add clang-format

This introduces clang-format to enforce a consistent code style for Stockfish.

Having a documented and consistent style across the code will make contributing easier
for new developers, and will make larger changes to the codebase easier to make.

To facilitate formatting, this PR includes a Makefile target (`make format`) to format the code,
this requires clang-format (version 17 currently) to be installed locally.

Installing clang-format is straightforward on most OS and distros
(e.g. with https://apt.llvm.org/, brew install clang-format, etc), as this is part of quite commonly
used suite of tools and compilers (llvm / clang).

Additionally, a CI action is present that will verify if the code requires formatting,
and comment on the PR as needed. Initially, correct formatting is not required, it will be
done by maintainers as part of the merge or in later commits, but obviously this is encouraged.

fixes https://github.com/official-stockfish/Stockfish/issues/3608
closes https://github.com/official-stockfish/Stockfish/pull/4790

Co-Authored-By: Joost VandeVondele <Joost.VandeVondele@gmail.com>

src/misc.h

@@ -33,12 +33,13 @@ namespace Stockfish {
 
 std::string engine_info(bool to_uci = false);
 std::string compiler_info();
-void prefetch(void* addr);
-void start_logger(const std::string& fname);
-void* std_aligned_alloc(size_t alignment, size_t size);
-void std_aligned_free(void* ptr);
-void* aligned_large_pages_alloc(size_t size); // memory aligned by page size, min alignment: 4096 bytes
-void aligned_large_pages_free(void* mem); // nop if mem == nullptr
+void        prefetch(void* addr);
+void        start_logger(const std::string& fname);
+void*       std_aligned_alloc(size_t alignment, size_t size);
+void        std_aligned_free(void* ptr);
+void*       aligned_large_pages_alloc(
+        size_t size);                      // memory aligned by page size, min alignment: 4096 bytes
+void aligned_large_pages_free(void* mem);  // nop if mem == nullptr
 
 void dbg_hit_on(bool cond, int slot = 0);
 void dbg_mean_of(int64_t value, int slot = 0);
@@ -46,15 +47,19 @@ void dbg_stdev_of(int64_t value, int slot = 0);
 void dbg_correl_of(int64_t value1, int64_t value2, int slot = 0);
 void dbg_print();
 
-using TimePoint = std::chrono::milliseconds::rep; // A value in milliseconds
+using TimePoint = std::chrono::milliseconds::rep;  // A value in milliseconds
 static_assert(sizeof(TimePoint) == sizeof(int64_t), "TimePoint should be 64 bits");
 inline TimePoint now() {
-  return std::chrono::duration_cast<std::chrono::milliseconds>
-        (std::chrono::steady_clock::now().time_since_epoch()).count();
+    return std::chrono::duration_cast<std::chrono::milliseconds>(
+             std::chrono::steady_clock::now().time_since_epoch())
+      .count();
 }
 
 
-enum SyncCout { IO_LOCK, IO_UNLOCK };
+enum SyncCout {
+    IO_LOCK,
+    IO_UNLOCK
+};
 std::ostream& operator<<(std::ostream&, SyncCout);
 
 #define sync_cout std::cout << IO_LOCK
@@ -64,34 +69,37 @@ std::ostream& operator<<(std::ostream&, SyncCout);
 // align_ptr_up() : get the first aligned element of an array.
 // ptr must point to an array of size at least `sizeof(T) * N + alignment` bytes,
 // where N is the number of elements in the array.
-template <uintptr_t Alignment, typename T>
-T* align_ptr_up(T* ptr)
-{
-  static_assert(alignof(T) < Alignment);
+template<uintptr_t Alignment, typename T>
+T* align_ptr_up(T* ptr) {
+    static_assert(alignof(T) < Alignment);
 
-  const uintptr_t ptrint = reinterpret_cast<uintptr_t>(reinterpret_cast<char*>(ptr));
-  return reinterpret_cast<T*>(reinterpret_cast<char*>((ptrint + (Alignment - 1)) / Alignment * Alignment));
+    const uintptr_t ptrint = reinterpret_cast<uintptr_t>(reinterpret_cast<char*>(ptr));
+    return reinterpret_cast<T*>(
+      reinterpret_cast<char*>((ptrint + (Alignment - 1)) / Alignment * Alignment));
 }
 
 
 // IsLittleEndian : true if and only if the binary is compiled on a little-endian machine
-static inline const union { uint32_t i; char c[4]; } Le = { 0x01020304 };
+static inline const union {
+    uint32_t i;
+    char     c[4];
+} Le                                    = {0x01020304};
 static inline const bool IsLittleEndian = (Le.c[0] == 4);
 
 
-template <typename T, std::size_t MaxSize>
+template<typename T, std::size_t MaxSize>
 class ValueList {
 
-public:
-  std::size_t size() const { return size_; }
-  void push_back(const T& value) { values_[size_++] = value; }
-  const T* begin() const { return values_; }
-  const T* end() const { return values_ + size_; }
-  const T& operator[](int index) const { return values_[index]; }
+   public:
+    std::size_t size() const { return size_; }
+    void        push_back(const T& value) { values_[size_++] = value; }
+    const T*    begin() const { return values_; }
+    const T*    end() const { return values_ + size_; }
+    const T&    operator[](int index) const { return values_[index]; }
 
-private:
-  T values_[MaxSize];
-  std::size_t size_ = 0;
+   private:
+    T           values_[MaxSize];
+    std::size_t size_ = 0;
 };
 
 
@@ -112,23 +120,31 @@ private:
 
 class PRNG {
 
-  uint64_t s;
+    uint64_t s;
 
-  uint64_t rand64() {
+    uint64_t rand64() {
 
-    s ^= s >> 12, s ^= s << 25, s ^= s >> 27;
-    return s * 2685821657736338717LL;
-  }
+        s ^= s >> 12, s ^= s << 25, s ^= s >> 27;
+        return s * 2685821657736338717LL;
+    }
 
-public:
-  PRNG(uint64_t seed) : s(seed) { assert(seed); }
+   public:
+    PRNG(uint64_t seed) :
+        s(seed) {
+        assert(seed);
+    }
 
-  template<typename T> T rand() { return T(rand64()); }
+    template<typename T>
+    T rand() {
+        return T(rand64());
+    }
 
-  // Special generator used to fast init magic numbers.
-  // Output values only have 1/8th of their bits set on average.
-  template<typename T> T sparse_rand()
-  { return T(rand64() & rand64() & rand64()); }
+    // Special generator used to fast init magic numbers.
+    // Output values only have 1/8th of their bits set on average.
+    template<typename T>
+    T sparse_rand() {
+        return T(rand64() & rand64() & rand64());
+    }
 };
 
 inline uint64_t mul_hi64(uint64_t a, uint64_t b) {
@@ -152,16 +168,16 @@ inline uint64_t mul_hi64(uint64_t a, uint64_t b) {
 // Peter Österlund.
 
 namespace WinProcGroup {
-  void bindThisThread(size_t idx);
+void bindThisThread(size_t idx);
 }
 
 namespace CommandLine {
-  void init(int argc, char* argv[]);
+void init(int argc, char* argv[]);
 
-  extern std::string binaryDirectory;  // path of the executable directory
-  extern std::string workingDirectory; // path of the working directory
+extern std::string binaryDirectory;   // path of the executable directory
+extern std::string workingDirectory;  // path of the working directory
 }
 
-} // namespace Stockfish
+}  // namespace Stockfish
 
-#endif // #ifndef MISC_H_INCLUDED
+#endif  // #ifndef MISC_H_INCLUDED