = false;
       else
@@ -343,7 +354,8 @@ static bool parse_default(char *str, upb_fielddef *f) {
       break;
     }
     case UPB_TYPE_FLOAT: {
-      float val = strtof(str, &end);
+      /* XXX: Need to write our own strtof, since it's not available in c89. */
+      float val = strtod(str, &end);
       if (errno == ERANGE || *end)
         success = false;
       else
@@ -365,10 +377,11 @@ static bool parse_default(char *str, upb_fielddef *f) {
 }
 
 static bool field_endmsg(void *closure, const void *hd, upb_status *status) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
   upb_fielddef *f = r->f;
-  // TODO: verify that all required fields were present.
+  UPB_UNUSED(hd);
+
+  /* TODO: verify that all required fields were present. */
   assert(upb_fielddef_number(f) != 0);
   assert(upb_fielddef_name(f) != NULL);
   assert((upb_fielddef_subdefname(f) != NULL) == upb_fielddef_hassubdef(f));
@@ -382,8 +395,8 @@ static bool field_endmsg(void *closure, const void *hd, upb_status *status) {
       upb_fielddef_setdefaultcstr(f, r->default_string, NULL);
     } else {
       if (r->default_string && !parse_default(r->default_string, f)) {
-        // We don't worry too much about giving a great error message since the
-        // compiler should have ensured this was correct.
+        /* We don't worry too much about giving a great error message since the
+         * compiler should have ensured this was correct. */
         upb_status_seterrmsg(status, "Error converting default value.");
         return false;
       }
@@ -393,48 +406,54 @@ static bool field_endmsg(void *closure, const void *hd, upb_status *status) {
 }
 
 static bool field_onlazy(void *closure, const void *hd, bool val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
+
   upb_fielddef_setlazy(r->f, val);
   return true;
 }
 
 static bool field_onpacked(void *closure, const void *hd, bool val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
+
   upb_fielddef_setpacked(r->f, val);
   return true;
 }
 
 static bool field_ontype(void *closure, const void *hd, int32_t val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
+
   upb_fielddef_setdescriptortype(r->f, val);
   return true;
 }
 
 static bool field_onlabel(void *closure, const void *hd, int32_t val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
+
   upb_fielddef_setlabel(r->f, val);
   return true;
 }
 
 static bool field_onnumber(void *closure, const void *hd, int32_t val) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
   bool ok = upb_fielddef_setnumber(r->f, val, NULL);
+  UPB_UNUSED(hd);
+
   UPB_ASSERT_VAR(ok, ok);
   return true;
 }
 
 static size_t field_onname(void *closure, const void *hd, const char *buf,
                            size_t n, const upb_bufhandle *handle) {
-  UPB_UNUSED(hd);
-  UPB_UNUSED(handle);
   upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
   char *name = upb_strndup(buf, n);
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+
+  /* XXX: see comment at the top of the file. */
   upb_fielddef_setname(r->f, name, NULL);
   free(name);
   return n;
@@ -442,11 +461,12 @@ static size_t field_onname(void *closure, const void *hd, const char *buf,
 
 static size_t field_ontypename(void *closure, const void *hd, const char *buf,
                                size_t n, const upb_bufhandle *handle) {
-  UPB_UNUSED(hd);
-  UPB_UNUSED(handle);
   upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
   char *name = upb_strndup(buf, n);
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+
+  /* XXX: see comment at the top of the file. */
   upb_fielddef_setsubdefname(r->f, name, NULL);
   free(name);
   return n;
@@ -454,11 +474,12 @@ static size_t field_ontypename(void *closure, const void *hd, const char *buf,
 
 static size_t field_onextendee(void *closure, const void *hd, const char *buf,
                                size_t n, const upb_bufhandle *handle) {
-  UPB_UNUSED(hd);
-  UPB_UNUSED(handle);
   upb_descreader *r = closure;
-  // XXX: see comment at the top of the file.
   char *name = upb_strndup(buf, n);
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+
+  /* XXX: see comment at the top of the file. */
   upb_fielddef_setcontainingtypename(r->f, name, NULL);
   free(name);
   return n;
@@ -466,31 +487,35 @@ static size_t field_onextendee(void *closure, const void *hd, const char *buf,
 
 static size_t field_ondefaultval(void *closure, const void *hd, const char *buf,
                                  size_t n, const upb_bufhandle *handle) {
+  upb_descreader *r = closure;
   UPB_UNUSED(hd);
   UPB_UNUSED(handle);
-  upb_descreader *r = closure;
-  // Have to convert from string to the correct type, but we might not know the
-  // type yet, so we save it as a string until the end of the field.
-  // XXX: see comment at the top of the file.
+
+  /* Have to convert from string to the correct type, but we might not know the
+   * type yet, so we save it as a string until the end of the field.
+   * XXX: see comment at the top of the file. */
   free(r->default_string);
   r->default_string = upb_strndup(buf, n);
   return n;
 }
 
-// Handlers for google.protobuf.DescriptorProto (representing a message).
+/* Handlers for google.protobuf.DescriptorProto (representing a message). */
 static bool msg_startmsg(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
-  upb_deflist_push(&r->defs, UPB_UPCAST(upb_msgdef_new(&r->defs)));
+  UPB_UNUSED(hd);
+
+  upb_deflist_push(&r->defs,
+                   upb_msgdef_upcast_mutable(upb_msgdef_new(&r->defs)));
   upb_descreader_startcontainer(r);
   return true;
 }
 
 static bool msg_endmsg(void *closure, const void *hd, upb_status *status) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
   upb_msgdef *m = upb_descreader_top(r);
-  if(!upb_def_fullname(UPB_UPCAST(m))) {
+  UPB_UNUSED(hd);
+
+  if(!upb_def_fullname(upb_msgdef_upcast_mutable(m))) {
     upb_status_seterrmsg(status, "Encountered message with no name.");
     return false;
   }
@@ -500,32 +525,35 @@ static bool msg_endmsg(void *closure, const void *hd, upb_status *status) {
 
 static size_t msg_onname(void *closure, const void *hd, const char *buf,
                          size_t n, const upb_bufhandle *handle) {
-  UPB_UNUSED(hd);
-  UPB_UNUSED(handle);
   upb_descreader *r = closure;
   upb_msgdef *m = upb_descreader_top(r);
-  // XXX: see comment at the top of the file.
+  /* XXX: see comment at the top of the file. */
   char *name = upb_strndup(buf, n);
-  upb_def_setfullname(UPB_UPCAST(m), name, NULL);
-  upb_descreader_setscopename(r, name);  // Passes ownership of name.
+  UPB_UNUSED(hd);
+  UPB_UNUSED(handle);
+
+  upb_def_setfullname(upb_msgdef_upcast_mutable(m), name, NULL);
+  upb_descreader_setscopename(r, name);  /* Passes ownership of name. */
   return n;
 }
 
 static bool msg_onendfield(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
   upb_msgdef *m = upb_descreader_top(r);
+  UPB_UNUSED(hd);
+
   upb_msgdef_addfield(m, r->f, &r->defs, NULL);
   r->f = NULL;
   return true;
 }
 
 static bool pushextension(void *closure, const void *hd) {
-  UPB_UNUSED(hd);
   upb_descreader *r = closure;
+  UPB_UNUSED(hd);
+
   assert(upb_fielddef_containingtypename(r->f));
   upb_fielddef_setisextension(r->f, true);
-  upb_deflist_push(&r->defs, UPB_UPCAST(r->f));
+  upb_deflist_push(&r->defs, upb_fielddef_upcast_mutable(r->f));
   r->f = NULL;
   return true;
 }