FPSTR not portable between ESP8266 and ESP32

[dok-net]

Board

ESP32 Dev Module

Device Description

DevKitC

Version

latest master (checkout manually)

IDE Name

Arduino IDE

Operating System

Windows 10

Description

After all these years, the following MCVE still does not compile without changes on both ESP8266 Core master and ESP32 Core master.
Shouldn't FPSTR correctly be defined as a noop on ESP32 instead of ... __FlashStringHelper ...?

Sketch

#if defined(ESP8266)
#include <ESP8266mDNS.h>
#elif defined(ESP32)
#include <ESPmDNS.h>
#endif

static const char MDNSNAME[] PROGMEM = "esp"; // your device's MDNS host name

void setup()
{
    MDNS.begin(FPSTR(MDNSNAME));
}

void loop()
{
}

Debug Message

Compiling on ESP8266 works, on ESP32 fails:

fpstr_issue.ino: In function void setup()
 
fpstr_issue.ino: 11:31: error: no matching function for call to 'MDNSResponder::begin(const __FlashStringHelper*)
   MDNS.begin(FPSTR(MDNSNAME))
 
fpstr_issue.ino:4: In file included from
ESPmDNS.h:57: note  candidate  bool MDNSResponder  begin(const char*)
   bool begin(const char* hostName)
   ^~~~~
ESPmDNS.h:57: note    no known conversion for argument 1 from const __FlashStringHelper* to const char*
Error compiling project sources
Build failed for project 'fpstr_issue'

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