Experiment: C++17 support (#9874)

* Add C++17 support

* Add C++17 runtime probes and update build configurations for STM32 and Portduino

* Remove unflags

* Update C++ standard flags across the platforms

* Convert a couple of instances to structured bindings

* NRF52 platform.txt to add C++17 support

* Still need the unflags apparently

* Remove C++17 runtime probe tests from test_main.cpp

* Reconfigured doesnt need a nodiscard

* Remove nodiscard attribute from init() method in RadioInterface

* Remove mbedtls/error.h from build flags

Removed include directive for mbedtls/error.h from build flags.

* Fix IRAM overflow

* Fix IRAM overflow

* Add build flag to exclude MQTT from rak11200

* Update C++ standard from gnu17 to gnu++17

src/mesh/NextHopRouter.cpp

@@ -23,7 +23,7 @@ ErrorCode NextHopRouter::send(meshtastic_MeshPacket *p)
     p->relay_node = nodeDB->getLastByteOfNodeNum(getNodeNum()); // First set the relayer to us
     wasSeenRecently(p);                                         // FIXME, move this to a sniffSent method
 
-    p->next_hop = getNextHop(p->to, p->relay_node); // set the next hop
+    p->next_hop = getNextHop(p->to, p->relay_node).value_or(NO_NEXT_HOP_PREFERENCE); // set the next hop
     LOG_DEBUG("Setting next hop for packet with dest %x to %x", p->to, p->next_hop);
 
     // If it's from us, ReliableRouter already handles retransmissions if want_ack is set. If a next hop is set and hop limit is
@@ -170,10 +170,10 @@ bool NextHopRouter::perhapsRebroadcast(const meshtastic_MeshPacket *p)
  * Get the next hop for a destination, given the relay node
  * @return the node number of the next hop, 0 if no preference (fallback to FloodingRouter)
  */
-uint8_t NextHopRouter::getNextHop(NodeNum to, uint8_t relay_node)
+std::optional<uint8_t> NextHopRouter::getNextHop(NodeNum to, uint8_t relay_node)
 {
     if (isBroadcast(to))
-        return NO_NEXT_HOP_PREFERENCE;
+        return std::nullopt;
 
     meshtastic_NodeInfoLite *node = nodeDB->getMeshNode(to);
     if (node && node->next_hop) {
@@ -184,7 +184,7 @@ uint8_t NextHopRouter::getNextHop(NodeNum to, uint8_t relay_node)
         } else
             LOG_WARN("Next hop for 0x%x is 0x%x, same as relayer; set no pref", to, node->next_hop);
     }
-    return NO_NEXT_HOP_PREFERENCE;
+    return std::nullopt;
 }
 
 PendingPacket *NextHopRouter::findPendingPacket(GlobalPacketId key)

src/mesh/NextHopRouter.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "FloodingRouter.h"
+#include <optional>
 #include <unordered_map>
 
 /**
@@ -146,7 +147,7 @@ class NextHopRouter : public FloodingRouter
      * Get the next hop for a destination, given the relay node
      * @return the node number of the next hop, 0 if no preference (fallback to FloodingRouter)
      */
-    uint8_t getNextHop(NodeNum to, uint8_t relay_node);
+    std::optional<uint8_t> getNextHop(NodeNum to, uint8_t relay_node);
 
     /** Check if we should be rebroadcasting this packet if so, do so.
      *  @return true if we did rebroadcast */

src/mesh/RadioInterface.h

@@ -156,7 +156,7 @@ class RadioInterface
     virtual ErrorCode send(meshtastic_MeshPacket *p) = 0;
 
     /** Return TX queue status */
-    virtual meshtastic_QueueStatus getQueueStatus()
+    [[nodiscard]] virtual meshtastic_QueueStatus getQueueStatus()
     {
         meshtastic_QueueStatus qs;
         qs.res = qs.mesh_packet_id = qs.free = qs.maxlen = 0;
@@ -182,22 +182,22 @@ class RadioInterface
     virtual bool reconfigure();
 
     /** The delay to use for retransmitting dropped packets */
-    uint32_t getRetransmissionMsec(const meshtastic_MeshPacket *p);
+    [[nodiscard]] uint32_t getRetransmissionMsec(const meshtastic_MeshPacket *p);
 
     /** The delay to use when we want to send something */
-    uint32_t getTxDelayMsec();
+    [[nodiscard]] uint32_t getTxDelayMsec();
 
     /** The CW to use when calculating SNR_based delays */
-    uint8_t getCWsize(float snr);
+    [[nodiscard]] uint8_t getCWsize(float snr);
 
     /** The worst-case SNR_based packet delay */
-    uint32_t getTxDelayMsecWeightedWorst(float snr);
+    [[nodiscard]] uint32_t getTxDelayMsecWeightedWorst(float snr);
 
     /** Returns true if we should rebroadcast early like a ROUTER */
-    bool shouldRebroadcastEarlyLikeRouter(meshtastic_MeshPacket *p);
+    [[nodiscard]] bool shouldRebroadcastEarlyLikeRouter(meshtastic_MeshPacket *p);
 
     /** The delay to use when we want to flood a message. Use a weighted scale based on SNR */
-    uint32_t getTxDelayMsecWeighted(meshtastic_MeshPacket *p);
+    [[nodiscard]] uint32_t getTxDelayMsecWeighted(meshtastic_MeshPacket *p);
 
     /** If the packet is not already in the late rebroadcast window, move it there */
     virtual void clampToLateRebroadcastWindow(NodeNum from, PacketId id) { return; }
@@ -215,18 +215,18 @@ class RadioInterface
      *
      * @return num msecs for the packet
      */
-    uint32_t getPacketTime(const meshtastic_MeshPacket *p, bool received = false);
-    virtual uint32_t getPacketTime(uint32_t totalPacketLen, bool received = false) = 0;
+    [[nodiscard]] uint32_t getPacketTime(const meshtastic_MeshPacket *p, bool received = false);
+    [[nodiscard]] virtual uint32_t getPacketTime(uint32_t totalPacketLen, bool received = false) = 0;
 
     /**
      * Get the channel we saved.
      */
-    uint32_t getChannelNum();
+    [[nodiscard]] uint32_t getChannelNum();
 
     /**
      * Get the frequency we saved.
      */
-    virtual float getFreq();
+    [[nodiscard]] virtual float getFreq();
 
     /// Some boards (1st gen Pinetab Lora module) have broken IRQ wires, so we need to poll via i2c registers
     virtual bool isIRQPending() { return false; }
@@ -246,7 +246,7 @@ class RadioInterface
      *
      * Used as the first step of
      */
-    size_t beginSending(meshtastic_MeshPacket *p);
+    [[nodiscard]] size_t beginSending(meshtastic_MeshPacket *p);
 
     /**
      * Some regulatory regions limit xmit power.

src/mesh/Router.h

@@ -58,14 +58,14 @@ class Router : protected concurrency::OSThread, protected PacketHistory
     /** Allocate and return a meshpacket which defaults as send to broadcast from the current node.
      * The returned packet is guaranteed to have a unique packet ID already assigned
      */
-    meshtastic_MeshPacket *allocForSending();
+    [[nodiscard]] meshtastic_MeshPacket *allocForSending();
 
     /** Return Underlying interface's TX queue status */
-    meshtastic_QueueStatus getQueueStatus();
+    [[nodiscard]] meshtastic_QueueStatus getQueueStatus();
 
     /**
      * @return our local nodenum */
-    NodeNum getNodeNum();
+    [[nodiscard]] NodeNum getNodeNum();
 
     /** Wake up the router thread ASAP, because we just queued a message for it.
      * FIXME, this is kinda a hack because we don't have a nice way yet to say 'wake us because we are 'blocked on this queue'

src/mesh/TransmitHistory.cpp

@@ -141,12 +141,12 @@ bool TransmitHistory::saveToDisk()
         file.write((uint8_t *)&header, sizeof(header));
 
         uint8_t written = 0;
-        for (auto &pair : history) {
+        for (const auto &[key, epochSeconds] : history) {
             if (written >= MAX_ENTRIES)
                 break;
             Entry entry{};
-            entry.key = pair.first;
-            entry.epochSeconds = pair.second;
+            entry.key = key;
+            entry.epochSeconds = epochSeconds;
             file.write((uint8_t *)&entry, sizeof(entry));
             written++;
         }