fixup provide a flags field with ALIAS info etc

- curl_easy_option_by_id() returns the non-alias version

- PROGRESSDATA is now an alias to CURLOPT_XFERINFODATA instead of the other
  way around

docs/libcurl/curl_easy_option_by_id.3

@@ -32,7 +32,9 @@ const struct curl_easyoption *curl_easy_option_by_id(CURLoption id);
 Given a CURLoption \fBid\fP, this function returns a pointer to the
 curl_easyoption struct, holding information about the
 \fIcurl_easy_setopt(3)\fP option using that id. The option id is the CURLOPT_
-prefix ones provided in the standard curl/curl.h header file.
+prefix ones provided in the standard curl/curl.h header file. This function
+will return the non-aliases version for the cases where there is an alias
+function as well.
 
 If libcurl has no option with the given id, this function returns NULL.
 .SH AVAILABILITY

docs/libcurl/curl_easy_option_next.3

@@ -44,22 +44,26 @@ struct curl_easyoption {
   const char *name;
   CURLoption id;
   curl_easytype type;
+  unsigned int flags;
 };
 
 const struct curl_easyoption *
 curl_easy_option_next(const struct curl_easyoption *prev);
 .fi
 .SH DESCRIPTION
 This function returns a pointer to the first or the next curl_easyoption
-struct, providing an ability to iterate over all known optiosn for
+struct, providing an ability to iterate over all known options for
 \fIcurl_easy_setopt(3)\fP in this instance of libcurl.
 
 Pass a \fBNULL\fP argument as \fBprev\fP to get the first option returned, or
 pass in the current option to get the next one returned. If there is no more
-options to return, \fIcurl_easy_option_next(3)\fP returns NULL.
+option to return, \fIcurl_easy_option_next(3)\fP returns NULL.
 
 The options returned by this functions are the ones known to this libcurl and
 information about what argument type they want.
+
+If the \fBCURLOT_FLAG_ALIAS\fP bit is set in the flags field, it means the
+name is provided for backwards compatibility as an alias.
 .SH AVAILABILITY
 This function was added in libcurl 7.71.0
 .SH RETURN VALUE

include/curl/curl.h

@@ -1172,8 +1172,8 @@ typedef enum {
 
   /* Data passed to the CURLOPT_PROGRESSFUNCTION and CURLOPT_XFERINFOFUNCTION
      callbacks */
-  CURLOPT(CURLOPT_PROGRESSDATA, CURLOPTTYPE_CBPOINT, 57),
-#define CURLOPT_XFERINFODATA CURLOPT_PROGRESSDATA
+  CURLOPT(CURLOPT_XFERINFODATA, CURLOPTTYPE_CBPOINT, 57),
+#define CURLOPT_PROGRESSDATA CURLOPT_XFERINFODATA
 
   /* We want the referrer field set automatically when following locations */
   CURLOPT(CURLOPT_AUTOREFERER, CURLOPTTYPE_LONG, 58),

include/curl/options.h

@@ -38,12 +38,19 @@ typedef enum {
   CURLOT_FUNCTION /* function pointer */
 } curl_easytype;
 
+/* Flag bits */
+
+/* "alias" means it is provided for old programs to remain functional,
+   we prefer another name */
+#define CURLOT_FLAG_ALIAS (1<<0)
+
 /* The CURLOPTTYPE_* id ranges can still be used to figure out what type/size
    to use for curl_easy_setopt() for the given id */
 struct curl_easyoption {
   const char *name;
   CURLoption id;
   curl_easytype type;
+  unsigned int flags;
 };
 
 CURL_EXTERN const struct curl_easyoption *
@@ -59,4 +66,3 @@ curl_easy_option_next(const struct curl_easyoption *prev);
 } /* end of extern "C" */
 #endif
 #endif /* CURLINC_OPTIONS_H */
-

lib/easygetopt.c

@@ -39,7 +39,8 @@ static struct curl_easyoption *lookup(const char *name, CURLoption id)
           return o;
       }
       else {
-        if(o->id == id)
+        if((o->id == id) && !(o->flags & CURLOT_FLAG_ALIAS))
+          /* don't match alias options */
           return o;
       }
       o++;
@@ -53,7 +54,7 @@ const struct curl_easyoption *curl_easy_option_by_name(const char *name)
   return lookup(name, 0);
 }
 
-const struct curl_easyoption *curl_easy_option_by_id (CURLoption id)
+const struct curl_easyoption *curl_easy_option_by_id(CURLoption id)
 {
   return lookup(NULL, id);
 }