Use modern C++ attributes instead of __attribute__ voodoo.

This is quite nice, although I wish [[gnu::always_inline]] implied inline.
Also "gnu::" is kind of a wart, but whatcha gonna do.

Kernel/Console.h

@@ -1,7 +1,6 @@
 #pragma once
 
 #include <AK/CircularQueue.h>
-#include <AK/Compiler.h>
 #include <AK/Vector.h>
 #include <Kernel/CharacterDevice.h>
 
@@ -14,7 +13,7 @@ public:
 class Console final : public CharacterDevice {
     AK_MAKE_ETERNAL
 public:
-    static Console& the() PURE;
+    static Console& the();
 
     Console();
     virtual ~Console() override;

Kernel/DevPtsFS.h

@@ -8,7 +8,7 @@ class SlavePTY;
 
 class DevPtsFS final : public SynthFS {
 public:
-    static DevPtsFS& the() PURE;
+    [[gnu::pure]] static DevPtsFS& the();
 
     virtual ~DevPtsFS() override;
     static RetainPtr<DevPtsFS> create();

Kernel/KSyms.cpp

@@ -74,11 +74,11 @@ static void load_ksyms_from_data(const ByteBuffer& buffer)
 void dump_backtrace(bool use_ksyms)
 {
     if (!current) {
-        HANG;
+        hang();
         return;
     }
     if (use_ksyms && !ksyms_ready) {
-        HANG;
+        hang();
         return;
     }
     struct RecognizedSymbol {

Kernel/KSyms.h

@@ -8,7 +8,7 @@ struct KSym {
     const char* name;
 };
 
-const KSym* ksymbolicate(dword address) PURE;
+const KSym* ksymbolicate(dword address);
 void load_ksyms();
 void init_ksyms();
 

Kernel/Keyboard.h

@@ -29,7 +29,7 @@ public:
         bool is_press() const { return flags & Is_Press; }
     };
 
-    static Keyboard& the() PURE;
+    [[gnu::pure]] static Keyboard& the();
 
     virtual ~Keyboard() override;
     Keyboard();

Kernel/MemoryManager.h

@@ -217,7 +217,7 @@ class MemoryManager {
     friend class VMObject;
     friend ByteBuffer procfs$mm(InodeIdentifier);
 public:
-    static MemoryManager& the() PURE;
+    [[gnu::pure]] static MemoryManager& the();
 
     static void initialize();
 

Kernel/ProcFS.h

@@ -11,7 +11,7 @@ class ProcFSInode;
 class ProcFS final : public FS {
     friend class ProcFSInode;
 public:
-    static ProcFS& the() PURE;
+    [[gnu::pure]] static ProcFS& the();
 
     virtual ~ProcFS() override;
     static RetainPtr<ProcFS> create();

Kernel/Process.h

@@ -171,8 +171,8 @@ public:
     int sys$lseek(int fd, off_t, int whence);
     int sys$kill(pid_t pid, int sig);
     int sys$geterror() { return m_error; }
-    void sys$exit(int status) NORETURN;
-    void sys$sigreturn() NORETURN;
+    [[noreturn]] void sys$exit(int status);
+    [[noreturn]] void sys$sigreturn();
     pid_t sys$waitpid(pid_t, int* wstatus, int options);
     void* sys$mmap(const Syscall::SC_mmap_params*);
     int sys$munmap(void*, size_t size);
@@ -230,8 +230,8 @@ public:
 
     static void initialize();
 
-    void crash() NORETURN;
-    static int reap(Process&) WARN_UNUSED_RESULT;
+    [[noreturn]] void crash();
+    [[nodiscard]] static int reap(Process&);
 
     const TTY* tty() const { return m_tty; }
     void set_tty(TTY* tty) { m_tty = tty; }

Kernel/StdLib.cpp

@@ -125,8 +125,7 @@ int memcmp(const void* v1, const void* v2, size_t n)
     return 0;
 }
 
-void __cxa_pure_virtual() NORETURN;
-void __cxa_pure_virtual()
+[[noreturn]] void __cxa_pure_virtual()
 {
     ASSERT_NOT_REACHED();
 }

Kernel/TSS.h

@@ -2,7 +2,7 @@
 
 #include <AK/Types.h>
 
-struct TSS32 {
+struct [[gnu::packed]] TSS32 {
     word backlink, __blh;
     dword esp0;
     word ss0, __ss0h;
@@ -20,4 +20,4 @@ struct TSS32 {
     word gs, __gsh;
     word ldt, __ldth;
     word trace, iomapbase;
-} PACKED;
+};

Kernel/VirtualFileSystem.h

@@ -54,7 +54,7 @@ public:
         RetainPtr<FS> m_guest_fs;
     };
 
-    static VFS& the() PURE;
+    [[gnu::pure]] static VFS& the();
 
     VFS();
     ~VFS();

Kernel/i386.cpp

@@ -10,10 +10,10 @@
 
 //#define PAGE_FAULT_DEBUG
 
-struct DescriptorTablePointer {
+struct [[gnu::packed]] DescriptorTablePointer {
     word size;
     void* address;
-} PACKED;
+};
 
 static DescriptorTablePointer s_idtr;
 static DescriptorTablePointer s_gdtr;
@@ -144,9 +144,9 @@ void exception_6_handler(RegisterDump& regs)
 
     if (current->is_ring0()) {
         kprintf("Oh shit, we've crashed in ring 0 :(\n");
-        HANG;
+        hang();
     }
-    HANG;
+    hang();
 
     current->crash();
 }
@@ -219,7 +219,7 @@ void exception_13_handler(RegisterDumpWithExceptionCode& regs)
 
     if (current->is_ring0()) {
         kprintf("Oh shit, we've crashed in ring 0 :(\n");
-        HANG;
+        hang();
     }
 
     current->crash();
@@ -313,7 +313,7 @@ void exception_14_handler(RegisterDumpWithExceptionCode& regs)
         asm ("movl %%cr3, %%eax":"=a"(cr3)); \
         asm ("movl %%cr4, %%eax":"=a"(cr4)); \
         kprintf("CR0=%x CR2=%x CR3=%x CR4=%x\n", cr0, cr2, cr3, cr4); \
-        HANG; \
+        hang(); \
     }
 
 EH(0, "Divide error")
@@ -385,7 +385,7 @@ void gdt_init()
 static void unimp_trap()
 {
     kprintf("Unhandled IRQ.");
-    HANG;
+    hang();
 }
 
 void register_irq_handler(byte irq, IRQHandler& handler)

Kernel/i386.h

@@ -6,7 +6,7 @@
 #define PAGE_SIZE 4096
 #define PAGE_MASK 0xfffff000
 
-union Descriptor {
+union [[gnu::packed]] Descriptor {
     struct {
         word limit_lo;
         word base_lo;
@@ -55,7 +55,7 @@ union Descriptor {
         limit_lo = (dword)l & 0xffff;
         limit_hi = ((dword)l >> 16) & 0xff;
     }
-} PACKED;
+};
 
 class IRQHandler;
 
@@ -73,7 +73,12 @@ void gdt_free_entry(word);
 Descriptor& get_gdt_entry(word selector);
 void write_gdt_entry(word selector, Descriptor&);
 
-#define HANG asm volatile( "cli; hlt" );
+[[noreturn]] static inline void hang()
+{
+    asm volatile("cli; hlt");
+    for (;;) { }
+}
+
 #define LSW(x) ((dword)(x) & 0xFFFF)
 #define MSW(x) (((dword)(x) >> 16) & 0xFFFF)
 #define LSB(x) ((x) & 0xFF)
@@ -182,7 +187,7 @@ private:
     LinearAddress m_laddr;
 };
 
-struct RegisterDump {
+struct [[gnu::packed]] RegisterDump {
     word ss;
     word gs;
     word fs;
@@ -202,9 +207,9 @@ struct RegisterDump {
     dword eflags;
     dword esp_if_crossRing;
     word ss_if_crossRing;
-} PACKED;
+};
 
-struct RegisterDumpWithExceptionCode {
+struct [[gnu::packed]] RegisterDumpWithExceptionCode {
     word ss;
     word gs;
     word fs;
@@ -226,7 +231,7 @@ struct RegisterDumpWithExceptionCode {
     dword eflags;
     dword esp_if_crossRing;
     word ss_if_crossRing;
-} PACKED;
+};
 
 struct FPUState {
     dword cwd;

Kernel/init.cpp

@@ -44,8 +44,7 @@ NullDevice* dev_null;
 VFS* vfs;
 
 #ifdef STRESS_TEST_SPAWNING
-static void spawn_stress() NORETURN;
-static void spawn_stress()
+[[noreturn]] static void spawn_stress()
 {
     dword last_sum_alloc = sum_alloc;
 
@@ -62,8 +61,7 @@ static void spawn_stress()
 }
 #endif
 
-static void init_stage2() NORETURN;
-static void init_stage2()
+[[noreturn]] static void init_stage2()
 {
     Syscall::initialize();
 
@@ -135,8 +133,7 @@ static void init_stage2()
     ASSERT_NOT_REACHED();
 }
 
-void init() NORETURN;
-void init()
+[[noreturn]] void init()
 {
     cli();
 

Kernel/kassert.h

@@ -3,7 +3,7 @@
 #include "kprintf.h"
 #include "i386.h"
 
-void __assertion_failed(const char* msg, const char* file, unsigned line, const char* func) NORETURN;
+[[noreturn]] void __assertion_failed(const char* msg, const char* file, unsigned line, const char* func);
 
 #define ASSERT(expr) (static_cast<bool>(expr) ? (void)0 : __assertion_failed(#expr, __FILE__, __LINE__, __PRETTY_FUNCTION__))
 #define CRASH() do { asm volatile("ud2"); } while(0)

Kernel/kmalloc.cpp

@@ -14,11 +14,10 @@
 
 #define SANITIZE_KMALLOC
 
-typedef struct
-{
+struct [[gnu::packed]] allocation_t {
     dword start;
     dword nchunk;
-} PACKED allocation_t;
+};
 
 #define CHUNK_SIZE  128
 #define POOL_SIZE   (1024 * 1024)
@@ -103,8 +102,7 @@ void* kmalloc_impl(dword size)
 
     if (sum_free < real_size) {
         kprintf("%s<%u> kmalloc(): PANIC! Out of memory (sucks, dude)\nsum_free=%u, real_size=%x\n", current->name().characters(), current->pid(), sum_free, real_size);
-        HANG;
-        return 0L;
+        hang();
     }
 
     chunks_needed = real_size / CHUNK_SIZE;
@@ -164,9 +162,7 @@ void* kmalloc_impl(dword size)
     }
 
     kprintf("%s<%u> kmalloc(): PANIC! Out of memory (no suitable block for size %u)\n", current->name().characters(), current->pid(), size);
-    HANG;
-
-    return nullptr;
+    hang();
 }
 
 void kfree(void *ptr)

Kernel/kmalloc.h

@@ -1,12 +1,14 @@
 #pragma once
 
+#include <AK/Types.h>
+
 //#define KMALLOC_DEBUG_LARGE_ALLOCATIONS
 
 void kmalloc_init();
-void* kmalloc_impl(dword size) __attribute__ ((malloc));
-void* kmalloc_eternal(size_t) __attribute__ ((malloc));
-void* kmalloc_page_aligned(size_t) __attribute__ ((malloc));
-void* kmalloc_aligned(size_t, size_t alignment) __attribute__ ((malloc));
+[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_impl(size_t);
+[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_eternal(size_t);
+[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_page_aligned(size_t);
+[[gnu::malloc, gnu::returns_nonnull, gnu::alloc_size(1)]] void* kmalloc_aligned(size_t, size_t alignment);
 void kfree(void*);
 void kfree_aligned(void*);
 
@@ -20,7 +22,7 @@ extern volatile size_t kmalloc_sum_page_aligned;
 inline void* operator new(size_t, void* p) { return p; }
 inline void* operator new[](size_t, void* p) { return p; }
 
-ALWAYS_INLINE void* kmalloc(size_t size)
+[[gnu::always_inline]] inline void* kmalloc(size_t size)
 {
 #ifdef KMALLOC_DEBUG_LARGE_ALLOCATIONS
     // Any kernel allocation >= 1M is 99.9% a bug.

Kernel/kprintf.h

@@ -1,7 +1,5 @@
 #pragma once
 
-#include <AK/Compiler.h>
-
 extern "C" {
 int dbgprintf(const char *fmt, ...);
 int kprintf(const char *fmt, ...);

Kernel/types.h

@@ -1,11 +1,7 @@
 #pragma once
 
-#include <AK/Compiler.h>
 #include <AK/Types.h>
 
-#define PACKED __attribute__ ((packed))
-#define PURE __attribute__ ((pure))
-
 typedef dword __u32;
 typedef word __u16;
 typedef byte __u8;
@@ -43,10 +39,10 @@ typedef dword nlink_t;
 typedef dword blksize_t;
 typedef dword blkcnt_t;
 
-struct FarPtr {
+struct [[gnu::packed]] FarPtr {
     dword offset { 0 };
     word selector { 0 };
-} PACKED;
+};
 
 class PhysicalAddress {
 public: