Replace std::snprintf() with wpi::format_to_n_c_str() (#5645)

fmtlib uses consteval format string processing, which makes it more
efficient than std::snprintf().

snprintf()s in libuv, mpack, processstarter, and wpigui were left alone.
processstarter uses stdlib only, and wpigui only depends on imgui.

fmt::format_to_n() is analogous to std::format_to_n()
(https://en.cppreference.com/w/cpp/utility/format/format_to_n)

wpi::format_to_n_c_str() is a wrapper which adds the trailing NUL.

glass/src/lib/native/cpp/hardware/AnalogGyro.cpp

@@ -4,6 +4,8 @@
 
 #include "glass/hardware/AnalogGyro.h"
 
+#include <wpi/StringExtras.h>
+
 #include "glass/DataSource.h"
 #include "glass/other/DeviceTree.h"
 
@@ -11,7 +13,8 @@ using namespace glass;
 
 void glass::DisplayAnalogGyroDevice(AnalogGyroModel* model, int index) {
   char name[32];
-  std::snprintf(name, sizeof(name), "AnalogGyro[%d]", index);
+  wpi::format_to_n_c_str(name, sizeof(name), "AnalogGyro[{}]", index);
+
   if (BeginDevice(name)) {
     // angle
     if (auto angleData = model->GetAngleData()) {

glass/src/lib/native/cpp/hardware/AnalogInput.cpp

@@ -5,6 +5,7 @@
 #include "glass/hardware/AnalogInput.h"
 
 #include <imgui.h>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -22,9 +23,9 @@ void glass::DisplayAnalogInput(AnalogInputModel* model, int index) {
   std::string& name = GetStorage().GetString("name");
   char label[128];
   if (!name.empty()) {
-    std::snprintf(label, sizeof(label), "%s [%d]###name", name.c_str(), index);
+    wpi::format_to_n_c_str(label, sizeof(label), "{} [{}]###name", name, index);
   } else {
-    std::snprintf(label, sizeof(label), "In[%d]###name", index);
+    wpi::format_to_n_c_str(label, sizeof(label), "In[{}]###name", index);
   }
 
   if (model->IsGyro()) {

glass/src/lib/native/cpp/hardware/AnalogOutput.cpp

@@ -4,6 +4,8 @@
 
 #include "glass/hardware/AnalogOutput.h"
 
+#include <wpi/StringExtras.h>
+
 #include "glass/Context.h"
 #include "glass/DataSource.h"
 #include "glass/Storage.h"
@@ -30,9 +32,9 @@ void glass::DisplayAnalogOutputsDevice(AnalogOutputsModel* model) {
       std::string& name = GetStorage().GetString("name");
       char label[128];
       if (!name.empty()) {
-        std::snprintf(label, sizeof(label), "%s [%d]###name", name.c_str(), i);
+        wpi::format_to_n_c_str(label, sizeof(label), "{} [{}]###name", name, i);
       } else {
-        std::snprintf(label, sizeof(label), "Out[%d]###name", i);
+        wpi::format_to_n_c_str(label, sizeof(label), "Out[{}]###name", i);
       }
 
       double value = analogOutData->GetValue();

glass/src/lib/native/cpp/hardware/Encoder.cpp

@@ -6,6 +6,7 @@
 
 #include <fmt/format.h>
 #include <imgui.h>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -70,10 +71,11 @@ void glass::DisplayEncoder(EncoderModel* model) {
   std::string& name = GetStorage().GetString("name");
   char label[128];
   if (!name.empty()) {
-    std::snprintf(label, sizeof(label), "%s [%d,%d]###header", name.c_str(),
-                  chA, chB);
+    wpi::format_to_n_c_str(label, sizeof(label), "{} [{},{}]###header", name,
+                           chA, chB);
   } else {
-    std::snprintf(label, sizeof(label), "Encoder[%d,%d]###header", chA, chB);
+    wpi::format_to_n_c_str(label, sizeof(label), "Encoder[{},{}]###header", chA,
+                           chB);
   }
 
   // header

glass/src/lib/native/cpp/hardware/Gyro.cpp

@@ -5,12 +5,13 @@
 #include "glass/hardware/Gyro.h"
 
 #include <cmath>
+#include <numbers>
 
 #define IMGUI_DEFINE_MATH_OPERATORS
 
 #include <imgui.h>
 #include <imgui_internal.h>
-#include <numbers>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -65,7 +66,8 @@ void glass::DisplayGyro(GyroModel* m) {
                   color, 1.2f);
     if (major) {
       char txt[16];
-      std::snprintf(txt, sizeof(txt), "%d°", i);
+      wpi::format_to_n_c_str(txt, sizeof(txt), "{}°", i);
+
       draw->AddText(
           center + (direction * radius * 1.25) - ImGui::CalcTextSize(txt) * 0.5,
           primaryColor, txt, nullptr);

glass/src/lib/native/cpp/hardware/PCM.cpp

@@ -9,6 +9,7 @@
 
 #include <imgui.h>
 #include <wpi/SmallVector.h>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -46,10 +47,10 @@ bool glass::DisplayPCMSolenoids(PCMModel* model, int index,
   std::string& name = GetStorage().GetString("name");
   char label[128];
   if (!name.empty()) {
-    std::snprintf(label, sizeof(label), "%s [%d]###header", name.c_str(),
-                  index);
+    wpi::format_to_n_c_str(label, sizeof(label), "{} [{}]###header", name,
+                           index);
   } else {
-    std::snprintf(label, sizeof(label), "PCM[%d]###header", index);
+    wpi::format_to_n_c_str(label, sizeof(label), "PCM[{}]###header", index);
   }
 
   // header
@@ -111,7 +112,8 @@ void glass::DisplayCompressorDevice(PCMModel* model, int index,
 void glass::DisplayCompressorDevice(CompressorModel* model, int index,
                                     bool outputsEnabled) {
   char name[32];
-  std::snprintf(name, sizeof(name), "Compressor[%d]", index);
+  wpi::format_to_n_c_str(name, sizeof(name), "Compressor[{}]", index);
+
   if (BeginDevice(name)) {
     // output enabled
     if (auto runningData = model->GetRunningData()) {

glass/src/lib/native/cpp/hardware/PWM.cpp

@@ -5,6 +5,7 @@
 #include "glass/hardware/PWM.h"
 
 #include <imgui.h>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -22,9 +23,9 @@ void glass::DisplayPWM(PWMModel* model, int index, bool outputsEnabled) {
   std::string& name = GetStorage().GetString("name");
   char label[128];
   if (!name.empty()) {
-    std::snprintf(label, sizeof(label), "%s [%d]###name", name.c_str(), index);
+    wpi::format_to_n_c_str(label, sizeof(label), "{} [{}]###name", name, index);
   } else {
-    std::snprintf(label, sizeof(label), "PWM[%d]###name", index);
+    wpi::format_to_n_c_str(label, sizeof(label), "PWM[{}]###name", index);
   }
 
   int led = model->GetAddressableLED();

glass/src/lib/native/cpp/hardware/PowerDistribution.cpp

@@ -5,9 +5,9 @@
 #include "glass/hardware/PowerDistribution.h"
 
 #include <algorithm>
-#include <cstdio>
 
 #include <imgui.h>
+#include <wpi/StringExtras.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
@@ -36,7 +36,8 @@ static float DisplayChannel(PowerDistributionModel& pdp, int channel) {
 
 void glass::DisplayPowerDistribution(PowerDistributionModel* model, int index) {
   char name[128];
-  std::snprintf(name, sizeof(name), "PowerDistribution[%d]", index);
+  wpi::format_to_n_c_str(name, sizeof(name), "PowerDistribution[{}]", index);
+
   if (CollapsingHeader(name)) {
     // temperature
     if (auto tempData = model->GetTemperatureData()) {