fix clang support.

Tested:
  make all apps + tests apps/ on x86_64
  make CC=clang all apps + tests apps/ on x86_64

Signed-off-by: David Decotigny <ddecotig@gmail.com>
Signed-off-by: Nigel Croxon <ncroxon@redhat.com>

Make.defaults

@@ -101,6 +101,7 @@ endif
 ifeq ($(ARCH),x86_64)
   GCCVERSION   := $(shell $(CC) -dumpversion | cut -f1 -d.)
   GCCMINOR     := $(shell $(CC) -dumpversion | cut -f2 -d.)
+  USING_CLANG  := $(shell $(CC) -v 2>&1 | grep -q 'clang version' && echo clang)
 
   # Rely on GCC MS ABI support?
   GCCNEWENOUGH := $(shell ( [ $(GCCVERSION) -gt "4" ]           \
@@ -109,6 +110,8 @@ ifeq ($(ARCH),x86_64)
                           && echo 1)
   ifeq ($(GCCNEWENOUGH),1)
     CPPFLAGS += -DGNU_EFI_USE_MS_ABI -maccumulate-outgoing-args --std=c11
+  else ifeq ($(USING_CLANG),clang)
+    CPPFLAGS += -DGNU_EFI_USE_MS_ABI --std=c11
   endif
 
   CFLAGS += -mno-red-zone
@@ -159,7 +162,7 @@ CFLAGS  += $(ARCH3264) -g -O2 -Wall -Wextra -Werror \
 else
 CFLAGS  += $(ARCH3264) -g -O2 -Wall -Wextra -Werror \
            -fshort-wchar -fno-strict-aliasing \
-           -fno-merge-constants -ffreestanding -fno-stack-protector \
+           -fno-merge-all-constants -ffreestanding -fno-stack-protector \
            -fno-stack-check
 endif
 

apps/debughook.c

@@ -37,8 +37,13 @@ GetVariable(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner)
 EFI_GUID DUMMY_GUID =
 {0x55aad538, 0x8f82, 0x4e2a, {0xa4,0xf0,0xbe, 0x59, 0x13, 0xb6, 0x5f, 0x1e}};
 
-static void
-__attribute__((__optimize__("0")))
+#if defined(__clang__)
+# define _OPTNONE __attribute__((optnone))
+#else
+# define _OPTNONE __attribute__((__optimize__("0")))
+#endif
+
+static _OPTNONE void
 DebugHook(void)
 {
 	EFI_GUID guid = DUMMY_GUID;

inc/x86_64/efibind.h

@@ -25,6 +25,8 @@ Revision History
 #if defined(GNU_EFI_USE_MS_ABI)
     #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
         #define HAVE_USE_MS_ABI 1
+    #elif defined(__clang__)
+        #define HAVE_USE_MS_ABI 1
     #else
         #error Compiler is too old for GNU_EFI_USE_MS_ABI
     #endif

lib/guid.c

@@ -97,7 +97,7 @@ static struct {
 	{  &SMapId,                                         L"ShellDevPathMap" },
 	{  &SAliasId,                                       L"ShellAlias" },
 
-	{  NULL }
+	{  NULL, NULL }
 };
 
 //