Use std::string_view and fmtlib across all libraries (#3402)

- Twine, StringRef, Format, and NativeFormatting have been removed
- Logging now uses fmtlib style formatting
- Nearly all uses of wpi::outs/errs have been replaced with fmt::print() or
std::puts()/std::fputs() (for unformatted strings).
- A wpi/fmt/raw_ostream.h header has been added to enable
fmt::print() with wpi::raw_ostream

hal/src/main/native/athena/HAL.cpp

@@ -9,6 +9,7 @@
 #include <unistd.h>
 
 #include <atomic>
+#include <cstdio>
 #include <cstdlib>
 #include <fstream>
 #include <thread>
@@ -16,8 +17,8 @@
 #include <FRC_NetworkCommunication/FRCComm.h>
 #include <FRC_NetworkCommunication/LoadOut.h>
 #include <FRC_NetworkCommunication/UsageReporting.h>
+#include <fmt/format.h>
 #include <wpi/mutex.h>
-#include <wpi/raw_ostream.h>
 #include <wpi/timestamp.h>
 
 #include "HALInitializer.h"
@@ -330,18 +331,19 @@ static bool killExistingProgram(int timeout, int mode) {
     // see if the pid is around, but we don't want to mess with init id=1, or
     // ourselves
     if (pid >= 2 && kill(pid, 0) == 0 && pid != getpid()) {
-      wpi::outs() << "Killing previously running FRC program...\n";
+      std::puts("Killing previously running FRC program...");
       kill(pid, SIGTERM);  // try to kill it
       std::this_thread::sleep_for(std::chrono::milliseconds(timeout));
       if (kill(pid, 0) == 0) {
         // still not successful
-        wpi::outs() << "FRC pid " << pid << " did not die within " << timeout
-                    << "ms. Force killing with kill -9\n";
+        fmt::print(
+            "FRC pid {} did not die within {} ms. Force killing with kill -9\n",
+            pid, timeout);
         // Force kill -9
         auto forceKill = kill(pid, SIGKILL);
         if (forceKill != 0) {
           auto errorMsg = std::strerror(forceKill);
-          wpi::outs() << "Kill -9 error: " << errorMsg << "\n";
+          fmt::print("Kill -9 error: {}\n", errorMsg);
         }
         // Give a bit of time for the kill to take place
         std::this_thread::sleep_for(std::chrono::milliseconds(250));
@@ -378,7 +380,6 @@ HAL_Bool HAL_Initialize(int32_t timeout, int32_t mode) {
 
   setlinebuf(stdin);
   setlinebuf(stdout);
-  wpi::outs().SetUnbuffered();
 
   prctl(PR_SET_PDEATHSIG, SIGTERM);
 
@@ -412,11 +413,11 @@ HAL_Bool HAL_Initialize(int32_t timeout, int32_t mode) {
     int32_t status = 0;
     uint64_t rv = HAL_GetFPGATime(&status);
     if (status != 0) {
-      wpi::errs()
-          << "Call to HAL_GetFPGATime failed in wpi::Now() with status "
-          << status
-          << ". Initialization might have failed. Time will not be correct\n";
-      wpi::errs().flush();
+      fmt::print(stderr,
+                 "Call to HAL_GetFPGATime failed in wpi::Now() with status {}. "
+                 "Initialization might have failed. Time will not be correct\n",
+                 status);
+      std::fflush(stderr);
       return 0u;
     }
     return rv;